ASYMMETRICALLY BONDED ? LIGANDS I. HINGING AWAY FROM METAL OF SUBSTITUTED ALLYLS: SYNTHESES OF 1-syn-METHYL AND -PHENYL COMPLEXES, AND THE MOLECULAR STRUCTURES OF ((η-1-Ph-C3H4)Pd(tmeda))BF4, ((η-C5H5)Pd(η-1-Ph-C3H4)), AND ((phen)Mo(CO)2(NCS)(η-1-Ph-C3H4)) AT 185 K

Article abstract of DOI:10.1016/0022-328X(86)82060-5

Seven new complexes of (η-1-Me-C3H4) and (η-1-Ph-C3H4) with symmetric metal ligand backbones have been synthesised and spectroscopically characterised.Crystals of three of them, ((η-1-Ph-C3H4)Pd(tmeda))BF4 (4), ((η-C5H5)Pd(η-1-Ph-C3H4)) (5), and ((phen)Mo(CO)2(NCS)(η-1-Ph-C3H4)) (8), were suitable for X-ray diffraction studies. 4 is orthorhombic, Pca2₁, with four ion pairs in a cell of dimensions a 11.326(4), b 16.048(5) and c 9.950(3) angstroem.Using 4431 data measured at 185 K, R converged at 0.0311.Crystals of 5 are monoclinic, P2₁/c, with a 14.2255(19), b 5.8203(11), c 13.837(5) angstroem and β 91.287(21) deg at 185 K, Z=4. 3064 amplitudes have been used to afford R=0.0267. for 8 the monoclinic cell is a 15.658(4), b 9.473(3), c 15.666(6) angstroem, and β 113.95(3) deg, P2₁/a, Z=4.Low temperature (185 K) data were collected, and 3734 used to refine the structure to R=0.0362.The molecular structures of 4,5, and 8 all reveal an η-1-syn-Ph-C3H4 ligand that is asymmetrically bonded to the metal atom, such that M-C(1) > M-C(3).Analysis of intra- and intermolecular contacts strongly suggests that, at least for 5, the distortion in the metal-allyl bonding is electronic in origin.