Insertion and cycloaddition reactivity of a transition-metal N-metalloimine

E Hevia, J Perez, V Riera, D Miguel

Research output: Contribution to journalArticle

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Abstract

The presence of electron-releasing main-group-metal substituents on the nitrogen atom increases the reactivity of imines A towards dipolar reagents such as isocyanates1 and ketenes.2 We speculated that, in addition to this inductive effect, a low-oxidation transition-metal substituent would contribute a destabilizing interaction between the lone pair on the nitrogen atom and the filled metal d orbitals.3 However, all structurally characterized M(NCR2) complexes have essentially linear M-N-C geometries4 as a result of π donation of the lone pair on the nitrogen atom to empty metal orbitals. Thus, these azavinylidene5 complexes B are more related to alkylideneammonium cations than to imines.6
Herein we report the synthesis, structure, and a preliminary account of the reactivity of an N-metalloimine (type A) which contains a transition-metal fragment. The reaction of KNCPh2 with [Re(OTf)(CO)3(bpy)] (bpy=2,2′-bipyridine) afforded the complex [Re(NCPh2)(CO)3(bpy)] (1), which was characterized spectroscopically and by X-ray diffraction (Figure 1 a). For comparison, the structure of the imine complex [Re(HNCPh2)(CO)3(bpy)]+ (2), synthesized as its triflate salt by reaction of 1 with HOTf, was also determined (Figure 1 b). The Re-N-C angle (133.9(4)°) for the alkylideneamido group of 1, even smaller than the Re-N-C angle (138.9(2)°) of 2, indicates the absence of N-to-Re π donation. The larger deviations from linearity in previously known azavinylidene complexes (152.9(4)° and 157.2(4)° for [OsCl(NCMe2)(CCH3)(PiPr3)2][OTf]7 and [OsCl(NCMe2)(CHPh)(PiPr3)2],8 respectively) can be related to the presence of bulky ancillary ligands, whereas such effects are absent in 1. The ReNCPh2 distance (2.113(4) Å) in 1 is comparable to the ReN(H)CPh2 distance (2.192(3) Å) in 2, which is in agreement with the lack of multiple-bond character of the ReN bond.
LanguageEnglish
Pages3858-3860
Number of pages3
JournalAngewandte Chemie
Volume41
Issue number20
DOIs
Publication statusPublished - 2002

Fingerprint

Cycloaddition
Cycloaddition Reaction
Transition metals
Metals
Nitrogen
Carbon Monoxide
Atoms
Imines
Positive ions
2,2'-Dipyridyl
Ligands
Salts
X ray diffraction
Oxidation
Electrons
X-Ray Diffraction
Cations

Keywords

  • cycloaddition
  • imines
  • insertion
  • isocyanates
  • rhenium
  • TRIRUTHENIUM CARBONYL CLUSTER
  • complexes
  • nitriles
  • bonds

Cite this

Hevia, E ; Perez, J ; Riera, V ; Miguel, D . / Insertion and cycloaddition reactivity of a transition-metal N-metalloimine. In: Angewandte Chemie. 2002 ; Vol. 41, No. 20. pp. 3858-3860.
@article{08b5b71e7cc44f31a3c6af5797a5f387,
title = "Insertion and cycloaddition reactivity of a transition-metal N-metalloimine",
abstract = "The presence of electron-releasing main-group-metal substituents on the nitrogen atom increases the reactivity of imines A towards dipolar reagents such as isocyanates1 and ketenes.2 We speculated that, in addition to this inductive effect, a low-oxidation transition-metal substituent would contribute a destabilizing interaction between the lone pair on the nitrogen atom and the filled metal d orbitals.3 However, all structurally characterized M(NCR2) complexes have essentially linear M-N-C geometries4 as a result of π donation of the lone pair on the nitrogen atom to empty metal orbitals. Thus, these azavinylidene5 complexes B are more related to alkylideneammonium cations than to imines.6Herein we report the synthesis, structure, and a preliminary account of the reactivity of an N-metalloimine (type A) which contains a transition-metal fragment. The reaction of KNCPh2 with [Re(OTf)(CO)3(bpy)] (bpy=2,2′-bipyridine) afforded the complex [Re(NCPh2)(CO)3(bpy)] (1), which was characterized spectroscopically and by X-ray diffraction (Figure 1 a). For comparison, the structure of the imine complex [Re(HNCPh2)(CO)3(bpy)]+ (2), synthesized as its triflate salt by reaction of 1 with HOTf, was also determined (Figure 1 b). The Re-N-C angle (133.9(4)°) for the alkylideneamido group of 1, even smaller than the Re-N-C angle (138.9(2)°) of 2, indicates the absence of N-to-Re π donation. The larger deviations from linearity in previously known azavinylidene complexes (152.9(4)° and 157.2(4)° for [OsCl(NCMe2)(CCH3)(PiPr3)2][OTf]7 and [OsCl(NCMe2)(CHPh)(PiPr3)2],8 respectively) can be related to the presence of bulky ancillary ligands, whereas such effects are absent in 1. The ReNCPh2 distance (2.113(4) {\AA}) in 1 is comparable to the ReN(H)CPh2 distance (2.192(3) {\AA}) in 2, which is in agreement with the lack of multiple-bond character of the ReN bond.",
keywords = "cycloaddition, imines, insertion, isocyanates, rhenium, TRIRUTHENIUM CARBONYL CLUSTER, complexes, nitriles, bonds",
author = "E Hevia and J Perez and V Riera and D Miguel",
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Insertion and cycloaddition reactivity of a transition-metal N-metalloimine. / Hevia, E ; Perez, J ; Riera, V ; Miguel, D .

In: Angewandte Chemie, Vol. 41, No. 20, 2002, p. 3858-3860.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Insertion and cycloaddition reactivity of a transition-metal N-metalloimine

AU - Hevia, E

AU - Perez, J

AU - Riera, V

AU - Miguel, D

PY - 2002

Y1 - 2002

N2 - The presence of electron-releasing main-group-metal substituents on the nitrogen atom increases the reactivity of imines A towards dipolar reagents such as isocyanates1 and ketenes.2 We speculated that, in addition to this inductive effect, a low-oxidation transition-metal substituent would contribute a destabilizing interaction between the lone pair on the nitrogen atom and the filled metal d orbitals.3 However, all structurally characterized M(NCR2) complexes have essentially linear M-N-C geometries4 as a result of π donation of the lone pair on the nitrogen atom to empty metal orbitals. Thus, these azavinylidene5 complexes B are more related to alkylideneammonium cations than to imines.6Herein we report the synthesis, structure, and a preliminary account of the reactivity of an N-metalloimine (type A) which contains a transition-metal fragment. The reaction of KNCPh2 with [Re(OTf)(CO)3(bpy)] (bpy=2,2′-bipyridine) afforded the complex [Re(NCPh2)(CO)3(bpy)] (1), which was characterized spectroscopically and by X-ray diffraction (Figure 1 a). For comparison, the structure of the imine complex [Re(HNCPh2)(CO)3(bpy)]+ (2), synthesized as its triflate salt by reaction of 1 with HOTf, was also determined (Figure 1 b). The Re-N-C angle (133.9(4)°) for the alkylideneamido group of 1, even smaller than the Re-N-C angle (138.9(2)°) of 2, indicates the absence of N-to-Re π donation. The larger deviations from linearity in previously known azavinylidene complexes (152.9(4)° and 157.2(4)° for [OsCl(NCMe2)(CCH3)(PiPr3)2][OTf]7 and [OsCl(NCMe2)(CHPh)(PiPr3)2],8 respectively) can be related to the presence of bulky ancillary ligands, whereas such effects are absent in 1. The ReNCPh2 distance (2.113(4) Å) in 1 is comparable to the ReN(H)CPh2 distance (2.192(3) Å) in 2, which is in agreement with the lack of multiple-bond character of the ReN bond.

AB - The presence of electron-releasing main-group-metal substituents on the nitrogen atom increases the reactivity of imines A towards dipolar reagents such as isocyanates1 and ketenes.2 We speculated that, in addition to this inductive effect, a low-oxidation transition-metal substituent would contribute a destabilizing interaction between the lone pair on the nitrogen atom and the filled metal d orbitals.3 However, all structurally characterized M(NCR2) complexes have essentially linear M-N-C geometries4 as a result of π donation of the lone pair on the nitrogen atom to empty metal orbitals. Thus, these azavinylidene5 complexes B are more related to alkylideneammonium cations than to imines.6Herein we report the synthesis, structure, and a preliminary account of the reactivity of an N-metalloimine (type A) which contains a transition-metal fragment. The reaction of KNCPh2 with [Re(OTf)(CO)3(bpy)] (bpy=2,2′-bipyridine) afforded the complex [Re(NCPh2)(CO)3(bpy)] (1), which was characterized spectroscopically and by X-ray diffraction (Figure 1 a). For comparison, the structure of the imine complex [Re(HNCPh2)(CO)3(bpy)]+ (2), synthesized as its triflate salt by reaction of 1 with HOTf, was also determined (Figure 1 b). The Re-N-C angle (133.9(4)°) for the alkylideneamido group of 1, even smaller than the Re-N-C angle (138.9(2)°) of 2, indicates the absence of N-to-Re π donation. The larger deviations from linearity in previously known azavinylidene complexes (152.9(4)° and 157.2(4)° for [OsCl(NCMe2)(CCH3)(PiPr3)2][OTf]7 and [OsCl(NCMe2)(CHPh)(PiPr3)2],8 respectively) can be related to the presence of bulky ancillary ligands, whereas such effects are absent in 1. The ReNCPh2 distance (2.113(4) Å) in 1 is comparable to the ReN(H)CPh2 distance (2.192(3) Å) in 2, which is in agreement with the lack of multiple-bond character of the ReN bond.

KW - cycloaddition

KW - imines

KW - insertion

KW - isocyanates

KW - rhenium

KW - TRIRUTHENIUM CARBONYL CLUSTER

KW - complexes

KW - nitriles

KW - bonds

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DO - 10.1002/1521-3773(20021018)41:20<3858::AID-ANIE3858>3.0.CO;2-J

M3 - Article

VL - 41

SP - 3858

EP - 3860

JO - Angewandte Chemie International Edition

T2 - Angewandte Chemie International Edition

JF - Angewandte Chemie International Edition

SN - 1433-7851

IS - 20

ER -