Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010300458X/bm1527sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010300458X/bm1527Isup2.hkl |
CCDC reference: 211730
Complex (I) was prepared from Pd(PPh3)4 and tcne, following the literature method of Fitton & McKeon (1968). The crystal used for this study was grown from CH2Cl2/pentane (1:3).
Following an initial refinement, high displacement parameters for the dichloromethane Cl atoms indicated disorder in the solvent. Two orientations were refined [C50A/Cl5A/Cl5B (occupany 1/2) and C50B/Cl5C/Cl5D (occupany 1/5)], giving a total solvent occupany of 0.7. The C—Cl distances were restrained to 1.75 (2) Å, and the Cl—C—Cl angle restrained to be tetrahedral by restraining the Cl···Cl distances within a given disorder component to be 2.86 (2) Å. All non-H atoms, except those of the minor solvent component, were refined anisotropically, and all H atoms were placed in calculated positions and refined using a riding model. The fixed C—H distances used were 0.95 Å for Csp2—H and 0.99 Å for Csp3—H. For all H atoms, Uiso(H) was set to 1.2Ueq(C).
Tetracyanoethene (tcne) is a highly electron-deficient alkene that has found use both as a ligand in transition-metal chemistry (Kaim & Moscherosch, 1994) and as an electron acceptor in intermolecular charge-transfer complexes (Schneider & Mohammad-Ali, 1996). It can coordinate to metal atoms or ions through its N-donors (σ-coordination) or through its C═C double bond (π-coordination) and, particularly when π-bound, is one of the strongest π-acceptor ligands known (Kaim & Moscherosch, 1994). One of the first π-coordinated tcne complexes to be synthesized was [Pd(PPh3)2(tcne)] (Fitton & McKeon, 1968), although this was not crystallographically characterized at the time. We now report the structure analysis of a 0.7-solvate of [Pd(PPh3)2(tcne)], (I).
The asymmetric unit of (I) contains one bis(η2-tetracyanoethene)(triphenylphosphine)palladium molecule in a general position (Fig. 1) and a CH2Cl2 molecule disordered over two orientations whose occupancies sum to 0.70. The tcne ligand is π-bound to the Pd atom, as expected. The two Pd—P bond lengths in (I) are equal within standard uncertainties, while the three angles P12—Pd1—P31 [108.12 (2)°], P12—Pd1—X [125.6 (3)°] and P31—Pd1—X [126.3 (3)°], where X is the centre of the C2═C3 bond, sum to exactly 360°, confirming the planarity at the Pd centre. Hence, the Pd centre can be thought of as having a coordination geometry which, if the tcne ligand is deemed to occupy one coordination site, corresponds to an almost perfect isoceles triangle. However, the tcne ligand is twisted slightly out of this trigonal plane, the dihedral angle between the Pd1/P12/P31 and Pd1/C2/C3 planes being 6.3 (2)°. This distortion is also reflected in the C—C—Pd angles involving the four cyano groups of the tcne moiety, in that the angle C6—C2—Pd1 is 6.4 (3)° wider than C4—C2—Pd1, and C8—C3—Pd1 is 5.9 (3)° wider than C10—C3—Pd1. These distortions might be attributed to intramolecular steric contacts between the cyano groups and the faces of phenyl substituents in the molecule, as illustrated by the following distances: C4···C13 = 3.468 (4), N5···C18 = 3.471 (4), N7···C30 = 3.449 (4), C8···C38 = 3.382 (4) and C10···C39 = 3.315 (4) Å. Since the radius of a C atom participating in a π-bond is 1.70 Å (Pauling, 1960), these distances place these cyano groups and their adjacent phenyl rings within the sum of the relevant van der Waals radii. There are also some close intermolecular N···C distances that might similarly influence the geometry of the tcne ligand, notably N7···C21i = 3.434 (4), N9···C40ii = 3.436 (4), N9···C46iii = 3.243 (4) and N11···C22iv = 3.408 (4) Å [symmetry codes: (i) -1 + x, y, -1 + z; (ii) x, 0.5 - y, 0.5 + z; (iii) 1 + x, 0.5 - y, 0.5 + z; (iv) 1 + x, y, 1 + z]. Related distortions of the tcne framework are also present in other Pd/tcne complexes containing aryl phosphine co-ligands (Kranenburg et al., 1997; Mashima et al., 1998).
The degree of charge transfer from the Pd atom to the tcne ligand in (I) is evident in two parameters (Kaim & Moscherosch, 1994). First, the C2═C3 bond length of 1.488 (4) Å is substantially longer than in uncoordinated tcne [1.328 (5) and 1.344 (3) Å in the monoclinic (Chaplot et al., 1991) and cubic (Little et al., 1971) phases of this compound, respectively]. Second, the coordinated alkene C atoms in (I) are significantly pyramidalized. This is evidenced both by the C—C—C bond angles at the tcne ligand, which lie between 115.3 (2) and 118.0 (2)°, compared to 120° in free tcne, and by the dihedral angle of 56.34 (16)° between the least-squares planes formed by the two C(CN)2 fragments (C2/C4/C6/N5/N7 and C3/C8/C10/N9/N11) of the tcne ligand. This angle is 0° in the uncoordinated alkene. Both these parameters are within the ranges previously observed in other Pd–tcne complexes (Zagorodnikov et al., 1989; Tsubouchi et al., 1994; Kranenburg et al., 1997; Mashima et al., 1998; van Belzen et al., 1998; Canovese et al., 2000) and indicate partial rehybridization of the alkene C═C bond caused by substantial Pd → tcne back-donation into the tcne π* orbitals.
The molecular structure of (I) is visually indistinguishable from that of its Pt analogue [Pt(PPh3)2(tcne)] (Bombieri et al., 1970), and the metal–carbon distances in the two compounds are not signifcantly different. However, the Pd—P bonds in (I) are 0.039 (9)–0.041 (8) Å longer than those in the Pt compound, presumably reflecting improved back-bonding between the phosphine ligands and the Pt 5 d orbitals, as opposed to the Pd 4 d orbitals. The low precision of the structure analysis on the Pt complex prevents any more detailed comparison of the two compounds.
There are two intermolecular N···H contacts of ca 2.5 Å in (I), which are within the sum of the van der Waals radii of H (1.2 Å) and N (1.5 Å) (Pauling, 1960) and so could correspond to weak C—H···N interactions (Table 2). There are no other noteworthy intermolecular interactions in the lattice.
Data collection: COLLECT (Nonius, 1999); cell refinement: DENZO–SMN (Otwinowski & Minor, 1997); data reduction: DENZO–SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: ORTEX (McArdle, 1995); software used to prepare material for publication: local program.
Fig. 1. The molecular structure of the [Pd(PPh3)2(tcne)] molecule in (I), showing the atom-numbering scheme and 50% probability displacement ellipsoids. H atoms have been omitted for clarity. |
[Pd(C6N4)(C18H15P)2]·0.7CH2Cl2 | F(000) = 1662 |
Mr = 818.49 | Dx = 1.399 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 10.3363 (1) Å | Cell parameters from 29108 reflections |
b = 37.2805 (4) Å | θ = 2.7–27.5° |
c = 10.8142 (1) Å | µ = 0.69 mm−1 |
β = 111.1463 (7)° | T = 150 K |
V = 3886.57 (7) Å3 | Plate, yellow-orange |
Z = 4 | 0.50 × 0.40 × 0.13 mm |
Nonius KappaCCD area-detector diffractometer | 8877 independent reflections |
Radiation source: fine-focus sealed tube | 7450 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.053 |
Detector resolution: 9.091 pixels mm-1 | θmax = 27.5°, θmin = 2.7° |
area–detector scans | h = −13→12 |
Absorption correction: multi-scan (SORTAV; Blessing, 1995) | k = −48→48 |
Tmin = 0.724, Tmax = 0.916 | l = −13→14 |
29108 measured reflections |
Refinement on F2 | Primary atom site location: heavy-atom method |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.039 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.110 | H-atom parameters constrained |
S = 1.02 | w = 1/[σ2(Fo2) + (0.0582P)2 + 3.3475P] where P = (Fo2 + 2Fc2)/3 |
8877 reflections | (Δ/σ)max = 0.001 |
482 parameters | Δρmax = 0.75 e Å−3 |
6 restraints | Δρmin = −0.80 e Å−3 |
[Pd(C6N4)(C18H15P)2]·0.7CH2Cl2 | V = 3886.57 (7) Å3 |
Mr = 818.49 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.3363 (1) Å | µ = 0.69 mm−1 |
b = 37.2805 (4) Å | T = 150 K |
c = 10.8142 (1) Å | 0.50 × 0.40 × 0.13 mm |
β = 111.1463 (7)° |
Nonius KappaCCD area-detector diffractometer | 8877 independent reflections |
Absorption correction: multi-scan (SORTAV; Blessing, 1995) | 7450 reflections with I > 2σ(I) |
Tmin = 0.724, Tmax = 0.916 | Rint = 0.053 |
29108 measured reflections |
R[F2 > 2σ(F2)] = 0.039 | 6 restraints |
wR(F2) = 0.110 | H-atom parameters constrained |
S = 1.02 | Δρmax = 0.75 e Å−3 |
8877 reflections | Δρmin = −0.80 e Å−3 |
482 parameters |
Experimental. Detector set at 30 mm from sample with different 2theta offsets 1 degree phi exposures for chi=0 degree settings 1 degree omega exposures for chi=90 degree settings Using multiple and symmetry-related data measurements via the program SORTAV See R·H. Blessing, Acta Cryst (1995), A51, 33–38 |
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. Following an initial refinement, high displacement parameters for the CH2Cl2 Cl atoms indicated disorder in the solvent. Two orientations were refined: C50A, CL5A, CL5B (occupany 1/2) and C50B, CL5C, CL5D (occupany 1/5), giving a total solvent occupany of 0.7. The C—Cl distances were restrained to 1.75 (2) Å, and the Cl—C—Cl angle restrained to be tetrahedral by restraining the Cl···Cl distances within a given disorder component to be 2.86 (2) Å. All non-H atoms except those of the minor solvent component were refined anisotropically, and all H atoms were placed in calculated positions and refined using a riding model. The fixed C—H distances used were: C{sp2—H 0.95 and C{sp3—H 0.99 Å. For all H atoms Uiso(H) was set to 1.2Ueq(C). |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
Pd1 | 0.879438 (19) | 0.355759 (5) | 0.218305 (18) | 0.02122 (7) | |
C2 | 1.0947 (3) | 0.36751 (8) | 0.2848 (3) | 0.0261 (5) | |
C3 | 1.0669 (3) | 0.33489 (7) | 0.3505 (3) | 0.0258 (5) | |
C4 | 1.1498 (3) | 0.36185 (8) | 0.1814 (3) | 0.0325 (6) | |
N5 | 1.1906 (3) | 0.35611 (8) | 0.0976 (3) | 0.0481 (7) | |
C6 | 1.1429 (3) | 0.39943 (8) | 0.3631 (3) | 0.0310 (6) | |
N7 | 1.1799 (3) | 0.42471 (7) | 0.4260 (3) | 0.0430 (6) | |
C8 | 1.1072 (3) | 0.30087 (8) | 0.3138 (3) | 0.0287 (6) | |
N9 | 1.1400 (3) | 0.27435 (7) | 0.2797 (3) | 0.0400 (6) | |
C10 | 1.0702 (3) | 0.33830 (8) | 0.4847 (3) | 0.0304 (6) | |
N11 | 1.0673 (3) | 0.34175 (8) | 0.5890 (3) | 0.0439 (7) | |
P12 | 0.77131 (7) | 0.403298 (18) | 0.07959 (6) | 0.02304 (14) | |
C13 | 0.8793 (3) | 0.41541 (7) | −0.0149 (3) | 0.0280 (6) | |
C14 | 0.9642 (3) | 0.44548 (9) | 0.0157 (4) | 0.0426 (7) | |
H14 | 0.9677 | 0.4604 | 0.0881 | 0.051* | |
C15 | 1.0437 (4) | 0.45364 (10) | −0.0595 (4) | 0.0548 (10) | |
H15 | 1.1025 | 0.4741 | −0.0382 | 0.066* | |
C16 | 1.0378 (4) | 0.43200 (10) | −0.1663 (4) | 0.0534 (10) | |
H16 | 1.0877 | 0.4386 | −0.2213 | 0.064* | |
C17 | 0.9601 (3) | 0.40116 (10) | −0.1923 (3) | 0.0433 (8) | |
H17 | 0.9600 | 0.3857 | −0.2623 | 0.052* | |
C18 | 0.8817 (3) | 0.39261 (8) | −0.1155 (3) | 0.0347 (6) | |
H18 | 0.8294 | 0.3710 | −0.1321 | 0.042* | |
C19 | 0.5969 (3) | 0.40151 (7) | −0.0466 (2) | 0.0234 (5) | |
C20 | 0.5686 (3) | 0.41279 (8) | −0.1764 (3) | 0.0283 (6) | |
H20 | 0.6413 | 0.4217 | −0.2021 | 0.034* | |
C21 | 0.4338 (3) | 0.41096 (8) | −0.2688 (3) | 0.0310 (6) | |
H21 | 0.4146 | 0.4189 | −0.3572 | 0.037* | |
C22 | 0.3283 (3) | 0.39779 (8) | −0.2325 (3) | 0.0310 (6) | |
H22 | 0.2371 | 0.3960 | −0.2966 | 0.037* | |
C23 | 0.3545 (3) | 0.38707 (8) | −0.1031 (3) | 0.0318 (6) | |
H23 | 0.2811 | 0.3784 | −0.0779 | 0.038* | |
C24 | 0.4886 (3) | 0.38904 (7) | −0.0104 (3) | 0.0271 (5) | |
H24 | 0.5066 | 0.3818 | 0.0785 | 0.033* | |
C25 | 0.7646 (3) | 0.44308 (7) | 0.1753 (3) | 0.0268 (5) | |
C26 | 0.6956 (3) | 0.47404 (8) | 0.1121 (3) | 0.0327 (6) | |
H26 | 0.6500 | 0.4742 | 0.0185 | 0.039* | |
C27 | 0.6932 (3) | 0.50442 (8) | 0.1851 (3) | 0.0392 (7) | |
H27 | 0.6468 | 0.5254 | 0.1414 | 0.047* | |
C28 | 0.7586 (3) | 0.50419 (9) | 0.3218 (3) | 0.0427 (8) | |
H28 | 0.7566 | 0.5250 | 0.3718 | 0.051* | |
C29 | 0.8265 (4) | 0.47370 (9) | 0.3854 (3) | 0.0432 (8) | |
H29 | 0.8714 | 0.4736 | 0.4791 | 0.052* | |
C30 | 0.8292 (3) | 0.44301 (8) | 0.3122 (3) | 0.0351 (6) | |
H30 | 0.8755 | 0.4220 | 0.3563 | 0.042* | |
P31 | 0.70937 (7) | 0.314709 (18) | 0.21734 (6) | 0.02179 (14) | |
C32 | 0.6199 (3) | 0.32600 (7) | 0.3304 (3) | 0.0255 (5) | |
C33 | 0.6226 (4) | 0.36083 (8) | 0.3745 (3) | 0.0380 (7) | |
H33 | 0.6726 | 0.3787 | 0.3475 | 0.046* | |
C34 | 0.5522 (4) | 0.36994 (9) | 0.4584 (3) | 0.0488 (9) | |
H34 | 0.5549 | 0.3939 | 0.4888 | 0.059* | |
C35 | 0.4789 (4) | 0.34426 (9) | 0.4972 (3) | 0.0412 (7) | |
H35 | 0.4302 | 0.3506 | 0.5536 | 0.049* | |
C36 | 0.4761 (3) | 0.30931 (9) | 0.4540 (3) | 0.0345 (6) | |
H36 | 0.4256 | 0.2916 | 0.4808 | 0.041* | |
C37 | 0.5471 (3) | 0.30002 (8) | 0.3716 (3) | 0.0277 (5) | |
H37 | 0.5460 | 0.2759 | 0.3430 | 0.033* | |
C38 | 0.7857 (3) | 0.27074 (7) | 0.2726 (3) | 0.0239 (5) | |
C39 | 0.8694 (3) | 0.26617 (8) | 0.4061 (3) | 0.0302 (6) | |
H39 | 0.8766 | 0.2849 | 0.4676 | 0.036* | |
C40 | 0.9419 (3) | 0.23452 (9) | 0.4490 (3) | 0.0364 (7) | |
H40 | 0.9988 | 0.2318 | 0.5397 | 0.044* | |
C41 | 0.9321 (3) | 0.20671 (8) | 0.3603 (3) | 0.0377 (7) | |
H41 | 0.9839 | 0.1853 | 0.3894 | 0.045* | |
C42 | 0.8455 (3) | 0.21070 (8) | 0.2284 (3) | 0.0372 (7) | |
H42 | 0.8354 | 0.1915 | 0.1677 | 0.045* | |
C43 | 0.7740 (3) | 0.24251 (7) | 0.1854 (3) | 0.0305 (6) | |
H43 | 0.7161 | 0.2450 | 0.0949 | 0.037* | |
C44 | 0.5763 (3) | 0.30641 (7) | 0.0559 (2) | 0.0242 (5) | |
C45 | 0.4382 (3) | 0.29906 (8) | 0.0378 (3) | 0.0307 (6) | |
H45 | 0.4096 | 0.2984 | 0.1120 | 0.037* | |
C46 | 0.3428 (3) | 0.29268 (8) | −0.0886 (3) | 0.0372 (7) | |
H46 | 0.2488 | 0.2877 | −0.1008 | 0.045* | |
C47 | 0.3845 (3) | 0.29357 (8) | −0.1974 (3) | 0.0391 (7) | |
H47 | 0.3190 | 0.2890 | −0.2837 | 0.047* | |
C48 | 0.5210 (3) | 0.30103 (8) | −0.1800 (3) | 0.0359 (7) | |
H48 | 0.5494 | 0.3016 | −0.2542 | 0.043* | |
C49 | 0.6163 (3) | 0.30763 (7) | −0.0538 (3) | 0.0285 (6) | |
H49 | 0.7098 | 0.3130 | −0.0421 | 0.034* | |
C50A | 0.4009 (9) | 0.4757 (2) | 0.3254 (9) | 0.058 (2) | 0.50 |
H50A | 0.4919 | 0.4879 | 0.3516 | 0.069* | 0.50 |
H50B | 0.3996 | 0.4614 | 0.4020 | 0.069* | 0.50 |
Cl5A | 0.3825 (8) | 0.44728 (15) | 0.1937 (6) | 0.0752 (14) | 0.50 |
Cl5B | 0.2705 (3) | 0.50773 (6) | 0.2870 (3) | 0.0735 (7) | 0.50 |
C50B | 0.431 (2) | 0.4699 (4) | 0.3583 (15) | 0.036 (5)* | 0.20 |
H50C | 0.4116 | 0.4561 | 0.4282 | 0.043* | 0.20 |
H50D | 0.5306 | 0.4758 | 0.3916 | 0.043* | 0.20 |
Cl5C | 0.3916 (18) | 0.4434 (3) | 0.2177 (14) | 0.054 (3)* | 0.20 |
Cl5D | 0.3358 (8) | 0.5094 (2) | 0.3292 (8) | 0.074 (2)* | 0.20 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pd1 | 0.01970 (11) | 0.02101 (11) | 0.02254 (11) | −0.00022 (7) | 0.00713 (8) | −0.00028 (7) |
C2 | 0.0221 (12) | 0.0271 (13) | 0.0290 (13) | −0.0020 (10) | 0.0092 (10) | 0.0014 (11) |
C3 | 0.0227 (12) | 0.0269 (14) | 0.0257 (12) | 0.0003 (10) | 0.0063 (10) | 0.0007 (10) |
C4 | 0.0267 (14) | 0.0331 (15) | 0.0369 (15) | −0.0016 (11) | 0.0105 (12) | 0.0046 (12) |
N5 | 0.0478 (17) | 0.0532 (19) | 0.0527 (18) | 0.0048 (13) | 0.0296 (15) | 0.0062 (13) |
C6 | 0.0266 (14) | 0.0318 (15) | 0.0314 (14) | −0.0037 (11) | 0.0066 (11) | 0.0029 (12) |
N7 | 0.0432 (15) | 0.0370 (15) | 0.0421 (15) | −0.0091 (12) | 0.0074 (12) | −0.0027 (12) |
C8 | 0.0239 (13) | 0.0298 (15) | 0.0283 (13) | 0.0024 (11) | 0.0045 (10) | 0.0044 (11) |
N9 | 0.0370 (14) | 0.0343 (14) | 0.0466 (15) | 0.0085 (11) | 0.0124 (12) | 0.0031 (12) |
C10 | 0.0278 (14) | 0.0285 (14) | 0.0305 (14) | −0.0059 (11) | 0.0054 (11) | 0.0002 (11) |
N11 | 0.0517 (17) | 0.0473 (16) | 0.0342 (14) | −0.0151 (13) | 0.0171 (12) | −0.0059 (12) |
P12 | 0.0221 (3) | 0.0207 (3) | 0.0263 (3) | 0.0006 (2) | 0.0086 (3) | 0.0002 (2) |
C13 | 0.0250 (13) | 0.0253 (13) | 0.0351 (14) | 0.0030 (10) | 0.0125 (11) | 0.0027 (11) |
C14 | 0.0395 (17) | 0.0331 (16) | 0.064 (2) | −0.0038 (13) | 0.0287 (16) | −0.0024 (15) |
C15 | 0.050 (2) | 0.0358 (18) | 0.096 (3) | −0.0045 (16) | 0.047 (2) | 0.0039 (19) |
C16 | 0.053 (2) | 0.047 (2) | 0.083 (3) | 0.0108 (17) | 0.051 (2) | 0.0189 (19) |
C17 | 0.0446 (18) | 0.049 (2) | 0.0452 (18) | 0.0096 (15) | 0.0268 (15) | 0.0048 (15) |
C18 | 0.0335 (15) | 0.0336 (16) | 0.0412 (16) | 0.0013 (12) | 0.0188 (13) | 0.0013 (13) |
C19 | 0.0243 (12) | 0.0197 (12) | 0.0265 (12) | 0.0022 (10) | 0.0096 (10) | −0.0013 (10) |
C20 | 0.0280 (13) | 0.0305 (14) | 0.0287 (13) | 0.0016 (11) | 0.0129 (11) | 0.0022 (11) |
C21 | 0.0306 (14) | 0.0340 (15) | 0.0272 (13) | 0.0054 (12) | 0.0092 (11) | −0.0004 (11) |
C22 | 0.0249 (13) | 0.0284 (14) | 0.0361 (15) | 0.0014 (11) | 0.0065 (11) | −0.0068 (12) |
C23 | 0.0259 (14) | 0.0304 (15) | 0.0433 (16) | 0.0001 (11) | 0.0175 (12) | 0.0010 (12) |
C24 | 0.0275 (13) | 0.0251 (13) | 0.0320 (13) | 0.0031 (11) | 0.0145 (11) | 0.0034 (11) |
C25 | 0.0246 (13) | 0.0246 (13) | 0.0318 (13) | −0.0020 (10) | 0.0108 (11) | −0.0042 (11) |
C26 | 0.0296 (14) | 0.0291 (15) | 0.0398 (15) | 0.0029 (11) | 0.0131 (12) | 0.0000 (12) |
C27 | 0.0379 (16) | 0.0282 (15) | 0.0550 (19) | 0.0013 (13) | 0.0211 (14) | −0.0049 (14) |
C28 | 0.0458 (18) | 0.0331 (16) | 0.054 (2) | −0.0046 (14) | 0.0240 (16) | −0.0171 (14) |
C29 | 0.0459 (18) | 0.0440 (19) | 0.0390 (17) | −0.0017 (15) | 0.0144 (14) | −0.0127 (14) |
C30 | 0.0361 (16) | 0.0326 (15) | 0.0357 (15) | 0.0015 (12) | 0.0120 (13) | −0.0043 (12) |
P31 | 0.0217 (3) | 0.0220 (3) | 0.0225 (3) | −0.0008 (2) | 0.0090 (2) | −0.0009 (2) |
C32 | 0.0266 (13) | 0.0271 (13) | 0.0240 (12) | 0.0013 (10) | 0.0106 (10) | −0.0009 (10) |
C33 | 0.053 (2) | 0.0290 (15) | 0.0405 (17) | −0.0009 (13) | 0.0274 (15) | −0.0011 (12) |
C34 | 0.078 (3) | 0.0323 (17) | 0.0508 (19) | 0.0055 (17) | 0.0406 (19) | −0.0052 (15) |
C35 | 0.0514 (19) | 0.0445 (18) | 0.0384 (16) | 0.0091 (15) | 0.0291 (15) | 0.0016 (14) |
C36 | 0.0320 (15) | 0.0434 (17) | 0.0306 (14) | 0.0023 (13) | 0.0143 (12) | 0.0061 (12) |
C37 | 0.0283 (13) | 0.0285 (14) | 0.0287 (13) | −0.0011 (11) | 0.0131 (11) | −0.0012 (11) |
C38 | 0.0230 (12) | 0.0239 (12) | 0.0275 (12) | −0.0003 (10) | 0.0124 (10) | 0.0023 (10) |
C39 | 0.0308 (14) | 0.0298 (14) | 0.0306 (14) | −0.0028 (11) | 0.0116 (11) | 0.0042 (11) |
C40 | 0.0315 (15) | 0.0385 (17) | 0.0350 (15) | −0.0015 (13) | 0.0067 (12) | 0.0114 (13) |
C41 | 0.0366 (16) | 0.0290 (15) | 0.0514 (18) | 0.0079 (12) | 0.0206 (14) | 0.0132 (13) |
C42 | 0.0467 (17) | 0.0270 (15) | 0.0443 (17) | 0.0046 (13) | 0.0242 (14) | 0.0011 (13) |
C43 | 0.0341 (15) | 0.0270 (14) | 0.0309 (14) | 0.0020 (11) | 0.0126 (12) | 0.0000 (11) |
C44 | 0.0252 (13) | 0.0196 (12) | 0.0255 (12) | 0.0011 (10) | 0.0064 (10) | −0.0010 (10) |
C45 | 0.0272 (14) | 0.0323 (15) | 0.0331 (14) | −0.0015 (11) | 0.0115 (11) | −0.0022 (12) |
C46 | 0.0267 (14) | 0.0371 (17) | 0.0404 (16) | −0.0017 (12) | 0.0029 (12) | −0.0063 (13) |
C47 | 0.0402 (17) | 0.0338 (16) | 0.0314 (15) | 0.0037 (13) | −0.0014 (13) | −0.0058 (12) |
C48 | 0.0452 (17) | 0.0360 (16) | 0.0246 (13) | 0.0072 (13) | 0.0104 (12) | 0.0008 (12) |
C49 | 0.0316 (14) | 0.0265 (14) | 0.0288 (13) | 0.0011 (11) | 0.0127 (11) | 0.0006 (11) |
C50A | 0.032 (5) | 0.076 (6) | 0.061 (5) | −0.003 (4) | 0.012 (4) | 0.014 (5) |
Cl5A | 0.084 (3) | 0.081 (3) | 0.069 (3) | 0.0022 (18) | 0.038 (3) | −0.006 (2) |
Cl5B | 0.087 (2) | 0.0419 (11) | 0.109 (2) | 0.0124 (12) | 0.0561 (19) | 0.0252 (12) |
Pd1—C2 | 2.123 (3) | C29—H29 | 0.9500 |
Pd1—C3 | 2.099 (3) | C30—H30 | 0.9500 |
Pd1—P12 | 2.3304 (7) | P31—C44 | 1.817 (3) |
Pd1—P31 | 2.3279 (7) | P31—C38 | 1.824 (3) |
C2—C6 | 1.441 (4) | P31—C32 | 1.828 (3) |
C2—C4 | 1.442 (4) | C32—C33 | 1.380 (4) |
C2—C3 | 1.488 (4) | C32—C37 | 1.395 (4) |
C3—C8 | 1.435 (4) | C33—C34 | 1.394 (4) |
C3—C10 | 1.445 (4) | C33—H33 | 0.9500 |
C4—N5 | 1.150 (4) | C34—C35 | 1.377 (5) |
C6—N7 | 1.145 (4) | C34—H34 | 0.9500 |
C8—N9 | 1.148 (4) | C35—C36 | 1.381 (5) |
C10—N11 | 1.146 (4) | C35—H35 | 0.9500 |
P12—C13 | 1.821 (3) | C36—C37 | 1.387 (4) |
P12—C25 | 1.824 (3) | C36—H36 | 0.9500 |
P12—C19 | 1.828 (3) | C37—H37 | 0.9500 |
C13—C14 | 1.388 (4) | C38—C43 | 1.389 (4) |
C13—C18 | 1.389 (4) | C38—C39 | 1.400 (4) |
C14—C15 | 1.383 (5) | C39—C40 | 1.385 (4) |
C14—H14 | 0.9500 | C39—H39 | 0.9500 |
C15—C16 | 1.392 (6) | C40—C41 | 1.391 (5) |
C15—H15 | 0.9500 | C40—H40 | 0.9500 |
C16—C17 | 1.372 (5) | C41—C42 | 1.392 (4) |
C16—H16 | 0.9500 | C41—H41 | 0.9500 |
C17—C18 | 1.390 (4) | C42—C43 | 1.386 (4) |
C17—H17 | 0.9500 | C42—H42 | 0.9500 |
C18—H18 | 0.9500 | C43—H43 | 0.9500 |
C19—C20 | 1.392 (4) | C44—C49 | 1.390 (4) |
C19—C24 | 1.392 (4) | C44—C45 | 1.397 (4) |
C20—C21 | 1.393 (4) | C45—C46 | 1.387 (4) |
C20—H20 | 0.9500 | C45—H45 | 0.9500 |
C21—C22 | 1.376 (4) | C46—C47 | 1.392 (5) |
C21—H21 | 0.9500 | C46—H46 | 0.9500 |
C22—C23 | 1.386 (4) | C47—C48 | 1.383 (5) |
C22—H22 | 0.9500 | C47—H47 | 0.9500 |
C23—C24 | 1.389 (4) | C48—C49 | 1.387 (4) |
C23—H23 | 0.9500 | C48—H48 | 0.9500 |
C24—H24 | 0.9500 | C49—H49 | 0.9500 |
C25—C30 | 1.388 (4) | C50A—Cl5A | 1.730 (7) |
C25—C26 | 1.399 (4) | C50A—Cl5B | 1.735 (7) |
C26—C27 | 1.386 (4) | C50A—H50A | 0.9900 |
C26—H26 | 0.9500 | C50A—H50B | 0.9900 |
C27—C28 | 1.386 (5) | C50B—Cl5D | 1.732 (10) |
C27—H27 | 0.9500 | C50B—Cl5C | 1.734 (10) |
C28—C29 | 1.382 (5) | C50B—H50C | 0.9900 |
C28—H28 | 0.9500 | C50B—H50D | 0.9900 |
C29—C30 | 1.397 (4) | ||
C2—Pd1—C3 | 41.26 (10) | C28—C29—H29 | 119.9 |
C2—Pd1—P12 | 105.18 (8) | C30—C29—H29 | 119.9 |
C2—Pd1—P31 | 146.60 (8) | C25—C30—C29 | 120.2 (3) |
C3—Pd1—P12 | 146.19 (8) | C25—C30—H30 | 119.9 |
C3—Pd1—P31 | 105.64 (7) | C29—C30—H30 | 119.9 |
P12—Pd1—P31 | 108.12 (2) | C44—P31—C38 | 104.46 (12) |
C6—C2—C4 | 115.3 (2) | C44—P31—C32 | 106.97 (12) |
C6—C2—C3 | 118.7 (2) | C38—P31—C32 | 104.53 (12) |
C4—C2—C3 | 116.7 (2) | C44—P31—Pd1 | 115.13 (9) |
C6—C2—Pd1 | 117.86 (19) | C38—P31—Pd1 | 110.66 (8) |
C4—C2—Pd1 | 111.46 (19) | C32—P31—Pd1 | 114.13 (9) |
C3—C2—Pd1 | 68.50 (14) | C33—C32—C37 | 119.3 (3) |
C8—C3—C10 | 116.8 (2) | C33—C32—P31 | 119.7 (2) |
C8—C3—C2 | 117.8 (2) | C37—C32—P31 | 121.0 (2) |
C10—C3—C2 | 118.0 (2) | C32—C33—C34 | 120.2 (3) |
C8—C3—Pd1 | 115.36 (18) | C32—C33—H33 | 119.9 |
C10—C3—Pd1 | 109.44 (18) | C34—C33—H33 | 119.9 |
C2—C3—Pd1 | 70.23 (14) | C35—C34—C33 | 120.2 (3) |
N5—C4—C2 | 177.3 (3) | C35—C34—H34 | 119.9 |
N7—C6—C2 | 179.1 (3) | C33—C34—H34 | 119.9 |
N9—C8—C3 | 177.0 (3) | C34—C35—C36 | 120.0 (3) |
N11—C10—C3 | 177.0 (3) | C34—C35—H35 | 120.0 |
C13—P12—C25 | 105.84 (13) | C36—C35—H35 | 120.0 |
C13—P12—C19 | 103.26 (12) | C35—C36—C37 | 120.1 (3) |
C25—P12—C19 | 102.94 (12) | C35—C36—H36 | 119.9 |
C13—P12—Pd1 | 107.52 (9) | C37—C36—H36 | 119.9 |
C25—P12—Pd1 | 111.15 (9) | C36—C37—C32 | 120.2 (3) |
C19—P12—Pd1 | 124.58 (9) | C36—C37—H37 | 119.9 |
C14—C13—C18 | 119.5 (3) | C32—C37—H37 | 119.9 |
C14—C13—P12 | 122.0 (2) | C43—C38—C39 | 118.6 (3) |
C18—C13—P12 | 118.4 (2) | C43—C38—P31 | 122.5 (2) |
C15—C14—C13 | 119.8 (3) | C39—C38—P31 | 118.7 (2) |
C15—C14—H14 | 120.1 | C40—C39—C38 | 120.5 (3) |
C13—C14—H14 | 120.1 | C40—C39—H39 | 119.7 |
C14—C15—C16 | 120.2 (3) | C38—C39—H39 | 119.7 |
C14—C15—H15 | 119.9 | C39—C40—C41 | 120.5 (3) |
C16—C15—H15 | 119.9 | C39—C40—H40 | 119.7 |
C17—C16—C15 | 120.2 (3) | C41—C40—H40 | 119.7 |
C17—C16—H16 | 119.9 | C40—C41—C42 | 119.1 (3) |
C15—C16—H16 | 119.9 | C40—C41—H41 | 120.4 |
C16—C17—C18 | 119.6 (3) | C42—C41—H41 | 120.4 |
C16—C17—H17 | 120.2 | C43—C42—C41 | 120.2 (3) |
C18—C17—H17 | 120.2 | C43—C42—H42 | 119.9 |
C13—C18—C17 | 120.5 (3) | C41—C42—H42 | 119.9 |
C13—C18—H18 | 119.8 | C42—C43—C38 | 121.0 (3) |
C17—C18—H18 | 119.8 | C42—C43—H43 | 119.5 |
C20—C19—C24 | 119.1 (2) | C38—C43—H43 | 119.5 |
C20—C19—P12 | 122.2 (2) | C49—C44—C45 | 119.4 (2) |
C24—C19—P12 | 118.6 (2) | C49—C44—P31 | 117.3 (2) |
C19—C20—C21 | 120.0 (3) | C45—C44—P31 | 123.3 (2) |
C19—C20—H20 | 120.0 | C46—C45—C44 | 119.9 (3) |
C21—C20—H20 | 120.0 | C46—C45—H45 | 120.0 |
C22—C21—C20 | 120.3 (3) | C44—C45—H45 | 120.0 |
C22—C21—H21 | 119.9 | C45—C46—C47 | 120.1 (3) |
C20—C21—H21 | 119.9 | C45—C46—H46 | 119.9 |
C21—C22—C23 | 120.3 (3) | C47—C46—H46 | 119.9 |
C21—C22—H22 | 119.8 | C48—C47—C46 | 120.1 (3) |
C23—C22—H22 | 119.8 | C48—C47—H47 | 120.0 |
C22—C23—C24 | 119.6 (3) | C46—C47—H47 | 120.0 |
C22—C23—H23 | 120.2 | C47—C48—C49 | 119.9 (3) |
C24—C23—H23 | 120.2 | C47—C48—H48 | 120.1 |
C23—C24—C19 | 120.6 (3) | C49—C48—H48 | 120.1 |
C23—C24—H24 | 119.7 | C48—C49—C44 | 120.6 (3) |
C19—C24—H24 | 119.7 | C48—C49—H49 | 119.7 |
C30—C25—C26 | 119.2 (3) | C44—C49—H49 | 119.7 |
C30—C25—P12 | 120.1 (2) | Cl5A—C50A—Cl5B | 112.3 (5) |
C26—C25—P12 | 120.7 (2) | Cl5A—C50A—H50A | 109.1 |
C27—C26—C25 | 120.5 (3) | Cl5B—C50A—H50A | 109.1 |
C27—C26—H26 | 119.8 | Cl5A—C50A—H50B | 109.1 |
C25—C26—H26 | 119.8 | Cl5B—C50A—H50B | 109.1 |
C26—C27—C28 | 120.0 (3) | H50A—C50A—H50B | 107.9 |
C26—C27—H27 | 120.0 | Cl5D—C50B—Cl5C | 112.8 (8) |
C28—C27—H27 | 120.0 | Cl5D—C50B—H50C | 109.0 |
C29—C28—C27 | 120.0 (3) | Cl5C—C50B—H50C | 109.0 |
C29—C28—H28 | 120.0 | Cl5D—C50B—H50D | 109.0 |
C27—C28—H28 | 120.0 | Cl5C—C50B—H50D | 109.0 |
C28—C29—C30 | 120.1 (3) | H50C—C50B—H50D | 107.8 |
Experimental details
Crystal data | |
Chemical formula | [Pd(C6N4)(C18H15P)2]·0.7CH2Cl2 |
Mr | 818.49 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 150 |
a, b, c (Å) | 10.3363 (1), 37.2805 (4), 10.8142 (1) |
β (°) | 111.1463 (7) |
V (Å3) | 3886.57 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.69 |
Crystal size (mm) | 0.50 × 0.40 × 0.13 |
Data collection | |
Diffractometer | Nonius KappaCCD area-detector |
Absorption correction | Multi-scan (SORTAV; Blessing, 1995) |
Tmin, Tmax | 0.724, 0.916 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 29108, 8877, 7450 |
Rint | 0.053 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.039, 0.110, 1.02 |
No. of reflections | 8877 |
No. of parameters | 482 |
No. of restraints | 6 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.75, −0.80 |
Computer programs: COLLECT (Nonius, 1999), DENZO–SMN (Otwinowski & Minor, 1997), DENZO–SMN, SHELXS97 (Sheldrick, 1997a), SHELXL97 (Sheldrick, 1997b), ORTEX (McArdle, 1995), local program.
Pd1—C2 | 2.123 (3) | Pd1—P12 | 2.3304 (7) |
Pd1—C3 | 2.099 (3) | Pd1—P31 | 2.3279 (7) |
C2—Pd1—C3 | 41.26 (10) | C3—Pd1—P12 | 146.19 (8) |
C2—Pd1—P12 | 105.18 (8) | C3—Pd1—P31 | 105.64 (7) |
C2—Pd1—P31 | 146.60 (8) | P12—Pd1—P31 | 108.12 (2) |
C—H···N | C—H | H···N | C···N | C—H···N | H···N≡C |
C23v—H23v···N5 | 0.95 | 2.54 | 3.400 (4) | 151 | 150 |
C40vi—H40vi···N9 | 0.95 | 2.49 | 3.436 (4) | 178 | 106 |
Symmetry codes: (v) 1+x, y, z; (vi) x, 0.5-y, -0.5+z. |
Tetracyanoethene (tcne) is a highly electron-deficient alkene that has found use both as a ligand in transition-metal chemistry (Kaim & Moscherosch, 1994) and as an electron acceptor in intermolecular charge-transfer complexes (Schneider & Mohammad-Ali, 1996). It can coordinate to metal atoms or ions through its N-donors (σ-coordination) or through its C═C double bond (π-coordination) and, particularly when π-bound, is one of the strongest π-acceptor ligands known (Kaim & Moscherosch, 1994). One of the first π-coordinated tcne complexes to be synthesized was [Pd(PPh3)2(tcne)] (Fitton & McKeon, 1968), although this was not crystallographically characterized at the time. We now report the structure analysis of a 0.7-solvate of [Pd(PPh3)2(tcne)], (I).
The asymmetric unit of (I) contains one bis(η2-tetracyanoethene)(triphenylphosphine)palladium molecule in a general position (Fig. 1) and a CH2Cl2 molecule disordered over two orientations whose occupancies sum to 0.70. The tcne ligand is π-bound to the Pd atom, as expected. The two Pd—P bond lengths in (I) are equal within standard uncertainties, while the three angles P12—Pd1—P31 [108.12 (2)°], P12—Pd1—X [125.6 (3)°] and P31—Pd1—X [126.3 (3)°], where X is the centre of the C2═C3 bond, sum to exactly 360°, confirming the planarity at the Pd centre. Hence, the Pd centre can be thought of as having a coordination geometry which, if the tcne ligand is deemed to occupy one coordination site, corresponds to an almost perfect isoceles triangle. However, the tcne ligand is twisted slightly out of this trigonal plane, the dihedral angle between the Pd1/P12/P31 and Pd1/C2/C3 planes being 6.3 (2)°. This distortion is also reflected in the C—C—Pd angles involving the four cyano groups of the tcne moiety, in that the angle C6—C2—Pd1 is 6.4 (3)° wider than C4—C2—Pd1, and C8—C3—Pd1 is 5.9 (3)° wider than C10—C3—Pd1. These distortions might be attributed to intramolecular steric contacts between the cyano groups and the faces of phenyl substituents in the molecule, as illustrated by the following distances: C4···C13 = 3.468 (4), N5···C18 = 3.471 (4), N7···C30 = 3.449 (4), C8···C38 = 3.382 (4) and C10···C39 = 3.315 (4) Å. Since the radius of a C atom participating in a π-bond is 1.70 Å (Pauling, 1960), these distances place these cyano groups and their adjacent phenyl rings within the sum of the relevant van der Waals radii. There are also some close intermolecular N···C distances that might similarly influence the geometry of the tcne ligand, notably N7···C21i = 3.434 (4), N9···C40ii = 3.436 (4), N9···C46iii = 3.243 (4) and N11···C22iv = 3.408 (4) Å [symmetry codes: (i) -1 + x, y, -1 + z; (ii) x, 0.5 - y, 0.5 + z; (iii) 1 + x, 0.5 - y, 0.5 + z; (iv) 1 + x, y, 1 + z]. Related distortions of the tcne framework are also present in other Pd/tcne complexes containing aryl phosphine co-ligands (Kranenburg et al., 1997; Mashima et al., 1998).
The degree of charge transfer from the Pd atom to the tcne ligand in (I) is evident in two parameters (Kaim & Moscherosch, 1994). First, the C2═C3 bond length of 1.488 (4) Å is substantially longer than in uncoordinated tcne [1.328 (5) and 1.344 (3) Å in the monoclinic (Chaplot et al., 1991) and cubic (Little et al., 1971) phases of this compound, respectively]. Second, the coordinated alkene C atoms in (I) are significantly pyramidalized. This is evidenced both by the C—C—C bond angles at the tcne ligand, which lie between 115.3 (2) and 118.0 (2)°, compared to 120° in free tcne, and by the dihedral angle of 56.34 (16)° between the least-squares planes formed by the two C(CN)2 fragments (C2/C4/C6/N5/N7 and C3/C8/C10/N9/N11) of the tcne ligand. This angle is 0° in the uncoordinated alkene. Both these parameters are within the ranges previously observed in other Pd–tcne complexes (Zagorodnikov et al., 1989; Tsubouchi et al., 1994; Kranenburg et al., 1997; Mashima et al., 1998; van Belzen et al., 1998; Canovese et al., 2000) and indicate partial rehybridization of the alkene C═C bond caused by substantial Pd → tcne back-donation into the tcne π* orbitals.
The molecular structure of (I) is visually indistinguishable from that of its Pt analogue [Pt(PPh3)2(tcne)] (Bombieri et al., 1970), and the metal–carbon distances in the two compounds are not signifcantly different. However, the Pd—P bonds in (I) are 0.039 (9)–0.041 (8) Å longer than those in the Pt compound, presumably reflecting improved back-bonding between the phosphine ligands and the Pt 5 d orbitals, as opposed to the Pd 4 d orbitals. The low precision of the structure analysis on the Pt complex prevents any more detailed comparison of the two compounds.
There are two intermolecular N···H contacts of ca 2.5 Å in (I), which are within the sum of the van der Waals radii of H (1.2 Å) and N (1.5 Å) (Pauling, 1960) and so could correspond to weak C—H···N interactions (Table 2). There are no other noteworthy intermolecular interactions in the lattice.