Stereochemically non-rigid transition metal complexes of2,6-bis[(1-phenylimino) ethyl]pyridine (BIP)Part 1. Dynamic NMR studies of[M( C6F 5) 2(BIP)] (M = Pd II or Pt II)

The complexes [M(C6Fs)2(BIP)] (M = Pd n or Pt n, BIP = 2,6-bis[(1-phenylimino)ethyl]pyridine) have been synthesised and characterisedas involving BIP as a bidentate chelate ligand. In solution they undergo 1,4 metallotropic shifts of the M(C~Fs) z moiety, E,Zisomerisation of the pendant imine bond, and restricted C-C rotation of the pendant portion of the BIP ligand. 1H and 9F dynamic NMRstudies yielded activation energies for these three types of fluxion. AG* (298 K) values for the three processes were 89.6, 86.6 and47.4kJmol 1 respectively for the Pt rt complex. Values for the Pd II complex were significantly lower in magnitude, namely 71.6, 70.4and 41.8 kJ mol- 1 respectively.