A study on the stabilisation of phosphorus (V) stabilised lanthanide carbenes and other di-λ 5σ 4 -phosphorane lanthanide complexes

Abstract

The synthesis, stabilisation and characterisation of various lanthanide complexes of isoelectronic di-λ5 σ4-phosphorane ligands was attempted. These isoelectronic di-λ5 σ4-phosphorane ligands are divided into the carbene and non-carbene groups where the central moieties of the ligands are C2- for the former and Nand O for the latter group. Lanthanide complexation proved difficult in most cases however the study did yield interesting novel results. Two novel crystal structures for the non-carbene precursor di-λ5 σ4-phosphorane ligands HN(Ph2PO)2 and O((iPrNH)2PO)2 have been structurally characterised through PXRD and SXRD respectively and chemically through IR, 1H and 31P NMR and GC-MS. A novel complex for O((Et2N)2PO)2 namely Ca2(O((Et2N)2PO)2)2(NO3)4(H2O)2 was characterised by SXRD from serendipitously collected crystals. PXRD data for K[HC(Ph2PNiPr)2], which has not been previously structurally characterised, was collected. IR, 1H NMR and PXRD data for an as of yet unknown complex of HN(Ph2PS)2 with hydrated Eu(ClO4)3 was also collected and characterisation is also being undertaken. Stabilisation studies were undertaken using co-crystallisation techniques. These co-crystallisation studies dealt mainly with amorphous products of the synthesis of [Sm(C(Ph2PNSiMe3)2)(NCy2)(THF)] which were believed to principally contain methanide analogues of the desired carbene. The co-crystallisation studies indicated that co-crystallisation was difficult to achieve and that its use in stabilisation is limited.