metal-organic compounds m136 # 2003 International Union of Crystallography DOI: 10.1107/S010827010300458X Acta Cryst. (2003). C59, m136–m138 (g 2 -Tetracyanoethene)bis(triphenyl- phosphine-jP)palladium–dichloro- methane (1/0.7) Zoe Shackleton, Colin A. Kilner, Gavin D. Reid and Malcolm A. Halcrow* Department of Chemistry, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, England Correspondence e-mail: m.a.halcrow@chem.leeds.ac.uk Received 7 February 2003 Accepted 26 February 2003 Online 21 March 2003 The title compound, [Pd(C 6 N 4 )(C 18 H 15 P) 2 ]0.7CH 2 Cl 2 , shows a planar coordination geometry around the metal atom that is an almost perfect isosceles triangle if the tetracyanoethene (tcne) ligand is deemed to occupy a single coordination site. The framework of the tcne ligand shows small distortions due to intramolecular steric contacts between the C N groups and phenyl rings of the triphenylphosphine ligands. Comment 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 (-coordination) or through its C C double bond (-coordination) and, parti- cularly when -bound, is one of the strongest -acceptor ligands known (Kaim & Moscherosch, 1994). One of the first -coordinated tcne complexes to be synthesized was [Pd- (PPh 3 ) 2 (tcne)] (Fitton & McKeon, 1968), although this was not crystallographically characterized at the time. We now report the structure analysis of the 0.7-solvate of [Pd(PPh 3 ) 2 - (tcne)], (I). The asymmetric unit of (I) contains one ( 2 -tetracyano- ethene)bis(triphenylphosphine)palladium molecule in a general position (Fig. 1) and a CH 2 Cl 2 molecule disordered over two orientations whose occupancies sum to 0.70. The tcne ligand is -bound to the Pd atom, as expected. The two Pd—P bond lengths in (I) are equal within standard uncer- tainties, 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 isosceles 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 C6—C2—Pd1 angle 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 the phenyl substituents in the molecule, as illu- strated 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) A ˚ . Since the radius of a C atom participating in a -bond is 1.70 A ˚ (Pauling, 1960), these distances place the 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C21 i = 3.434 (4), N9C40 ii = 3.436 (4), N9C46 iii = 3.243 (4) and N11C22 iv = 3.408 (4) A ˚ [symmetry codes: (i) 1+ x, y, 1+ z; (ii) x, 1 2  y, 1 2 + z; (iii) 1 + x, 1 2  y, 1 2 + 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 & Moscher- Acta Crystallographica Section C Crystal Structure Communications ISSN 0108-2701 Figure 1 The molecular structure of the [Pd(PPh 3 ) 2 (tcne)] molecule in (I), showing the atom-numbering scheme and 50% probability displacement ellip- soids. H atoms have been omitted for clarity.