PREPARATION OF CIS-[MOI4(PH(2)PCH(2)CH(2)PPH(2))](-) AND STRUCTURE OF(THF)(3)NA(MU-I)(3)MOI(PH(2)PCH(2)CH(2)PPH(2)) WITH A NEW COORDINATION ENVIRONMENT AROUND SODIUM

The complex cis-[MoI4(dppe)](-) is obtained in good yields from trans- [MoI4(THF)(2)](-) and dppe (dppe=1,2-bis(diphenylphosphino)ethane) or directly from the interaction of MoI3(THF)(3), I- and dppe and has bee n isolated as the PPh(4) and Na(THF)(3) salts. The sodium salt has bee n characterized crystallographically: monoclinic P2(1)/n, a=12.790(2), b=16.512(7), c=23.117(4) Angstrom, beta=103.65(1)degrees, V=4744(1) A ngstrom(3), D-calc=1.84 g cm(-3), Z=4, R=0.039 for 4485 independent ob served reflections (F-o(2) greater than or equal to 3 sigma(F-o(2))). The structure features an octahedral coordination around both Na and M o atoms in an overall face-sharing bioctahedral structure with the two metals being bridged by three iodide ligands. This is an unprecedente d case of a structure containing an O3I3 coordination for Na ions and iodide ligands bridging sodium with a transition metal. The H-1 NMR pr operties of the complex are also examined in comparison to those of th e MoI3(dppe)(THF) precursor.