Dynamic behaviour of carbon-metallated palladium hydrazone complexes. Crystal structures of [{Pd[CH2CMe2C(N–NMePh)Me]Cl}2] and [{Pd[CH2C(N–NMePh)But]Cl}2]

Abstract

The carbon-palladated species [{[graphic omitted]–NMePh)Me]Cl}₂](1a) and [{[graphic omitted]MePh)Bu^t]Cl}₂](2) have in the solid state a trans geometry and are planar; their crystal structures have been determined by X-ray methods. These species, as well as the bromo- and iodo-derivatives of (1a) and the complex [{[graphic omitted]Me₂)Bu^t]Cl}₂], exhibit temperature-dependent n.m.r. spectra which have been interpreted on the basis of cis–trans isomerization of the complexes and of hindered rotation about the N–N single bond of the hydrazone. The latter process is also present in the mononuclear species obtained from (1a) by bridge-splitting reactions with triphenylphosphine, pyridine, and acetylacetonate. Crystals of (1a) are triclinic, space group P, a= 10.642(8), b= 11.793(9), c= 6.269(6)Å, α= 98.05(6), β= 97.46(6), γ= 111.91(7)°, and Z= 1. Crystals of (2) are monoclinic, space group P2₁/a, a= 24.059(12), b= 10.035(8), c= 6.018(5)Å, β= 95.39(5)°, and Z= 2.