The reactivity of the unsaturated dimeric rhenium complexes [Re2H2(CO)6{(EtO)2POP(OEt)2}] and [Re2H2(CO)6(Ph2PCH2PPh2)]: X-ray crystal structure of [Re2H(CO)6(Ph2PCH2PPh2){µ-NC(H)Me}

Abstract

The complexes [Re2H2(CO)6(L–L)][L–L =(EtO)2POP(OEt)2(tedip)(1) or Ph2PCH2PPh2(dppm)(2)] react with P(OMe)3 giving 1 : 1 adducts which exist in solution in two isomeric forms, both containing a terminal H and a (µ–H) ligand. Both (1) and (2) react with RNC (R = But, Bun, p-MeOC6H4, or p-MeC6H4SO2CH2) to give the complexes [Re2H(CO)6(L–L)(µ-HCNR)](5) containing an NC-bonded formimidoyl ligand. With CH3CN (1) and (2) react to give a major product formulated as [Re2H(CO)6(L–L){µ-NC(H)Me}][(6), L–L = tedip; (7a), L–L = dppm] and containing an N-bonded ethylideneimino group; for the product with L–L = dppm this formulation has been confirmed by an X-ray diffraction study. The complex crystallises in the monoclinic space group P21/n with a= 9.765(3), b= 29.940(8), c= 11.813(4)Å, β= 104.69(2)°, and Z= 4. The structure was solved by a combination of direct methods and Fourier difference techniques, and refined by full-matrix least squares to R= 0.071 for 2 614 unique, observed diffractometer data. The minor product obtained in the reaction of (2) with CH3CN is suggested on the basis of spectroscopic evidence to be [Re2H(CO)6(dppm)(µ-HNCMe)](7b) containing an NC-bonded acetimidoyl ligand. Both (1) and (2) form an unstable adduct with CO but do not react with HCCH, H2CCH2, or MeO2CCCCO2Me.