The benzene-Ru(II)-supported trilacunary heteropolytungstates [(RUC6H6)(2)XW9O34](6-) (X = Si, 1; Ge, 2) have been synthesized and characterized by multinuclear solution NMR (W-183, C-13, H-1, Si-29), UV-vis and IR spectroscopy, electrochemistry, and elemental analysis. Single-crystal X-ray analysis was carried out on Rb2Na4[(RuC6H6)(2)SiW(9)O34](.) 21 H2O (RbNa-1), which crystallizes in the triclinic system, space group P1, with a = 11.9415(2) angstrom, b = 13.3123(2) angstrom, c = 19.4927(4) angstrom, alpha = 96.6460(10)degrees, beta = 95.1570(10)degrees, gamma = 98.2560(10)degrees, and Z = 2 and on CS2Na4-[(RUC6H6)(2)GeW9O34](.)19.5H(2)O (CsNa-2), which crystallizes also in the triclinic system, space group)1q, with a = 11.930(4) angstrom, b = 13.353(4) angstrom, c = 19.586(6) angstrom, alpha = 95.982(5)degrees, beta = 95.414(6)degrees, gamma = 98.142(5)degrees, and Z = 2. The novel polyanion structure consists of two (RUC61-16) units linked to a trilacunary (XW9034) Keggin fragment via Ru-O(W) and Ru-O(X) bonds resulting in an assembly with C,, symmetry. Polyanions 1 and 2 were synthesized by reaction of [RUC61-16C1212 with [A-a-XW9034110- in aqueous buffer medium (pH 6.0). Both 1 and 2 are stable in solution as indicated by the expected 5-line pattern (2:122:2) in the 183 W NIVIR and the expected C-13, H-1, and Si-29 spectra. Descriptions of the respective electrochemical behaviors of the W centers and the Ru centers in 1 and 2 are given in media where these processes are clearly defined. In a pH = 3 acetate medium, the cyclic voltarnmetry of the W centers shows the known fingerprint of the trilacunary alpha-[XW9O34](n-) (X = Ge, Si) moieties. The presence of the (RuC6H6) substituents imparts a good stability to these fragments in solution. Stepwise oxidation of the Ru centers was suspected in pH = 5 acetate medium, but only the first step was well-separated from a large current composite wave. The stepwise oxidation was finally observed clearly in a DMF-water (90/10 v/v) mixture and shows two well-behaved Ru oxidation processes. A short comparison is made with DMSO-bearing Ru polyoxo metalates.