ALKYL GROUP ISOMERIZATION STUDIES WITH UNUSUALLY STABLE ALKYLMETAL COMPLEXES OF PALLADIUM AND PLATINUM - SECONDARY PRIMARY ALKYL ISOMERIZATION EQUILIBRIA IN THE ABSENCE OF STERIC INFLUENCES FROM ANCILLARY LIGANDS

The unusually stable palladium(II) and platinum(II)derivatives [R2NCS2] M(PR’3)(alkyl) (R = Me, Et; R’ = Et, Ph) undergo Isomerization of the alkyl ligand when heated (Pt, 120 °C; Pd, 75 °C) in solution. For primary/secondary alkyl pairs (alkyl = n-propyl/isopropyl, n-butyl/sec-butyl) the positions of the isomerization equilibria are similar, 9/1.0 for platinum and 10/1.0 for palladium. This 1.6-1.7 kcal/mol free energy difference between the isomers represents the bond energy difference of primary versus secondary alkylmetal complexes in the absence of steric constraints imposed by other ligands in the coordination sphere. © 1990, American Chemical Society. All rights reserved.