Metal—ligand bonds methanation

As typified by the ethanolysis of (CH3)2Pd(PEt3)2, many solvolyses of metal-carbon bonds are found to be quite complex when studied in detail. Even the generalization that the C—M bond hydrolyzes to give alkane and metal ion is not universally valid. Schrauzer and Windgassen (23) found that a methylcobalt compound with dimethylglyoxime ligands gave methane and methyl chloride in a 3 1 ratio on treatment with hot concentrated hydrochloric acid. Traces of ethane also formed, apparently by thermal decomposition with formation of methyl radicals. Warm concentrated KOH solution decomposed this complex with formation of methane. 

The ALMO-EDA scheme was used to analyze a wide range of methane CH bond cleavage transition states for metal-ligand complexes that have been reported experimentally to promote or catalyze CH activation [57]. This included late transition metals such as Rh(lll), Rh(l), lr(ni), Pt(n), Pd(ll), Ru(II), and Au(III) and early transition metals such as Sc(lll) and W(ll). Ligands attached to these metal centers range from phosphine, N-heterocycle, and halide to 0-donors. Three specific examples of transition states analyzed and their ALMO-EDA interaction energy components are shown in Scheme 10. 

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