| Autor: |
Wlodarczyk, Andrzej, P. Maher, John, Coles, Simon, E. Hibbs, David, H. B. Hursthouse, Michael, M. Abdul Malik, K. |
| Zdroj: |
Journal of the Chemical Society, Dalton Transactions; January 1997, Vol. 1997 Issue: 15 p2597-2606, 10p |
| Abstrakt: |
The binuclear -oxo compounds [{Mo(NO)[HB(dmpz)3]X}2(-O)] (dmpz = 3,5-dimethylpyrazol-1-yl; X = I or Cl) have been prepared. These can occur as enantiomers, one of which (X = I) has been characterised previously, and a single-crystal X-ray diffraction study of the other enantiomer (X = I) established that the molecule has a slightly asymmetric Mo–O–Mo link. The binuclear complexes undergo two one-electron reductions (Ef1 and Ef2) and one one-electron oxidation, established by cyclic voltammetry, the separation between Ef1 and Ef2 being ca. 1000 mV indicating that there is extremely strong interaction between the metal-containing redox centres. The EPR, IR and electronic spectra of the reduced monoanionic species [{Mo(NO)[HB(dmpz)3]Cl}2(-O)] - (S = ½) are consistent with valence-trapped (Class I) behaviour which is unusual in compounds with such short bridges. Formation of [{Mo(NO)[HB(dmpz)3]X}2(-O)] involves prior generation of [Mo(NO){HB(dmpz)3}X(OH)] (X = Cl or I) by hydrolysis of [Mo(NO){HB(dmpz)3}X2] and reaction of the monohydroxide with [Mo(NO){HB(dmpz)3}X2]. The compound [Mo(NO){HB(dmpz)3}(OH)2] is also formed by reaction of [Mo(NO){HB(dmpz)3}I2] with water in solution and on contact with silica gel in dichloromethane. Its structure has been determined crystallographically, and it can be dehydrated on silica gel into [{Mo(NO)[HB(dmpz)3](-O)}2] which appears to contain a symmetrical {Mo(-O)2Mo} bridging system. |
| Databáze: |
Supplemental Index |
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