MONO-DIAZENIDO AND BIS-DIAZENIDO COMPLEXES OF RHENIUM(III) CONTAININGBIDENTATE DITERTIARY PHOSPHINE-LIGANDS - THE CRYSTAL AND MOLECULAR-STRUCTURES OF 2)-(PH(2)PCH(2)CH2PPH(2))(2)][PF6]CENTER-DOT-2DMF, RE(NNC6H4CL-4(2)(ME(2)P-CH(2)CH(2)PME(2))(2)][PF6] AND (NNC(6)H(4)ME-4)(ME(2)PCH(2)-CH(2)PME(2))(2)][PF6]

Reaction of the Re-III bis-diazenido starting materials [ReCl(NNC(6)H( 4)X-4)(2)(PPh(3))(2)] (X = Cl 1 or Me 2) with excess dppe (Ph(2)PCH(2) CH(2)PPh(2)) in methanol-toluene under reflux gave the novel orange-br own, formally 20-electron Re-III bis-diazenido cations [Re(NNC(6)H(4)X -4)(2)(dppe)(2)](+) (X = Cl or Me) in good yield by addition of a suit able anion to the cooled reaction mixture. Reaction of 1 and 2 with th e more reducing dmpe (Me(2)PCH(2)CH(2)PMe(2)) ligand gave the formally 20-electron bis-diazenido cation [Re(NNC(6)H(4)X-4)(2)(dmpe)(2)](+) f or X = Cl but the 18-electron mono-diazenido cation [ReCl(NNC(6)H(4)X- 4)(dmpe)(2)](+) for X = Me. The structures of complexes [Re(NNC(6)H(4) Me-4)(2)(dppe)(2)][PF6]. 2dmf (dmf = dimethylformamide) 5, [Re(NNC6H4C l-4)(2)(dmpe)(2)][PF6] 6 and [ReCl(NNC(6)H(4)Me-4)(dmpe)(2)][PF6] 7 ha ve been determined: 5, triclinic, space group P ($) over bar 1, a = 13 .046(3), b = 13.250(3), c = 12.233(4) Angstrom, alpha = 110.74(2), bet a = 95.86(2), gamma = 115.83(2)degrees, Z = 1, R = 0.040; 6 monoclinic , space group P2(1)/c, a = 8.992(2), b = 21.947(2), c = 18.982(2) Angs trom, beta = 91.45(1)degrees, Z = 4, R = 0.056; 7 orthorhombic, space group Pnma, a = 19.298(2), b = 11.327(2), c = 13.960(2) Angstrom, alph a = beta = gamma = 90 degrees, Z = 4, R = 0.042. All three complexes h ave pseudo-octahedral co-ordination with four P donors in a planar equ atorial array. The M-N-N angle of the diazenide ligands is found to be dependent on the steric requirements of the diphosphine ligands, the smaller dmpe ligand permitting the M-N-N angles in 6 to decrease to 14 7.3(5) and 149.0(4)degrees compared to values of around 162.7(2)degree s for the dppe complex 5. Reaction of [NH4][ReO4] with the arylhydrazi ne hydrochloride 4-MeC(6)H(4)NHNH(2) . HCl in CH2Cl2 in the presence o f SiMe(3)Cl and pyridine (py) gave the new hydrazide [ReCl3{NN(SiMe(3) )C(6)H(4)Me-4}(2)(py)]. Subsequent reaction with PPh(3) in MeOH gave t he Re-III diazenide [Re(OMe)(NNC(6)H(4)Me-4)(2)(PPh(3))(2)], and overa ll this provides a route for the synthesis of Re diazenides directly f rom perrhenate.