FORMATION, REACTIONS, AND SOLUTION DYNAMICS OF [M(ETA-1-C5H4R)(C6H4-2-X)(PET3)2] (M = PD, PT)

Reactions of [M(η5-C5H4R)(C6H4-2-X)] (M = Pd, R = H, Me, SiMe3, X = N=NPh or R = H, X = CH=NMe, 2-C5H4N; M = Pt, R = H, SiMe3, X = N=NPh) with PEt3 in toluene solution produce the adducts [Pd[M(η5-C5H4R)(C6H4-2-X)] (PEt3)] and trans-[M(η1-C5H4R)(C6H4-2-X)] (PEt3)2] but none of the ionic [M(C6H4-2-X)(PEt3)3]+C5H4R- found in halogenated solvents. Instead, the reactive intermediates cis[M(η1-C5H4R)(C6H4-2-X)] (PEt3)2] are detected at -80 °C, but these isomerize as the temperature is raised. The fluxional η1-C5H4R groups of trans-[M(η1-C5H4R)(C6H4-2-X)] (PEt3)2] undergo rapid rotation about the M-C bonds at ambient temperature, resulting in apparent magnetic equivalence of the PEt3 groups. At temperatures around -90 °C bond rotation is slowed sufficiently to allow detection of the nonequivalent P atoms by NMR spectroscopy. The palladium complexes decompose slowly at 25 °C, but the platinum species isomerize readily to sp2-carbon-bonded vinylic cyclopentadienyl derivatives. At low temperatures the effects of restricted rotation about the Pt-C bonds of the vinylic cyclopentadienyl compounds can be deduced from the detection of syn and anti rotational isomers in solution. © 1990, American Chemical Society. All rights reserved.