The Synthesis, Structure and Solution and Gas Phase Properties of Complexes of Scandium and Lanthanide Triflates with the phosphine oxide ligands PhP(O)(C2H4P(O)Ph2)2 and P(O)(C2H4P(O)Ph2)3

The synthesis and structures of complexes of PhP(O)(C2H4POPh2)2, L1, and P(O)(C2H4POPh2)3, L2, respectively, with scandium and lanthanide triflates are described. Single crystal x-ray structures of complexes of the octahedral [ScL13](OTf)3, dodecahedral [Nd(OTf)(H2O)(L1)2](OTf)2 and [Ln(OTf)(H2O)(L2)2](OTf)2 (Ln = La, Gd), and the dimeric [{Er(OTf)2(H2O)(−L2)}2](OTf)2 and [{Er(OTf)2(EtOH)(−L2)}2](OTf)2, which have distorted pentagonal bipyramidal geometry around Er, have been determined. The solution properties of the complexes have been investigated by 19F and 31P NMR spectroscopy which show that the complexes of L1 are fluxional with exchange of inequivalent coordinated Ph2PO groups in solution. Complexes of L2 show the same process and exchange between coordinated and pendant arms of the ligand. The stability in the gas phase has been investigated by electrospray mass spectrometry (ESMS) and tandem ESMS where, in addition to loss of triflate, L1 and L2, loss of diphenylphosphine oxide and Ph2POC2H4OSO2CF3 are shown to be significant decomposition pathways for complexes of both ligands. A brief study of the catalytic properties of a range of complexes shows that the alkenylation of 1,4-dimethoxybenzene with phenylacetylene in nitromethane does not occur at 80oC for complexes of L1 or L2.