Chemical assembly of the nanosized clusters of clusters: Syntheses, structures, characterization, and materials studies of the tricobalt clusterocarboxylates.

摘要

The logical synthesis of large inorganic/organometallic cluster assemblies (i.e. clusters of clusters) from the cluster substituted carboxylic acids {dollar}rm(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm Csb6 Hsb4(CHsb2)sb2 COsb2 Hrbrack{dollar} (I) and {dollar}rm (CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2 Hrbrack{dollar} (II) has been examined. During chemical assemblies I behaves as a simple organic carboxylic acid but II does not. The difference is attributed to the conjugation between the cluster and COOH in II but not I, which makes the carboxylate anion of II not only a {dollar}sigma{dollar} donor but under certain circumstance a {dollar}pi{dollar}-acceptor.; According to the nature of a multimetal core, the clusters of clusters can be classified into two types: Wernerian and non-Wernerian. In the Wernerian theme, II reacts with {dollar}rm ZnEtsb2{dollar} to yield a cluster of clusters {dollar}rm Znsb4 O{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb6{dollar} (III). In addition, in the presence of air, II spontaneously forms {dollar}rm Cosb4 O{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb6{dollar} (IV). It also reacts with {dollar}rm CdMesb2{dollar} to yield {dollar}alpha{dollar}-{dollar}rm Cdsb2{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb4{dollar} (VIII), {dollar}rmbeta{dollar}-{dollar}rm Cdsb2{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb4{dollar} (IX). In the non-Wernerian theme, II reacts with {dollar}rm Mosb2(CHsb3 COsb2)sb4{dollar} at room temperature rapidly to give {dollar}rm Mosb2{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb3(CHsb3 COsb2) ({lcub}bf V{rcub}), Mosb2{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb4{dollar} (VI) and {dollar}rm Mosb2{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2rbrack{rcub}sb4{lcub}(CO)sb9 Cosb3lbrackmusb3{dollar}-{dollar}rm CCOsb2 Hrbrack{rcub}sb2{dollar} (VII). It also reacts with {dollar}rm CdMesb2{dollar} under cadmium rich condition to give {dollar}rmlbrack(CO)sb3 CoCdsb3rbracklbrack(CO)sb9 Cosb3(musb3{dollar}-{dollar}rm CCOsb2)rbracksb3(eta{dollar}-{dollar}rm THF)sb3{dollar} (X).; X-ray single crystal diffraction and FT-IR spectroscopy reveal four major cluster arrays: pseudo-octahedral(III, IV), square-planar(VI, VII), isosceles triangular(V), equilateral triangular(X). VII is an exclusive example of quadruply bonded M(II) compound containing carbonyls or carboxylic acids as axial ligands. The compound X represents an important new structural type containing {dollar}rmlbrack Cdsb3 Co(CO)sb3rbracksp{lcub}3+{rcub}{dollar} core in which the cadmium is in an rare oxidation state Cd(I). The intense blue color of V, VI, VII is contributed to {dollar}rmdelta(Mosb2)tosigmasp{lcub}*{rcub}(Cosb3){dollar} intramolecular charge transfer. Electrochemical study suggests reversible three electron reduction and one electron oxidation for non-Wernerian species V but irreversible processes for the Wernerian III, IV, and VIII. The conversion of III into a nano-porous, high surface area ceramic materials has been achieved by thermolysis in low temperature.