Kurethara S. Bose

Synthesis of a new class of Mo-Fe-S clusters containing the MoS2Fe2 unit

Abstract A new synthetic route to Mo-Fe-S clusters related to nitrogenase has been developed, in which the bridging sulfides originate with the iron reagent (rather than with MoS2−4, as is the case for other known Mo-Fe-S clusters). This route produces clusters containing the novel Mo(μ3-S)2Fe2 structural unit, which is only the third known type of such a cluster (in addition to those containing the “linear” MoS2Fe and “cubane” MoFe3S4 units). Reaction of the [Fe2S2(CO)6]2− dianion with MoCl5 has been found to produce at least four new clusters, including two Fe-S carbonyl clusters and two novel Mo-Fe-S clusters, including I. Complex I, isolated as the Ph4As+ salt, has been identified as the [MoOFe5S6(CO)12]2− dianion by a single-crystal structure determination: space group P21/n, monoclinic, Z = 4; a = 14.127(6) A, b = 17.818(5) A, c = 26.802(18) A, β = 94.51(2)°, V = 6726 A3; current R = 8.9%, Rw = 9.4%; 2768 unique data with F2 > 3σ(F2). Complex I can also be prepared in higher yield from the reaction of MoOCl3·2THF with excess [Fe2S2(CO)6]2− or [Fe4S4(CO)12]2−.