Carbido complexes

Whether these results will also have an impact on the theory of metallaallenes is difficult to predict at least for the compounds Cp (CO)2Mn = M = Mn(CO)2Cp, (M = Ge, Sn, Pb) a linear structure is established and also linear p-carbido complexes are known [198], Recently, a germanium compound has been synthesized which is directly comparable with 22. In this case, the starting material for the synthesis is not a monomeric base adduct, but a dimeric germylene complex which is cleaved by Na2Fe(CO)4 in pyridine to form 72 [199],... 

Dihalocarbene complexes are useful precursors to new carbenes by nucleophilic displacement of the chlorine substituents. This has been nicely illustrated for Fe(TPP)(=CCl2) by its reaction with two equivalents of Re(CO)5J to give the unusual /t-carbido complex Fe(TPP)=C=Re(CO)4Re(CO)5 which also contains a rhenium-rhenium bond. " The carbido carbon resonance was observed at 211.7 ppm in the C NMR spectrum. An X-ray crystal structure showed a very short Fe=C bond (1.605(13) A, shorter than comparable carbyne complexes) and a relatively long Re=C bond (1.957( 12) A) (Fig. 4, Table III). " ... 

Chisholm and his group recently succeeded in transforming a metal carbonyl into a stable fi4-carbido complex W4( 4-C)(/t-NMe)(0-i-Pr)12 1 The 13C-NMR signal for the (/ 4-C)4 ligand is 366.8 ppm [5] which can be considered as a realistic model of a surface bound carbido species in the sense of the original proposal by Fischer and Tropsch (Fig. 2). Upon addition of hydrogen, surface bound carbide can be stepwise transformed into methane. 

From Metal Carbenes to Open-Shell Metal Carbyne and Carbido Complexes... 

Although Heppert s discovery and the subsequent work by Grubbs and others has received special attention, it must be emphasized that prior to the studies on ruthenium carbido complexes Christopher Cummins from MIT had reported the preparation of the anionic molybdenum carbide [CMo N(R)Ar 3] (R =... 

A. Hejl, T. M. Trnka, M. W. Day, and R. H. Grubbs, Terminal Ruthenium Carbido Complexes as cr-Donor Ligands, Chem. Commun. 2002, 2524-2525. 

As has been noted elsewhere (17) the environment of the a carbon atom of the acetylide type ligands such as those observed in bonding modes M8, M13, and M18 resembles, to an extent, that of a carbido carbon. As the nuclearity of the cluster with which the acetylene interacts increases, the similarity between the environments also increases. In the case of Ru5(CO)13(p-PPh2)(C=CPh) (431), the structure is closely related to the carbido complex Ru5C(CO)15 (432). 

Beck and co-workers achieved the synthesis of the -carbido complex 12 by reaction of the porphyrin iron dihalocarbene complex 11 with jjenta-... 

The bimetallic carbido complex Tp Mo = CFe(CO)2Cp (CO)2 undergoes photolytic insertion of CS2 into the C-Fe bond, with concomitant loss of one CO ligand from the Fe centre, to form the dithiocarboxylate-containing derivative Tp Mo = CCS2Fe(CO)Cp (CO)2. Photolytic substitution of both CO ligands at Fe forms Tp Mo = CFe(L )2Cp (CO)2 derivatives (L = PMe3, CN Bu). These substitutions are accompanied by a lowered frequency of the CO absorptions and the very low field carbide chemical shifts (>450ppm) in the C H NMR spectra ... 

The X-ray structure of this complex was reported by Bottomley and coworkers [88]. Remarkably, the electronic structure of such a complex was predicted before its preparation [72], Reduction of trichloromethyltrimethyl-silane by iron(II) tetraarylporphyrins in the presence of a reducing agent also leads to the carbide complex [89]. This surprising result can be explained by the involvement of an unstable a-silylcarbene ferroporphyrin complex. A het-erometallic /i2-carbido complex was isolated from the reaction of a dichloro carbene iron porphyrin and pentacarbonylrhenate (Eq. 13) [90]. The X-ray structure of this trinuclear complex, [(TPP)Fe = C = Re(CO)4Re(CO)5], shows a 1,3-dimetalla-allene system. 

We also have found new examples of rare -carbido complexes M=C=M. 

Another route to p.-Carbido complexes which we have found is oxidative addition of Lalor s halocarbyne complexes [21] to zero valent triphenylphosphine compounds of nickel, palladium and platinum. In these reactions the heterodimetalla cyclopropenes could be isolated which isomerize at higher temperatures to the dimetalla allene complexes. The first adducts of arylcarbyne complexes to zerovalent platinum complexes (arylcarbyne as analogue of ace-... 

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