A HYDROGEN-BONDED CHAIN INVOLVING BOTH N-H...N AND N-H...CO HYDROGEN-BONDS - LOW-TEMPERATURE X-RAY CRYSTAL-STRUCTURE OF [(NMP)3H2][CO(CO)4]2 (NMP = N-METHYLPIPERAZINE)

[(NMP)3H2][Co(CO)4]2 (1; NMP = N-methylpiperazine) is the first example of a compound which exhibits both conventional hydrogen bonding, in which a proton lies between two electronegative nonmetal centers, and hydrogen bonding involving an electron-rich metal center. In this case N-H...N and N-H...Co hydrogen bonds give rise to a five-component hydrogen-bonded chain. Furthermore, two secondary ammonium centers (N(11) and N(31)) simultaneously function as hydrogen-bond donors to an amine center and to a d10 cobalt center. The crystal structure of 1 has been determined at 135(5) K by X-ray diffraction.