Stereochemically non-rigid transition metal complexes of 2,6-bis[(1-phenylimino) ethyl]pyridine (BIP) part 1. Dynamic NMR studies of [M(C6F5) 2(BIP)] (M = PdII or PtII)

Abstract

The complexes [M(C6F5)2(BIP)] (M = PdII or PtII, BIP = 2,6-bis[(1-phenylimino)ethyl]pyridine) have been synthesised and characterised as involving BIP as a bidentate chelate ligand. In solution they undergo 1,4 metallotropic shifts of the M(C6 F5)2 moiety, E,Z isomerisation of the pendant imine bond, and restricted C-C rotation of the pendant portion of the BIP ligand. 1H and 19F dynamic NMR studies yielded activation energies for these three types of fluxion. ΔG≠ (298 K) values for the three processes were 89.6, 86.6 and 47.4kJmol−1 respectively for the PtII complex. Values for the PdII complex were significantly lower in magnitude, namely 71.6, 70.4 and 41.8 kJ mol−1 respectively.