Synthesis and solution fluxionality of rhenium(I) carbonyl complexes of 2,4,6-tris(pyrazol-1-yl)-1,3,5-triazines (L), [ReX(CO)(3)L] (X=Cl, Br or I). Characterization of [{ReX(CO)(3)}(2)L] (X=Cl or Br)

被引:22
作者
Gelling, A
Orrell, KG
Osborne, AG
Sik, V
机构
来源
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS | 1996年 / 16期
关键词
D O I
10.1039/dt9960003371
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
The stable octahedral complexes fac-[ReX(CO)(3)L] [X=Cl, Br or I; L=2,4,6-tris(4-methylpyrazol-1-yl)-1,3,5-triazine (tmpzt) or 2,4,6-tris(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine (tdmpzt)] have been prepared in which the substituted triazines act as bidentate chelate ligands. In solution; the complexes;are fluxional with the nitrogen ligand oscillating between two equivalent bonding modes. Rates and activation energies for the,fluxion have been investigated by dynamic NMR methods. Activation energies Delta G double dagger (298.15 K) are in the range 47-72 kJ mol(-1) and are dependent on the steric requirements of the pyrazole groups. At low temperatures changes in the H-1 NMR spectra are interpreted in terms of varying rates of rotation of one of the unco-ordinated pyrazole rings. The non-fluxional dimetallic complexes [{ReX(CO)(3)}(2)L] (X=Cl or Br; L=tdmpzt) were also isolated and structurally characterized by H-1 NMR spectroscopy.
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页码:3371 / 3377
页数:7
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