SYNTHESIS OF TRICARBONYL DERIVATIVES OF RHENIUM(I) WITH GROUP-16 DONOR ATOMS - CRYSTAL AND MOLECULAR-STRUCTURE OF APHTHALENEDISULFIDE-BIS[FAC-TRICARBONYLRHENIUM(I)]

The tetrahydrofuran adduct Re2Br2(CO)(6)(THF)(2) reacts with 1,8-napht halenedisulfide (NDS) to give Re2Br2(CO)(6)(NDS), which crystallizes i n the monoclinic system, space group P2(1)/c, with cell constants a=10 .071(4), b=21.229(5), c=10.135(7) Angstrom; beta=105.73(5)degrees, and Z=4 molecules per unit cell. The final R value is 0.044 for 2035 data (Mo-K-alpha). The Re2Br2(CO)(6) fragment is the same as in all previo usly determined structures of this series, having bridging bromides an d a fac tricarbonyl arrangement about each rhenium atom. The rhenium a toms are also bridged by the disulfide fragment of NDS forming two fiv e-membered rings of composition Re-S-S-Re-Br. The fold angle across th e Br ... Br vector is 29 degrees. The Re-Br distances are unequal, wit h the shorter distances to the bromine closer to the naphthalene fragm ent; this bromine is further from the S-S bridge than the other. The R e-S and S-C distances average 2.48 and 1.78 Angstrom, respectively, wh ile the S-S bond is 2.16 Angstrom long. Both the Re-S-S-Re and C-S-S-C torsion angles are nearly 0 degrees, which is a significant distincti on from the previously investigated structures of this type. The NDS l igand is significantly non-planar, and this may be due to steric repul sion from the nearby carbonyl groups. The dibenzyldisulfide and dibenz yldiselenide complexes Re-2(mu-I)(2)(CO)(6)(E(2)Bz(2)), E=S, Se, have been prepared starting from the same THF rhenium(I) precursor. The Se NMR data of the dibenzyldiselenide complex show a downfield shift of a bout 165 ppm with respect to the uncomplexed molecule under the same c onditions. Bis(dimethylphosphine)ethane gives ReI(CO)(3)(Me(2)PCH(2)CH (2)PMe(2)); iodide abstraction from the latter by silver triflate gave Re(SO3CF3)(CO)(3)(Me(2)PCH(2)CH(2)PMe(2)), which is suggested to cont ain the monodentate triflato ligand.