Selective Dialkylation of a Doubly Linked Dicyclopentadiene Ligand and the Ensuing Ruthenium Complexes

The selective alkylation (Me or tert-butyl) of a doubly linked dicyclopentadiene ligand is presented. The reaction of (C5H3(t-Bu))2(CMe2)2 (4a,b), the di-tert-butyl-substituted ligand, with RuCl3·3H2O in MeOH at 140 °C for 15 min, followed by heating in CHCl3, gave the chloro-bridged complex cis-{(η5-C5H2(t-Bu))2(CMe2)2}­Ru2(μ-Cl)2Cl2 (5) in 28% yield. Reduction of 5 with Zn in MeCN gave the chloro-bridged tetrakis­(acetonitrile) complex cis-[{(η5-C5H2(t-Bu))2(CMe2)2}­Ru2(MeCN)4(μ-Cl)]+ (6) in 62% yield. Addition of AgOTf to 6 in MeCN removed the bridging chloro ligand and gave [cis-{(η5-C5H2(t-Bu))2(CMe2)2}­Ru2(MeCN)6]­[OTf]2 (7) in 38% yield. The X-ray crystal structures of 5 and 6 are reported.