Synthesis, characterization, and reactions of tetrakis(nitrile)chromium(II) tetrafluoroborate complexes

Rui T. Henriques; Eberhardt Herdtweck; Fritz E. Kühn; André D. Lopes; Janos Mink; Carlos C. Romão

doi:10.1039/a708988k

Synthesis, characterization, and reactions of tetrakis(nitrile)chromium(II) tetrafluoroborate complexes

Rui T. Henriques, Eberhardt Herdtweck, Fritz E. Kühn, André D. Lopes, Janos Mink, Carlos C. Romão

Associate Professorship of Molecular Catalysis

Research output: Contribution to journal › Article › peer-review

61 Scopus citations

Abstract

Reaction of chromium(II) acetate with HBF₄ in nitrile solutions led to air-sensitive, paramagnetic complexes of the general formula [Cr(NCR)₄][BF₄]₂ (R = Me, Bu^t or Ph). In contrast to an earlier report of the synthesis of [Cr(NCMe)₄][BF₄]₂ by electrochemical methods, these compounds are blue. The crystal structure of [Cr(NCMe)₄][BF₄]₂ has been determined. The chromium(II) cation is surrounded by nitrile ligands in a square-planar manner. The BF₄^- counter ions are located at the apical positions of an elongated octahedron. Magnetic susceptibility measurements yielded μ_eff = 4.9 μ_B at 300 K which is characteristic for a d⁴ high-spin complex. The paramagnetic complexes [Cr(NCR)₄][BF₄]₂ are easy to prepare and can be used for the high-yield synthesis of several other chromium derivatives in low oxidation states like [Cr(py)₄][BF₄]₂, [Cr(C₅H₅)₂], [Cr(dppe)₂][BF₄]₂ and [Cr(NO)(NCMe)₅][BF₄]₂.

Original language	English
Pages (from-to)	1293-1297
Number of pages	5
Journal	Journal of the Chemical Society. Dalton Transactions
Issue number	8
DOIs	https://doi.org/10.1039/a708988k
State	Published - 21 Apr 1998

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title = "Synthesis, characterization, and reactions of tetrakis(nitrile)chromium(II) tetrafluoroborate complexes",

abstract = "Reaction of chromium(II) acetate with HBF4 in nitrile solutions led to air-sensitive, paramagnetic complexes of the general formula [Cr(NCR)4][BF4]2 (R = Me, But or Ph). In contrast to an earlier report of the synthesis of [Cr(NCMe)4][BF4]2 by electrochemical methods, these compounds are blue. The crystal structure of [Cr(NCMe)4][BF4]2 has been determined. The chromium(II) cation is surrounded by nitrile ligands in a square-planar manner. The BF4- counter ions are located at the apical positions of an elongated octahedron. Magnetic susceptibility measurements yielded μeff = 4.9 μB at 300 K which is characteristic for a d4 high-spin complex. The paramagnetic complexes [Cr(NCR)4][BF4]2 are easy to prepare and can be used for the high-yield synthesis of several other chromium derivatives in low oxidation states like [Cr(py)4][BF4]2, [Cr(C5H5)2], [Cr(dppe)2][BF4]2 and [Cr(NO)(NCMe)5][BF4]2.",

author = "Henriques, {Rui T.} and Eberhardt Herdtweck and K{\"u}hn, {Fritz E.} and Lopes, {Andr{\'e} D.} and Janos Mink and Rom{\~a}o, {Carlos C.}",

year = "1998",

month = apr,

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doi = "10.1039/a708988k",

language = "English",

pages = "1293--1297",

journal = "Journal of the Chemical Society. Dalton Transactions",

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T1 - Synthesis, characterization, and reactions of tetrakis(nitrile)chromium(II) tetrafluoroborate complexes

AU - Henriques, Rui T.

AU - Herdtweck, Eberhardt

AU - Kühn, Fritz E.

AU - Lopes, André D.

AU - Mink, Janos

AU - Romão, Carlos C.

PY - 1998/4/21

Y1 - 1998/4/21

N2 - Reaction of chromium(II) acetate with HBF4 in nitrile solutions led to air-sensitive, paramagnetic complexes of the general formula [Cr(NCR)4][BF4]2 (R = Me, But or Ph). In contrast to an earlier report of the synthesis of [Cr(NCMe)4][BF4]2 by electrochemical methods, these compounds are blue. The crystal structure of [Cr(NCMe)4][BF4]2 has been determined. The chromium(II) cation is surrounded by nitrile ligands in a square-planar manner. The BF4- counter ions are located at the apical positions of an elongated octahedron. Magnetic susceptibility measurements yielded μeff = 4.9 μB at 300 K which is characteristic for a d4 high-spin complex. The paramagnetic complexes [Cr(NCR)4][BF4]2 are easy to prepare and can be used for the high-yield synthesis of several other chromium derivatives in low oxidation states like [Cr(py)4][BF4]2, [Cr(C5H5)2], [Cr(dppe)2][BF4]2 and [Cr(NO)(NCMe)5][BF4]2.

AB - Reaction of chromium(II) acetate with HBF4 in nitrile solutions led to air-sensitive, paramagnetic complexes of the general formula [Cr(NCR)4][BF4]2 (R = Me, But or Ph). In contrast to an earlier report of the synthesis of [Cr(NCMe)4][BF4]2 by electrochemical methods, these compounds are blue. The crystal structure of [Cr(NCMe)4][BF4]2 has been determined. The chromium(II) cation is surrounded by nitrile ligands in a square-planar manner. The BF4- counter ions are located at the apical positions of an elongated octahedron. Magnetic susceptibility measurements yielded μeff = 4.9 μB at 300 K which is characteristic for a d4 high-spin complex. The paramagnetic complexes [Cr(NCR)4][BF4]2 are easy to prepare and can be used for the high-yield synthesis of several other chromium derivatives in low oxidation states like [Cr(py)4][BF4]2, [Cr(C5H5)2], [Cr(dppe)2][BF4]2 and [Cr(NO)(NCMe)5][BF4]2.

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U2 - 10.1039/a708988k

DO - 10.1039/a708988k

M3 - Article

AN - SCOPUS:33748903405

SN - 0300-9246

SP - 1293

EP - 1297

JO - Journal of the Chemical Society. Dalton Transactions

JF - Journal of the Chemical Society. Dalton Transactions

IS - 8

ER -

Synthesis, characterization, and reactions of tetrakis(nitrile)chromium(II) tetrafluoroborate complexes

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