Contrasting the Group 6 metal-metal bonding in sodium dichromate(II) and sodium dimolybdate(II) polymethyl complexes: synthetic, x-ray crystallographic and theoretical studies

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Abstract

Extending the class of group 6 metal-metal bonded methylate compounds supported by alkali metal counter-ions, the first sodium octamethylmolybdate(II) complex [(TMEDA)Na]4Mo2Me8 and heptamethylchromate(II) relations [(donor)Na]3Cr2Me7 (donor is TMEDA or TMCDA) are reported. The former was made by treating [(Et2O)Li]4Mo2Me8 with four equivalents of NaOtBu/TMEDA in ether; whereas the latter resulted from introducing TMEDA or TMCDA to ether solutions of octamethyldichromate [(Et2O)Na]4Cr2Me8. X-ray crystallography revealed [(TMEDA)Na]4Mo2Me8 is dimeric with square pyramidal Mo centres [including a short Mo–Mo interaction of 2.1403(3) Å] each with four methyl groups in a mutually eclipsed conformation. In dinuclear [(TMCDA)Na]3Cr2Me7 trigonal bi-pyramidal Cr centres each bond to three terminal methyl groups and one common Me bridge, that produces a strikingly short Cr–Cr contact of 1.9136(4) Å. Broken symmetry density functional theoretical calculations expose the multiconfigurational metal-metal bonding in these compounds with a Mo–Mo bond order of 3 computed for octamethylmolybdate(II). This is contrasted by the single Cr–Cr bond in heptamethylchromate(II) where the singlet ground state is derived by strong antiferromagnetic coupling between adjacent metal ions.
LanguageEnglish
Pages6392-6403
JournalDalton Transactions
Volume46
Early online date26 Jan 2017
DOIs
Publication statusE-pub ahead of print - 26 Jan 2017

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Metals
Sodium
X rays
Ether
Alkali Metals
Radiation counters
X ray crystallography
Ground state
Density functional theory
Metal ions
Conformations
phenyllithium
sodium bichromate

Keywords

  • group 6 metal-metal bonded methylate compounds
  • alkali metal counter-ions
  • metal-metal bonding
  • crystallographic characterisations
  • X-ray crystallography
  • synthesis

Cite this

@article{b8fa9ea72bae4ec285227fad69a774a2,
title = "Contrasting the Group 6 metal-metal bonding in sodium dichromate(II) and sodium dimolybdate(II) polymethyl complexes: synthetic, x-ray crystallographic and theoretical studies",
abstract = "Extending the class of group 6 metal-metal bonded methylate compounds supported by alkali metal counter-ions, the first sodium octamethylmolybdate(II) complex [(TMEDA)Na]4Mo2Me8 and heptamethylchromate(II) relations [(donor)Na]3Cr2Me7 (donor is TMEDA or TMCDA) are reported. The former was made by treating [(Et2O)Li]4Mo2Me8 with four equivalents of NaOtBu/TMEDA in ether; whereas the latter resulted from introducing TMEDA or TMCDA to ether solutions of octamethyldichromate [(Et2O)Na]4Cr2Me8. X-ray crystallography revealed [(TMEDA)Na]4Mo2Me8 is dimeric with square pyramidal Mo centres [including a short Mo–Mo interaction of 2.1403(3) {\AA}] each with four methyl groups in a mutually eclipsed conformation. In dinuclear [(TMCDA)Na]3Cr2Me7 trigonal bi-pyramidal Cr centres each bond to three terminal methyl groups and one common Me bridge, that produces a strikingly short Cr–Cr contact of 1.9136(4) {\AA}. Broken symmetry density functional theoretical calculations expose the multiconfigurational metal-metal bonding in these compounds with a Mo–Mo bond order of 3 computed for octamethylmolybdate(II). This is contrasted by the single Cr–Cr bond in heptamethylchromate(II) where the singlet ground state is derived by strong antiferromagnetic coupling between adjacent metal ions.",
keywords = "group 6 metal-metal bonded methylate compounds, alkali metal counter-ions, metal-metal bonding, crystallographic characterisations , X-ray crystallography, synthesis",
author = "Ross Campbell and Kennedy, {Alan R.} and Ross McLellan and Robertson, {Stuart D.} and Stephen Sproules and Mulvey, {Robert E.}",
year = "2017",
month = "1",
day = "26",
doi = "10.1039/C6DT04644D",
language = "English",
volume = "46",
pages = "6392--6403",
journal = "Dalton Transactions",
issn = "1477-9226",

}

TY - JOUR

T1 - Contrasting the Group 6 metal-metal bonding in sodium dichromate(II) and sodium dimolybdate(II) polymethyl complexes

T2 - Dalton Transactions

AU - Campbell, Ross

AU - Kennedy, Alan R.

AU - McLellan, Ross

AU - Robertson, Stuart D.

AU - Sproules, Stephen

AU - Mulvey, Robert E.

PY - 2017/1/26

Y1 - 2017/1/26

N2 - Extending the class of group 6 metal-metal bonded methylate compounds supported by alkali metal counter-ions, the first sodium octamethylmolybdate(II) complex [(TMEDA)Na]4Mo2Me8 and heptamethylchromate(II) relations [(donor)Na]3Cr2Me7 (donor is TMEDA or TMCDA) are reported. The former was made by treating [(Et2O)Li]4Mo2Me8 with four equivalents of NaOtBu/TMEDA in ether; whereas the latter resulted from introducing TMEDA or TMCDA to ether solutions of octamethyldichromate [(Et2O)Na]4Cr2Me8. X-ray crystallography revealed [(TMEDA)Na]4Mo2Me8 is dimeric with square pyramidal Mo centres [including a short Mo–Mo interaction of 2.1403(3) Å] each with four methyl groups in a mutually eclipsed conformation. In dinuclear [(TMCDA)Na]3Cr2Me7 trigonal bi-pyramidal Cr centres each bond to three terminal methyl groups and one common Me bridge, that produces a strikingly short Cr–Cr contact of 1.9136(4) Å. Broken symmetry density functional theoretical calculations expose the multiconfigurational metal-metal bonding in these compounds with a Mo–Mo bond order of 3 computed for octamethylmolybdate(II). This is contrasted by the single Cr–Cr bond in heptamethylchromate(II) where the singlet ground state is derived by strong antiferromagnetic coupling between adjacent metal ions.

AB - Extending the class of group 6 metal-metal bonded methylate compounds supported by alkali metal counter-ions, the first sodium octamethylmolybdate(II) complex [(TMEDA)Na]4Mo2Me8 and heptamethylchromate(II) relations [(donor)Na]3Cr2Me7 (donor is TMEDA or TMCDA) are reported. The former was made by treating [(Et2O)Li]4Mo2Me8 with four equivalents of NaOtBu/TMEDA in ether; whereas the latter resulted from introducing TMEDA or TMCDA to ether solutions of octamethyldichromate [(Et2O)Na]4Cr2Me8. X-ray crystallography revealed [(TMEDA)Na]4Mo2Me8 is dimeric with square pyramidal Mo centres [including a short Mo–Mo interaction of 2.1403(3) Å] each with four methyl groups in a mutually eclipsed conformation. In dinuclear [(TMCDA)Na]3Cr2Me7 trigonal bi-pyramidal Cr centres each bond to three terminal methyl groups and one common Me bridge, that produces a strikingly short Cr–Cr contact of 1.9136(4) Å. Broken symmetry density functional theoretical calculations expose the multiconfigurational metal-metal bonding in these compounds with a Mo–Mo bond order of 3 computed for octamethylmolybdate(II). This is contrasted by the single Cr–Cr bond in heptamethylchromate(II) where the singlet ground state is derived by strong antiferromagnetic coupling between adjacent metal ions.

KW - group 6 metal-metal bonded methylate compounds

KW - alkali metal counter-ions

KW - metal-metal bonding

KW - crystallographic characterisations

KW - X-ray crystallography

KW - synthesis

UR - http://pubs.rsc.org/en/journals/journalissues/dt

U2 - 10.1039/C6DT04644D

DO - 10.1039/C6DT04644D

M3 - Article

VL - 46

SP - 6392

EP - 6403

JO - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

ER -