A new polymorph of the heteronuclear cluster Ru4Pt2(CO)(18)

By reacting Ru(CO)(5) with the stoichiometric amount of Pt(C7H10)(3) (C7H10 = bicyclo[2.2.1]heptene) in heptane and by removing the excess of CO, two poly morphs of Ru4Pt2(CO)(18), 1, were isolated and characterized by X-ray diffraction, namely the already known monoclinic (! and a new orthorhombic (P) phase. Crystal data of the beta phase: space group Pna2(1): a = 17.738( 3). b = 15.596(2), c = 10.357(1), V = 2865 A(3). IR spectra (Nujol mulls) o f the two polymorphs are significantly different, while no difference was n oticed in solution. The air-stable compounds quickly decompose in a carbon monoxide atmosphere giving Ru3CO12 and the unstable [Pt(CO)](n), n less tha n or equal to 2.