SYNTHESIS OF EXTREMELY STABLE ALKYLPALLADIUM COMPLEXES OF THE TYPE (ME2NCS2)PD(PET3)(ALKYL) - CRYSTAL AND MOLECULAR-STRUCTURES OF THE ISOMERS (CH2CH2CH2CH2NCS2)PD(PET3)(NORMAL-PROPYL) AND (CH2CH2CH2CH2NCS2)PD(PET3)(ISOPROPYL)

The reaction of (R2NCS2)Pd(PEt3)Cl (R = Me, R2 = -(CH2)4-) with alkyllithium or Grignard reagents leads to the preparation of (R2NCS2)Pd(PEt3)(alkyl) (alkyl = methyl, n-propyl, isopropyl, n-butyl, sec-butyl) complexes. These alkylpalladium complexes can be heated in solution at 60-degrees-C without decomposition and thus appear to be the most thermally stable complexes containing an acyclic alkyl ligand with beta-hydrogen atoms to be reported for this metal. The solid-state structures of (activated CH2CH2CH2CH2NCS2)Pd(PEt3)(n-propyl) (1) and (activated CH2CH2CH2CH2NCS2)Pd(PEt3)(isopropyl) (2) have been determined by X-ray crystallography. Crystal data: 1, monoclinic, P2(1)/n, a = 8.227 (2) angstrom, b = 17.807 (4) angstrom, c = 13.299 (3) angstrom, beta = 96.60 (2)-degrees, V = 1948 angstrom 3, Z = 4, R(F) = 3.4%, and R(wF) = 4.5%; 2, monoclinic, P2(1)/n, a = 11.021 (3) angstrom, b = 17.836 (5) angstrom, c = 9.694 (3) angstrom, beta = 94.81 (2)-degrees, V = 1906 angstrom 3, Z = 4, R(F) = 2.8%, and R(wF) = 3.5%. The square-planar geometry of each complex is very similar. The main difference in the two structures is the longer Pd-S distance trans to the alkyl ligand in 2 indicating a greater trans influence for the isopropyl ligand. There are minimal intramolecular steric contacts between the alkyl ligand and the ancillary ligands, even for the bulkier isopropyl ligand.