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Inne
Complexes of heteroscorpionate trispyrazolylborate anionic ligands. Part III. X-ray crystallographic and NMR studies on cobalt(II) complexes with tris(pyrazolyl)borate anionic ligands obtained from 3,5-di-methylpyrazole and 3(5)-methyl,5(3)-phenylpyrazole.
Autorzy
Rok wydania
2001
Czasopismo
Numer woluminu
20
Strony
2551-2558
DOI
10.1016/S0277-5387(01)00854-3
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
Condensation of 2 equiv. of 5(3)-methyl,3(5)-phenylpyrazole and 1 equiv. of 3,5-di-methylpyrazole with NaBH4 resulted in the formation of sodium [hydrobis(3-phenyl,5-methylpyrazolyl)(3,5-di-methylpyrazolyl)borate]. The ligand was converted into the pentacoordinate [HB(3,5-di-Mepz)(3-Ph,5-Mepz)2]Co(NCS)(THF)·THF complex for which the molecular structure was determined by the X-ray crystallographic method. The geometry of the ligand in the cobalt(II) complex was compared with that of the homoscorpionate ligand in [HB(3-Ph,5-Mepz)3]Co(NCS)(THF)·0.5THF on the basis of X-ray structural data. The condition for the thermal conversion of the ligands in the studied Tp′Co(NCS) was established. The heating of the mentioned complexes at 428 K in propylbenzene resulted in a borotropic shift of 3-phenyl,5-methylpyrazolyl moieties resulting in the formation of new heteroscorpionates: the chiral [HB(3,5-di-Mepz)(3-Ph,5-Mepz)(3-Me,5-Phpz)]Co(NCS) and [HB(3-Me,5-Phpz)2(3-Ph,5-Mepz)]Co(NCS), which were characterized in solution by 1H NMR spectroscopy. Heteroscorpionate anionic hydro(3,5-di-methylpyrazolyl)bis(3-phenyl,5-methylpyrazolyl)borate ligand (Tp′) and its Tp′Co(NCS)(THF) complex have been synthesized. The structure of the compound was compared with that of the corresponding homoscorpionate TpPh,MeCo(NCS)(THF) complex. Both complexes undergo borotropic shift of the 3-Ph,5-Mepz moiety to form new heteroscorpionate complexes: the chiral [HB(3,5-di-Mepz)(3-Ph,5-Mepz)(3-Me,5-Phpz)]Co(NCS) and [HB(3-Ph,5-Mepz)(3-Me,5-Phpz)2]Co(NCS).
Słowa kluczowe
Heteroscorpionate tris(3-R-pyrazolyl)borate cobalt(II) complexes, Structure, NMR
Adres publiczny
https://doi.org/10.1016/S0277-5387(01)00854-3
Strona internetowa wydawcy
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