Cationic dihydrogen/dihydride complexes of osmium: Structure and dynamics

Jonathan D. Egbert; R. Morris Bullock; D. Michael Heinekey

doi:10.1021/om0700718

Cationic dihydrogen/dihydride complexes of osmium: Structure and dynamics

Jonathan D. Egbert, R. Morris Bullock, D. Michael Heinekey

Pacific Northwest National Laboratory

Research output: Contribution to journal › Article

14 Citations (Scopus)

Abstract

Reaction of Cp*Os(CO)₂Cl with [Et₃Si][BAr ₄^F] under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)₂(H₂)][BAr₄ ^F] (1) (Cp* = C₅Me₅; Ar^F = C₆F₅). When this reaction is carried out with HD gas, complex 1-d₁ results, with J_HD -24.5 Hz. When solutions of complex 1 are monitored by ¹H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with Na[BAr^F*₄] (Ar ^F* = 3,5-(CF₃)₂C₆H ₃) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H₂][BAr^F*₄] (2). At 295 K, complex 2 exists as a 10:1 mixture of cis and trans isomers. The ¹H NMR spectrum of the cis form in the hydride region exhibits a triplet with JHP = 6.5 Hz, due to rapid exchange of the hydrogen atoms. At low temperature, static spectra of the HH′PP′ spin system can be obtained, revealing quantum mechanical exchange coupling between the two hydride ligands. The observed J_HH′ is temperature dependent, varying from 133 Hz at 141 K to 176 Hz at 198 K. This is the first report of detectable exchange coupling between pairs of chemically equivalent hydrogen atoms.

Original language	English
Pages (from-to)	2291-2295
Number of pages	5
Journal	Organometallics
Volume	26
Issue number	9
DOIs	https://doi.org/10.1021/om0700718
Publication status	Published - Apr 23 2007

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ASJC Scopus subject areas

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

Cite this

Egbert, J. D., Bullock, R. M., & Heinekey, D. M. (2007). Cationic dihydrogen/dihydride complexes of osmium: Structure and dynamics. Organometallics, 26(9), 2291-2295. https://doi.org/10.1021/om0700718

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title = "Cationic dihydrogen/dihydride complexes of osmium: Structure and dynamics",

abstract = "Reaction of Cp*Os(CO)2Cl with [Et3Si][BAr 4F] under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)2(H2)][BAr4 F] (1) (Cp* = C5Me5; ArF = C6F5). When this reaction is carried out with HD gas, complex 1-d1 results, with JHD -24.5 Hz. When solutions of complex 1 are monitored by 1H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with Na[BArF*4] (Ar F* = 3,5-(CF3)2C6H 3) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H2][BArF*4] (2). At 295 K, complex 2 exists as a 10:1 mixture of cis and trans isomers. The 1H NMR spectrum of the cis form in the hydride region exhibits a triplet with JHP = 6.5 Hz, due to rapid exchange of the hydrogen atoms. At low temperature, static spectra of the HH′PP′ spin system can be obtained, revealing quantum mechanical exchange coupling between the two hydride ligands. The observed JHH′ is temperature dependent, varying from 133 Hz at 141 K to 176 Hz at 198 K. This is the first report of detectable exchange coupling between pairs of chemically equivalent hydrogen atoms.",

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N2 - Reaction of Cp*Os(CO)2Cl with [Et3Si][BAr 4F] under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)2(H2)][BAr4 F] (1) (Cp* = C5Me5; ArF = C6F5). When this reaction is carried out with HD gas, complex 1-d1 results, with JHD -24.5 Hz. When solutions of complex 1 are monitored by 1H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with Na[BArF*4] (Ar F* = 3,5-(CF3)2C6H 3) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H2][BArF*4] (2). At 295 K, complex 2 exists as a 10:1 mixture of cis and trans isomers. The 1H NMR spectrum of the cis form in the hydride region exhibits a triplet with JHP = 6.5 Hz, due to rapid exchange of the hydrogen atoms. At low temperature, static spectra of the HH′PP′ spin system can be obtained, revealing quantum mechanical exchange coupling between the two hydride ligands. The observed JHH′ is temperature dependent, varying from 133 Hz at 141 K to 176 Hz at 198 K. This is the first report of detectable exchange coupling between pairs of chemically equivalent hydrogen atoms.

AB - Reaction of Cp*Os(CO)2Cl with [Et3Si][BAr 4F] under hydrogen gas affords the cationic hydrogen complex [Cp*Os(CO)2(H2)][BAr4 F] (1) (Cp* = C5Me5; ArF = C6F5). When this reaction is carried out with HD gas, complex 1-d1 results, with JHD -24.5 Hz. When solutions of complex 1 are monitored by 1H NMR spectroscopy over several days, the gradual formation of a trans dihydride species is observed. Similarly, reaction of CpOs(dppm)Br with Na[BArF*4] (Ar F* = 3,5-(CF3)2C6H 3) under hydrogen affords the cationic dihydride complex [CpOs(dppm)H2][BArF*4] (2). At 295 K, complex 2 exists as a 10:1 mixture of cis and trans isomers. The 1H NMR spectrum of the cis form in the hydride region exhibits a triplet with JHP = 6.5 Hz, due to rapid exchange of the hydrogen atoms. At low temperature, static spectra of the HH′PP′ spin system can be obtained, revealing quantum mechanical exchange coupling between the two hydride ligands. The observed JHH′ is temperature dependent, varying from 133 Hz at 141 K to 176 Hz at 198 K. This is the first report of detectable exchange coupling between pairs of chemically equivalent hydrogen atoms.

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10.1021/om0700718