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

A low temperature X-ray crystal structure of the zwitterionic organometalli c compound Co(CO)(3){PPh2(C6H4NHMe2)} (2) provides the first example of an intramolecular N-H ... Co (d(10)) hydrogen bond. Synthesis and characteriza tion of such intramolecularly hydrogen-bonded systems have proven much more elusive than their counterparts that exist as intermolecularly hydrogen-bo nded salts. The molecular structure of 2 taken together with a series of pr eviously characterized N-H ... M (d10) hydrogen-bonded salts provides a ser ies of snapshots of the changes in geometry at the metal center as one prog resses along the pathway for protonation of the anion Co(CO)(3)L- (L = CO, PR3) to yield the metal hydride HCo(CO)(3)L. (C) 2000 Elsevier Science S.A. All rights reserved.