An intramolecular NH⋯Co hydrogen bond and a structure correlation study of the pathway for protonation of the Co(CO)3L− anion (L=CO, PR3)

A low temperature X-ray crystal structure of the zwitterionic organometallic compound Co(CO)3{PPh2(C6H4NHMe2)} (2) provides the first example of an intramolecular NH⋯Co (d10) hydrogen bond. Synthesis and characterization of such intramolecularly hydrogen-bonded systems have proven much more elusive than their counterparts that exist as intermolecularly hydrogen-bonded salts. The molecular structure of 2 taken together with a series of previously characterized NH⋯M (d10) hydrogen-bonded salts provides a series of snapshots of the changes in geometry at the metal center as one progresses along the pathway for protonation of the anion Co(CO)3L− (L=CO, PR3) to yield the metal hydride HCo(CO)3L.