| Abstrakt: |
The donoracceptor complexes [Fe(C5H5){C5H4QNHM(NO)(TpMe,Me)X}] {TpMe,Me = tris(3,5-dimethylpyrazolyl)borate; Q = nothing, M = Mo, X = Cl, Br, I; M = W, X = Cl; Q = C6H4, M = Mo, X = Cl, Br, I; M = W, X = Cl; Q = CH&z.dbd;CHC6H4 or N&z.dbd;NC6H4, M = Mo, X = Cl), which contain 16-valence electron metal nitrosyl centres, [Fe(C5H5){C5H4QpyMo(NO)(TpMe,Me)Cl}] (py = 4-pyridyl; Q = CH&z.dbd;CH, CH&z.dbd;CHCO, N&z.dbd;CH and C6H4CH&z.dbd;CH), [Fe(C5Me4H){C5H4CH&z.dbd;CHpyMo(NO)(TpMe,Me)Cl}] and [Fe(C5Me4H)(C5Me4QpyZ)] {Q = CH&z.dbd;CH or CH&z.dbd;N, Z = Mo(NO)(TpMe,Me)Cl or W(CO)5; Q&z.dbd;2,4-CH&z.dbd;CH(C4H2S)CH&z.dbd;CH, Z = W(CO)5 or Me+I−}, some of which contain 17-valence electron molybdenum nitrosyl centres, and [Fe(C5Me4H){C5Me4CH&z.dbd;CH(C4H2S)CH&z.dbd;CHpy}], have been characterised electrochemically, by their electronic spectra, and spectroelectrochemically. Hyper-Rayleigh scattering was used to determine the first hyperpolarisability, β, the data showing that (a) β is dependent on the metal in the acceptor fragment, (b) β increased when Cl or Br was replaced by I and (c) β increased when the number of methyl groups on the cyclopentadienyl rings increased. The β-values for comparable complexes containing {Mo(NO)(TpMe,Me)Cl} and {W(CO)5} moieties were similar. Chemical oxidation of the ferrocenyl or chemical reduction of the molybdenum nitrosyl acceptor fragments in selected complexes caused a reduction of between 25% and 100% in the NLO response. X-Ray structural studies of [Fe(C5H5){C5H4NHMo(NO)(TpMe,Me)Cl}] (P1&cmb.macr;) and [Fe(C5Me4H){C5Me4CH&z.dbd;CHpyMo(NO)(TpMe,Me)Cl}] (P1&cmb.macr;) are reported. |
