(The) coordination and organometallic chemistry of tridentate oxygen ligand, trimetaphosphate

Abstract

Tridentate oxygen ligand, trimetaphosphate, P$_3$O$_9^{3-}$ is expected to give opportunity for declocalization of the d electron density of metal ions coordinated to it via the P=O bridges, and consequently to be quite effective at stabilizing metal ions in their middle and high oxidation states. Also, because it has flexibility of its six-menbered ring, it is expected to show diverse reactivity with various bonding aspects. In spite of expectation, to date, a few metal complexes of trimetaphosphate have been reported and properties of this ligand are rarely known. In this dissertation, the new trimetaphosphate complexes were synthesized and the full characterization including the molecular structure analyses and the physical property measurements were carried out. From above experimental results, the properties of this ligand were characterized. First of all, homoleptic sandwich complexes of 3d transition metal, group 12 heavy metal and main group element, [M(P$_3$O$_9$)$_2$](NEt$_4$)$_\text{N}$ (n=4, M = Co(1), Ni(2), Cu(3), Mn(4), Fe(5), Zn(6), Cd(7), Hg(8); n=3, M = Fe(9), V(10), In(14)) were prepared from the reaction system of 2P$_3$O$_9$(TBA)$_3\cdot$2.5H$_2$O, [MCl$_4$](NEt$_4$)$_{n-2}$ and 2NEt$_4$Cl. Heteroleptic mixed sandwich complexes with [{HB(3,5-Me$_2$pz)$_3$}M(P$_3$O$_9$)](TBA) (M = V(11),In(15)) were synthesized from the reaction system of P$_3$O$_9$(TBA)$_3\cdot$2.5H$_2$O and [{HB(3,5-Me$_2$pz)$_3$}MCl$_2$(solv)] (M = V, solv=DMF; M=In, solv=CH$_3$CN). From valuation of d-d band positions in electronic spectra, it was confirmed that P$_3$O$_9^{3-}$ ligand exerts weak field strength than H$_2$O and is suprisingly hard ligand near that of DMSO and H$_2$O. These results are well agreed with magnetism and EPR spectrum. The redox processes by cyclic voltametry displayed the large shift of reduction couple to more negative potential and the shift of oxidation couple to more positive potential upon replacement of trispyrazolylborate ligand with P$_...