2-(methylamido)pyridine–borane: a tripod κ3N,H,H-ligand in trigonal bipyramidal rhodium(I) and iridium(I) complexes with an asymmetric coordination of its BH3 group

Javier Brugos, Javier A. Cabeza, Pablo Garcia-Álvarez, Alan R. Kennedy, Enrique Pérez-Carreño, Juan F. Van der Maelen

Research output: Contribution to journalArticle

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Abstract

The complexes [M(κ3N,H,H-mapyBH3)(cod)] (M = Rh, Ir; HmapyBH3 = 2-(methylamino)pyridine–borane; cod = 1,5-cyclooctadiene), which contain a novel anionic tripod ligand coordinated to the metal atom through the amido N atom and through two H atoms of the BH3 group, have been prepared by treating the corresponding [M2(μ-Cl)2(cod)2] (M = Rh, Ir) precursor with K[mapyBH3]. X-ray diffraction studies and a theoretical QTAIM analysis of their electron density have confirmed that the metal atoms of both complexes are in a very distorted trigonal bipyramidal coordination environment, in which two equatorial sites are asymmetrically spanned by the H–B–H fragment. While both 3c–2e BH–M interactions are more κ1H (terminal sigma coordination of the B–H bond) than κ2H,B (agostic-type coordination of the B–H bond), one BH–M interaction is more agostic than the other and this difference is more marked in the iridium complex than in the rhodium one. This asymmetry is not evident in solution, where the cod ligand and the BH3 group of these molecules participate in two concurrent dynamic processes of low activation energies (VT-NMR and DFT studies), namely, a rotation of the cod ligand that interchanges its two alkene fragments (through a square pyramidal transition state) and a rotation of the BH3 group about the B–N bond that equilibrates the three B–H bonds (through a square planar transition state). While the cod rotation has similar activation energy in 2 and 3, the barrier to the BH3 group rotation is higher in the iridium complex than in the rhodium one.
LanguageEnglish
Pages8905-8912
Number of pages8
JournalInorganic Chemistry
Volume55
Issue number17
Early online date12 Aug 2016
DOIs
Publication statusPublished - 12 Oct 2016

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tripods
Iridium
Rhodium
boranes
iridium
rhodium
pyridines
Ligands
Atoms
ligands
atoms
Activation energy
Metals
fragments
activation energy
Interchanges
Alkenes
Discrete Fourier transforms
metals
alkenes

Keywords

  • iridium complex
  • rhodium complex
  • anionic tripod ligand
  • trigonal bipyramidal coordination environment
  • asymmetry
  • cod ligand
  • amine-boranes
  • aminoboranes
  • borane-metal interactions
  • asymmetric chelating coordination

Cite this

Brugos, Javier ; Cabeza, Javier A. ; Garcia-Álvarez, Pablo ; Kennedy, Alan R. ; Pérez-Carreño, Enrique ; Van der Maelen, Juan F. / 2-(methylamido)pyridine–borane : a tripod κ3N,H,H-ligand in trigonal bipyramidal rhodium(I) and iridium(I) complexes with an asymmetric coordination of its BH3 group. In: Inorganic Chemistry. 2016 ; Vol. 55, No. 17. pp. 8905-8912.
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abstract = "The complexes [M(κ3N,H,H-mapyBH3)(cod)] (M = Rh, Ir; HmapyBH3 = 2-(methylamino)pyridine–borane; cod = 1,5-cyclooctadiene), which contain a novel anionic tripod ligand coordinated to the metal atom through the amido N atom and through two H atoms of the BH3 group, have been prepared by treating the corresponding [M2(μ-Cl)2(cod)2] (M = Rh, Ir) precursor with K[mapyBH3]. X-ray diffraction studies and a theoretical QTAIM analysis of their electron density have confirmed that the metal atoms of both complexes are in a very distorted trigonal bipyramidal coordination environment, in which two equatorial sites are asymmetrically spanned by the H–B–H fragment. While both 3c–2e BH–M interactions are more κ1H (terminal sigma coordination of the B–H bond) than κ2H,B (agostic-type coordination of the B–H bond), one BH–M interaction is more agostic than the other and this difference is more marked in the iridium complex than in the rhodium one. This asymmetry is not evident in solution, where the cod ligand and the BH3 group of these molecules participate in two concurrent dynamic processes of low activation energies (VT-NMR and DFT studies), namely, a rotation of the cod ligand that interchanges its two alkene fragments (through a square pyramidal transition state) and a rotation of the BH3 group about the B–N bond that equilibrates the three B–H bonds (through a square planar transition state). While the cod rotation has similar activation energy in 2 and 3, the barrier to the BH3 group rotation is higher in the iridium complex than in the rhodium one.",
keywords = "iridium complex, rhodium complex, anionic tripod ligand, trigonal bipyramidal coordination environment, asymmetry, cod ligand, amine-boranes, aminoboranes, borane-metal interactions, asymmetric chelating coordination",
author = "Javier Brugos and Cabeza, {Javier A.} and Pablo Garcia-{\'A}lvarez and Kennedy, {Alan R.} and Enrique P{\'e}rez-Carre{\~n}o and {Van der Maelen}, {Juan F.}",
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2-(methylamido)pyridine–borane : a tripod κ3N,H,H-ligand in trigonal bipyramidal rhodium(I) and iridium(I) complexes with an asymmetric coordination of its BH3 group. / Brugos, Javier; Cabeza, Javier A.; Garcia-Álvarez, Pablo; Kennedy, Alan R.; Pérez-Carreño, Enrique; Van der Maelen, Juan F.

In: Inorganic Chemistry, Vol. 55, No. 17, 12.10.2016, p. 8905-8912.

Research output: Contribution to journalArticle

TY - JOUR

T1 - 2-(methylamido)pyridine–borane

T2 - Inorganic Chemistry

AU - Brugos, Javier

AU - Cabeza, Javier A.

AU - Garcia-Álvarez, Pablo

AU - Kennedy, Alan R.

AU - Pérez-Carreño, Enrique

AU - Van der Maelen, Juan F.

N1 - This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/journal/inocaj

PY - 2016/10/12

Y1 - 2016/10/12

N2 - The complexes [M(κ3N,H,H-mapyBH3)(cod)] (M = Rh, Ir; HmapyBH3 = 2-(methylamino)pyridine–borane; cod = 1,5-cyclooctadiene), which contain a novel anionic tripod ligand coordinated to the metal atom through the amido N atom and through two H atoms of the BH3 group, have been prepared by treating the corresponding [M2(μ-Cl)2(cod)2] (M = Rh, Ir) precursor with K[mapyBH3]. X-ray diffraction studies and a theoretical QTAIM analysis of their electron density have confirmed that the metal atoms of both complexes are in a very distorted trigonal bipyramidal coordination environment, in which two equatorial sites are asymmetrically spanned by the H–B–H fragment. While both 3c–2e BH–M interactions are more κ1H (terminal sigma coordination of the B–H bond) than κ2H,B (agostic-type coordination of the B–H bond), one BH–M interaction is more agostic than the other and this difference is more marked in the iridium complex than in the rhodium one. This asymmetry is not evident in solution, where the cod ligand and the BH3 group of these molecules participate in two concurrent dynamic processes of low activation energies (VT-NMR and DFT studies), namely, a rotation of the cod ligand that interchanges its two alkene fragments (through a square pyramidal transition state) and a rotation of the BH3 group about the B–N bond that equilibrates the three B–H bonds (through a square planar transition state). While the cod rotation has similar activation energy in 2 and 3, the barrier to the BH3 group rotation is higher in the iridium complex than in the rhodium one.

AB - The complexes [M(κ3N,H,H-mapyBH3)(cod)] (M = Rh, Ir; HmapyBH3 = 2-(methylamino)pyridine–borane; cod = 1,5-cyclooctadiene), which contain a novel anionic tripod ligand coordinated to the metal atom through the amido N atom and through two H atoms of the BH3 group, have been prepared by treating the corresponding [M2(μ-Cl)2(cod)2] (M = Rh, Ir) precursor with K[mapyBH3]. X-ray diffraction studies and a theoretical QTAIM analysis of their electron density have confirmed that the metal atoms of both complexes are in a very distorted trigonal bipyramidal coordination environment, in which two equatorial sites are asymmetrically spanned by the H–B–H fragment. While both 3c–2e BH–M interactions are more κ1H (terminal sigma coordination of the B–H bond) than κ2H,B (agostic-type coordination of the B–H bond), one BH–M interaction is more agostic than the other and this difference is more marked in the iridium complex than in the rhodium one. This asymmetry is not evident in solution, where the cod ligand and the BH3 group of these molecules participate in two concurrent dynamic processes of low activation energies (VT-NMR and DFT studies), namely, a rotation of the cod ligand that interchanges its two alkene fragments (through a square pyramidal transition state) and a rotation of the BH3 group about the B–N bond that equilibrates the three B–H bonds (through a square planar transition state). While the cod rotation has similar activation energy in 2 and 3, the barrier to the BH3 group rotation is higher in the iridium complex than in the rhodium one.

KW - iridium complex

KW - rhodium complex

KW - anionic tripod ligand

KW - trigonal bipyramidal coordination environment

KW - asymmetry

KW - cod ligand

KW - amine-boranes

KW - aminoboranes

KW - borane-metal interactions

KW - asymmetric chelating coordination

UR - http://pubs.acs.org/journal/inocaj

U2 - 10.1021/acs.inorgchem.6b01427

DO - 10.1021/acs.inorgchem.6b01427

M3 - Article

VL - 55

SP - 8905

EP - 8912

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 17

ER -