A model for the CO-inhibited form of [NiFe] hydrogenase: synthesis of (CO)^sub 3^Fe(1/4 -S^sup t^Bu)^sub 3^Ni {SC^sub 6^H^sub 3^-2,6-(mesityl)^sub 2^} and reversible CO addition at the Ni site

A [NiFe] hydrogenase model compound having a distorted trigonal-pyramidal nickel center, ...Fe...Ni(SDmp), 1 (Dmp = ...-2,6-(mesityl)...), was synthesized from the reaction of the tetranuclear Fe-Ni-Ni-Fe complex ..., 2 with NaSDmp at -40 ...C. The nickel site of complex 1 was found to add CO or CN'Bu at -40 ...C to give ...Fe(S'Bu)...Ni(CO)(SDmp), 3, or ...Fe(S'Bu)...Ni(CN'Bu)(SDmp), 4, respectively. One of the CO bands of 3, appearing at 2055 cm... in the infrared spectrum, was assigned as the Ni-CO band, and this frequency is comparable to those observed for the CO-inhibited forms of [NiFe] hydrogenase. Like the CO-inhibited forms of [NiFe] hydrogenase, the coordination of CO at the nickel site of 1 is reversible, while the CN'Bu adduct 4 is more robust. (ProQuest: ... denotes formulae/symbols omitted.)