Easy access to phosphido-selenido clusters. Reaction of [Ru-3(CO)(12)] with Ph-2(pyth)PSe {pyth=5-(2-pyridyl)-2-thienyl} and crystal structure of [Ru-3(mu(3)-Se)(mu-PPh2)(mu-pyth)(CO)(6){P(pyth)Ph-2}]

The reaction of [Ru-3(CO)(12)] with Ph-2(pyth)PSe (pyth = 5-(2-pyridyl)-2-t hienyl) allows to obtain two novel clusters [Ru-3(mu (3)-Se)(2)(CO)(7){P(py th)Ph-2}(2)] 1 and [Ru-3(mu (3)-Se)(mu -PPh2)(mu -pyth)(CO)(6){P(pyth)Ph-2} ] 2 in satisfactory yields. The first one exhibits the well-known bicapped, open triangular, 50-electron nido-core, whereas 2, whose crystal structure has been determined, shows the rather rare Ru,Se tetrahedron with the Ph,P and pyth fragments as side-bridging ligands. Morever cluster 2 belongs to the exiguous family of selenido-phosphido clusters not easily achievable by other routes.