Mono-, di-, and tricarboxylic acids: Central building blocks for the formation of multinuclear transition metal complexes

The synthesis and characterization of the di-, tetra-, and hexanuclear tita nium(I)-copper(I) carboxylates ([Ti](C drop CSiMe3)(2)}CuO2CR2 (3) {3a: R-2 = Me, 3b: R-2 = C6H5, 3c: R-2 = CH2C6H5, 3d: R-2 = CH=CMe2; [Ti] (eta (5)- C5H4SiMe3)(2)Ti}, { [Ti](C dropC(t)Bu)(2))CuOC(O)-X-C(O)OH [12a: X = trans- CH=CH, 12b: X = CH2C(=CH2)], {[Ti](C dropC(t)Bu)(2)]CuOC(O)-X-C(O)OCu{((RC) -C-1 dropC)(2)[T1]} [R-1 = Bu-t, 13a: X= trans-CH=CH, 13b: X = cis-CH=CH, 1 3c: X = 1,4-C6H4, 13d: X = C dropC, R-1= SiMe3, 14a: X = trans-CH=CH, 14b: X = CH2C(- CH2)], [{[Ti](C dropC(t)Bu)(2)}CuO(O)C](2) (13e) as well as {[Ti ](C dropC(t)Bu)(2)C}CuO(O)C-1-C6H3(CO2H)(2)-3,5 (16), [{[Ti](C dropC(t)Bu)( 2))CuO(O)C](2)-1,3-C6H3(CO2H)-5 (17), and [{[Ti](C dropC(t)Bu)(2)}CuO(O)C]( 3)-C6H3-1,3,5 (18) is described. All of these complexes are easily accessib le by the reaction of {[Ti](C drop CR1)(2))CuMe (la: R-1 = SiMe3, 1b: R-1 = Bu-t) with the corresponding carboxylic acids in different stoichiometric ratios of the reactants. Furthermore, the preparation and reaction chemistr y of the alkyne-stabilized copper(I) percarboxylate {[Ti](C drop CSiMe3)(2) )}-CuO2C(O)C6H4Cl-3 (10) is discussed. As the central organic building bloc k, all complexes contain mono-, di-, or tricarboxylic units. The latter two allow for the subsequent addition of further titanium(rv)-copper(I) assemb lies onto these entities. The X-ray structure analyses of 3a and 13a are re ported. Within the {[Ti](C drop CR1)(2)}CuOC(O)R-2 array the copper(I) cent er is eta2-coordinated by both (RC)-C-1 dropC groups of the organometallic tweezer [Ti](C drop CR1)(2) and eta (1)-bonded by one oxygen atom of the O2 CR2 unit. Cyclic voltammetric studies on representative examples are presen ted and discussed comparatively.