Carbon monoxide-induced dinitrogen cleavage with group 4 metallocenes: Reaction scope and coupling to N-H bond formation and CO deoxygenation

Donald J. Knobloch; Emil Lobkovsky; Paul J. Chirik

doi:10.1021/ja104025v

Carbon monoxide-induced dinitrogen cleavage with group 4 metallocenes: Reaction scope and coupling to N-H bond formation and CO deoxygenation

Donald J. Knobloch, Emil Lobkovsky, Paul J. Chirik

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

77 Scopus citations

Abstract

The scope of CO-induced N ₂ cleavage in a series of zirconocene and hafnocene complexes containing activated, side-on bound dinitrogen ligands has been studied. In each case, bridging oxamidide ligands, [N ₂C ₂O ₂] ^4-, were formed from N-N bond cleavage coupled to N-C and C-C bond assembly. For the zirconium examples, [(η ⁵-C ₅Me ₄H) ₂Zr] ₂(μ ₂,η ²,η ²-N ₂) and [Me ₂Si(η ⁵-C ₅Me ₄)(η ⁵-C ₅H ₃-3- ^tBu)Zr] ₂(μ ₂,η ², η ²-N ₂), dinitrogen loss became competitive with N ₂ carbonylation, and significant quantities of the zirconocene dicarbonyl accompanied oxamidide formation. In contrast, the hafnocene complex [(η ⁵-C ₅Me ₄H) ₂Hf] ₂(μ ₂,η ²,η ²-N ₂) underwent clean carbonylative dinitrogen cleavage with no evidence of N ₂ loss. CO-induced N ₂ cleavage was also coupled to N-H bond formation by hydrogenation and C-H bond activation, as carbonylation of the zirconocene and hafnocene dinitrogen complexes in the presence of H ₂ or phenylacetylene furnished isocyanato metallocene complexes with bridging imido (μ-NH) ligands. In the case of the ansa-hafnocene dinitrogen complex, replacing the dihydrogen atmosphere with various primary silanes yielded an isocyanato hafnocene μ-oxo hydride resulting from cleavage of N ₂ and CO, the diatomics with the two strongest bonds in chemistry.

Original language	English (US)
Pages (from-to)	10553-10564
Number of pages	12
Journal	Journal of the American Chemical Society
Volume	132
Issue number	30
DOIs	https://doi.org/10.1021/ja104025v
State	Published - Aug 4 2010
Externally published	Yes

All Science Journal Classification (ASJC) codes

General Chemistry
Biochemistry
Catalysis
Colloid and Surface Chemistry

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10.1021/ja104025v

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@article{d24358b115a0428cbff84f396d569c99,

title = "Carbon monoxide-induced dinitrogen cleavage with group 4 metallocenes: Reaction scope and coupling to N-H bond formation and CO deoxygenation",

abstract = "The scope of CO-induced N 2 cleavage in a series of zirconocene and hafnocene complexes containing activated, side-on bound dinitrogen ligands has been studied. In each case, bridging oxamidide ligands, [N 2C 2O 2] 4-, were formed from N-N bond cleavage coupled to N-C and C-C bond assembly. For the zirconium examples, [(η 5-C 5Me 4H) 2Zr] 2(μ 2,η 2,η 2-N 2) and [Me 2Si(η 5-C 5Me 4)(η 5-C 5H 3-3- tBu)Zr] 2(μ 2,η 2, η 2-N 2), dinitrogen loss became competitive with N 2 carbonylation, and significant quantities of the zirconocene dicarbonyl accompanied oxamidide formation. In contrast, the hafnocene complex [(η 5-C 5Me 4H) 2Hf] 2(μ 2,η 2,η 2-N 2) underwent clean carbonylative dinitrogen cleavage with no evidence of N 2 loss. CO-induced N 2 cleavage was also coupled to N-H bond formation by hydrogenation and C-H bond activation, as carbonylation of the zirconocene and hafnocene dinitrogen complexes in the presence of H 2 or phenylacetylene furnished isocyanato metallocene complexes with bridging imido (μ-NH) ligands. In the case of the ansa-hafnocene dinitrogen complex, replacing the dihydrogen atmosphere with various primary silanes yielded an isocyanato hafnocene μ-oxo hydride resulting from cleavage of N 2 and CO, the diatomics with the two strongest bonds in chemistry.",

author = "Knobloch, {Donald J.} and Emil Lobkovsky and Chirik, {Paul J.}",

year = "2010",

month = aug,

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doi = "10.1021/ja104025v",

language = "English (US)",

volume = "132",

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journal = "Journal of the American Chemical Society",

issn = "0002-7863",

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T1 - Carbon monoxide-induced dinitrogen cleavage with group 4 metallocenes

T2 - Reaction scope and coupling to N-H bond formation and CO deoxygenation

AU - Knobloch, Donald J.

AU - Lobkovsky, Emil

AU - Chirik, Paul J.

PY - 2010/8/4

Y1 - 2010/8/4

N2 - The scope of CO-induced N 2 cleavage in a series of zirconocene and hafnocene complexes containing activated, side-on bound dinitrogen ligands has been studied. In each case, bridging oxamidide ligands, [N 2C 2O 2] 4-, were formed from N-N bond cleavage coupled to N-C and C-C bond assembly. For the zirconium examples, [(η 5-C 5Me 4H) 2Zr] 2(μ 2,η 2,η 2-N 2) and [Me 2Si(η 5-C 5Me 4)(η 5-C 5H 3-3- tBu)Zr] 2(μ 2,η 2, η 2-N 2), dinitrogen loss became competitive with N 2 carbonylation, and significant quantities of the zirconocene dicarbonyl accompanied oxamidide formation. In contrast, the hafnocene complex [(η 5-C 5Me 4H) 2Hf] 2(μ 2,η 2,η 2-N 2) underwent clean carbonylative dinitrogen cleavage with no evidence of N 2 loss. CO-induced N 2 cleavage was also coupled to N-H bond formation by hydrogenation and C-H bond activation, as carbonylation of the zirconocene and hafnocene dinitrogen complexes in the presence of H 2 or phenylacetylene furnished isocyanato metallocene complexes with bridging imido (μ-NH) ligands. In the case of the ansa-hafnocene dinitrogen complex, replacing the dihydrogen atmosphere with various primary silanes yielded an isocyanato hafnocene μ-oxo hydride resulting from cleavage of N 2 and CO, the diatomics with the two strongest bonds in chemistry.

AB - The scope of CO-induced N 2 cleavage in a series of zirconocene and hafnocene complexes containing activated, side-on bound dinitrogen ligands has been studied. In each case, bridging oxamidide ligands, [N 2C 2O 2] 4-, were formed from N-N bond cleavage coupled to N-C and C-C bond assembly. For the zirconium examples, [(η 5-C 5Me 4H) 2Zr] 2(μ 2,η 2,η 2-N 2) and [Me 2Si(η 5-C 5Me 4)(η 5-C 5H 3-3- tBu)Zr] 2(μ 2,η 2, η 2-N 2), dinitrogen loss became competitive with N 2 carbonylation, and significant quantities of the zirconocene dicarbonyl accompanied oxamidide formation. In contrast, the hafnocene complex [(η 5-C 5Me 4H) 2Hf] 2(μ 2,η 2,η 2-N 2) underwent clean carbonylative dinitrogen cleavage with no evidence of N 2 loss. CO-induced N 2 cleavage was also coupled to N-H bond formation by hydrogenation and C-H bond activation, as carbonylation of the zirconocene and hafnocene dinitrogen complexes in the presence of H 2 or phenylacetylene furnished isocyanato metallocene complexes with bridging imido (μ-NH) ligands. In the case of the ansa-hafnocene dinitrogen complex, replacing the dihydrogen atmosphere with various primary silanes yielded an isocyanato hafnocene μ-oxo hydride resulting from cleavage of N 2 and CO, the diatomics with the two strongest bonds in chemistry.

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U2 - 10.1021/ja104025v

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IS - 30

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Carbon monoxide-induced dinitrogen cleavage with group 4 metallocenes: Reaction scope and coupling to N-H bond formation and CO deoxygenation

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