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The crystal structure of the title compound, trans-[Pd(NCS)2(C6H13N3P)2](NCS)2, is one of the few pal­ladium(II) complexes containing two protonated water-soluble 1,3,5-tri­aza-7-phos­pha­adamantane (PTA) ligands re­ported to date. The compound displays a distorted square-planar geometry, with the Pd atom on an inversion centre and with the S atoms of the thio­cyanate counter-ions occupying the axial positions above and below the equatorial plane described by the phosphine and thio­cyanate ligands. Geometric parameters for the formal coordination polyhedron include a Pd—P distance of 2.2940 (8) Å, a Pd—S distance of 2.3509 (8) Å and a P—Pd—S angle of 89.45 (3)°. The effective cone angle for the PTA ligands was calculated as 114.5°.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010301521X/fa1019sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010301521X/fa1019Isup2.hkl
Contains datablock I

CCDC reference: 221056

Comment top

In the past few years, numerous 1,3,5-triaza-7-phosphaadamantane (PTA) complexes exhibiting catalytic activity have been reported (Alyea et al., 1993; Joó et al., 1996; Darensbourg et al., 1997, 1999). PTA is a neutral air-stable aliphatic phosphine with a small steric demand (Daigle et al., 1998; Otto & Roodt, 2001a). The potentially quadridentate PTA ligand coordinates to the metal centre only through the P atom, as observed in all the metal PTA complexes characterized to date (Cambridge Structural Database; Allen, 2002).

In this paper, we report the structure of trans- bis(thiocyanato)bis(PTA-H)palladium(II) thiocyanate (PTA-H is the protonated form of PTA), (I), as part of our systematic investigation of the basic coordination mode and solution properties of these complexes. The title compound is the first example of a square-planar complex that has a trans geometry and that contains protonated PTA ligands. Both PTA ligands are protonated at one of the N atoms, resulting in a dicationic complex, and therefore two thiocyanate counter-ions co-crystallize with the coordination compound to ensure neutrality. The compound, described by the phosphine and thiocyanate ligands, crystallizes as discrete distorted square-planar moieties, with the S atoms of the thiocyanate counter-ions in the apical positions above and below the equatorial plane showing weak interactions (see Fig. 1). This results in infinite chains of alternating cations and NCS counter-ions and is the first example of this interaction involving a Pd2+ metal centre and NCS (Allen, 2002).

The Pd atom is situated on an inversion center in the monoclinic space group P21/n, thus imposing planarity of the equatorial ligands with symmetry-equivalent ligands in a relative trans orientation. The angles in the coordination polyhedron are close to the ideal of 90°, the P—Pd—S10 angle being 89.45 (3)°. The Pd—S10 and Pd—P bonds in the coordination polyhedron are 2.3509 (8) and 2.2940 (8) Å, respectively. Both NCS– ligands as well as the NCS– counter-ions interact with the Pd metal centre via the S atoms in a manner indicative of a soft metal centre. The Pd—S11 interaction at the apical positions of the square plane, occupied by the NCS– counter-ions, is 3.4383 (9) Å and is thus significantly longer than the formal Pd—S10 bond. The Pd—S10—C10 angle [102.71 (10)°] is characteristic of a thiocyanate ligand coordinated via the S atom. Similarly, although only a weak interaction, the Pd—SCN moiety in the apical position shows a bent orientation, with a Pd—S11—C11 angle of 95.56 (9)°.

The C10—N10 and C11—N11 bond lengths are the same within the s.u. values, being 1.155 (3) and 1.158 (3) Å, respectively. However, the S10—C10 bond is 1.677 (3) Å, whereas the S11—C11 bond in the NCS counter-ion is significantly shorter [1.628 (3) Å]. This? is indicative of the resonance structure of the thiocyanate group, implying more of a double-bond character for the S11—C11 moiety?. Since Pd—S10 is a formal bond, the S atom donates electron density to the metal centre, thus resulting in the S10—C10 bond having more of a single-bond character and hence being a weaker bond. The S10—C10—N10 angle is 176.8 (3)°, while the S11—C11—N11 moiety is virtually linear [179.6 (3)°].

The P—C1, P—C2 and P—C3 bond distances do not differ significantly [1.837 (3), 1.834 (2) and 1.839 (2) Å, respectively], whereas the N1—C1, N2—C2 and N3—C3 bond distances show deviations. The longer N2—C2 bond [1.498 (3) versus 1.467 (3) and 1.470 (3) Å for N3—C3 and N1—C1] is observed because the N2 atom is protonated. This protonated N2—H2 moiety in turn participates in a fairly strong intermolecular interaction [H···N = 1.868 (9) Å] with the atom N11 of an adjacent NCS– counter-ion at (0.5 + x, −0.5 − y, −0.5 + z) (see also Fig. 2).

The effective cone angle (θE) for the PTA ligand in the title compound was calculated as 114.5°, using the real Pd—P distance (Otto et al., 2000). The Tolman cone angle (θT) was calculated as 114.8°, using a Pd—P distance of 2.28 Å, according to the original definition (Tolman, 1977). This value is comparable to the values of θE and θT calculated for PTA in trans-[PdBr2(PTA)2] (114.0° and 115.1°; Meij et al., 2002), [PtI2(PTA)3] (118.3 and 119.2°; Otto et al., 2001a) and trans-[PtI2(PTA)2] (117.3 and 118.2°; Otto et al., 2001b), confirming the rigid character of the ligand.

Experimental top

To an aqueous solution of cis-[PdCl2(PTA)2] (2.5 mg, 0.005 mmol) at pH 3.0–3.5 (HClO4) was added an excess (> 10 x) of KSCN (100 mg, 1.03 mmol). Evaporation of the solution at ambient temperature gave red crystals suitable for X-ray analysis. IR (KBr): ν(SCN) 2044 cm−1.

Refinement top

The intensity data were collected on a Nonius KappaCCD diffractometer using an exposure time of 40 s/frame. A total of 67 frames were collected with a frame width of 4° being used covering up to τ = 27.45°. Completeness of 97.4% was accomplished up to τ = 27.45°. The first 7 frames were recollected at the end of the data collection to check for decay.

Methylene H atoms were placed in idealized positions (C—H = 0.97–0.98 Å) and constrained to ride on their parent atoms, with Uiso(H) values of 1.2Ueq(C). The position of the H atom on atom N2 was determined from a Fourier difference map and the coordinates were refined with an isotropic displacement parameter constrained to 1.2Ueq(N).

Computing details top

Data collection: Collect (Nonius, 1998); cell refinement: Collect; data reduction: Collect; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg & Berndt, 1999); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. : The structure and numbering scheme of the molecule of (I), with displacement ellipsoids shown at the 30% probability level. Only the H atoms on the protonated N atoms of the PTA ligands are included, and these H atoms are represented by spheres of arbitrary size. [Symmetry code: (i) −x, −y, 1 − z.]
[Figure 2] Fig. 2. : A section of the unit cell of (I), showing the packing and the H2···N11 and S11···Pd interactions.
trans-bis(3,5-diaza-1-azonia-7-phosphaadamantane- κP)bis(thiocyanato-κS)palladium(II) bis(thiocyanate) top
Crystal data top
[Pd(NCS)2(C6H13N3P)2](NCS)2F(000) = 664
Mr = 655.05Dx = 1.761 Mg m3
Dm = 1.746 Mg m3
Dm measured by flotation in CH2I2/C6H6
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 7.5170 (15) ÅCell parameters from 2294 reflections
b = 12.733 (3) Åθ = 2.3–27.5°
c = 12.956 (3) ŵ = 1.25 mm1
β = 94.96 (3)°T = 293 K
V = 1235.4 (4) Å3Rectangles, red
Z = 20.30 × 0.22 × 0.16 mm
Data collection top
NONIUS KappaCCD
diffractometer
2766 independent reflections
Radiation source: fine-focus sealed tube2179 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.028
ω and ϕ scansθmax = 27.5°, θmin = 2.3°
Absorption correction: empirical
SADABS (Sheldrick, 1996)
h = 99
Tmin = 0.706, Tmax = 0.825k = 1516
6468 measured reflectionsl = 1616
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.029H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.057 w = 1/[σ2(Fo2) + (0.007P)2 + 0.768P]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
2766 reflectionsΔρmax = 0.58 e Å3
155 parametersΔρmin = 0.41 e Å3
0 restraintsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0021 (3)
Crystal data top
[Pd(NCS)2(C6H13N3P)2](NCS)2V = 1235.4 (4) Å3
Mr = 655.05Z = 2
Monoclinic, P21/nMo Kα radiation
a = 7.5170 (15) ŵ = 1.25 mm1
b = 12.733 (3) ÅT = 293 K
c = 12.956 (3) Å0.30 × 0.22 × 0.16 mm
β = 94.96 (3)°
Data collection top
NONIUS KappaCCD
diffractometer
2766 independent reflections
Absorption correction: empirical
SADABS (Sheldrick, 1996)
2179 reflections with I > 2σ(I)
Tmin = 0.706, Tmax = 0.825Rint = 0.028
6468 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0290 restraints
wR(F2) = 0.057H atoms treated by a mixture of independent and constrained refinement
S = 1.01Δρmax = 0.58 e Å3
2766 reflectionsΔρmin = 0.41 e Å3
155 parameters
Special details top

Experimental. First 7 frames repeated after data collection for intensity monitoring.

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

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Pd0.00000.00000.50000.01774 (9)
P0.09273 (8)0.01710 (5)0.33674 (5)0.01641 (15)
S100.26366 (8)0.08313 (5)0.56822 (5)0.02713 (17)
S110.32841 (9)0.17966 (5)0.57320 (6)0.03295 (19)
N20.3153 (3)0.05577 (17)0.19650 (16)0.0223 (5)
C20.2629 (3)0.07738 (19)0.30342 (18)0.0216 (6)
H2A0.36700.07190.35290.026*
H2B0.21610.14820.30670.026*
C30.2047 (3)0.13897 (19)0.3021 (2)0.0245 (6)
H3A0.12340.19760.30670.029*
H3B0.30770.15110.35110.029*
N10.0279 (3)0.01397 (17)0.12621 (15)0.0251 (5)
N30.2626 (3)0.13365 (16)0.19694 (16)0.0239 (5)
C10.0649 (3)0.0034 (2)0.22103 (18)0.0228 (5)
H1A0.12240.06470.22170.027*
H1B0.15660.05690.22180.027*
C110.1953 (3)0.2651 (2)0.6196 (2)0.0271 (6)
N110.1014 (3)0.3260 (2)0.6530 (2)0.0501 (7)
C60.1569 (3)0.0671 (2)0.11544 (19)0.0272 (6)
H6A0.19860.06370.04670.033*
H6B0.10120.13510.12300.033*
C40.1118 (3)0.1170 (2)0.1186 (2)0.0303 (6)
H4A0.02290.17100.12610.036*
H4B0.15380.12430.05020.036*
C50.3941 (3)0.0535 (2)0.1877 (2)0.0249 (6)
H5A0.49050.06280.24170.030*
H5B0.44350.06030.12130.030*
N100.1694 (3)0.2981 (2)0.5753 (2)0.0516 (8)
C100.2030 (4)0.2097 (2)0.5714 (2)0.0318 (7)
H20.402 (3)0.097 (2)0.182 (2)0.038*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pd0.01710 (14)0.02136 (16)0.01505 (15)0.00594 (12)0.00305 (10)0.00346 (12)
P0.0153 (3)0.0191 (4)0.0150 (3)0.0020 (3)0.0024 (3)0.0008 (3)
S100.0228 (3)0.0299 (4)0.0282 (4)0.0052 (3)0.0000 (3)0.0013 (3)
S110.0359 (4)0.0254 (4)0.0381 (4)0.0074 (3)0.0061 (3)0.0002 (3)
N20.0206 (11)0.0227 (12)0.0246 (12)0.0036 (10)0.0078 (10)0.0024 (10)
C20.0245 (13)0.0209 (13)0.0196 (14)0.0004 (11)0.0023 (11)0.0012 (11)
C30.0279 (14)0.0185 (13)0.0279 (15)0.0025 (11)0.0064 (12)0.0017 (11)
N10.0236 (11)0.0362 (14)0.0154 (11)0.0028 (10)0.0003 (9)0.0021 (10)
N30.0250 (11)0.0222 (12)0.0254 (13)0.0023 (10)0.0076 (10)0.0035 (9)
C10.0180 (12)0.0314 (14)0.0189 (13)0.0020 (12)0.0013 (10)0.0016 (12)
C110.0216 (13)0.0260 (15)0.0335 (16)0.0087 (12)0.0023 (12)0.0046 (13)
N110.0272 (13)0.0455 (16)0.078 (2)0.0014 (13)0.0094 (14)0.0276 (15)
C60.0300 (14)0.0341 (16)0.0180 (14)0.0041 (13)0.0050 (12)0.0065 (12)
C40.0324 (15)0.0335 (16)0.0253 (15)0.0023 (13)0.0048 (12)0.0112 (13)
C50.0208 (13)0.0302 (15)0.0249 (15)0.0045 (12)0.0080 (11)0.0021 (12)
N100.0445 (16)0.0338 (16)0.077 (2)0.0060 (13)0.0087 (15)0.0104 (15)
C100.0280 (15)0.0357 (18)0.0317 (17)0.0118 (13)0.0030 (13)0.0061 (14)
Geometric parameters (Å, º) top
Pd—P2.2940 (8)N1—C11.470 (3)
Pd—S102.3509 (8)N1—C41.462 (3)
Pd—S113.4383 (9)N1—C61.432 (3)
P—C11.837 (2)N3—C31.467 (3)
P—C21.834 (2)N3—C41.470 (3)
P—C31.839 (2)N3—C51.433 (3)
S10—C101.677 (3)C1—H1A0.9700
S11—C111.628 (3)C1—H1B0.9700
N2—C21.498 (3)C11—N111.158 (3)
N2—C51.520 (3)C6—H6A0.9700
N2—C61.525 (3)C6—H6B0.9700
N2—H20.87 (3)C4—H4A0.9700
C2—H2A0.9700C4—H4B0.9700
C2—H2B0.9700C5—H5A0.9700
C3—H3A0.9700C5—H5B0.9700
C3—H3B0.9700N10—C101.155 (3)
Pi—Pd—P180.0P—C3—H3B109.3
Pi—Pd—S1090.55 (3)H3A—C3—H3B108.0
P—Pd—S1089.45 (3)C6—N1—C4109.9 (2)
Pi—Pd—S10i89.45 (3)C6—N1—C1112.9 (2)
P—Pd—S10i90.55 (3)C4—N1—C1112.2 (2)
S10—Pd—S10i180.0C5—N3—C3111.9 (2)
Pi—Pd—S1187.17 (3)C5—N3—C4109.6 (2)
P—Pd—S1192.83 (3)C3—N3—C4112.05 (18)
S10—Pd—S1168.53 (3)N1—C1—P110.76 (16)
S10i—Pd—S11111.47 (3)N1—C1—H1A109.5
C2—P—C199.17 (11)P—C1—H1A109.5
C2—P—C398.79 (11)N1—C1—H1B109.5
C1—P—C399.05 (12)P—C1—H1B109.5
C2—P—Pd115.36 (8)H1A—C1—H1B108.1
C1—P—Pd121.17 (8)N1—C6—N2111.1 (2)
C3—P—Pd119.14 (8)N1—C6—H6A109.4
Pd—S10—C10102.71 (10)N2—C6—H6A109.4
Pd—S11—C1195.56 (9)N1—C6—H6B109.4
C2—N2—C5111.89 (19)N2—C6—H6B109.4
C2—N2—C6111.56 (18)H6A—C6—H6B108.0
C5—N2—C6108.75 (19)N1—C4—N3113.2 (2)
C2—N2—H2110.4 (18)N1—C4—H4A108.9
C5—N2—H2103.2 (18)N3—C4—H4A108.9
C6—N2—H2110.7 (18)N1—C4—H4B108.9
N2—C2—P109.96 (16)N3—C4—H4B108.9
N2—C2—H2A109.7H4A—C4—H4B107.7
P—C2—H2A109.7N3—C5—N2111.68 (18)
N2—C2—H2B109.7N3—C5—H5A109.3
P—C2—H2B109.7N2—C5—H5A109.3
H2A—C2—H2B108.2N3—C5—H5B109.3
N3—C3—P111.48 (16)N2—C5—H5B109.3
N3—C3—H3A109.3H5A—C5—H5B107.9
P—C3—H3A109.3S10—C10—N10176.8 (3)
N3—C3—H3B109.3S11—C11—N11179.6 (3)
S10—Pd—P—C1162.89 (10)S10—Pd—P—C339.68 (10)
S10—Pd—P—C277.57 (9)
Symmetry code: (i) x, y, z+1.

Experimental details

Crystal data
Chemical formula[Pd(NCS)2(C6H13N3P)2](NCS)2
Mr655.05
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)7.5170 (15), 12.733 (3), 12.956 (3)
β (°) 94.96 (3)
V3)1235.4 (4)
Z2
Radiation typeMo Kα
µ (mm1)1.25
Crystal size (mm)0.30 × 0.22 × 0.16
Data collection
DiffractometerNONIUS KappaCCD
diffractometer
Absorption correctionEmpirical
SADABS (Sheldrick, 1996)
Tmin, Tmax0.706, 0.825
No. of measured, independent and
observed [I > 2σ(I)] reflections
6468, 2766, 2179
Rint0.028
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.029, 0.057, 1.01
No. of reflections2766
No. of parameters155
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.58, 0.41

Computer programs: Collect (Nonius, 1998), Collect, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), DIAMOND (Brandenburg & Berndt, 1999), SHELXL97.

Selected geometric parameters (Å, º) top
Pd—P2.2940 (8)N2—C61.525 (3)
Pd—S102.3509 (8)N1—C11.470 (3)
Pd—S113.4383 (9)N1—C41.462 (3)
P—C11.837 (2)N1—C61.432 (3)
P—C21.834 (2)N3—C31.467 (3)
P—C31.839 (2)N3—C41.470 (3)
S10—C101.677 (3)N3—C51.433 (3)
S11—C111.628 (3)C11—N111.158 (3)
N2—C21.498 (3)N10—C101.155 (3)
N2—C51.520 (3)
Pi—Pd—P180.0Pd—S11—C1195.56 (9)
P—Pd—S1089.45 (3)S10—C10—N10176.8 (3)
Pd—S10—C10102.71 (10)S11—C11—N11179.6 (3)
Symmetry code: (i) x, y, z+1.
 

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