Linear Connection of Four Nitrile Molecules on the Tetraphosphine Complexes of Tungsten and Molybdenum

The tetrahydride complex [WH4(κ4-P4)] (P4 = meso-o-C6H4­(PPhCH2CH2PPh2)2) reacts with ArFCN (ArF = 3,5-(CF3)2C6H3) in toluene at 80 °C to give [W­(κ3-NCArFCArFNCArF­NCArFN)­(κ3-P4)]. The X-ray crystallographic study has revealed that four ArFCN molecules are connected linearly in the sequence NCCNCNCN. The resulting organic moiety is bound to the W center as a tridentate N-donor in a meridional fashion and constitutes a metallacyclic system containing fused five- and six-membered rings. The Mo analogue can be prepared by the reaction of [Mo­(η4-1,5-cyclooctadiene)­(κ4-P4)] with excess ArFCN.