Synthesis and Molecular Structure of Tetraruthenium Cluster Isomers with Different Electron Counts

Abstract

The two novel cluster species Ru 4 (CO) 12 (µ 4 -η 2 -C 8 H 10 ) (1) and Ru 4 (CO) 12 (µ 4 -η 2 :η 2 -C 8 H 10 ) (2) have been isolated from the thermolysis of Ru 3 (CO) 12 in octane in the presence of cycloocta-1,3-diene. The two clusters are isomers of formula Ru 4 (CO) 12 (C 8 H 10 ), differing only in the overall electron donation from the C 8 H 10 ligand to the cluster. Clusters 1 and 2 possess 60 and 62 electrons, respectively, and both are based on a butterfly framework of metal atoms, as shown by single-crystal X-ray diffraction experiments. The bonding interaction between the ligand and the cluster as well as the effect of the extra pair of electrons in 2 with respect to 1 has been investigated by extended Hu ¨ckel molecular orbital calculations.

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“…The structures of two related complexes have been reported previously, namely Ru 4 {µ 4 -MeCHC 2 CHCH 2 C(O)Me}(CO) 12 [9] and Ru 4 (µ 4 -C 8 H 10 )-(CO) 12 . [10] In these, the dimensions and geometries of the central C 4 Ru 4 portions of the molecules are closely similar to those found for (3). Electron counting shows the ligand acts as a six-electron donor; with the 12 terminal CO groups, the cluster is thus a 62 cluster valence electron (CVE) system, as expected for an M 4 cluster with five M-M bonds.…”

“…(a) Ru 3 (µ 3 -PhC 2 C=CHPh)(µ-OH)(CO) 9 (1) This complex was obtained as a minor crystalline product (3.8%) from the reaction between Ru 3 (CO) 10 (NCMe) 2 and PhC≡CC≡CPh, marginally suitable for an X-ray structural study. Several major products from this reaction have been described previously.…”

“…The formation of this complex probably occurs by reaction of the µ 3 -diyne precursor with traces of water (Scheme 1), as recently described for a similar osmium cluster. [5] (b) Ru 3 {µ 3 -C(OCH 2 CH=CH 2 )CHCCPh 2 OC(O)}(µ-dppm)-(µ-CO)(CO) 6 (2) The reactions between Ru 3 (µ-dppm)(CO) 10 and HC≡CCPh 2 -(OH), carried out in refluxing tetrahydrofuran (THF) for 1 h gave a complex mixture, from which 10 coloured bands separated after preparative thin-layer chromatography (TLC). To simplify the reaction, addition of Me 3 NO and MeCN to the mixture at -20ºC to give Ru 3 (µ-dppm)(CO) 8 -(NCMe) 2 as an intermediate, followed by a similar reaction with the alkyne and workup, gave four products.…”

Chapter 22. Organometallic chemistry of bi- and poly-nuclear complexes

“…The HOMO-LUMO gap of the SO-electron cluster is large enough for it to be thermodynamically stable even though a closed butterfly structure contains a more stable [RU,(CO),~] fragment. 98 ThermoIysis of [Ru3(C0),,] and 9-anthraacylphosphine gave several products, including [Ru,(p-H)(CO)g(p3-C1 4H 7PPh2)] and [Ru,(CO), 1(p4-C1 .H,PPh,)J, anthracyne compIexes arising from double metallation of one of the unsubstituted rings, and [Ru,(CO), 3(p5q l : q2: q 3 : q3-C,,H9-q1-PPh,)] 50, a bowtie cluster with an anthracene unit co-ordinated to the Ru, cluster framework via a q2-C=C double bond, two ,+-ally1 groups and a ql-a-interaction." Reaction of [Ru3(CO>,,] with 1,3,5-triisopropenyl benzene in refluxing octane gave two isomeric clusters of the formula [Ru,(CO),,(Cl,Hzo)].…”

Novel coordination modes of partially hydrogenated diyne ligands on metal carbonyl clusters †

“…This Scheme 1 coordination mode, which could be viewed as two linked σ,π-vinyl ligands, is relatively uncommon, although it has also been observed in the structure of [Ru 4 (CO) 12 (µ 4 -C 8 H 10 )] obtained by the 2,3 dehydrogenation of octa-1,3-diene in the reaction with [Ru 3 (CO) 12 ]. 14 In addition to the hydrogenation of diynes and dehydrogenation of dienes, dienediyl ligands may be obtained by an alkyne coupling reaction on a metal cluster. 1 These typically afford 1,3-diene-1,4-diyl ligands but, where SiMe 3 substituents are present on the alkynes, a 1,2-dilyl shift may occur to generate a coordinated 1,3-diene-1,3-diyl moiety.…”