Pentalene complexes

A tris(trimethylsilyl)pentalene complex was obtained in 15% yield from a trisubstituted cyclooctatriene with Ru3(CO)12 (75, 95) ... 

In certain cases cyclization of cyclooctatetraene occurs with Ru3(CO)j2, and pentalene complexes [62] are formed (209, 210), which are similar but not structurally related to the complexes [65] resulting from azulene and Ru3(CO)j2 (96, 700). 

Also open-chain Me3SiRu2(CO)4(CsHsSiMe3) and Ru COJs-pentalene complexes. Note that (MejSi)iRu(CO)4 acts as source of... 

A significant number of sandwich compounds of this general type are now known, although the subject will not be expounded upon here. In particular, it has proven feasible to construct such molecules from preexisting ferrocene derivatives. Alternatively, the pentalenyl dianion has been reported to react with FeCl2, CoCl2, and NiCl2 with direct formation of pentalene complexes.2S5,256)... 

Experiments with cyclooctatetraene and its methyl and phenyl derivatives have demonstrated that reaction with certain ruthenium carbonyl complexes can occur with transannular bonding to give pentalene complexes directly.253,264 The structures of these unique molecules have been confirmed by X-ray crystallography. 

Synthesis of Mixed Sandwich U(lll) Cyclooctatetraene and Pentalene Complexes... 

This article has reviewed the synthesis and reactivity towards small molecules of a range of U(lll) cyclooctatetraene and pentalene complexes. It is evident that in many cases the uranium centre is capable of tt back-bonding through the 5/ orbitals additionally, a C - C agostic interaction between a bound substrate and a U(IV) centre has been observed. Clearly uranium is capable of bonding with a degree of covalency , and this is perhaps why the reduction chemistry of U(III) is so rich and diverse, and not simply an iteration of low-valent lanthanide chemistry. 

A U(III) pentalene complex has been shown to be capable of binding and reducing N2, in a similar manner to the divalent lanthanide complexes reported by Evans. However, the reactivity of the COT complexes towards CO is completely novel for organometalUc compounds of any type, and shows considerable promise for the future design of a system capable of producing oxocarbon products from CO or CO2 catalytically. 

Summerscales OT, Cloke FGN (2008) Activation of Small Molecules by U(III) Cyclooctate-traene and Pentalene Complexes. 127 87-117 Sundqvist B (2004) Polymeric Fullerene Phases Formed Under Pressure 109 85-126 Szalewicz K, Patkowski K, Jeziorski B (2005) Intermolecular Interactions via Perturbation Theory From Diatoms to Biomolecules 116 43-117... 

Treatment of 5,8-bis(trimethylsilyl)cyclo-octa-l,3,6-triene or 3,5,8-tris(trimethyl-silyl)cyclo-octa-l,3,6-triene with triruthenium dodecacarbonyl gave the pentalene complexes (352 X = H or SiMe ). Tricarbonyl(Ti-cyclo-octa-l,5-diene)ruthenium and tricarbonyl(T)-cyclo-octa-l,3-diene)osmium have been prepared. They react with trityl fluoroborate to give cyclo-octadienylium complexes [(CgHn)M(CO)3] which react with anionic nucleophiles to give neutral compounds, some of which... 

Cloke FGN, Hitchcock PB. Reversible binding and reduction of dinitrogen by a uranium(III) pentalene complex. J Am Chem Soc. 2002 124 9352-9353. 

Hafner succeeded in the synthesis of the unsubstituted pentalene complex 142 as early as 1973 by irradiation of a [2+2] dimer in the presence of Fe2(CO)9, and substituted complexes such as 143 were obtained by treatment of the respective dihydropentalenes with pentacarbonyliron [165, 166]. In a remarkable reaction, ruthenium complex 144 was obtained by treatment of 1,3,5,7-cyclooctatetraene with cis-Ru(CO)4(GeMe3)2 (Scheme 10.50) [167]. 

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