Bis(imino)pyridyl iron and cobalt complexes: the effect of nitrogen substituents on ethylene oligomerisation and polymerisation - Britovsek,GJP; Gibson,VC; Kimberley,BS; Mastroianni,S; Redshaw,C; Solan,GA; White,AJP; Williams,DJ (JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 2001)