Hydridocobalt Complexes with Phosphine Ligands

Two different crystal structures (square pyramidal and trigonal bipyramidal) have been obtained for single crystals of HCo(CO)2(PPh3)2, 3. Neither structure contained a solvent of crystallization. The authors suggested that the force packing is sufficient to favor one or the other geometry. In solution, an equilibrium exists between the two isomers which interconvert rapidly.  

The characterization of if-112 coordinated to cobalt complex is not an easy feature. A careful NMR study reinvestigation by Heinekey et a/., based on Fimin measurement and the lack of resolvable H-D coupling in the monodeuterated form of the complex, led to a reformulation of the cobalt complex 4 as a highly dynamic dihydride species instead of an H2 adduct 77 -coordinated to the cobalt atom. Bianchini and co-workers have confirmed this observation and interpretation.  

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