Bimetallic complexes based on carboxylate and xanthateligands: Synthesis and electrochemical investigations?

Dalton Transactions Pub Date: 2009-05-15 DOI: 10.1039/B901822K

Abstract

The homobimetallic ruthenium(II) and osmium(II) complexes [{RuR(CO)(PPh3)2}2(S2COCH2C6H4CH2OCS2)] (R = CH[double bond, length as m-dash]CHBut, CH[double bond, length as m-dash]CHC6H4Me-4, C(C[triple bond, length as m-dash]CPh)[double bond, length as m-dash]CHPh, CH[double bond, length as m-dash]CHCPh2OH) and [{Os(CH[double bond, length as m-dash]CHC6H4Me-4)(CO)(PPh3)2}2(S2COCH2C6H4CH2OCS2)] form readily from the reactions of [MRCl(CO)(BTD)(PPh3)2] (M = Ru or Os; BTD = 2,1,3-benzothiadiazole) with the dixanthate KS2COCH2C6H4CH2OCS2K. Addition of KS2COCH2C6H4CH2OCS2K to two equivalents of cis-[RuCl2(dppm)2] leads to the formation of [{(dppm)2Ru}2(S2COCH2C6H4CH2OCS2)]2+. The benzoate complexes [RuR{O2CC6H4(CH2OH)-4}(CO)(PPh3)2] (R = CH[double bond, length as m-dash]CHBut, CH[double bond, length as m-dash]CHC6H4Me-4, C(C[triple bond, length as m-dash]CPh)[double bond, length as m-dash]CHPh) are obtained by treatment of [RuRCl(CO)(BTD)(PPh3)2] with 4-(hydroxymethyl)benzoic acid in the presence of base. Reaction of [RuHCl(CO)(PPh3)3] or [RuRCl(CO)(BTD)(PPh3)2] with 4-(hydroxymethyl)benzoic acid in the absence of base leads to formation of the chloride analogue [RuCl{O2CC6H4(CH2OH)-4}(CO)(PPh3)2]. The unsymmetrical complex [{Ru(CH[double bond, length as m-dash]CHC6H4Me-4)(CO)(PPh3)2}2(O2CC6H4CH2OCS2)] forms from the sequential treatment of [Ru(CH[double bond, length as m-dash]CHC6H4Me-4){O2CC6H4(CH2OH)-4}(CO)(PPh3)2] with base, CS2 and [Ru(CH[double bond, length as m-dash]CHC6H4Me-4)Cl(CO)(BTD)(PPh3)2]. The new mixed-donor xanthate-carboxylate ligand, KO2CC6H4CH2OCS2K is formed by treatment of 4-(hydroxymethyl)benzoic acid with excess KOH and two equivalents of carbon disulfide. This ligand reacts with two equivalents of [Ru(CH[double bond, length as m-dash]CHC6H4Me-4)Cl(BTD)(CO)(PPh3)2] or cis-[RuCl2(dppm)2] to yield [{(dppm)2Ru}2(O2CC6H4CH2OCS2)]2+ or [{Ru(CH[double bond, length as m-dash]CHC6H4Me-4)(CO)(PPh3)2}2(O2CC6H4CH2OCS2)], respectively. Electrochemical experiments are also reported in which communication between the metal centres is investigated.

Graphical abstract: Bimetallic complexes based on carboxylate and xanthate ligands: Synthesis and electrochemical investigations
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