| Autor: |
Stephen Davies, E., M. Aston, Georgina, L. Beddoes, Roy, Collison, David, Dinsmore, Andrew, Docrat, Arefa, A. Joule, John, R. Wilson, Clare, David Garner, C. |
| Zdroj: |
Journal of the Chemical Society, Dalton Transactions; November 7, 1998, Vol. 1998 Issue: 21 p3647-3656, 10p |
| Abstrakt: |
The reaction of [WO2(CN)4]4– with a series of dimethylamino- or thione-protected asymmetric dithiolenes (ene-1,2-dithiolates) has been used to synthesise [WO(dithiolene)2]2– complexes (dithiolene 4;= 4;–SC(H)C(R)S–, R 4;= 4;phenyl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl or quinoxalin-2-yl), which have been characterised by elemental analysis, spectroscopy and electrochemistry. The prototypical compound [PPh4]2[WO(sdt)2]·EtOH [sdt 4;= 4;styrenedithiolate, –SC(H)C(Ph)S–], crystallises in space group P 21/c with a 4;= 4;13.242(4), b 4;= 4;31.894(8), c 4;= 4;14.589(5) Å, β 4;= 4;113.80(2)°, and Z 4;= 4;4. The WOS4 moiety is square-based pyramidal with the O atom at the apex [W&z.dbd6;O 1.724(7) Å, W–Sav 2.37 Å, O–W–Sav 108.7°] and contains a cis geometry of the phenyl groups, although 1H NMR studies indicate that both cis and trans isomers are present in the isolated solid. The physical properties of all of the [WO(dithiolene)2]2– complexes are consistent with a retention of the WIVOS4 centre and each system undergoes a reversible electrochemical one-electron oxidation to the corresponding WV system. The variation in the dithiolene 1H NMR resonances, ν(W&z.dbd6;O) and ν(C&z.dbd6;C) (dithiolene) IR stretching frequencies, and the E½ values for the WV–WIV couple can be rationalised by a consideration of the nature of the aryl substituent. These data are compared to those of the analogous MoIV complexes and to those of the catalytic centres of the tungstoenzymes and their oxomolybdoenzyme counterparts. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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