Three different syntheses of trichloro(pentamethylcyclopentadienyl)molybdenum(IV) are described, i.e. (i) thermal decarbonylation of Cp*MoCl3(CO)2, (ii) reduction Of CP*MoCl4, and (iii) chlorination of [CP*MoCl2]2. A fourth route (conproportionation Of [CP*MoCl2]2 and CP*MoCl4) has been investigated by H-1-NMR. The product has a dinuclear, dichloro-bridged structure with a four-legged piano stool geometry around each metal atom; the two piano stools have a mutual anti arrangement and the two metals are 3.888(1) angstrom from each other, indicating the absence of a direct metal-metal bonding interaction. Crystal data : monoclinic, space group P2(1)/n, a = 8.424(l) angstrom, b = 13.323(4) angstrom, c = 11.266(2) angstrom, beta = 93.87(1)-degrees, V = 1261.6(8) angstrom3, Z = 2, R = 0.038, R(w) = 0.057 for 127 parameters and 1350 observed reflections with F(o)2> 3sigma(F(o)2). The temperature dependent magnetic moment of the material could be fit to the sum of two Bleany-Bowers equations. [CP*MoCl3]2 reacts readily with CO, Cl-, and PMe3 to afford Cp*MoCl3(CO)2, [Cp*MoCl4]-, and CP*MoCl3(PMe3), respectively, while the reaction with 1,2-bis(diphenylphosphino)ethane (dppe) affords the reduction product CP*MoCl2(dppe).