STEREOCHEMICALLY NONRIGID TRANSITION-METAL COMPLEXES OF 2,6-BIS[(1-PHENYLIMINO)ETHYL]PYRIDINE (BIP) .1. DYNAMIC NMR-STUDIES OF [M(C6F5)(2)(BIP)] (M=PD-II OR PT-II)

The complexes [M(C6F5)(2)(BIP)] (M = Pd-II or Pt-II, 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(C6F5)(2) moiety, E,Z isomerisation of the pendant imine bond, and restricted C-C rotation of the pendant portion of the BIP ligand. H-1 and F-19 dynamic NMR studies yielded ac tivation energies for these three types of fluxion. Delta G(not equal) (298K) Values for the three processes were 89.6, 86.6 and 47.4 kJ mol( -1) respectively for the Pt-II complex. Values for the Pd-II complex w ere significantly lower in magnitude, namely 71.6, 70.4 and 41.8 kJ mo l(-1) respectively.