Stereochemical nonrigidity of the square complex (PPh3)2Pt(HgGePh3)(GePh3)

Abstract 31 P, 195 Pt and 199 Hg NMR spectra of complex (PPh 3 ) 2 Pt(HgGePh 3 )(GePh 3 ) (I) have been studied. The spectra at temperatures below −40°C prove that ( I ) is a cis -isomer with the square-planar coordination of the Pt atom. The reversibility of temperature dependences of spectra, insensitivity of line shape to the solvent, concentration and presence of free phosphine establish the fluxional behaviour of ( I ). The activation parameters of the intramolecular rearrangement which is realized, most probably, through a digonal twist, are: Δ ≠ 298 = 51.5 ± 2.9 kJ/mol, ΔH ≠ = 59.3 ± 2.9 kJ/mol, ΔS ≠ = 26.2 ± 9.7 J/mol. K.