A TETRANUCLEAR BUTTERFLY CLUSTER OF MOLYBDENUM, [PPH(4)](2)[MO4I11]

Bis(tetraphenylphosphonium) undecaiodotetramolybdate, 2[PPh(4)](+)[Mo4 I11](2-), was Obtained by treating [Mo-2(MeCN)(8)](4+) with PPN+I- in dichloromethane. The four Mo atoms of the anion adopt a 'butterfly' ar rangement which can be viewed as a portion of an octahedron with two m issing mutually cis vertices. Ten of the eleven I atoms are located at the vertices of a cube in which the ideal octahedron would be inscrib ed; two of them cap the two triangular faces of the Mo-4 buttefly, fou r bridge the edges and four are terminally coordinated to the metal at oms. The eleventh I atom bridges the two 'wing-tip' metal atoms, The m etal-metal distances for four edges of the butterfly wings are in the range 2.533 (3)-2.547 (3) Angstrom, whereas the 'hinge' edge is slight ly longer [2.688 (3) Angstrom] and the separation between the two wing tips is 3.051 (3) Angstrom.