Crystal structures of chlorido­[dihy­droxybis­(1-imino­eth­oxy)]arsanido-κ3N,As,N′]platinum(II) and of a polymorph of chlorido­[dihy­droxybis­(1-imino­prop­oxy)arsanido-κ3N,As,N′]platinum(II)

Marogoa, N.R.; Kama, D.V.; Visser, H.G.; Schutte-Smith, M.

doi:10.1107/S2056989019016463

research communications

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 76| Part 2| February 2020| Pages 180-185

https://doi.org/10.1107/S2056989019016463

Open

access

Crystal structures of chlorido[dihydroxybis(1-iminoethoxy)]arsanido-κ³N,As,N′]platinum(II) and of a polymorph of chlorido[dihydroxybis(1-iminopropoxy)arsanido-κ³N,As,N′]platinum(II)

Nina R. Marogoa,^a D.V. Kama,^a Hendrik G. Visser ^a and M. Schutte-Smith ^a ^*

^aUniversity of the Free State, Department of Chemistry, PO Box 339, Nelson Mandela Drive, Bloemfontein, 9301, South Africa
^*Correspondence e-mail: schuttem@ufs.ac.za

Edited by M. Weil, Vienna University of Technology, Austria (Received 27 November 2019; accepted 6 December 2019; online 10 January 2020)

Each central platinum(II) atom in the crystal structures of chlorido[dihydroxybis(1-iminoethoxy)arsanido-κ³N,As,N′]platinum(II), [Pt(C₄H₁₀AsN₂O₄)Cl] (1), and of chlorido[dihydroxybis(1-iminopropoxy)arsanido-κ³N,As,N′]platinum(II), [Pt(C₆H₁₄AsN₂O₄)Cl] (2), is coordinated by two nitrogen donor atoms, a chlorido ligand and to arsenic, which, in turn, is coordinated by two oxygen donor ligands, two hydroxyl ligands and the platinum(II) atom. The square-planar and trigonal–bipyramidal coordination environments around platinum and arsenic, respectively, are significantly distorted with the largest outliers being 173.90 (13) and 106.98 (14)° for platinum and arsenic in (1), and 173.20 (14)° and 94.20 (9)° for (2), respectively. One intramolecular and four classical intermolecular hydrogen-bonding interactions are observed in the crystal structure of (1), which give rise to an infinite three-dimensional network. A similar situation (one intramolecular and four classical intermolecular hydrogen-bonding interactions) is observed in the crystal structure of (2). Various π-interactions are present in (1) between the platinum(II) atom and the centroid of one of the five-membered rings formed by Pt, As, C, N, O with a distance of 3.7225 (7) Å, and between the centroids of five-membered (Pt, As, C, N, O) rings of neighbouring molecules with distances of 3.7456 (4) and 3.7960 (6) Å. Likewise, weak π-interactions are observed in (2) between the platinum(II) atom and the centroid of one of the five-membered rings formed by Pt, As, C, N, O with a distance of 3.8213 (2) Å, as well as between the Cl atom and the centroid of a symmetry-related five-membered ring with a distance of 3.8252 (12) Å. Differences between (2) and the reported polymorph [Miodragović et al. (2013 ). Angew. Chem. Int. Ed. 52, 10749–10752] are discussed.

Keywords: crystal structure; arsenoplatin; platinum; cisplatin.

CCDC references: 1938096; 1938095

1. Chemical context

Platinum and arsenic compounds have shown great versatility in terms of applications in the biological and medicinal fields (Reedijk, 2009 ). Platinum compounds are still the most widely used drugs in the fight against cancer in spite of the serious side effects and the resistance of some types of cancers (Miller et al., 2002 ; Basu & Krishnamurthy, 2010 ; Jakupec et al., 2003 ; Kauffman et al., 2010 ; Wheate et al., 2010 ; Rosenberg et al., 1965 ; Marino et al., 2017 ; Aabo et al., 1998 ; Kelland, 2007 ; Shi et al., 2019 ). Tumoral malignancies have a high lethality rate and are among the most widespread and difficult diseases to treat. The need for the development of new drugs and treatment alternatives has increased as many of the available effective drugs are comparable and similar to each other (Ott, 2009 ; Burchenal, 1978 ). Platinum-based antitumour agents have guided and constructed the current tumor chemotherapy treatment, but the side effects complicate and inhibit their clinical application (Rosenberg et al., 1965; Marino et al., 2017; Basu & Krishnamurthy, 2010; Aabo et al., 1998; Kelland, 2007; Shi et al., 2019). Drug resistance is a major limiting factor in terms of the range of tumours that can be treated and the improvement of the therapy (Marino et al., 2017). Arsenic trioxide was approved by the FDA in 2000 for the treatment of acute promyelocytic leukemia, and since then several studies have shown that the combinatorial employment of arsenic and platinum-based cancer drugs has shown significant therapeutic potential (Wang et al., 2004 ; Shen et al., 2004 ; Emadi & Gore, 2010 ; Zhang et al., 2009 , 2010 ). These results led to the synthesis of complexes containing both platinum and arsenic (Swindell et al., 2013 ; Miodragović et al., 2013, 2019 ), which were called arsenoplatins. Initial results indicate that these complexes are able to bypass drug-resistance mechanisms that lower the effect of cisplatin and have higher cytotoxicity than cisplatin in some cases. To date, the studies of Miodragović et al. (2013, 2019) are the only crystallographic data available in the CCDC (Groom et al., 2016 ).

The structures reported here, [Pt(C₄H₁₀AsN₂O₄)Cl] (1), and [Pt(C₆H₁₄AsN₂O₄)Cl], (2), expand on this work and form part of an ongoing study on arsenoplatins, their solid- and solution-state behaviour and evaluation thereof.

2. Database survey

Two crystal structures similar to (1) were found after a search of the Cambridge Structure Database (CSD, Version 5.40, update of November 2019; Groom et al., 2016), both of which (ODOHAS, ODOHEW) were reported by Miodragović et al. (2013, 2019). They consist of the same arsenoplatin complex as (1), accompanied by an acetamide hemihydrate and acetamide solvent species in the unit cell, and crystallize in the P $[\overline{1}]$ and P2₁/n space groups, respectively. The search also revealed that (2) represents a polymorph, with the first crystal structure determination (ODOGOF; Miodragović et al., 2013) in the orthorhombic space group type Pbca, in contrast to space group type P2₁/c of (2).

3. Structural commentary

In (1) the square-planar coordination environment around platinum(II) is defined by two nitrogen donor atoms, a chlorido ligand and the coordination to arsenic. In turn, arsenic is coordinated by two oxygen donor atoms, two hydroxyl ligands and by platinum(II), completing a trigonal–bipyramidal coordination sphere (Fig. 1). The first (ODOHAS) of the other two structure reports with a chlorido[dihydroxybis(1-iminoethoxy)]arsanido]platinum(II) molecule (Miodragović et al., 2013) is different from (1) because of an acetamide solvent molecule in the unit cell and a different space group (P2₁/n), and the second (ODOHEW) crystallizes in the same space group as (1) (P $[\overline{1}]$ ) but with acetamide and hemihydrate solvent molecules in the unit cell. The bond lengths in the title compound compare very well with those in the two structures in literature. The Pt—As bond length of 2.2730 (12) Å and the Pt—Cl bond length of 2.3401 (15) Å are similar to 2.2732 (3) and 2.3272 (8) Å for ODOHEW, and 2.2729 (2) and 2.3328 (6) Å for ODOHAS. The Pt—N bond lengths vary between 1.999 (4) and 2.005 (4) Å, the As—O bond lengths between 1.898 (3) and 2.107 (3) Å, and the As—OH bond lengths between 1.722 (3) and 1.738 (3) Å. Overall, these molecular structures compare well. When comparing the Pt—As and Pt—Cl bond lengths to those of other platinum(II) complexes where As and Cl are in trans positions, it is clear that the Pt—As bond lengths do not vary significantly and range between 2.3333 (6) and 2.3599 (2) Å, while for the Pt—Cl bond lengths a greater variation is seen, in a range from 2.2917 (4) to 2.3927 (5) Å (Reinholdt & Bendix, 2017 ; Clegg, 2016 ; Dube et al., 2016 ; Imoto et al., 2017 ; Muessig et al., 2019 ). While the Pt—Cl length in (1) compares well with these trans complexes, the Pt—As bond length is somewhat smaller. The square-planar coordination around the central platinum(II) atom is distorted with N1—Pt1—N2 and N1—Pt1—As1 being 173.90 (13) and 85.18 (11)°, respectively, deviating from the expected 180 and 90°. The trigonal–bipyramidal coordination around the arsenic atom is significantly distorted with O4—As1—O6, O1—As1—O2 and O1—As1—Pt1 being 106.98 (14), 174.04 (11) and 95.35 (10)°, deviating from the ideal 120, 180 and 90°, respectively. Considering arsenic with a coordination number of 5, the index τ₅ parameter can be used to calculate any potential distortion (Addison et al., 1984 ). The τ₅ parameter is defined as (β – α)/60° with β the largest and α the second largest angle in the coordination sphere and was calculated as 0.794 for (1), suggesting a significantly distorted trigonal–bipyramidal shape around arsenic (τ₅ = 0 for an ideal square pyramid and 1 for an ideal trigonal bipyramid).

Figure 1
Molecular structures of (1) and (2), indicating the numbering schemes. Displacement ellipsoids are drawn at a probability level of 50%.

The coordination environments of the platinum and arsenic atoms in (2) are the same as in (1), i.e. Pt1 is coordinated by a chlorido ligand, two nitrogen donor atoms and arsenic, that is additionally bonded to two hydroxyl ligands and two oxygen donor atoms (Fig. 1). The Pt—As and Pt—Cl bond lengths of 2.2672 (8) Å and 2.3387 (11) Å in (2) are virtually identical with the bond lengths of 2.2687 (4) Å and 2.3361 (9) Å, respectively, in the orthorhombic polymorph reported by Miodragović et al. (2013). Again, these Pt—As and Pt—Cl bond lengths fit well into the ranges reported for other structures where As and Cl are in trans positions. The square-planar coordination environment around the platinum(II) atom is similarly distorted in the structures of the two polymorphs, with the ideal 180° (N—Pt—N) and 90° (N—Pt—Cl) angles deviating at 173.59 (13) and 94.68 (9)° for the structure determined by Miodragović et al. (2013) and 173.20 (14) (N1—Pt1—N2) and 94.16 (11)° (N1—Pt1—Cl1) for (2), respectively. The largest deviation of the trigonal–bipyramidal coordination sphere of the arsenic atom in the polymorphic structures pertains to the Pt—As—OH angle, with reported values of 129.78 (10) and 124.67 (9)° for the orthorhombic structure (Miodragović et al., 2013) and of 130.05 (11) and 124.46 (9)° for (2). The τ₅ parameter for (2) is calculated as 0.711.

When comparing the molecules of (1) and (2), it is clear that they do not differ much in terms of bond lengths and angles, with the only structural difference being the alkyl substituent on the ligand, viz. in (1) an ethyl and in (2) a propyl chain. The bond lengths around platinum are all similar (Pt—As, Pt—Cl, Pt—N) as well as the two pairs of As—OH distances. There is a slight variation in the As—O bond lengths, 1.898 (3) and 2.107 (3) Å for (1) and 1.946 (3) and 1.979 (3) Å for (2). The N1—Pt1—N2 bond angles are similar [173.90 (13)° for (1) and 173.20 (14)° for (2)] while there are slight differences for the N—Pt1—As1 and N—Pt—Cl1 bond angles: 85.18 (11) and 89.42 (11)° for (1), and 87.25 (10) and 86.05 (10)° for (2) (N1—Pt1—As1, N2—Pt1—As1), and 93.28 (11) and 92.34 (11)° for (1) and 94.16 (11) and 92.53 (10)° for (2) (N1—Pt1—Cl1, N2—Pt1—Cl1). The As1—Pt1—Cl1 bond angles also vary being 174.79 (3) and 178.51 (3)° for (1) and (2). The bond angles around arsenic are all in a similar range but have more variation in some of the angles, for instance 126.42 (10) and 130.05 (11)° (O6—As1—Pt1), 90.24 (9) and 94.20 (9)° (O2—As1—Pt1), and 95.35 (10) and 93.12 (8)° (O1—As1—Pt1) for (1) and (2), respectively. The trigonal– bipyramidal coordination environment around arsenic is distorted in both molecules with a τ₅ parameter value of 0.794 and 0.711 for (1) and (2). Thus, the As atom in (2) shows a slightly higher distortion than in (1).

4. Supramolecular features

In the crystal structure of (1), six hydrogen-bonding interactions are observed (Table 1), five intermolecular (N1—H1⋯O4ⁱ, N2—H2⋯O6ⁱⁱ, O4—H4⋯O2ⁱⁱⁱ, O6—H6⋯Cl1^iv, C3—H3B⋯Cl^v) and one intramolecular (O6—H6⋯O2), as illustrated in Fig. 2. Bifurcation creates inter- and intramolecular interactions that can contribute to the stability of the structure. One of the donor hydrogen atoms (H6) takes part in hydrogen-bonding interactions to an oxygen atom (O2) and a chloride atom (Cl1) and forms an unsymmetrical bifurcated bond. Overall, the four stronger intermolecular hydrogen-bonding interactions sustain an infinite three-dimensional framework (Fig. 3). An intermolecular cluster is formed from the strongest hydrogen-bonding interaction [O4⋯O2ⁱⁱⁱ = 2.750 (4) Å], which generates an infinite chain along the c-axis direction (as can be seen in Fig. 3). Various π-interactions are also observed in (1), defined by the platinum(II) atom of one molecule to the centroid of the (Pt1,As1,C2,N2,O2) ring with a Pt⋯centroid distance of 3.7225 (7) Å, by the centroid of the (Pt1,As1,C2,N2,O2) ring to the centroid of the (Pt1,As1,C2,N2,O2) (−x, −y, 1 − z) ring of an adjacent molecule with a distance of 3.7456 (4) Å, and by the centroid of the (Pt1,As1,C1,N1,O1) ring to the centroid of another (Pt1,As1,C1,N1,O2) (−x, −y, −z) ring with a distance of 3.7960 (6) Å (Fig. 4). When viewed along the c axis, individual molecules pack in `column-like' structures in an alternating head-to-tail fashion, as illustrated in Fig. 3.

Table 1
Hydrogen-bond geometry (Å, °) for 1

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O4ⁱ	0.901 (19)	2.50 (5)	3.077 (5)	122 (4)
N2—H2⋯O6ⁱⁱ	0.90 (2)	2.51 (4)	3.280 (5)	143 (5)
O4—H4⋯O2ⁱⁱⁱ	0.821 (19)	1.93 (2)	2.750 (4)	173 (6)
O6—H6⋯O2	0.827 (19)	2.27 (5)	2.643 (4)	108 (4)
O6—H6⋯Cl1^iv	0.827 (19)	2.45 (3)	3.191 (3)	149 (5)
C3—H3B⋯Cl1^v	0.96	2.72	3.613 (5)	155
Symmetry codes: (i) -x, -y, -z; (ii) x+1, y, z; (iii) -x, -y-1, -z+1; (iv) -x, -y, -z+1; (v) x-1, y, z.

Figure 2
Hydrogen-bonding interactions (indicated by purple dashed lines) observed in the structures of (1) and (2). Hydrogen atoms not involved in hydrogen-bonding interactions were omitted for clarity.

Figure 3
Illustration of the infinite three-dimensional frameworks formed by the hydrogen-bonding interactions in (1) and (2). Blue dashed lines indicate the infinite networks along the a axes, purple dashed lines along the b axes and gold dashed lines along the c axes. Hydrogen atoms not involved in the interactions were omitted for clarity.

Figure 4
π-interactions observed in the crystal structures of (1) and (2). Hydrogen atoms were omitted for clarity.

The crystal structure of (2) is likewise stabilized by one intramolecular (O6—H6⋯O1) and five intermolecular (N1—H1⋯O6ⁱ, N2—H2⋯Cl1ⁱⁱ, O4—H4⋯Cl1ⁱⁱⁱ, O6—H6⋯O4^iv, C6—H6A⋯Cl1ⁱⁱ) hydrogen-bonding interactions (Table 2, Fig. 2), again with an unsymmetrical bifurcated hydrogen bond involving atom H6 (bonding to O1 and O4) and a resulting three-dimensional network structure, as illustrated in Fig. 3. In addition, Cl1 is the acceptor of two hydrogen-bonding interactions. Two weak π-interactions are also observed in (2), one from Pt1 to the centroid of Pt1,As1,O1,C1,N1 with a distance of 3.8213 (2) Å and the other from Cl1 to a symmetry-related centroid (Pt1,As1,O1,C1,N1; 1 − x, −y, −z) with a distance of 3.8252 (12) Å (Fig. 4).

Table 2
Hydrogen-bond geometry (Å, °) for 2

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O6ⁱ	0.88 (5)	2.19 (5)	3.041 (4)	163 (5)
N2—H2⋯Cl1ⁱⁱ	0.854 (19)	2.71 (4)	3.408 (4)	140 (4)
O4—H4⋯Cl1ⁱⁱⁱ	0.82	2.28	3.071 (3)	161
O6—H6⋯O1	0.82	2.34	2.608 (4)	100
O6—H6⋯O4^iv	0.82	1.92	2.712 (4)	162
C6—H6A⋯Cl1ⁱⁱ	0.96	2.82	3.735 (5)	159
Symmetry codes: (i) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (ii) -x, -y, -z; (iii) -x+1, -y, -z; (iv) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

In comparison, molecules in (1) and (2) pack differently due to the presence of different alkyl chains (Fig. 3).

5. Synthesis and crystallization

Synthesis of 1

K₂PtCl₄ (416 mg, 1 mmol) was added to a 125 ml solution of 9:1 (v:v) CH₃CN/H₂O. The mixture was stirred at 363 K. Once the K₂PtCl₄ had dissolved, As₂O₃ (405 mg, 2.05 mmol) was added to the solution and refluxed at 363 K for 48 h. The mixture was then filtered, and the filtrate was left to stand at room temperature. Crystals suitable for X-ray crystallography were obtained by slow evaporation. Yield: 301 mg (66%). ¹H NMR (300.18 MHz, dimethyl sulfoxide-d₆): σ = 7.30 (OH, 2H,s), 6.69 (NH, 2H,s), 1.75 (CH₃, 6H, s) ppm. ¹³C NMR (150.95 MHz, dimethyl sulfoxide-d₆): σ =172 (CN), 23 (CH₃) ppm. ¹⁹⁵Pt NMR (242.99 MHz, dimethyl sulfoxide-d₆): σ = −3590.62 ppm. UV/Vis = λ = 285 nm, ∊ = 4029 dm³ mol⁻¹ cm⁻¹. Analysis calculated: C, 10.55; H, 2.21; N, 6.15. Found: C, 10.64; H, 2.22; N, 6.09%.

Synthesis of 2

K₂PtCl₄ (422 mg, 1.02 mmol) was added to a 50 ml solution of 9:1 (v:v) H₂O/CH₃CH₂CN. The mixture was stirred at room temperature. Once the K₂PtCl₄ had dissolved, As₂O₃ (400 mg, 2.02 mmol) was added to the solution and was stirred at room temperature for 96 h. The solution was cooled in an ice bath and then filtered. The filtrate was left to stand at room temperature. Crystals suitable for X-ray crystallography were obtained by slow evaporation. Yield: 278 mg (56%). ¹H NMR (600.28 MHz, dimethyl sulfoxide-d₆): δ = 8.89 (OH, 2H, s), 7.99 (NH, 2H, s), 2.48 (CH₂, 4H, q), 1.04 (CH₃, 6H, t). ¹³C NMR (150.95 MHz, dimethyl sulfoxide-d₆): δ = 176.18 (CN), 24.53 (CH₂), 11.70 (CH₃). ¹⁹⁵Pt NMR (242.99 MHz, dimethyl sulfoxide-d₆) = −3591.52. UV/Vis: λ_max = 270 nm, ∊ = 4231 L mol⁻¹ cm⁻¹. Analysis calculated C, 14.90; H, 2.92; N, 5.79. Found: C, 14.82; H, 2.91; N, 5.76.

6. Refinement

Crystal data and details of data collections and structure refinements are summarized in Table 3. Methyl and methylene hydrogen atoms were placed in geometrically idealized positions (C—H = 0.95–0.97 Å) and constrained to ride on their parent atoms [U_iso(H) = 1.5U_eq(C) and 1.2U_eq(C)]. The OH and NH hydrogen atoms were located in a difference-Fourier map and their positional parameters were constrained with O—H = 0.84 (2) Å and N—H = 0.89 (2) Å for (1), and N—H = 0.87 (2) Å for (2) with O—H distances fixed at 0.82 Å and with U_iso(H) = 1.5U_eq(O). For (2), the F_c versus F_o plot proved ten reflections to be outliers, and they were removed from the refinement as systematic errors.

Table 3
Experimental details

	(1)	2
Crystal data
Chemical formula	[PtCl(C₄H₁₀AsN₂O₄)]	[Pt(C₆H₁₄AsN₂O₄)Cl]
M_r	455.59	483.65
Crystal system, space group	Triclinic, P $[\overline{1}]$	Monoclinic, P2₁/c
Temperature (K)	100	100
a, b, c (Å)	7.272 (1), 8.099 (1), 9.350 (2)	8.9009 (3), 14.1270 (5), 9.6438 (3)
α, β, γ (°)	66.588 (5), 83.993 (5), 76.737 (5)	90, 98.243 (2), 90
V (Å³)	491.81 (14)	1200.11 (9)
Z	2	4
Radiation type	Mo Kα	Mo Kα
μ (mm⁻¹)	17.86	14.65
Crystal size (mm)	0.39 × 0.29 × 0.14	0.55 × 0.42 × 0.08

Data collection
Diffractometer	Bruker APEXII CCD	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2012 )	Multi-scan (SADABS; Bruker, 2012)
T_min, T_max	0.003, 0.090	0.001, 0.301
No. of measured, independent and observed [I > 2σ(I)] reflections	8305, 2435, 2345	41298, 2891, 2700
R_int	0.039	0.047
(sin θ/λ)_max (Å⁻¹)	0.667	0.661

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.020, 0.052, 1.18	0.022, 0.081, 1.05
No. of reflections	2411	2891
No. of parameters	136	148
No. of restraints	4	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.79, −2.05	1.53, −1.98
Computer programs: APEX2 and SAINT (Bruker, 2012), SHELXS97 (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ), DIAMOND (Brandenburg & Putz, 2005 ) and WinGX (Farrugia, 2012 ).

Supporting information

CCDC references: 1938096; 1938095

Crystal structure: contains datablocks global, 1, 2. DOI: https://doi.org/10.1107/S2056989019016463/wm5532sup1.cif

checkCIF report

Computing details top

For both structures, data collection: APEX2 (Bruker, 2012); cell refinement: SAINT (Bruker, 2012); data reduction: SAINT (Bruker, 2012); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 2012).

Chlorido[dihydroxybis(1-iminoethoxy)arsanido-κN,As,N']platinum(II) (1) top

Crystal data top

[Pt(C₄H₁₀AsN₂O₄)Cl]	Z = 2
M_r = 455.59	F(000) = 416
Triclinic, P1	D_x = 3.076 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71069 Å
a = 7.272 (1) Å	Cell parameters from 6890 reflections
b = 8.099 (1) Å	θ = 3.6–28.3°
c = 9.350 (2) Å	µ = 17.86 mm⁻¹
α = 66.588 (5)°	T = 100 K
β = 83.993 (5)°	Cuboid, colourless
γ = 76.737 (5)°	0.39 × 0.29 × 0.14 mm
V = 491.81 (14) Å³

Data collection top

Bruker APEXII CCD diffractometer	2345 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.039
Absorption correction: multi-scan (SADABS; Bruker, 2012)	θ_max = 28.3°, θ_min = 3.8°
T_min = 0.003, T_max = 0.090	h = −9→9
8305 measured reflections	k = −8→10
2435 independent reflections	l = −12→12

Refinement top

Refinement on F²	4 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.020	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.052	w = 1/[σ²(F_o²) + (0.017P)² + 1.0064P] where P = (F_o² + 2F_c²)/3
S = 1.18	(Δ/σ)_max = 0.001
2411 reflections	Δρ_max = 0.79 e Å⁻³
136 parameters	Δρ_min = −2.04 e Å⁻³

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Pt1	0.07024 (2)	0.05975 (2)	0.24814 (2)	0.00525 (6)
As1	−0.10555 (5)	−0.15921 (5)	0.31382 (4)	0.00631 (9)
Cl1	0.22859 (14)	0.30050 (13)	0.18937 (12)	0.01233 (19)
O4	−0.0662 (4)	−0.3392 (4)	0.2529 (3)	0.0115 (6)
O1	−0.2849 (4)	−0.0205 (4)	0.1539 (3)	0.0113 (6)
C3	−0.3872 (6)	0.2425 (6)	−0.0760 (5)	0.0130 (8)
H3B	−0.508229	0.285642	−0.037137	0.019*
H3A	−0.400172	0.162257	−0.125455	0.019*
H3C	−0.339248	0.345439	−0.150284	0.019*
C5	0.3527 (6)	−0.3940 (6)	0.6461 (5)	0.0136 (8)
H5A	0.451272	−0.333216	0.646809	0.02*
H5C	0.407126	−0.505519	0.630569	0.02*
H5B	0.285185	−0.422631	0.743999	0.02*
O2	0.0724 (4)	−0.3296 (4)	0.5035 (3)	0.0098 (6)
N2	0.2483 (5)	−0.1101 (5)	0.4204 (4)	0.0098 (7)
O6	−0.2912 (4)	−0.1890 (4)	0.4486 (3)	0.0109 (6)
N1	−0.1134 (5)	0.2051 (5)	0.0754 (4)	0.0099 (7)
C1	−0.2535 (6)	0.1403 (5)	0.0559 (4)	0.0083 (7)
C2	0.2192 (6)	−0.2701 (5)	0.5165 (5)	0.0090 (7)
H2	0.355 (5)	−0.091 (8)	0.448 (6)	0.025 (15)*
H1	−0.113 (8)	0.314 (4)	−0.004 (5)	0.025 (15)*
H6	−0.236 (7)	−0.202 (7)	0.527 (4)	0.017 (13)*
H4	−0.059 (8)	−0.438 (4)	0.328 (5)	0.026 (15)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pt1	0.00569 (9)	0.00337 (9)	0.00559 (9)	−0.00199 (6)	−0.00017 (6)	−0.00001 (6)
As1	0.00695 (19)	0.00417 (19)	0.00666 (18)	−0.00267 (14)	−0.00050 (14)	0.00001 (14)
Cl1	0.0149 (5)	0.0096 (4)	0.0132 (4)	−0.0071 (4)	0.0013 (4)	−0.0029 (4)
O4	0.0210 (15)	0.0055 (13)	0.0089 (13)	−0.0049 (11)	−0.0006 (11)	−0.0024 (11)
O1	0.0107 (14)	0.0101 (14)	0.0100 (13)	−0.0045 (11)	−0.0032 (11)	0.0013 (11)
C3	0.0101 (19)	0.014 (2)	0.0105 (18)	0.0002 (15)	−0.0032 (15)	−0.0015 (15)
C5	0.0084 (18)	0.0122 (19)	0.0143 (19)	−0.0030 (15)	−0.0055 (15)	0.0029 (15)
O2	0.0107 (14)	0.0059 (13)	0.0098 (13)	−0.0049 (10)	−0.0003 (11)	0.0016 (11)
N2	0.0068 (16)	0.0103 (17)	0.0109 (16)	−0.0039 (13)	−0.0017 (13)	−0.0010 (13)
O6	0.0062 (13)	0.0161 (14)	0.0095 (13)	−0.0038 (11)	0.0006 (11)	−0.0034 (11)
N1	0.0128 (17)	0.0059 (16)	0.0091 (16)	−0.0024 (13)	−0.0009 (13)	−0.0005 (13)
C1	0.0108 (18)	0.0048 (17)	0.0065 (17)	0.0022 (14)	−0.0007 (14)	−0.0013 (14)
C2	0.0082 (18)	0.0074 (18)	0.0092 (17)	0.0002 (14)	0.0004 (14)	−0.0021 (14)

Geometric parameters (Å, º) top

Pt1—N1	1.999 (4)	C3—H3A	0.96
Pt1—N2	2.005 (4)	C3—H3C	0.96
Pt1—As1	2.2730 (12)	C5—C2	1.501 (5)
Pt1—Cl1	2.3401 (15)	C5—H5A	0.96
As1—O4	1.722 (3)	C5—H5C	0.96
As1—O6	1.738 (3)	C5—H5B	0.96
As1—O1	1.898 (3)	O2—C2	1.302 (5)
As1—O2	2.107 (3)	N2—C2	1.301 (5)
O4—H4	0.821 (19)	N2—H2	0.90 (2)
O1—C1	1.316 (5)	O6—H6	0.827 (19)
C3—C1	1.491 (5)	N1—C1	1.306 (5)
C3—H3B	0.96	N1—H1	0.901 (19)

N1—Pt1—N2	173.90 (13)	H3B—C3—H3C	109.5
N1—Pt1—As1	85.18 (11)	H3A—C3—H3C	109.5
N2—Pt1—As1	89.42 (11)	C2—C5—H5A	109.5
N1—Pt1—Cl1	93.28 (11)	C2—C5—H5C	109.5
N2—Pt1—Cl1	92.34 (11)	H5A—C5—H5C	109.5
As1—Pt1—Cl1	174.79 (3)	C2—C5—H5B	109.5
O4—As1—O6	106.98 (14)	H5A—C5—H5B	109.5
O4—As1—O1	90.06 (14)	H5C—C5—H5B	109.5
O6—As1—O1	88.71 (14)	C2—O2—As1	116.5 (2)
O4—As1—O2	88.29 (13)	C2—N2—Pt1	122.5 (3)
O6—As1—O2	86.29 (13)	C2—N2—H2	109 (4)
O1—As1—O2	174.04 (11)	Pt1—N2—H2	129 (4)
O4—As1—Pt1	126.37 (10)	As1—O6—H6	100 (4)
O6—As1—Pt1	126.42 (10)	C1—N1—Pt1	121.7 (3)
O1—As1—Pt1	95.35 (10)	C1—N1—H1	109 (4)
O2—As1—Pt1	90.24 (9)	Pt1—N1—H1	130 (4)
As1—O4—H4	111 (4)	N1—C1—O1	121.2 (4)
C1—O1—As1	116.4 (3)	N1—C1—C3	122.7 (4)
C1—C3—H3B	109.5	O1—C1—C3	116.1 (4)
C1—C3—H3A	109.5	N2—C2—O2	121.1 (4)
H3B—C3—H3A	109.5	N2—C2—C5	121.7 (4)
C1—C3—H3C	109.5	O2—C2—C5	117.2 (3)

O4—As1—O1—C1	−123.0 (3)	As1—O1—C1—C3	175.8 (3)
O6—As1—O1—C1	130.0 (3)	Pt1—N2—C2—O2	1.2 (6)
Pt1—As1—O1—C1	3.5 (3)	Pt1—N2—C2—C5	−179.1 (3)
Pt1—N1—C1—O1	3.2 (6)	As1—O2—C2—N2	2.8 (5)
Pt1—N1—C1—C3	−177.2 (3)	As1—O2—C2—C5	−177.0 (3)
As1—O1—C1—N1	−4.6 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4ⁱ	0.901 (19)	2.50 (5)	3.077 (5)	122 (4)
N2—H2···O6ⁱⁱ	0.90 (2)	2.51 (4)	3.280 (5)	143 (5)
O4—H4···O2ⁱⁱⁱ	0.821 (19)	1.93 (2)	2.750 (4)	173 (6)
O6—H6···O2	0.827 (19)	2.27 (5)	2.643 (4)	108 (4)
O6—H6···Cl1^iv	0.827 (19)	2.45 (3)	3.191 (3)	149 (5)
C3—H3B···Cl1^v	0.96	2.72	3.613 (5)	155

Symmetry codes: (i) −x, −y, −z; (ii) x+1, y, z; (iii) −x, −y−1, −z+1; (iv) −x, −y, −z+1; (v) x−1, y, z.

Chlorido[dihydroxybis(1-iminopropoxy)arsanido-κN,As,N']platinum(II) (2) top

Crystal data top

[Pt(C₆H₁₄AsN₂O₄)Cl]	F(000) = 896
M_r = 483.65	D_x = 2.677 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 9966 reflections
a = 8.9009 (3) Å	θ = 3.6–28.4°
b = 14.1270 (5) Å	µ = 14.65 mm⁻¹
c = 9.6438 (3) Å	T = 100 K
β = 98.243 (2)°	Plate, colourless
V = 1200.11 (9) Å³	0.55 × 0.42 × 0.08 mm
Z = 4

Data collection top

Bruker APEXII CCD diffractometer	2700 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.047
Absorption correction: multi-scan (SADABS; Bruker, 2012)	θ_max = 28.0°, θ_min = 4.4°
T_min = 0.001, T_max = 0.301	h = −11→11
41298 measured reflections	k = −18→18
2891 independent reflections	l = −12→12

Refinement top

Refinement on F²	Primary atom site location: heavy-atom method
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.022	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.081	w = 1/[σ²(F_o²) + (0.0629P)² + 1.201P] where P = (F_o² + 2F_c²)/3
S = 1.05	(Δ/σ)_max < 0.001
2891 reflections	Δρ_max = 1.53 e Å⁻³
148 parameters	Δρ_min = −1.97 e Å⁻³
1 restraint

Special details top

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Pt1	0.33235 (2)	0.06675 (2)	0.08616 (2)	0.00918 (9)
As1	0.47791 (4)	0.19900 (3)	0.11318 (4)	0.00918 (11)
Cl1	0.17867 (12)	−0.06796 (6)	0.05304 (12)	0.0183 (2)
O4	0.6100 (3)	0.2309 (2)	0.0038 (3)	0.0127 (5)
H4	0.676165	0.190233	0.007601	0.019*
O1	0.6421 (3)	0.13513 (19)	0.2392 (3)	0.0127 (5)
O6	0.4810 (3)	0.2897 (2)	0.2331 (3)	0.0150 (6)
H6	0.524135	0.27179	0.309457	0.022*
C5	0.1062 (5)	0.2938 (3)	−0.1667 (4)	0.0168 (8)
H5B	0.167052	0.336047	−0.21515	0.02*
H5A	0.047602	0.332619	−0.110998	0.02*
C2	0.2107 (5)	0.2323 (3)	−0.0697 (4)	0.0127 (7)
N2	0.1856 (4)	0.1445 (2)	−0.0450 (3)	0.0134 (6)
C4	0.7743 (6)	0.0425 (4)	0.5043 (5)	0.0297 (10)
H4B	0.79075	0.109321	0.495994	0.045*
H4A	0.861994	0.014145	0.557876	0.045*
H4C	0.68723	0.032054	0.550648	0.045*
O2	0.3329 (3)	0.27611 (19)	−0.0081 (3)	0.0130 (5)
C1	0.6203 (5)	0.0463 (3)	0.2667 (4)	0.0119 (7)
C3	0.7473 (5)	−0.0015 (3)	0.3597 (4)	0.0180 (8)
H3B	0.8395	0.002883	0.317329	0.022*
H3A	0.723211	−0.068067	0.368096	0.022*
N1	0.4959 (4)	0.0020 (2)	0.2166 (3)	0.0129 (6)
C6	−0.0037 (5)	0.2407 (3)	−0.2757 (5)	0.0260 (10)
H6B	0.052289	0.198648	−0.327478	0.039*
H6C	−0.058897	0.285263	−0.338787	0.039*
H6A	−0.073555	0.204823	−0.229549	0.039*
H1	0.489 (6)	−0.057 (4)	0.244 (6)	0.026 (17)*
H2	0.106 (4)	0.120 (4)	−0.090 (5)	0.023 (14)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Pt1	0.01054 (13)	0.00700 (12)	0.00989 (12)	−0.00034 (4)	0.00112 (8)	−0.00025 (4)
As1	0.0127 (2)	0.00657 (19)	0.00790 (18)	−0.00061 (13)	0.00022 (15)	−0.00002 (12)
Cl1	0.0126 (5)	0.0103 (5)	0.0318 (6)	−0.0023 (3)	0.0029 (4)	−0.0018 (3)
O4	0.0132 (14)	0.0138 (12)	0.0109 (11)	−0.0004 (10)	0.0009 (10)	0.0029 (10)
O1	0.0149 (14)	0.0097 (12)	0.0127 (12)	−0.0006 (10)	−0.0008 (10)	0.0028 (10)
O6	0.0258 (16)	0.0084 (13)	0.0092 (12)	0.0020 (11)	−0.0026 (11)	−0.0014 (9)
C5	0.014 (2)	0.0172 (19)	0.0180 (18)	0.0012 (15)	−0.0003 (15)	0.0040 (15)
C2	0.0152 (19)	0.0142 (18)	0.0086 (15)	0.0040 (15)	0.0014 (13)	−0.0010 (13)
N2	0.0125 (16)	0.0132 (16)	0.0143 (15)	−0.0009 (13)	0.0008 (13)	0.0009 (12)
C4	0.032 (3)	0.035 (3)	0.019 (2)	0.010 (2)	−0.0082 (19)	−0.001 (2)
O2	0.0139 (14)	0.0104 (12)	0.0139 (12)	−0.0002 (10)	−0.0010 (10)	0.0018 (10)
C1	0.016 (2)	0.0103 (16)	0.0107 (16)	0.0016 (15)	0.0053 (14)	−0.0001 (13)
C3	0.020 (2)	0.0132 (18)	0.0191 (18)	0.0038 (15)	−0.0020 (16)	0.0029 (14)
N1	0.0178 (17)	0.0085 (15)	0.0122 (14)	0.0028 (12)	0.0013 (12)	0.0019 (12)
C6	0.023 (2)	0.029 (2)	0.022 (2)	0.0019 (18)	−0.0081 (18)	0.0108 (18)

Geometric parameters (Å, º) top

Pt1—N1	2.003 (3)	C2—N2	1.289 (5)
Pt1—N2	2.010 (3)	C2—O2	1.316 (5)
Pt1—As1	2.2672 (8)	N2—H2	0.854 (19)
Pt1—Cl1	2.3387 (11)	C4—C3	1.514 (6)
As1—O6	1.724 (3)	C4—H4B	0.96
As1—O4	1.747 (3)	C4—H4A	0.96
As1—O2	1.946 (3)	C4—H4C	0.96
As1—O1	1.979 (3)	C1—N1	1.303 (5)
O4—H4	0.82	C1—C3	1.500 (5)
O1—C1	1.303 (4)	C3—H3B	0.97
O6—H6	0.82	C3—H3A	0.97
C5—C2	1.498 (5)	N1—H1	0.88 (5)
C5—C6	1.527 (6)	C6—H6B	0.96
C5—H5B	0.97	C6—H6C	0.96
C5—H5A	0.97	C6—H6A	0.96

N1—Pt1—N2	173.20 (14)	C2—N2—Pt1	121.9 (3)
N1—Pt1—As1	87.25 (10)	C2—N2—H2	117 (4)
N2—Pt1—As1	86.05 (10)	Pt1—N2—H2	121 (4)
N1—Pt1—Cl1	94.16 (11)	C3—C4—H4B	109.5
N2—Pt1—Cl1	92.53 (10)	C3—C4—H4A	109.5
As1—Pt1—Cl1	178.51 (3)	H4B—C4—H4A	109.5
O6—As1—O4	105.44 (14)	C3—C4—H4C	109.5
O6—As1—O2	86.12 (13)	H4B—C4—H4C	109.5
O4—As1—O2	86.48 (13)	H4A—C4—H4C	109.5
O6—As1—O1	89.28 (12)	C2—O2—As1	116.2 (2)
O4—As1—O1	89.27 (13)	O1—C1—N1	122.0 (4)
O2—As1—O1	172.68 (11)	O1—C1—C3	115.7 (4)
O6—As1—Pt1	130.05 (11)	N1—C1—C3	122.2 (4)
O4—As1—Pt1	124.46 (9)	C1—C3—C4	111.8 (4)
O2—As1—Pt1	94.20 (9)	C1—C3—H3B	109.3
O1—As1—Pt1	93.12 (8)	C4—C3—H3B	109.3
As1—O4—H4	109.5	C1—C3—H3A	109.3
C1—O1—As1	116.5 (2)	C4—C3—H3A	109.3
As1—O6—H6	109.5	H3B—C3—H3A	107.9
C2—C5—C6	115.1 (3)	C1—N1—Pt1	121.1 (3)
C2—C5—H5B	108.5	C1—N1—H1	116 (4)
C6—C5—H5B	108.5	Pt1—N1—H1	123 (4)
C2—C5—H5A	108.5	C5—C6—H6B	109.5
C6—C5—H5A	108.5	C5—C6—H6C	109.5
H5B—C5—H5A	107.5	H6B—C6—H6C	109.5
N2—C2—O2	121.5 (3)	C5—C6—H6A	109.5
N2—C2—C5	124.4 (4)	H6B—C6—H6A	109.5
O2—C2—C5	114.1 (3)	H6C—C6—H6A	109.5

C6—C5—C2—N2	−21.3 (6)	As1—O1—C1—N1	−1.4 (5)
C6—C5—C2—O2	159.6 (3)	As1—O1—C1—C3	178.6 (3)
O2—C2—N2—Pt1	−1.3 (5)	O1—C1—C3—C4	63.1 (5)
C5—C2—N2—Pt1	179.8 (3)	N1—C1—C3—C4	−116.9 (4)
N2—C2—O2—As1	3.5 (5)	O1—C1—N1—Pt1	2.7 (5)
C5—C2—O2—As1	−177.5 (2)	C3—C1—N1—Pt1	−177.4 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O6ⁱ	0.88 (5)	2.19 (5)	3.041 (4)	163 (5)
N2—H2···Cl1ⁱⁱ	0.854 (19)	2.71 (4)	3.408 (4)	140 (4)
O4—H4···Cl1ⁱⁱⁱ	0.82	2.28	3.071 (3)	161
O6—H6···O1	0.82	2.34	2.608 (4)	100
O6—H6···O4^iv	0.82	1.92	2.712 (4)	162
C6—H6A···Cl1ⁱⁱ	0.96	2.82	3.735 (5)	159

Symmetry codes: (i) −x+1, y−1/2, −z+1/2; (ii) −x, −y, −z; (iii) −x+1, −y, −z; (iv) x, −y+1/2, z+1/2.

Funding information

We would like to thank the University of the Free State and the South African National Research Foundation (NRF) for financial support. Part of this work is based on the research supported by the National Research Foundation.

References

Aabo, K., Adams, M., Adnitt, P., Alberts, D. S., Athanazziou, A., Barley, V., Bell, D. R., Bianchi, U., Bolis, G., Brady, M. F., Brodovsky, H. S., Bruckner, H., Buyse, M., Canetta, R., Chylak, V., Cohen, C. J., Colombo, N., Conte, P. F., Crowther, D., Edmonson, J. H., Gennatas, C., Gilbey, E., Gore, M., Guthrie, D., Kaye, S., Laing, A., Landoni, F., Leonard, R., Lewis, C., Liu, P., Mangioni, C., Marsoni, S., Meerpohl, H., Omura, G., Parmar, M., Pater, J., Pecorelli, S., Presti, M., Sauerbrei, W., Skarlos, D., Smalley, R., Solomon, H., Stewart, L., Sturgeon, J., Tattersall, M., Wharton, J., ten Bokkel Huinink, W., Tomirotti, M., Torri, W., Trope, C., Turbow, M., Vermorken, J., Webb, M., Wilbur, D., Williams, C., Wiltshaw, E. & Yeap, B. (1998). Br. J. Cancer, 78, 1479–1487. Web of Science CrossRef CAS PubMed Google Scholar
Addison, A. W., Rao, T. N., Reedijk, J., van Rijn, J. & Verschoor, G. C. (1984). J. Chem. Soc. Dalton Trans. pp. 1349–1356. CSD CrossRef Web of Science Google Scholar
Basu, A. & Krishnamurthy, S. (2010). J. Nucleic Acids, 2010, 1–16. Google Scholar
Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2012). APEX2, SAINT and SADABS. Bruker AXS Inc, Madison, Wisconsin, USA. Google Scholar
Burchenal, J. H. (1978). Biochimie, 60, 915–923. CrossRef Web of Science Google Scholar
Clegg, W. (2016). Private communication (refcode: CCDC 1470767). CCDC, Cambridge, England. https:/doi.org/10.5517/ccdc.csd.cc1lcg3j Google Scholar
Dube, J. W., Zheng, Y., Thiel, W. & Alcarazo, M. (2016). J. Am. Chem. Soc. 138, 6869–6877. Web of Science CSD CrossRef CAS PubMed Google Scholar
Emadi, A. & Gore, S. D. (2010). Blood Rev. 24, 191–199. Web of Science CrossRef CAS PubMed Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Groom, C. R., Bruno, I. J., Lightfoot, M. P. & Ward, S. C. (2016). Acta Cryst. B72, 171–179. Web of Science CrossRef IUCr Journals Google Scholar
Imoto, H., Sasaki, H., Tanaka, S., Yumura, T. & Naka, K. (2017). Organometallics, 36, 2605–2611. Web of Science CSD CrossRef CAS Google Scholar
Jakupec, M. A., Galanski, M. & Keppler, B. K. (2003). Rev. Physiol. Biochem. Pharmacol. 146, 1–54. Web of Science CrossRef PubMed CAS Google Scholar
Kauffman, G. B., Pentimalli, R., Doldi, S. & Hall, M. D. (2010). Plat. Met. Rev. 54, 250–256. Web of Science CrossRef CAS Google Scholar
Kelland, L. (2007). Nat. Rev. Cancer, 7, 573–584. Web of Science CrossRef PubMed CAS Google Scholar
Marino, T., Parise, A. & Russo, N. (2017). Phys. Chem. Chem. Phys. 19, 1328–1334. Web of Science CrossRef CAS PubMed Google Scholar
Miller, W. H., Schipper, H. M., Lee, J. S., Singer, J. & Waxman, S. (2002). Cancer Res. 62, 3893–3903. Web of Science PubMed CAS Google Scholar
Miodragović, D., Swindell, E. P., Waxali, Z. S., Bogachkov, A. & O'Halloran, T. V. (2019). Inorg. Chim. Acta, 496, 119030. Google Scholar
Miodragović, D. U., Quentzel, J. A., Kurutz, J. W., Stern, C. L., Ahn, R. W., Kandela, I., Mazar, A. & O'Halloran, T. V. (2013). Angew. Chem. Int. Ed. 52, 10749–10752. Google Scholar
Muessig, J. H., Stennett, T. E., Schmidt, U., Dewhurst, R. D., Mailänder, L. & Braunschweig, H. (2019). Dalton Trans. 48, 3547–3550. Web of Science CSD CrossRef CAS PubMed Google Scholar
Ott, I. (2009). Coord. Chem. Rev. 253, 1670–1681. Web of Science CrossRef CAS Google Scholar
Reedijk, J. (2009). Eur. J. Inorg. Chem. 2009, pp. 1303–1312. Web of Science CrossRef Google Scholar
Reinholdt, A. & Bendix, J. (2017). Inorg. Chem. 56, 12492–12497. Web of Science CSD CrossRef CAS PubMed Google Scholar
Rosenberg, B., Van Camp, I. & Krigas, T. (1965). Nature, 205, 698–699. CrossRef PubMed CAS Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Sheldrick, G. M. (2015). Acta Cryst. C71, 3–8. Web of Science CrossRef IUCr Journals Google Scholar
Shen, Z.-X., Shi, Z.-Z., Fang, J., Gu, B.-W., Li, J.-M., Zhu, Y.-M., Shi, J.-Y., Zheng, P.-Z., Yan, H., Liu, Y.-F., Chen, Y., Shen, Y., Wu, W., Tang, W., Waxman, S., De Thé, H., Wang, Z.-Y., Chen, S.-J. & Chen, Z. (2004). Proc. Natl Acad. Sci. USA, 101, 5328–5335. Web of Science CrossRef PubMed CAS Google Scholar
Shi, H., Clarkson, G. J. & Sadler, P. J. (2019). Inorg. Chim. Acta, 489, 230–235. Web of Science CSD CrossRef CAS Google Scholar
Swindell, E. P., Hankins, P. L., Chen, H., Miodragović, D. U. & O'Halloran, T. V. (2013). Inorg. Chem. 52, 12292–12304. Web of Science CrossRef CAS PubMed Google Scholar
Wang, G., Li, W., Cui, J., Gao, S., Yao, C., Jiang, Z., Song, Y., Yuan, C. J., Yang, Y., Liu, Z. & Cai, L. (2004). Hematol. Oncol. 22, 63–71. Web of Science CrossRef PubMed Google Scholar
Wheate, N. J., Walker, S., Craig, G. E. & Oun, R. (2010). Dalton Trans. 39, 8113–8127. Web of Science CrossRef CAS PubMed Google Scholar
Zhang, N., Wu, Z.-M., McGowan, E., Shi, J., Hong, Z.-B., Ding, C.-W., Xia, P. & Di, W. (2009). Cancer Sci. 100, 2459–2464. Web of Science CrossRef PubMed CAS Google Scholar
Zhang, X.-W., Yan, X.-J., Zhou, Z.-R., Yang, F.-F., Wu, Z.-Y., Sun, H.-B., Liang, W.-X., Song, A.-X., Lallemand-Breitenbach, V., Jeanne, M., Zhang, Q.-Y., Yang, H.-Y., Huang, Q.-H., Zhou, G.-B., Tong, J.-H., Zhang, Y., Wu, J.-H., Hu, H. Y., de Thé, H., Chen, S.-J. & Chen, Z. (2010). Science, 328, 240–243. Web of Science CrossRef CAS PubMed Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 76| Part 2| February 2020| Pages 180-185

https://doi.org/10.1107/S2056989019016463

Open

access

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Plain Text
		Text

Format		BIBTeX
		EndNote
		RefMan
		Refer
		Medline
		CIF
		SGML
		Plain Text
		Text

Search IUCr Journals		doi		Advanced search
Author		volume	page

research communications\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)