MOLECULAR-STRUCTURES OF MIXED-LIGAND PALLADIUM(II) AND PLATINUM(II) ALKYL COMPLEXES, INCLUDING 3 ISOMORPHOUS COMPOUNDS

The crystal structures of the complexes [PdMe(beta-dik) (PPh3)] [beta-dik = acetylacetonate (acac) or monothioacetylacetonate (sacac)] and [PtEt(beta-dik)(PPh3)] have been determined. All four complexes crystallize in the triclinic space group P1BAR with two molecules in the unit cell. They have a slightly distorted square-planar geometry. For the pair of acac complexes O(1)-Pd-O(2) 88.8(2), 0(l)-Pt-O(2) 89.2(2), C(O)-Pd-P 88.3(2) and C(O)-Pt-P 92.7(2)-degrees; Pd-C 2.003(9), Pt-C 2.013(9), Pd-P 2.209(2) and Pt-P 2.182(2) angstrom. For the two sacac complexes, S(1)-Pd-0(2) 91.35(9), S(l)-Pt-0(2) 91.59(9), C(O)-Pd-S(l) 86.4(2) and C(O)-Pt-S(1) 86.8(1)-degrees; Pd-C 2.033(7), Pt-C 2.058(6) angstrom, Pd-P 2.274(l) and Pt-P 2.247(1) angstrom. Comparison of the M-C bonds in the structures shows a slight lengthening in complexes containing the sacac ligand, consistent with the previously observed enhanced carbonylation activity of the platinum sacac complex over that of the analogous acac compound. A comparison of M-P bonds reveals that those of Pt are consistently shorter than those of Pd, in agreement with proposed relative bond strengths.