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The title compound, cis-[PtCl2(CH3NH2)2], was obtained from the reaction of K2PtCl4 with CH3NH2·HCl and CH3COOK. The single-crystal structure has been reported previously [Wimmer, Wimmer, Jaud, Johnson & Castan (1988). Inorg. Chim. Acta, 144, 25–30], but no three-dimensional coordinates are available. We have carried out an ab initio crystal structure determination using X-ray powder diffraction techniques. The crystal structure consists of discrete mol­ecules, with the PtII atom in a slightly distorted square-planar coordination environment. The methyl groups lie on the same side of the plane defined by the two N and two Cl atoms. Mol­ecules are connected via inter­molecular N—H...Cl hydrogen bonds to form two-dimensional layers perpendicular to the b axis. The methyl­amine groups protrude from these layers, forming organic inter­layers.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807048428/lh2492sup1.cif
Contains datablocks global, I

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600536807048428/lh2492Isup2.rtv
Contains datablock I

CCDC reference: 667130

Key indicators

  • Powder X-ray study
  • T = 293 K
  • Mean [sigma](N-C) = 0.019 Å
  • R factor = 0.000
  • wR factor = 0.000
  • Data-to-parameter ratio = 26.3

checkCIF/PLATON results

No syntax errors found



Alert level C REFI023_ALERT_1_C _refine_diff_density_max is missing Maximum value of final difference map (e A-3). The following tests will not be performed DIFMN_01,DIFMX_01,DIFMX_02 REFI024_ALERT_1_C _refine_diff_density_min is missing Minimum value of final difference map (e A-3). The following tests will not be performed DIFMN_01,DIFMN_02,DIFMN_03 SHFSU01_ALERT_2_C The absolute value of parameter shift to su ratio > 0.05 Absolute value of the parameter shift to su ratio given 0.100 Additional refinement cycles may be required. PLAT080_ALERT_2_C Maximum Shift/Error ............................ 0.10 PLAT164_ALERT_4_C Nr. of Refined C-H H-Atoms in Heavy-At Struct... 6 PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 = 3 PLAT745_ALERT_1_C D-H Calc 0.900(19), Rep 0.90000 ...... Missing su N1 -H1A 1.555 1.555 PLAT745_ALERT_1_C D-H Calc 0.900(14), Rep 0.90000 ...... Missing su N1 -H1B 1.555 1.555 PLAT745_ALERT_1_C D-H Calc 0.900(13), Rep 0.90000 ...... Missing su N2 -H2A 1.555 1.555 PLAT745_ALERT_1_C D-H Calc 0.900(13), Rep 0.90000 ...... Missing su N2 -H2B 1.555 1.555 PLAT746_ALERT_1_C H...A Calc 2.797(12), Rep 2.80000 ...... Missing su H1A -CL2 1.555 3.657 PLAT746_ALERT_1_C H...A Calc 2.477(10), Rep 2.48000 ...... Missing su H1B -CL2 1.555 1.554 PLAT746_ALERT_1_C H...A Calc 2.696(9), Rep 2.70000 ...... Missing su H2A -CL2 1.555 1.554 PLAT746_ALERT_1_C H...A Calc 2.829(16), Rep 2.83000 ...... Missing su H2B -CL2 1.555 3.757 PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) . 1.17 Ratio
Alert level G PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt1 (2) 1.91
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 15 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 10 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 1 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 1 ALERT type 5 Informative message, check

Comment top

The title complex, cis-[Pt(CH3NH2)2Cl2], has attracted attention due to its biological activity especially in connection with cancer chemotherapy (Clere & Hoechele, 1973; Clere, 1974). Reports on cis-[Pt(CH3NH2)2Cl2] can be found in the literature as early as the nineteen fifties (Grinberg & Gildengershel, 1951; Gildengershel, 1956). X-ray diffraction data were published by Watt et al. (1967) and a single-crystal structure was determined by Wimmer et al. (1988). This group found the existence of two forms A and B. Concisely the form A is build from molecules cis-[Pt(CH3NH2)2Cl2] in the conformation where both methyl groups lie on the same side of the plane delimited by the two chloride and the two nitrogen atoms (motif A). The form B consists of molecules of two possible conformations: above mentioned motif A and a motif B where methyl groups are on the both side of "platinum" plane. Unfortunately the publication (Wimmer et al., 1988) does not present the 3-D coordinates of the structures, and that hinders the detailed analysis of reasons for the different types of conformations. Here we present the results of crystal structure determination of cis-[Pt(CH3NH2)2Cl2] in form A obtained applying another synthetic approach without using AgI as it was done by Wimmer et al. (1988) following Dhara (1970). Another important feature follows from application of the X-ray powder technique that allows ascribing the structure to bulk sample of the substance.

The crystal structure of cis-bis(metylamine) dichloro platimun(II) consists of discrete molecules. The geometry of the molecule is presented in Fig. 2. The Pt atom has slightly distorted square-planar coordination enviroment consisting of two N and two Cl atoms. The torsion angle Cl2—Cl1—N1—N2 = 177.5°. The distances Pt1—N1, Pt1—N2, Pt1—Cl1 and Pt1—Cl2 are 2.083 (14) Å, 2.088 (12) Å, 2.303 (5) Å and 2.343 (4) Å respectively and these correspond well to known in literature values (Arpalahti et al., 1988; Wimmer et al., 1988; Kirik et al., 1996; Wells, 1984; Allen, 2002; ICSD, 2007). Metylamine as a ligand does not induce essential distortions of the molecule. The N1—Pt1—N2 angle is 90.0 (4)°. The N···Cl contacts in the molecule are of 3.081 (16) Å and 3.095 (15) Å. Methyl-groups are oriented to one side of the PtN2Cl2plane. Molecules conjugate in pairs due to (Cl···H—N) intermolecular bounding with centrosymmetric orientation respectively each other. N···Cl contacts between nearest molecules are of 3.296 (16) Å and 3.462 (16) Å. The shortest (Pt···Pt) distance in pairs equals to 3.372 (2) Å. The pairs comprise double layers stretched along (ac)-plane with methylamine ligands protruding from layers forming organic interlayers (Fig. 3). This type of packing is also typical for other methylamine containing compound (Kirik & Starkov, 2007).

Related literature top

The title compound was previously reported by Watt et al. (1967) and Wimmer et al. (1988). For related compounds, see: Arpalahti et al. (1988); Clere (1974); Clere & Hoechele (1973); Dhara (1970); Gildengershel (1956); Grinberg & Gildengershel (1951); Kirik & Starkov (2007); Kirik et al. (1996); Wells (1984). Searches were conducted using the Cambridge Structural Database (Version?; Allen, 2002) and the Inorganic Crystal Structure Database (Version 2007–1; ICSD, 2007). X-ray powder diffraction data have been deposited in the JCPDS-ICDD PDF-2 database (ICDD, 2005). For analysis techniques, see: Kirik (1985); Kirik et al. (1979); Le Bail et al. (1988); Rietveld (1969); Visser (1969); Wiles & Young (1981). [Original long list of references has been rearranged to make it more informative. Please check.]

Experimental top

For the preparation of cis-[Pt(CH3NH2)2Cl2] the salt K2PtCl4 in amount of 4 g was dissolved in 20 ml of water. Then 3 g of CH3NH2·HCl and 4 g CH3COOK were added to the solution. The mixture was slightly heated until solution became colorless and then cooled down to room temperature. The solution was kept during 3 h at room temperature, pH was adjusted close to 8 by KOH solution. The light yellow precipitate was filtered, washed and dried. Elemental chemical analysis confirmed the chemical formula of the substance.

Refinement top

The structure determination was carried out by the X-ray powder diffraction technique. The experimental data were collected using DRON-4 automatic diffractometer, equipped with a secondary flat graphite monochromator in conjunction with a scintillation detector. Cu Kα radiation was used (λ1 = 1.54056 Å, λ2 = 1.54439 Å). The sample was prepared by top-loading the standard quartz sample holder with cutting the excess of well grained substance. The diffraction pattern was scanned with the step of 0.02° 2θ and counting time of 5 sec./step in the most informative angular range from 9° to 115% 2θ at room temperature. Corundum was used as the external standard. The powder pattern of cis-bis(methylamine) dichloro platimun(II) is presented in Fig. 1. X-ray powder diffraction data have been deposited in JCPDS-ICDD PDF2 database (ICDD, 2005). Cell parameters were obtained from d-spaces by indexing and refining using programs described in (Visser, 1969; Kirik et al., 1979). The space group was determined from the analysis of systematic absences. The structural investigations were carried out using a full-profile structure analysis package based on a modified version of the Rietveld refinement program DBWS-9006PC (Wiles & Young, 1981; Kirik, 1985). The intensities of 50 reflections were estimated from the powder pattern by means of the full-profile fitting procedure (Le Bail et al., 1988) and used in the Patterson synthesis. Atoms of Pt and Cl were located directly from the Patterson map. Positions of light atoms N and C were defined from a difference Fourier synthesis. The final refinement was carried out by Rietveld method (Rietveld, 1969; Wiles & Young, 1981). H-atoms were not located, but they were included in the refined structure models and rigidly connected to their C and N atoms with N—H = 0.90 and C—H = 0.96 Å and Uiso(H) = 0.152 Å2.

Structure description top

The title complex, cis-[Pt(CH3NH2)2Cl2], has attracted attention due to its biological activity especially in connection with cancer chemotherapy (Clere & Hoechele, 1973; Clere, 1974). Reports on cis-[Pt(CH3NH2)2Cl2] can be found in the literature as early as the nineteen fifties (Grinberg & Gildengershel, 1951; Gildengershel, 1956). X-ray diffraction data were published by Watt et al. (1967) and a single-crystal structure was determined by Wimmer et al. (1988). This group found the existence of two forms A and B. Concisely the form A is build from molecules cis-[Pt(CH3NH2)2Cl2] in the conformation where both methyl groups lie on the same side of the plane delimited by the two chloride and the two nitrogen atoms (motif A). The form B consists of molecules of two possible conformations: above mentioned motif A and a motif B where methyl groups are on the both side of "platinum" plane. Unfortunately the publication (Wimmer et al., 1988) does not present the 3-D coordinates of the structures, and that hinders the detailed analysis of reasons for the different types of conformations. Here we present the results of crystal structure determination of cis-[Pt(CH3NH2)2Cl2] in form A obtained applying another synthetic approach without using AgI as it was done by Wimmer et al. (1988) following Dhara (1970). Another important feature follows from application of the X-ray powder technique that allows ascribing the structure to bulk sample of the substance.

The crystal structure of cis-bis(metylamine) dichloro platimun(II) consists of discrete molecules. The geometry of the molecule is presented in Fig. 2. The Pt atom has slightly distorted square-planar coordination enviroment consisting of two N and two Cl atoms. The torsion angle Cl2—Cl1—N1—N2 = 177.5°. The distances Pt1—N1, Pt1—N2, Pt1—Cl1 and Pt1—Cl2 are 2.083 (14) Å, 2.088 (12) Å, 2.303 (5) Å and 2.343 (4) Å respectively and these correspond well to known in literature values (Arpalahti et al., 1988; Wimmer et al., 1988; Kirik et al., 1996; Wells, 1984; Allen, 2002; ICSD, 2007). Metylamine as a ligand does not induce essential distortions of the molecule. The N1—Pt1—N2 angle is 90.0 (4)°. The N···Cl contacts in the molecule are of 3.081 (16) Å and 3.095 (15) Å. Methyl-groups are oriented to one side of the PtN2Cl2plane. Molecules conjugate in pairs due to (Cl···H—N) intermolecular bounding with centrosymmetric orientation respectively each other. N···Cl contacts between nearest molecules are of 3.296 (16) Å and 3.462 (16) Å. The shortest (Pt···Pt) distance in pairs equals to 3.372 (2) Å. The pairs comprise double layers stretched along (ac)-plane with methylamine ligands protruding from layers forming organic interlayers (Fig. 3). This type of packing is also typical for other methylamine containing compound (Kirik & Starkov, 2007).

The title compound was previously reported by Watt et al. (1967) and Wimmer et al. (1988). For related compounds, see: Arpalahti et al. (1988); Clere (1974); Clere & Hoechele (1973); Dhara (1970); Gildengershel (1956); Grinberg & Gildengershel (1951); Kirik & Starkov (2007); Kirik et al. (1996); Wells (1984). Searches were conducted using the Cambridge Structural Database (Version?; Allen, 2002) and the Inorganic Crystal Structure Database (Version 2007–1; ICSD, 2007). X-ray powder diffraction data have been deposited in the JCPDS-ICDD PDF-2 database (ICDD, 2005). For analysis techniques, see: Kirik (1985); Kirik et al. (1979); Le Bail et al. (1988); Rietveld (1969); Visser (1969); Wiles & Young (1981). [Original long list of references has been rearranged to make it more informative. Please check.]

Computing details top

Data collection: DRON-4 data collection software; cell refinement: POWDER (Kirik et al., 1979); data reduction: DRON-4 data collection software; program(s) used to solve structure: modified DBWM (Wiles & Young, 1981); program(s) used to refine structure: modified DBWM (Wiles & Young, 1981); molecular graphics: SHELXTL (Siemens, 1989); software used to prepare material for publication: SHELXTL (Siemens, 1989).

Figures top
[Figure 1] Fig. 1. Observed (dots), calculated (superimposed solid) and difference profiles after the Rietveld refinement. The reflection positions are marked by ticks.
[Figure 2] Fig. 2. The molecular structure of cis-[Pt(CH3NH2)2Cl2] shown as a ball and stick respentation. Dashed lines indicate intramolecular interactions.
[Figure 3] Fig. 3. Part of the crystal structure of cis-[Pt(CH3NH2)2Cl2] with hydrogen bonds shown as dashed lines.
cis-dichloridobis(methylamine)platinum(II) top
Crystal data top
[PtCl2(CH5N)2]F(000) = 592.0
Mr = 328.10Final cell parameters are obtained from the Rietveld refinement
Monoclinic, P21/nDx = 2.982 Mg m3
Hall symbol: -P 2ynCu Kα radiation
a = 7.4512 (1) ÅT = 293 K
b = 15.7995 (2) ÅParticle morphology: thin powder
c = 6.3015 (1) Åyellow
β = 99.930 (3)°circular flate plate, 20.0 × 20.0 mm
V = 730.73 (2) Å3Specimen preparation: Prepared at 293 K and 101 kPa, cooled at 0 K min1
Z = 4
Data collection top
DRON-4 powder
diffractometer
Specimen mounting: packed powder pellet
Radiation source: conventional sealed tubeData collection mode: reflection
Graphite monochromator2θmin = 9.0°, 2θmax = 115.0°, 2θstep = 0.02°
Refinement top
Refinement on F2Profile function: Pearson VII (Wiles & Young, 1981
Least-squares matrix: full38 parameters
Rp = 0.0590 restraints
Rwp = 0.0800 constraints
Rexp = 0.056H-atom parameters not refined
RBragg = 0.035Weighting scheme based on measured s.u.'s
R(F2) = 0.036(Δ/σ)max = 0.1
Excluded region(s): nonePreferred orientation correction: March–Dollase correction (Dollase, 1986)
Crystal data top
[PtCl2(CH5N)2]β = 99.930 (3)°
Mr = 328.10V = 730.73 (2) Å3
Monoclinic, P21/nZ = 4
a = 7.4512 (1) ÅCu Kα radiation
b = 15.7995 (2) ÅT = 293 K
c = 6.3015 (1) Åcircular flate plate, 20.0 × 20.0 mm
Data collection top
DRON-4 powder
diffractometer
Data collection mode: reflection
Specimen mounting: packed powder pellet2θmin = 9.0°, 2θmax = 115.0°, 2θstep = 0.02°
Refinement top
Rp = 0.05938 parameters
Rwp = 0.0800 restraints
Rexp = 0.056H-atom parameters not refined
RBragg = 0.035(Δ/σ)max = 0.1
R(F2) = 0.036
Special details top

Refinement. R_prof-backgr = 0.059

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Pt10.8950 (2)0.0946 (1)0.9978 (2)0.0121*
Cl11.1570 (6)0.1223 (4)1.2400 (6)0.0197*
Cl20.7322 (5)0.0594 (3)1.2720 (6)0.0186*
N10.6610 (13)0.0672 (10)0.7760 (14)0.0234*
H1A0.6022 (13)0.0245 (10)0.8290 (14)0.152*
H1B0.6954 (13)0.0484 (10)0.6543 (14)0.152*
C21.0380 (12)0.2250 (11)0.7050 (12)0.0226*
H2C1.1018 (12)0.2353 (11)0.5875 (12)0.152*
H2D0.9164 (12)0.2470 (11)0.6698 (12)0.152*
H2E1.1007 (12)0.2525 (11)0.8324 (12)0.152*
N21.0300 (11)0.1280 (10)0.7460 (10)0.0231*
H2A0.9738 (11)0.1028 (10)0.6245 (10)0.152*
H2B1.1446 (11)0.1078 (10)0.7751 (10)0.152*
C10.5240 (12)0.1410 (9)0.7160 (10)0.0237*
H1C0.4220 (12)0.1214 (9)0.6134 (10)0.152*
H1D0.4823 (12)0.1606 (9)0.8432 (10)0.152*
H1E0.5831 (12)0.1865 (9)0.6543 (10)0.152*
Geometric parameters (Å, º) top
Pt1—Cl12.303 (5)Cl2—H2Bi2.829 (16)
Pt1—Cl22.343 (4)N1—H1A0.90 (1)
Pt1—N12.083 (14)N1—H1B0.90 (1)
Pt1—N22.088 (12)N2—H2A0.90 (1)
N1—C11.553 (18)N2—H2B0.90 (1)
N2—C21.56 (3)C1—H1C0.96 (1)
Pt1—Pt1i3.372 (2)C1—H1D0.96 (1)
Cl1—H2Aii2.995 (4)C1—H1E0.96 (1)
Cl1—H1Ai3.010 (15)C2—H2C0.96 (1)
Cl1—H2B2.924 (4)C2—H2D0.96 (1)
Cl1—H1Bi2.945 (16)C2—H2E0.96 (1)
Cl1—H2B2.924 (4)
Cl1—Pt1—Cl292.5 (2)Pt1—N2—H2A108.6 (6)
Cl1—Pt1—N289.5 (2)Pt1—N2—H2B108.6 (6)
Cl2—Pt1—N188.0 (2)N1—C1—H1C109.4 (14)
N1—Pt1—N290.0 (4)N1—C1—H1D109.4 (6)
Pt1—N1—C1116.5 (6)N1—C1—H1E109.4 (6)
Pt1—N2—C2114.3 (6)N2—C2—H2C109.4 (16)
Pt1—N1—H1A108.1 (6)N2—C2—H2D109.4 (15)
Pt1—N1—H1B108.1 (6)N2—C2—H2E109.4 (14)
Symmetry codes: (i) x+2, y, z+2; (ii) x, y, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···Cl2iii0.902.803.517 (13)138
N1—H1B···Cl2iv0.902.483.311 (10)154
N2—H2A···Cl2iv0.902.703.569 (9)163
N2—H2B···Cl2i0.902.833.462 (15)128
Symmetry codes: (i) x+2, y, z+2; (iii) x+1, y, z+2; (iv) x, y, z1.

Experimental details

Crystal data
Chemical formula[PtCl2(CH5N)2]
Mr328.10
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)7.4512 (1), 15.7995 (2), 6.3015 (1)
β (°) 99.930 (3)
V3)730.73 (2)
Z4
Radiation typeCu Kα
Specimen shape, size (mm)Circular flate plate, 20.0 × 20.0
Data collection
DiffractometerDRON-4 powder
diffractometer
Specimen mountingPacked powder pellet
Data collection modeReflection
Scan method?
2θ values (°)2θmin = 9.0 2θmax = 115.0 2θstep = 0.02
Refinement
R factors and goodness of fitRp = 0.059, Rwp = 0.080, Rexp = 0.056, RBragg = 0.035, R(F2) = 0.036, χ2 = 2.045
No. of parameters38
H-atom treatmentH-atom parameters not refined
(Δ/σ)max0.1

Computer programs: DRON-4 data collection software, POWDER (Kirik et al., 1979), modified DBWM (Wiles & Young, 1981), SHELXTL (Siemens, 1989).

Selected geometric parameters (Å, º) top
Pt1—Cl12.303 (5)Pt1—N12.083 (14)
Pt1—Cl22.343 (4)Pt1—N22.088 (12)
Cl1—Pt1—Cl292.5 (2)Cl2—Pt1—N188.0 (2)
Cl1—Pt1—N289.5 (2)N1—Pt1—N290.0 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1A···Cl2i0.902.803.517 (13)138
N1—H1B···Cl2ii0.902.483.311 (10)154
N2—H2A···Cl2ii0.902.703.569 (9)163
N2—H2B···Cl2iii0.902.833.462 (15)128
Symmetry codes: (i) x+1, y, z+2; (ii) x, y, z1; (iii) x+2, y, z+2.
 

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