Rhenium-(), -() and -() complexes of the [α 2 -P 2 W 17 O 61 ] 10Ϫ isomer, a mono-lacunary derivative of the [α-P 2 W 18 O 62 ] 6Ϫ (Wells-Dawson) ion have been prepared and characterized by multinuclear NMR spectroscopy, electrospray mass spectrometry and electron paramagnetic resonance spectroscopy, among other techniques. The molecules have the formulation [α 2 -ReOP 2 W 17 O 61 ] nϪ, where n = 7,6,5 for Re V , Re VI and Re VII , respectively. 183 W NMR spectroscopy for the Re V and Re VII analogs shows that the molecules have C s symmetry, as expected for substitution in the α 2 site. Simulations of the X-band and Q-band EPR spectra of the Re VI analog, using C s symmetry, allow determination of the g, hyperfine and quadrupole coupling tensors. X-Band, Q-band and W-band EPR spectroscopy show extreme variations in linewidths due to random strains or distortions of the complex.

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The reaction of [(C(5)Me(5))M(MeCN)(3)](PF(6))(2) with (C(5)Me(5))(2)Ru(2)S(4) gives the cluster compounds [(C(5)Me(5))(3)MRu(2)S(4)(MeCN)](PF(6))(2), 1(PF(6))(2) (M = Rh) and 3(PF(6))(2) (M = Ir). Crystallographic studies of 1(PF(6))(2) show that the dication consists of an asymmetric RhRu(2)S(4) core containing an isosceles triangle of metal atoms with a Ru-Ru bond of 2.88 Å. The three metal atoms are joined by two &mgr;(3)-eta(1):eta(2):eta(1-)S(2) units, each persulfide being monodentate toward Rh. NMR studies show that 1(2+) is stereochemically nonrigid such that the two Ru(C(5)Me(5)) resonances coalesce at higher temperatures. The dynamic processes involving 1(2+) are unaffected by added (C(5)Me(5))Rh(MeCN)(3)(2+), ruling out dissociation of the (C(5)Me(5))Rh center. Exchange of the (C(5)Me(5))Ru sites in [(C(5)Me(5))(2)(C(5)Me(4)Et)RhRu(2)S(4)(MeCN)](PF(6))(2), 2(PF(6))(2), is associated with coalescence of the pairs of C(5)Me(4)Et resonances, suggesting that the dynamics in 1(2+) involve racemization. It is proposed that these dynamics proceed via the "base-free" intermediate [(C(5)Me(5))(3)RhRu(2)S(4)](2+), wherein one S-S bond has been cleaved. Solutions of 1(2+) react with acetone to give the S-acetonyl derivative [(C(5)Me(5))(3)RhRu(2)S(3)(SCH(2)COCH(3))]PF(6), 4(PF(6)). This species, which is not fluxional on the NMR time scale, is a rare example of a metal sulfido cluster with a trigonal prismatic M(3)S(3) core. There is one metal-metal bond of 2.75 Å between the two Ru atoms, spanned by the acetonylthio ligand. The M-S distances are nearly equivalent at 2.33 Å while the S-S bonding distance is 2.12 Å. This reaction is reversed by acid to give 1(2+) and acetone.

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