Synthesis and characterization of some tungstoruthenate polyoxometalates derived from lacunary polytungstates. Reactivity at the ruthenium center and effects of the polytungstate ligand
Some ruthenium derivatives of Keggin and [alpha]-Dawson heteropoly-tungstates were synthesized and characterized. The tungstoruthenate [PW[sub 11]O[sub 39]Ru[sup III](H[sub 2]O)][sup 4[minus]] (1), is derived by reaction of [Ru(H[sub 2]O)[sub 6]][sup 2+] with the lacunary tungstophosphate. Results of [sup 183]W NMR, visible, near-infrared, and EPR spectroscopy confirm that the ruthenium ion occupies the expected position in the heteropolyanion and demonstrate that the lacunary polytungstate is a [pi]-acceptor ligand. Mechanisms for [sup 183]W and [sup 31]P isotropic shifts are proposed. Electrochemical investigation of 1 shows that ruthenium is reducible/oxidizable to the corresponding aquaruthenium(II) (2), oxoruthenium(IV), and oxoruthenium(V) derivatives. [PW[sub 11]O[sub 39]Ru[sup II](L)][sup 5[minus]] species (L = R[sub 2]S, R[sub 2]SO, pyridine, active alkenes) were prepared, and the substitution rate of dimethyl sulfoxide (DMSO) on 2 was measured. Rotation of [eta][sup 2]-bound alkene ligands on Ru[sup II] was observed by [sup 183]W, [sup 13]C and [sup 1]H NMR. The electron exchange rate for [PW[sub 11]O[sub 39]Ru[sup III/II](H[sub 2]O)][sup 4[minus]/5[minus]] is five orders of magnitude greater than that for [Ru(H[sub 2]O)[sub 6]][sup 3+/2+]. The rhombic-site symmetry and ligand field parameters of Ru[sup III] in the tungstoruthenates with L = H[sub 2]O, pyridine, DMSO were defined by simulation of the EPR spectra. 1 catalyzes the electro-oxidation of DMSO to the sulfone and the epoxidation of trans-stilbene by iodosylbenzene. 2 was shown to reduce DMSO to the sulfide electrocatalytically.
- Research Organization:
- Georgetown Univ., Washington, DC (United States)
- OSTI ID:
- 7102149
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Optimum conditions for intercalation of lacunary tungstophosphate(V) anions into layered Ni(II)-Zn(II) hydroxyacetate
Equilibria between {alpha} and {beta} isomers of Keggin heteropolytungstates