Diphosphine dioxide complexes of lanthanum and lutetium – The effects of ligand architecture and counter-anion

Abstract

The reaction of bis(diphenylphosphino)methane dioxide (dppmO2) with LaCl3, LaI3 or LaCl3/[NH4][PF6] produces [La(dppmO2)4]Y3 (Y=Cl, I, PF6) which contain eight-coordinate, distorted square antiprismatic cations. In contrast, LaCl3 or LaCl3/[NH4][PF6] and 1,2-bis(diphenylphosphino)ethane dioxide (dppeO2) produce the polymer [LaCl3(dppeO2)1.5]n, which has a six-coordinate La centre with three mer-chlorides and three Ph2P(O)CH2-donors from three different diphosphine dioxide ligands. The bulkier 1,2-bis(diphenylphosphino)benzene dioxide (PPO2) forms [LaCl2(PPO2)2(H2O)2]Cl and [LaCl2(PPO2)2(H2O)2][PF6], which contain eight-coordinate La, and also the seven-coordinate [LaCl(PPO2)3][PF6]2. The smaller lutetium ion favours six-coordination in [LuCl2(dppmO2)2]Cl, [LuI2(dppmO2)2]I, [LuCl(dppmO2)2(H2O)][PF6]2·2H2O, [LuCl2(PPO2)2]Cl, [LuI2(PPO2)2]I and [Lu(PPO2)2(H2O)2][PF6]3. All complexes were characterised by microanalysis, IR, 1H and 31P{1H} NMR spectroscopy. X-ray crystal structures are reported for [La(dppmO2)4]Y3 (Y=I, PF6), [LaCl3(dppeO2)1.5]n, [LaCl2(PPO2)2(H2O)(EtOH)]Cl and [LaCl(PPO2)3][PF6]2.