The complexes [ML(NO)X(NHQNH₂)][L = tris(3,5-dimethylpyrazolyl)borate; M = Mo, X = I, Q =(C₆H₄)₂Y where Y = O, SO₂, CH₂, or CH₂CH₂; M = W, X = Cl, Q =(C₆H₄)₂O], [MoL(NO)I(NHCH₂CH₂C₆H₄NH₂)], [ML(NO)X(OQOH)][M = Mo, X = I, Q =(C₆H₄)₂Y where Y = nothing or S; X = Cl, Q =(C₆H₄)₂S], and [ML(NO)X(OCH₂C₆H₄CH₂OH)](M = Mo, X = I; M = W, X = Cl) have been prepared. The bimetallic complexes [{ML(NO)X}₂(NHQNH)][M = Mo, X = I, Q =(C₆H₄)₂Y where Y = O, SO₂, CH₂, or CH₂CH₂; M = W, X = Cl, Q =(C₆H₄)₂O], [{MoL(NO)I}₂(NHCH₂CH₂C₆H₄NH)], [{MoL(NO)X}₂(OQO)][X = I, Q =(C₆H₄)₂ Y where Y = nothing or S; X = Cl, Q =(C₆H₄)₂ Y where Y = nothing, S, SO₂, CO, or COC₆H₄C₆H₄CO], and [{ML(NO)X}₂(OCH₂C₆H₄CH₂O)](M = Mo, X = I; M = W, X = Cl) were obtained either from the monometallics by reaction with [ML(NO)X₂] or by direct reaction of the latter with the appropriate arylamine or phenol. The heterobimetallic [MoL(NO)I(NHC₆H₄OC₆H₄NH)WL(NO)Cl] was also prepared and all compounds were characterised spectroscopically. The monometallic species underwent a single, usually reversible, one-electron reduction determined by cyclic voltammetry (in CH₃CN using a Pt electrode). Values of E_½ were dependent on M, X, and the nature of the heteroatom ligand. The bimetallic species underwent two one-electron reductions, investigated by differential pulse polarography. The separation between the redox potentials (ΔE_½) varied from 45 mV (negligible interaction between redox centres) to 138 mV (weak interaction), depending on the nature of the bridging ligand.