Alkane complexes intramolecular coordination

Now, one must wonder if there is any limit to the ability of metals to bond in a stable way to other o bonds, including those in non-reactive molecules like alkanes. In fact, evidence for an intermediate methane complex has been found at low temperature in the reductive elimination of methane from a cationic rhenium methyl hydride [34]. The ab initio theoretical study of the intermolecular process of oxidative addition of a methane C - H bond has led to the location of transition states where the bond is partially broken [35]. The same results have been fond for intramolecular oxidative additions which are related to agostic interactions. In fact, agostic interaction itself is a kind of non-oxidative coordination [15,36]. For unsaturated substrates like ethylene, the activation of a C - H bond seems to follow an intermolecular path, without any previous coordination of the double bond. A feasible explanation consists here of the fact that metal orbitals suitable for ethylene coordination are the same as those which are responsible for oxidative addition, thus making the processes competitive [37]. 

A route to non-racemic P-stereogenic vinylphosphine-boranes, e.g., (100), is afforded by the addition of methylphenylphosphine-borane with alkynes in the presence of a chiral diphosphine-palladium catalyst. The ehiral diphosphine-platinum complex-catalysed addition of diethylphosphine to the diene cis,cis-muco-nitrile has given the new diphosphine (101) as a 3 2 mixture of diastereoisomers. Further work has been reported on the use of cyclopentadienyliron complexes that act as metal templates for the intramolecular hydrophosphination of coordinated vinylphosphines with 1,2-diphosphino-alkanes and -benzenes, leading to 1,4,7-triphosphacyclononanes, e.g., (102), capable of further elaboration to form new cyclic phosphines. 

---