Investigations into cerium(III) and cerium(IV) nitrate complexes with tris-1-naphthylyphosphine oxide and bis-1-naphthlyalklyphosphine oxides

The reaction between ammonium cerium(IV) nitrate (CAN) and tris-1-naphthylphosphine oxide (Nap 3 PO, L 1 ), bis-1-naphthylmethlyphosphine oxide (Nap 2 MePO, L 2 ) and bis-1-naphthylethlyphosphine oxide (Nap 2 EtPO, L 3 ) have been investigated. The 31 P NMR spectra show that complex formation occurs readily in CD 3 CN solution and more slowly in CDCl 3 . Isolation of bulk Ce(IV) complexes was difficult due to decomposition to Ce(III) during crystallisation. The Ce(IV) complexes can be characterised in solution by multinuclear NMR ( 1 H, 13 C and 31 P) spectroscopy and show that decomposition to Ce(III) occurs in CD 3 CN with Ce(IV) being more stable in CDCl 3 . The structures of the ligands Nap 2 MePO and Nap 2 EtPO and the complexes [Ce(NO 3 ) 3 (Nap 2 MePO) 3 ], [Ce(NO 3 ) 3 (Nap 2 EtPO) 3 ] and [Ce(NO 3 ) 4 (Nap 2 EtPO) 2 ] have been determined. Ce(IV) solutions undergo reduction to Ce(III) during the electrospray ionisation mass spectra process. The tandem mass spectra of [Ce(NO 3 ) 2 L n ] + show that loss of ligand is favoured for for high values of n whilst for n = 2 loss of NO 2 generating Ce(IV) oxo complexes is increasingly important. • Identification of Ce(IV) nitrate complexes in solution. • Structural characterisation of Ce(III) and Ce(IV) complexes. • Identification of fragmentation pathways producing Ce(IV) in the gas phase.