CYANIDE AND METHYLISOCYANIDE COMPLEXES OF RHENIUM(I) [NBU4][REX(CN)(DPPE)2] (X=CL OR CN, DPPE = PH2PCH2CH2PPH2) AND TRANS-[REX(CNME)(DPPE)2] (X=H, F, CL OR CN) - CRYSTAL-STRUCTURES OF TRANS-[REX(CNME)(DPPE)2] (X=H OR CL)

Reaction of trans[ReCl(N2)(dppe)2] (dppe = Ph2PCH2CH2PPh2) with [NBu4]CN gives [NBu4][ReCl(CN)(dppe)2] (1) which, upon further reaction with [NBu4][trans-Re(CN)2(dppe)2] (2) which is readily oxidized to [Re(CN)2(dppe)2] (3). Treatment of 1 with Me3SiCF3SO3 affords [ReH(CNMe)(dppe)2] (4) which is also obtained by reaction of trans-[ReCl(CNMe)(dppe)2] (5) with Li[BEt3H]. Compound 5 reacts with [NBu4]CN (in the presence of Tl[BF4]) or [NBu4]F to give trans-[Re(CN)(CNMe)(dppe)2] (6) or trans-[ReF(CNMe)(dppe)2] (7) respectively. The crystal structures of 4 and 5 have been determined by X-ray diffraction analyses which indicate very bent isocyanide ligands (CNC angles of 147.7(7)-degrees and 139.4(10)-degrees respectively) and rather short Re-C bond lengths (1.947(6) angstrom and 1.861(12) angstrom respectively). Cyclic voltammetry shows that in aprotic solvent these complexes undergo two successive single-electron reversible oxidations. The oxidation potential of the first oxidation, for 7, allows the estimation of the electrochemical parameter P(L) of fluoride as - 1.3 V.