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)](3-)

The anionic clusters [Fe5MN(CO)(14)Cp](2-) [M = Mo (1) or W (2)] were synth esized 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 [M-2(CO)(10)](2-) under the same conditi ons. 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(eta(6 )-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 ha ve been determined; they consist of six metal atoms, arranged in octahedral metal cages encapsulating a mu(6)-N Ligand. The cyclo-pentadienyl ligand i s bound to Mo in 1 and to W in 2; these anions have three edge-bridging car bonyl groups and eleven terminal carbonyl groups. The cluster 3 possesses t hree molybdenum atoms in a fac arrangement, and the carbonyl Ligands are al l terminal, or asymmetrically bridging. Inspection of the interatomic dista nces suggests that molybdenum interacts preferentially with the carbonyl an d 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 o wing to crystal disorder. Analytical and spectroscopic data (infrared and H -1 NMR) are all consistent with the proposed formula.