Heterometallic Nitrido-Carbonyl Clusters − Synthesis and Characterization of [Fe5MN(CO)14(C5H5)]2, [Fe3M3N(CO)18]3 (M = Mo, W) and [HFe5MoN(CO)16]2 and Solid-State Structures of [Fe5MoN(CO)14(C5H5)]2, [Fe5WN(CO)14(C5H5)]2, and [Fe3Mo3N(CO)18

Abstract

The anionic clusters [Fe5MN(CO)14Cp]2− [M = Mo (1) or W (2)] were synthesized from [Fe4N(CO)12]− and [MCp(CO)3]− in refluxing acetonitrile. The clusters [Fe3M3N(CO)18]3− [M = Mo (3) or W (4)] were prepared by reaction of [Fe4N(CO)12]− with [M2(CO)10]2− under the same conditions. The molybdenum-containing anions 1 and 3 are obtained in higher yields than 2 and 4. The reaction of the tetranuclear iron cluster with [Mo(η6-Me3C6H3)(CO)3] affords a mixture of [Fe3Mo3N(CO)18]3− and [HFe5MoN(CO)16]2− (5). The solid state structures of the clusters 1, 2 and 3 have been determined; they consist of six metal atoms, arranged in octahedral metal cages encapsulating a μ6-N ligand. The cyclopentadienyl ligand is bound to Mo in 1 and to W in 2; these anions have three edge-bridging carbonyl groups and eleven terminal carbonyl groups. The cluster 3 possesses three molybdenum atoms in a fac arrangement, and the carbonyl ligands are all terminal, or asymmetrically bridging. Inspection of the interatomic distances suggests that molybdenum interacts preferentially with the carbonyl and the nitrido ligands, whereas the iron atoms bind strongly with the other metal centres. The solid state structure of 5 could not be fully resolved owing to crystal disorder. Analytical and spectroscopic data (infrared and 1H NMR) are all consistent with the proposed formula.