Platinum(II) and Palladium(II) Dichalcogenolene Complexes Containing the Ligand Tri(1-cyclohepta-2,4,6-trienyl)phosphane. Molecular Structure, Intramolecular Dynamics in Solution, and the Absolute Signs of Coupling Constants 1J(195Pt, 77Se) and 2J(77Se, Pt, 31P)

Abstract

Tri(1-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7)3 (1), serves as a bidentate chelatinglig and [P] in platinum(II) and palladium(II) complexes. Here the synthesis of the four dichalcogenolene complexes [P]M[E2C2(CO2Me)2] (4) (M = Pt) and 5 (M = Pd) with E = S (a) and Se (b) from the reaction of the respective dicyclopentadienyltitanium dichalcogenolenes, Cp2Ti[E2C2(CO2Me)2], and [P]MCl2 with M = Pt (2) and Pd (3) is reported. At room temperature, the complexes 4 and 5 are fluxional with respect to the NMR time scale, and the nature of the dynamic process is discussed. The complexes have been characterised by 1H, 13C, 31P, 77Se and 195Pt NMR spectroscopy. The signs of the coupling constants 1J(195Pt, 77Se) (< 0) and 2J(77Se, 31P) (> 0) were obtained by selective 31P{195Pt} and 31P{77Se} spin tickling experiments. The crystal structure of 4b was determined by X-ray analysis.