SUBSTITUTED METAL-CARBONYLS .26. ONE-STEP SYNTHESIS, STRUCTURES, NMR,AND DYNAMIC LASER-LIGHT SCATTERING OF RE-2(MU-OME)(2)[MU-PH(2)P(CH2)(N)PPH(2)](CO)(6) (N=1-4)

Oxidative decarbonylation of Re-2(CO)(10) by Me(3)NO in a mixture of T HF and MeOH followed by addition of alkyl-chained diphosphine Ph(2)P(C H2)(n)PPh(2) (PP) (n = 1-4) gives Re-2(mu-OMe)(2)-(mu-PP)(CO)(6) in 34 , 29, 28, and 10% yields, respectively. This methanolytic oxidation ac ross the Re-Re bond provides a general and one-step route for the synt hesis of these dirhenium hexacarbonyl complexes with diphosphine and m ethoxo bridges. The molecular structure of Re-2(mu-OMe)(2)(mu-Ph(2)PCH (2)PPh(2))(CO)(6) was determined by single-crystal X-ray diffraction a nalysis. It contains two fac-[Re(CO)s] moieties bridged by dppm and tw o methoxo ligands. The {Re2O2} core is significantly more planar than that in the Fe(C(5)H(4)PPh(2))(2) analogue. That such a dinuclear core is maintained in spite of the different steric demands of the differe nt bridging diphosphines illustrates the great geometric tolerance of the bridging methoxo groups. The fluxionality of the dppm, dppe, and d ppp complexes has been studied and compared by molecular modeling and solution H-1 NMR spectroscopy. Dynamic laserlight scattering (DLS) sho ws that the dppe complex aggregates in CH2Cl2 to form small clusters w ith an average radius of similar to 370 nm. The use of a combination o f DLS and NMR in organometallic chemistry is unprecedented.