Unusual coordination behaviour of the ferrocenyl-terpyridine ligand with group 11 complexes

Abstract

Complexes of the ligand Fcterpy (Fcterpy = 4′-ferrocenyl-2,2′:6′,2′-terpyridine) with group 11 metals display different coordination modes. The reaction with complexes [Cu(NO3)(PPh3)2] or [M(OTf)(PR3)] (OTf = trifluoromethyl sulphonate) gives the species [M(Fcterpy)(PR3)]X (M = Cu, X = PF6, PR3 = PPh3 (1); M = Ag, X = OTf, PR3 = PPh3 (2), PPh2Me (3); M = Au, X = OTf, PR3 = PPh3 (4)) in which the ligand is coordinated as a tridentate chelate to the metal. Treatment with [Cu(NCMe)4]PF6 or Ag(OTf) in 1:1 molar ratio gives the dinuclear complexes [M2(Fcterpy)2]X2 (M = Cu (5), Ag (6)), in which the ligand is tetradentate because the central pyridine group is bonded to two metals. The reaction with the gold(I) complex [Au(C6F5)(tht)] (tht = tetrahydrothiophene) leads to the first example of a terpyridine ligand bonded to three metal atoms, [Au3(C6F5)3(Fcterpy)] (7); in the product of the corresponding reaction with the gold(III) derivative [Au(C6F5)3(OEt2)] to give [Au(C6F5)3(Fcterpy)] (8), the ligand is monodentate, which is also unusual for a terpyridine ligand.Key words: copper, silver, gold, terpyridine, ferrocene derivatives