Carborane Complexes of Ruthenium: Synthesis of the Bimetal Compounds [MRu(μ-CC6H4Me-4)(CO)4(η5-7,8-C2B9H11){κ3-HB(pz)3}] (M = Mo or W) and Their Reactions with Sulfur and Selenium,

Addition of the reagent [Ru(CO) 2 (thf)( η 5 -7,8-C 2 B 9 H 11 )] (thf = tetrahydrofuran) to the compounds [M(⋮CC 6 H 4 Me-4)(CO) 2 { κ 3 -HB(pz) 3 }] (M = Mo or W, HB(pz) 3 = hydrotris(pyrazol-1-yl)borato) in CH 2 Cl 2 affords, respectively, the bimetal species [MRu( μ -CC 6 H 4 Me-4)(CO) 4 ( η 5 -7,8-C 2 B 9 H 11 ){ κ 3 -HB(pz) 3 }] (M = Mo ( 4a ), M = W ( 4b )). These complexes are readily cleaved by donor molecules, including thf, but they are stable in CH 2 Cl 2 or toluene. X-ray diffraction studies established the molecular structures of 4b and the related species [WRu( μ -CC 6 H 4 Me-4)(CO) 4 ( η 5 -7,8-C 2 B 9 H 11 )( η 5 -C 5 H 5 )] ( 2b ). In both molecules very long Ru−W bonds (ca. 3 Å) are asymmetrically bridged by the tolylmethylidyne groups ( μ -C−W av 1.92 Å, μ -C−Ru av 2.21 Å). The complexes 4 react with sulfur or selenium in CH 2 Cl 2 to give the compounds [MRu( μ -1 κ C α,1:2 κ E -ECC 6 H 4 Me-4)(CO) 4 ( η 5 -7,8-C 2 B 9 H 11 ){ κ 3 -HB(pz) 3 }] (M = Mo, E = S ( 6a ), Se ( 6c ); M = W, E = S ( 6b ), Se ( 6d )). The structure of 6b was established by X-ray diffraction. The molecule possesses an unusual structure in which Ru(CO) 2 ( η 5 -7,8-C 2 B 9 H 11 ) and W(CO) 2 { κ 3 -HB(pz) 3 } units are bridged by a thioacyl group which is η 2 -coordinated to the tungsten through its carbon and sulfur atoms and bound to the ruthenium only through the sulfur atom. There is no metal−metal bond as both the W and Ru atoms have filled valence shells. The NMR data for the new compounds are reported and discussed.