The heterobimetallic complexes CpRu(PPh3)(μ-Cl)(μ-dppm)PdCl2 (1) [dppm = bis(diphenylphosphino)methane], CpRu(PPh3)Cl(μ-dppm)AuCl (2), and CpRu(PPh3)(μ-Cl)(μ-dppm)PtCl2 (3) were synthesized by the reaction of CpRu(PPh3)Cl(η1-dppm) (4) with Pd(COD)Cl2, AuPPh3Cl, and Pt(COD)Cl2, respectively. Compounds 1 and 2 were characterized by X-ray crystallography. Electrochemical oxidation of CH3OH in the presence of 1, 2, or 3 leads to considerable enhancement of the oxidative currents and formation of the organic products CH2(OCH3)2 and HCOOCH3. Addition of water increases both the current and the proportion of the more highly oxidized product, HCOOCH3. Current efficiencies obtained with heterobinuclear complexes 1−3 were significantly higher than those obtained using the model compound CpRuCl(η2-dppm) (5) as catalyst.

ansa-Calcocene compounds are effective reagents for the synthesis of ansa-chromocene complexes from CrCl 2 in the presence of a trapping ligand such as carbon monoxide or an isonitrile. A variety of ansa-chromocene carbonyl and tert-butyl isocyanide complexes have been prepared in this manner in high yields. The X-ray crystal structure of one of these complexes,CrCO, is described. Electrochemical studies on these complexes show that the isonitrile derivatives are more easily oxidized than the carbonyl derivatives. Preliminary examination of the reactivity of these complexes indicates that the nature of the substitution along the ethanediyl ansa-bridge influences the relative stabilities of the carbonyl complexes to oxidation in air, the ease with which the carbonyl ligands undergo substitution with tert-butyl isocyanide, and the relative sensitivities of the tert-butyl isocyanide adducts to photodecomposition. The ansa-bridge substitution also appears to influence the ability of the complexes to undergo structural changes, such as ring slippage, as revealed in their cyclic voltammograms.

1-E-benzylidene-4,7-dimethylindene (1) is reductively coupled by activated calcium to form two isomers, trans-Ph2C2H2-rac-(η5-4,7-Me2−C9H4)2Ca(THF)2 (trans-rac-2) and cis-Ph2C2H2-meso-(η5-4,7-Me2−C9H4)2Ca(THF)2 (cis-meso-2) in an approximately 1:1 ratio. Reaction of the calcium species with FeCl2 produces a mixture of the corresponding trans-rac and cis-meso ferrocenophane species (3) along with another ferrocenophane isomer that is presumed to be either the trans-meso or cis-rac isomer. Thus, the relative geometry of the indenyl rings is not retained entirely during the transfer of the ligand framework from calcium to iron. A complete scrambling of the indenyl ring geometry appears to occur upon transfer of the ligand framework from calcium to zirconium. The results of X-ray crystal structure determinations of 1-E-benzylidene-4,7-dimethylindene, trans-Ph2C2H2-rac-(η5-4,7-Me2−C9H4)2Ca(THF)2, and trans-Ph2C2H2-rac-(η5-4,7-Me2−C9H4)2Fe are described.

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Key indicatorsSingle-crystal X-ray study T = 213 K Mean '(C±C) = 0.004 A Ê R factor = 0.062 wR factor = 0.117 Data-to-parameter ratio = 15.1 For details of how these key indicators were automatically derived from the article, see