Transformations in Transition-Metal Carbonyls Containing Arsenic: Exploring the Chemistry of [Et4N]2[HAs{Fe(CO)4}3] in the Search for Single-Source Precursors for Advanced Metal Pnictide Materials

Abstract

The chemistry of [Et4N]2[HAs{Fe(CO)4}3] ([Et4N]2[I]) has been explored with the goal of preparing heterometallic compounds for use as single-source precursors to metal pnictide phases. Reaction of AgPF6 with [Et4N]2[I] in THF produces [Et4N][HAs{Fe2(CO)6(μ-CO)(μ-H)}{Fe(CO)4}] in 12% yield, but the yield is improved to 71% if the reaction is carried out with added [Et4N][HFe(CO)4]. The structure possesses rare As–H and {Fe2(CO)6(μ-CO)(μ-H)} fragments. The addition of [CPh3][BF4] to [Et4N]2[I] in THF gives [Et4N][Fe3(CO)9(μ-CO){μ3-AsFe(CO)4}] in 45% yield. This compound is also obtained as a minor product from oxidation of [Et4N]2[I] with 1 equiv of AgPF6, AsCl3, SbCl3, or BiCl3 in THF. The cluster consists of an Fe3As tetrahedron with an isolated Fe(CO)4 unit bound to the arsenic in a spiked-tetrahedral arrangement. Refluxing [Et4N]2[I] with 1 equiv of AgPF6 in THF produces [Et4N][(μ-H)2Fe3(CO)9){μ3-AsFe(CO)4}]. This cluster is similar to [Et4N][Fe3(CO)9(μ-CO){μ3-AsFe(CO)4}] with the bridging CO being repl...