Cp2M compounds

Ethynylruthenocene acetylides, preparation, 6, 642 ETL, see Electron-transporting layer ET reactions, see Electron-transfer reactions Europium complexes with arenes, 4, 118-119 Cp2Ln compounds, 4, 27 CpLnX2 compounds, 4, 29-30 Cp2M compounds, 4, 63 cyclooctatetraenyl compounds, 4, 122-123 heterobimetallic compounds without direct M—M bonds,... 

Except for Cp2Ru and Cp2Os the second and third row elements do not form stable isolable Cp2M compounds and conventional syntheses may lead to hydrides such as Cp2ReH or Cp2WH2 by H abstraction. A rhenocene is a dimer with a... 

In 1987 Tapper et al. reported the first stable Mo and W complexed phosphinidenes 52 with two Cp ligands on the transition metal from the reaction of Mes PCl with Cp2M(H)Li [91]. Niecke et al. approached the syntheses of similar compounds with instead a NHMes substituent using Mes NPCl and Cp2M(H)Li... 

In typical metallocene compounds. Cp2M, all of the C—C bonds are of the same length and the rings are parallel. However, there are several cyclopeniadienyl com-... 

The conversion of CO + H2 (syn-gas) to hydrocarbons and oxygenates (Fischer-Tropsch chemistry)119 is of considerable industrial importance and recently the activation and fixation of carbon monoxide in homogeneous systems has been an active area for research.120,121 The early transition elements and the early actinide elements, in particular zirconium124 and thorium,125 126 supported by two pentamethylcyclopentadienyl ligands have provided a rich chemistry in the non-catalytic activation of CO. Reactions of alkyl and hydride ligands attached to the Cp2M centers with CO lead to formation of reactive tf2-acyl or -formyl compounds.125,126 These may be viewed in terms of the resonance forms (1) and (2) shown below. 

In compounds where the ion acts as a bidentate ligand (that means forming a five-membered MS4 ring system), an envelope as well as a half-chair conformation is possible. In [Cp2M(S4)j (M = Mo, W) (complexes with tetrahedral coordination of the metal ion)128 and in [M(S4)2]2 (M = Ni (44), Pd) the half-chair conformation is found,129 whereas several complexes with a square-pyramidal coordination of Mo and W show the envelope conformation (for details see Section 16.1.7.4).130,131... 

The 14-electron species denoted here as Cp2M (M = Ti, Zr), generated from Group 4 metallocenes, mediate useful oxidative cyclizations of dienes 231 [103,104], enynes 233 [105] and diynes 235 [105,106] via the metallacycles 232, 234 and 236. These metallacycles are useful intermediates, which are hydrogenolysed, carbonylated, halogenated, attacked by electrophiles and converted to functionalized cyclic compounds such as 238 and 239 [107],... 

Bonding. The bonding in Cp2M(H)(CO) and Cp2M(H)(C2H4) complexes has been discussed from the molecular-orbital viewpoint. It is of interest that such compounds are predicted only for those metals with two or fewer d electrons in the M(III) state (79). 

One of the most important carbon 7i-donors are the cyclopentadienes and their heteroanalogues, for instance 15 and 16. In general, cyclopentadiene itself forms three general types of mononuclear Cp transition metal complexes Cp2M 3 (symmetric molecules with mutually parallel Cp rings examples M = Fe, Cr, Ni), Cp2ML 124 [bent metallocenes, L = H, R, CO, etc. (n=l-3)], and half-sandwich compounds CpML 125 (n — 1 4) [21b], In the bent sandwich complexes... 

In Section III, we also discussed the spin-ladder behavior of dithiolene complex-based compounds, namely, (p-EPYNN) Ni(dmit)2], (DT-TTF)2-[Au(mnt)2], and [Cp2M(dmid)](TCNQF4). All of these compounds display semiconducting behavior and no interplay of electrical and magnetic properties was reported. 

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