Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates

Tamara E. Hanna; Ivan Keresztes; Emil Lobkovsky; Wesley H. Bernskoetter; Paul J. Chirik

doi:10.1021/om049817h

Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates

Tamara E. Hanna
, Ivan Keresztes
, Emil Lobkovsky
, Wesley H. Bernskoetter
, Paul J. Chirik

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

133 Scopus citations

Abstract

The synthesis and reactivity of the end-on bound dinitrogen complex [(η ⁵-C ₅H ₃-1,3-(SiMe ₃₎₂₎₂Ti] ₂(μ ₂,η ¹,η ¹-N ₂) is described. The solid state structure of the dinitrogen compound reveals a weakly activated end-on bound N ₂ ligand with an N-N bond length of 1.164(5) Å. Displacement of the N ₂ ligand by organic azides has been used to prepare monomeric, base-free titanocene imido complexes, (η ⁵-C ₅H ₃-1,3-(SiMe ₃₎₂₎₂Ti=NR (R = SiMe ₃, 2,4,6-Me ₃-C ₆H ₂). While unreactive toward C-H bonds, the Ti-N linkage is readily hydrogenated and participates in group transfer reactions with unsaturated organic molecules such as carbon monoxide and benzophenone. Reaction of the N ₂ complex with Ph ₂CN ₂ allowed isolation of (η5-C ₅H ₃-1,3-(SiMe ₃₎₂₎₂Ti(N ₂CPh ₂), which exists as a mixture of interconverting η ² and n ¹ isomers in solution. The diazoalkane complex also participates in "imido-like" reactivity, producing (η ⁵-C ₅H ₃-1,3-(SiMe ₃₎₂₎₂Ti(NHN=CPh ₂)H upon addition of H ₂. Changing the diazoalkane to Me ₃SiCHN ₂ resulted in isolation of the double cyclometalated titanocene (η ⁵-C ₅H ₃-η ¹-SiM ₂CH ₂-3-SiMe ₃₎₂Ti, arising from facile intramolecular C-H activation of the cyclopentadienyl substituent by a transient titanocene alkylidene.

Original language	English (US)
Pages (from-to)	3448-3458
Number of pages	11
Journal	Organometallics
Volume	23
Issue number	14
DOIs	https://doi.org/10.1021/om049817h
State	Published - Jul 5 2004
Externally published	Yes

All Science Journal Classification (ASJC) codes

Physical and Theoretical Chemistry
Organic Chemistry
Inorganic Chemistry

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10.1021/om049817h

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@article{c65ecae3dcee4ac4a93043d3b6e7f58d,

title = "Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates",

abstract = "The synthesis and reactivity of the end-on bound dinitrogen complex [(η 5-C 5H 3-1,3-(SiMe 3)2)2Ti] 2(μ 2,η 1,η 1-N 2) is described. The solid state structure of the dinitrogen compound reveals a weakly activated end-on bound N 2 ligand with an N-N bond length of 1.164(5) {\AA}. Displacement of the N 2 ligand by organic azides has been used to prepare monomeric, base-free titanocene imido complexes, (η 5-C 5H 3-1,3-(SiMe 3)2)2Ti=NR (R = SiMe 3, 2,4,6-Me 3-C 6H 2). While unreactive toward C-H bonds, the Ti-N linkage is readily hydrogenated and participates in group transfer reactions with unsaturated organic molecules such as carbon monoxide and benzophenone. Reaction of the N 2 complex with Ph 2CN 2 allowed isolation of (η5-C 5H 3-1,3-(SiMe 3)2)2Ti(N 2CPh 2), which exists as a mixture of interconverting η 2 and n 1 isomers in solution. The diazoalkane complex also participates in {"}imido-like{"} reactivity, producing (η 5-C 5H 3-1,3-(SiMe 3)2)2Ti(NHN=CPh 2)H upon addition of H 2. Changing the diazoalkane to Me 3SiCHN 2 resulted in isolation of the double cyclometalated titanocene (η 5-C 5H 3-η 1-SiM 2CH 2-3-SiMe 3)2Ti, arising from facile intramolecular C-H activation of the cyclopentadienyl substituent by a transient titanocene alkylidene.",

author = "Hanna, \{Tamara E.\} and Ivan Keresztes and Emil Lobkovsky and Bernskoetter, \{Wesley H.\} and Chirik, \{Paul J.\}",

year = "2004",

month = jul,

day = "5",

doi = "10.1021/om049817h",

language = "English (US)",

volume = "23",

pages = "3448--3458",

journal = "Organometallics",

issn = "0276-7333",

publisher = "American Chemical Society",

number = "14",

}

Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates. / Hanna, Tamara E.; Keresztes, Ivan; Lobkovsky, Emil et al.
In: Organometallics, Vol. 23, No. 14, 05.07.2004, p. 3448-3458.

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

TY - JOUR

T1 - Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates

AU - Hanna, Tamara E.

AU - Keresztes, Ivan

AU - Lobkovsky, Emil

AU - Bernskoetter, Wesley H.

AU - Chirik, Paul J.

PY - 2004/7/5

Y1 - 2004/7/5

N2 - The synthesis and reactivity of the end-on bound dinitrogen complex [(η 5-C 5H 3-1,3-(SiMe 3)2)2Ti] 2(μ 2,η 1,η 1-N 2) is described. The solid state structure of the dinitrogen compound reveals a weakly activated end-on bound N 2 ligand with an N-N bond length of 1.164(5) Å. Displacement of the N 2 ligand by organic azides has been used to prepare monomeric, base-free titanocene imido complexes, (η 5-C 5H 3-1,3-(SiMe 3)2)2Ti=NR (R = SiMe 3, 2,4,6-Me 3-C 6H 2). While unreactive toward C-H bonds, the Ti-N linkage is readily hydrogenated and participates in group transfer reactions with unsaturated organic molecules such as carbon monoxide and benzophenone. Reaction of the N 2 complex with Ph 2CN 2 allowed isolation of (η5-C 5H 3-1,3-(SiMe 3)2)2Ti(N 2CPh 2), which exists as a mixture of interconverting η 2 and n 1 isomers in solution. The diazoalkane complex also participates in "imido-like" reactivity, producing (η 5-C 5H 3-1,3-(SiMe 3)2)2Ti(NHN=CPh 2)H upon addition of H 2. Changing the diazoalkane to Me 3SiCHN 2 resulted in isolation of the double cyclometalated titanocene (η 5-C 5H 3-η 1-SiM 2CH 2-3-SiMe 3)2Ti, arising from facile intramolecular C-H activation of the cyclopentadienyl substituent by a transient titanocene alkylidene.

AB - The synthesis and reactivity of the end-on bound dinitrogen complex [(η 5-C 5H 3-1,3-(SiMe 3)2)2Ti] 2(μ 2,η 1,η 1-N 2) is described. The solid state structure of the dinitrogen compound reveals a weakly activated end-on bound N 2 ligand with an N-N bond length of 1.164(5) Å. Displacement of the N 2 ligand by organic azides has been used to prepare monomeric, base-free titanocene imido complexes, (η 5-C 5H 3-1,3-(SiMe 3)2)2Ti=NR (R = SiMe 3, 2,4,6-Me 3-C 6H 2). While unreactive toward C-H bonds, the Ti-N linkage is readily hydrogenated and participates in group transfer reactions with unsaturated organic molecules such as carbon monoxide and benzophenone. Reaction of the N 2 complex with Ph 2CN 2 allowed isolation of (η5-C 5H 3-1,3-(SiMe 3)2)2Ti(N 2CPh 2), which exists as a mixture of interconverting η 2 and n 1 isomers in solution. The diazoalkane complex also participates in "imido-like" reactivity, producing (η 5-C 5H 3-1,3-(SiMe 3)2)2Ti(NHN=CPh 2)H upon addition of H 2. Changing the diazoalkane to Me 3SiCHN 2 resulted in isolation of the double cyclometalated titanocene (η 5-C 5H 3-η 1-SiM 2CH 2-3-SiMe 3)2Ti, arising from facile intramolecular C-H activation of the cyclopentadienyl substituent by a transient titanocene alkylidene.

UR - https://www.scopus.com/pages/publications/3142765396

UR - https://www.scopus.com/pages/publications/3142765396#tab=citedBy

U2 - 10.1021/om049817h

DO - 10.1021/om049817h

M3 - Article

AN - SCOPUS:3142765396

SN - 0276-7333

VL - 23

SP - 3448

EP - 3458

JO - Organometallics

JF - Organometallics

IS - 14

ER -

Synthesis of a base-free titanium imido and a transient alkylidene from a titanocene dinitrogen complex. Studies on Ti=NR hydrogenation, nitrene group transfer, and comparison of 1,2-addition rates

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