O. Gambino

Reactions of Ru3(CO)12 with asymmetrically substituted acetylenes. A new type of interaction between acetylenes and a metal-atom cluster

Abstract The compounds Ru 3 (CO) 9 X (where XC 2 (t-Bu)H and C 2 (Ph)H) have been obtaned from the reactions of Ru 3 (CO) 12 with t-BuCCH and PhCCH. Their IR, NMR and mass spectra are reported and discussed. A hydrido signal in the NMR spectrum and other evidence point to a new type of structure, different from that proposed by Blount and his coworkers for Fe 3 (CO) 9 C 2 Ph 2 .

The chemistry of dodecacarbonyltriruthenium I. Acetylene derivatives of dodecacarbonyltriruthenium

Abstract Substitutions of carbonyl groups in Ru 3 (CO) 12 by diphenylacetylene and tetraphenylcyclopentadienone are described. Nine compounds, six of which are trinuclear ruthenium carbonyl acetylenes, were isolated from the reaction with diphenylacetylene in inert solvents. In methyl alcohol two Ru 3 (CO) 8 (C 2 Ph 2 ) 2 isomers were obtained, a violet one having only terminal carbonyls and an orange-yellow one with bridging carbonyl groups. The thermal decomposition of the products and replacements of carbonyl groups with basic ligands (mainly triphenylphosphine) were studied. A compound Ru 3 (CO) 5 (C 2 Ph2) 2 (PPh 3 ) 3 , containing bridging carbonyl groups, is also described. The greater tendency of the ruthenium carbonyl than of iron carbonyl to retain the trinuclear cluster in these reactions is discussed, with emphasis on the fact that the ruthenium carbonyl can give rise to bridged carbonyl compounds even when such groups are not present in the original structure.

Stereochemically nonrigid carbonyl complexes of group VIII B metal clusters

Abstract The variable temperature 13 C-nmr of M 3 (CO) 12 (M = Fe, Ru, Os) have been studied. Fe3(CO)12 and Ru 3 (CO) 12 give one sharp resonance down to −100° C. Os 3 (CO) 12 shows two resonances at room temperature which coalesce to a single resonance at +150 C. Possible mechanisms for carbonyl averaging are considered. The 13C-nmr of the acetylenic complexes HM3(CO)9C2C(CH3)3 (M = Ru, Os) were examined and shown to be stereochemically nonrigid. Both the osmium and ruthenium compounds show axial equatorial exchange on the metal atom which is sigmabonded to one of the acetylenic carbons. Only the ruthenium compound shows exchange between metal atoms in the temperature range examined. The importance of bridging intermediates in this exchange process is discussed.

Butadienic derivatives and metal carbonyls II. Some rearrangements of butadienic ligands in reactions with dodecacarbonyltriruthenium

Abstract Isomerization and rearrangement of ligands L, such as 1,4-trans,trans-diphenyl-1,3-butadiene, hexadiene isomers, isoprene and 1,3-butadiene, occur in the reactions with Ru3(CO)12 to give trimetallic complexes of molecular formula HRu3(O)9(L-H), in addition to bi- and monometallic complexes of known structure. On the contrary the diene skeleton is always maintained when L is 2,3-dimethyl-1,3-butadiene. Structures of HRu3(CO)9(L-H) complexes are suggested and some novel features in their proton n.m.r. spectra are described.

Reactions of Ru3(CO)12 with chalcogen compounds

Abstract Attempts to synthesize the compounds Ru3(CO)9X2(X = S,Se,Te) bytreating Ru3(CO)12 in alkaline solution with chalcogen compounds gave the substituted hydrides of the series H2Ru3(CO)9X (X = S,Se,Te), which were isolated and characterised. The same products were obtained under other conditions also. The NMR and mass spectra are discussed, and possible structures for these paramagnetic complexes are suggested.

Acetylenic derivatives of metal carbonyls I. Substitution reactions of CO2(CO)6C2RR′ complexes

Abstract In this work the substitution reactions were studied, of one acetylenic derivative, by another, in the complexes Co 2 (CO) 6 C 2 RR′ in which R and R′CF 3 , COOCH 3 , C 6 H 5 , CH 2 Cl, CH 3 , CH 2 N(C 2 H 5 ) 2 and H. On the basis of such reactions, relative stabilities of the various acetylenic derivatives were determined and discussed in terms of the acceptor character of the different acetylenes. Also reported are the preparations and properties of some new compounds of this series.

Chalcogen derivatives of iron carbonyls I. Substituted derivatives of Fe3(CO)9X2 Complexes (X=S, Se, Te) with ligands

Abstract Series of mono- and disubstituted derivatives of Fe3(CO)9X2 complexes (X= S, Se, Te) with ligands are prepared. Different reactions are found with the Te compound, which also gives additional derivatives. An explanation is proposed, referred to the difference in electron attracting power of the chalcogen atoms. Also the preparations, the properties and the main infrared absorption frequencies of the new compounds are reported.

Acetylenic derivatives of metal carbonyls XII. Diphenylacetylenic derivatives of dodecacarbonyltriosmium

The reaction of the complex (C6H5C2C6H5)2Os3(CO)8 (I) with CO has been investigated and a structure suggested for the compound, (C6H5C2C6H5)2Os3(CO)9, thus obtained. This consists basically of an Os3 cluster, in which one of the osmium atoms belongs to a osmacyclopentadiene ring, and to which only terminal carbonyl groups are bonded. The formation of this product from (I) and CO was found to be a second-order process. The reactions of complex (I) with halogens have also been investigated, and the resulting binuclear derivatives identified.

Acetylenic derivatives of metal carbonyls. Part XV. Reaction of dodecacarbonyltriosmium with unsymmetrically substituted alkynes

Abstract Dodecacarbonyltriosmium and phenylacetylene (L) in refluxing benzene give Os 3 (CO) 10 L, Os 3 (CO) 10 L 2 , Os 3 (CO) 9 L and HOs 3 (CO) 9 (LH) as primary products. Reactivity of these complexes is investigated and formation of 1,2,4-triphenylbenzene in a sequence starting from Os 3 (CO) 10 L is described. Corresponding reactions with propyne and 1-butyne exhibit a close analogy with those of phenylacetylene. A partially different behaviour is shown by methylphenylacetylene (L′), which reacts with dodecacarbonyltriosmium to give two isomers of molecular formula HOs 3 (CO) 8 (L′H)L′ as main products. These complexes are suggested to be isostructural with an analogous compound obtained from diphenylacetylene. The main factors affecting the reaction trends are considered.

Electronic interactions in multicluster arrays. An electrochemical approach. Part I

An electrochemical study on the electronic interactions occurring between the two ‘CCo3(CO)9’ redox cores in the dimers Co3(CO)9(CC)Co3(CO)9 and Co3(CO)9(CCCC)Co3(CO)9 is reported. In both derivatives, two well resolved peaks/waves are observed in several solvents by cyclic, square wave voltammetry and d.c. polarography, respectively, for the (0,0)/(0,1−) and (0,1−)/(1−,1−) reduction processes. The differences in electrode potentials of the two first reductions, ΔE°′, indicate a moderate electronic interaction between the redox centres in both compounds, which mainly occurs via the carbon chains.