Pure carbon coordination

Our results for the three coordination modes considered here indicate that the CO2 molecule prefers to adopt either a mixed carbon-oxygen coordination (III) or a pure coordination ( ) to the metal center, while a pure carbon coordination ( ) appears to be unfavorable. Further, the results suggest a rather weak CO - transition metal bond consistent with the low stability of adsorbed CO and CO2 in molecular complexes. 

X-ray diffraction confirms linear coordination in Au(PPh3)(C=CC6F5) and Au(H2NCHMe2)(C=CPh) with the short Au-C bonds (1.935-1.99 A) expected for bonds to sp hybridized carbon. Decomposition of these compounds in the vapour above 150°C is a potential route to very pure gold films [162],... 

Polymerization in electrostatic systems like the ones mentioned above is stericaUy inhibited by alkyl substitution at the a-carbon which must assume a coordination number greater than 4. Coates and Glockhng have treated this inhibition of polymerization in terms of decreased electronegative character of the branched alkyl groups. Therefore, stimulated by the idea that f-afkylhthium compounds may exist as low polymers or even as monomeric molecules, Weiner and coworkers and Kottke and Stalke have isolated f-butyllithium as a pure substance for the first time and characterised it by spectroscopic methods and X-ray diffraction. The colourless crystalline solid was found to be tetrameric over a range of concentrations in both benzene and hexane ... 

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