Dinuclear molybdenum complexes derived from diphenols: electrochemical interactions and reduced species
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- 作者：Abdul-Rahman ; Azilah ; Amoroso ; Angelo A. ; Branston ; Timothy N. ; Das ; Amitava ; Maher ; John P. ; et. al.
- 关键词：nitrosyl ; tris(pyrazolyl)borate ; molybdenum ; spin correlation ; electrochemical interaction ; diphenols
- 刊名：Polyhedron
- 出版年：1997
- 出版时间：October 15, 1997
- 年：1997
- 卷：16
- 期：2
- 页码：4353-4362
- 全文大小：815 K
文摘
The new diphenolato complexes [{Mo(NO){HB(dmpz)3}Cl}2Q] where dmpz = 3,5-dimethyl-pyrazolyl and Q = OC6H4(C6H4)nC6H4O (n = 1 or 2), OC6H4CR
CRC6H4O (R = H or Et), and OC6H4 CHCHC6H4CHCHC6H4O have been prepared and their electrochemical properties (cyclic and differential pulse voltammetry) compared with previously reported analogues where Q = OC6H4O, OC6H4EC6H4O (E = SO2, CO and S), OC6H4 (CO)C6H4 C6H4(CO)C6H4O and 1,5- and 2,7-O2C10H6. The electrochemical interaction between the redox centres in the new complexes is very weak, in contrast to that in the 1,4-benzenediolato and naphthalendiolato species. The EPR spectra of the reduced mixed-valence species [{Mo(NO){HB(dmpz)3}Cl}2Q]− where Q = 1,3- and 1,4-OC6H4O and OC6H4SC6H4O shows that they are valence-trapped at room temperature, whereas those of the dianions [{Mo(NO){HB(dmpz)3}Cl}2Q]2− where Q = 1,4-OC6H4O, OC6H4EC6H4O (E = CO or S) and OC6H4CHCHC6H4CHCHC6H4O shows that the unpaired spins on each molybdenum centre are strongly correlated (J, the spin exchange integral 
AMo, the metal-hyperfine coupling constant). The electrochemical properties and the comproportionation constants for the reaction [{Mo(NO){HB(dmpz)3} Cl}2Q]+ [{Mo(NO){HB(dmpz)3}Cl}2Q]2− 
2[{Mo(NO) {HB(dmpz)3}Cl}2Q]− where Q = diphenolato bridge, are compared with related compounds containing benzenediamido and dianilido bridges.
CRC6H4O (R = H or Et), and OC6H4 CHCHC6H4CHCHC6H4O have been prepared and their electrochemical properties (cyclic and differential pulse voltammetry) compared with previously reported analogues where Q = OC6H4O, OC6H4EC6H4O (E = SO2, CO and S), OC6H4 (CO)C6H4 C6H4(CO)C6H4O and 1,5- and 2,7-O2C10H6. The electrochemical interaction between the redox centres in the new complexes is very weak, in contrast to that in the 1,4-benzenediolato and naphthalendiolato species. The EPR spectra of the reduced mixed-valence species [{Mo(NO){HB(dmpz)3}Cl}2Q]− where Q = 1,3- and 1,4-OC6H4O and OC6H4SC6H4O shows that they are valence-trapped at room temperature, whereas those of the dianions [{Mo(NO){HB(dmpz)3}Cl}2Q]2− where Q = 1,4-OC6H4O, OC6H4EC6H4O (E = CO or S) and OC6H4CHCHC6H4CHCHC6H4O shows that the unpaired spins on each molybdenum centre are strongly correlated (J, the spin exchange integral AMo, the metal-hyperfine coupling constant). The electrochemical properties and the comproportionation constants for the reaction [{Mo(NO){HB(dmpz)3} Cl}2Q]+ [{Mo(NO){HB(dmpz)3}Cl}2Q]2− 2[{Mo(NO) {HB(dmpz)3}Cl}2Q]− where Q = diphenolato bridge, are compared with related compounds containing benzenediamido and dianilido bridges.