Rational design of rhodium complexes featuring κ4-N,N,N,N- and κ5-N,N,N,P,P-Bis(imino)pyridine ligands

Hagit Ben-Daat, Gabriel B. Hall, Thomas L. Groy, Ryan Trovitch

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The addition of aminoalkyl-substituted 2,6-bis(imino)pyridine (or pyridine diimine, PDI) ligands to [(COD)RhCl]2 (COD = 1,5-cyclooctadiene) resulted in the formation of rhodium monochloride complexes with the general formula (NPDI)RhCl (NPDI = iPr2 NEtPDI or Me2NPrPDI). The investigation of (iPr2NEtPDI)RhCl and ( Me2NPrPDI)RhCl by single-crystal X-ray diffraction verified the absence of amine arm coordination and a pseudo square-planar geometry about rhodium. Replacement of the chloride ligand with an outer-sphere anion was achieved by adding AgBF4 directly to ( iPr2NEtPDI)RhCl to form [(iPr 2NEtPDI)Rh][BF4]. Alternatively, this complex was prepared by chelate addition following the salt metathesis reaction between AgBF4 and [(COD)RhCl]2. Using the latter method, both [(NPDI)Rh][BF4] complexes were isolated and found to exhibit κ4-N,N,N,N-PDI coordination regardless of arm length or steric bulk. In contrast, the metallation of PPDI chelates featuring alkylphosphane imine substituents (PPDI = Ph 2PEtPDI or Ph2PPrPDI) resulted in the formation of cationic complexes featuring κ5-N, N,N,P,P-PDI coordination in all instances, [(PPDI)Rh][X] (X = Cl, BF4). Adjusting the metallation stoichiometry allowed the preparation of [(Ph2PPrPDI)Rh][(COD)RhCl2], as validated by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. The coordinative flexibility of newly prepared PDI ligands has been evaluated following their addition to [(COD)RhCl]2. Tailoring this chelate class to include donor atoms has allowed the preparation of complexes featuring tetradentate and pentadentate PDI coordination.

Original languageEnglish
Pages (from-to)4430-4442
Number of pages13
JournalEuropean Journal of Inorganic Chemistry
Issue number25
DOIs
Publication statusPublished - Sep 2013

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Rhodium
Ligands
Single crystals
X ray diffraction
Imines
Stoichiometry
Nuclear magnetic resonance spectroscopy
Amines
Anions
pyridine
Chlorides
Salts
Atoms
Geometry

Keywords

  • Coordination modes
  • Electronic structure
  • Ligand design
  • Non-innocent ligands
  • Rhodium

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Rational design of rhodium complexes featuring κ4-N,N,N,N- and κ5-N,N,N,P,P-Bis(imino)pyridine ligands. / Ben-Daat, Hagit; Hall, Gabriel B.; Groy, Thomas L.; Trovitch, Ryan.

In: European Journal of Inorganic Chemistry, No. 25, 09.2013, p. 4430-4442.

Research output: Contribution to journalArticle

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title = "Rational design of rhodium complexes featuring κ4-N,N,N,N- and κ5-N,N,N,P,P-Bis(imino)pyridine ligands",
abstract = "The addition of aminoalkyl-substituted 2,6-bis(imino)pyridine (or pyridine diimine, PDI) ligands to [(COD)RhCl]2 (COD = 1,5-cyclooctadiene) resulted in the formation of rhodium monochloride complexes with the general formula (NPDI)RhCl (NPDI = iPr2 NEtPDI or Me2NPrPDI). The investigation of (iPr2NEtPDI)RhCl and ( Me2NPrPDI)RhCl by single-crystal X-ray diffraction verified the absence of amine arm coordination and a pseudo square-planar geometry about rhodium. Replacement of the chloride ligand with an outer-sphere anion was achieved by adding AgBF4 directly to ( iPr2NEtPDI)RhCl to form [(iPr 2NEtPDI)Rh][BF4]. Alternatively, this complex was prepared by chelate addition following the salt metathesis reaction between AgBF4 and [(COD)RhCl]2. Using the latter method, both [(NPDI)Rh][BF4] complexes were isolated and found to exhibit κ4-N,N,N,N-PDI coordination regardless of arm length or steric bulk. In contrast, the metallation of PPDI chelates featuring alkylphosphane imine substituents (PPDI = Ph 2PEtPDI or Ph2PPrPDI) resulted in the formation of cationic complexes featuring κ5-N, N,N,P,P-PDI coordination in all instances, [(PPDI)Rh][X] (X = Cl, BF4). Adjusting the metallation stoichiometry allowed the preparation of [(Ph2PPrPDI)Rh][(COD)RhCl2], as validated by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. The coordinative flexibility of newly prepared PDI ligands has been evaluated following their addition to [(COD)RhCl]2. Tailoring this chelate class to include donor atoms has allowed the preparation of complexes featuring tetradentate and pentadentate PDI coordination.",
keywords = "Coordination modes, Electronic structure, Ligand design, Non-innocent ligands, Rhodium",
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T1 - Rational design of rhodium complexes featuring κ4-N,N,N,N- and κ5-N,N,N,P,P-Bis(imino)pyridine ligands

AU - Ben-Daat, Hagit

AU - Hall, Gabriel B.

AU - Groy, Thomas L.

AU - Trovitch, Ryan

PY - 2013/9

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N2 - The addition of aminoalkyl-substituted 2,6-bis(imino)pyridine (or pyridine diimine, PDI) ligands to [(COD)RhCl]2 (COD = 1,5-cyclooctadiene) resulted in the formation of rhodium monochloride complexes with the general formula (NPDI)RhCl (NPDI = iPr2 NEtPDI or Me2NPrPDI). The investigation of (iPr2NEtPDI)RhCl and ( Me2NPrPDI)RhCl by single-crystal X-ray diffraction verified the absence of amine arm coordination and a pseudo square-planar geometry about rhodium. Replacement of the chloride ligand with an outer-sphere anion was achieved by adding AgBF4 directly to ( iPr2NEtPDI)RhCl to form [(iPr 2NEtPDI)Rh][BF4]. Alternatively, this complex was prepared by chelate addition following the salt metathesis reaction between AgBF4 and [(COD)RhCl]2. Using the latter method, both [(NPDI)Rh][BF4] complexes were isolated and found to exhibit κ4-N,N,N,N-PDI coordination regardless of arm length or steric bulk. In contrast, the metallation of PPDI chelates featuring alkylphosphane imine substituents (PPDI = Ph 2PEtPDI or Ph2PPrPDI) resulted in the formation of cationic complexes featuring κ5-N, N,N,P,P-PDI coordination in all instances, [(PPDI)Rh][X] (X = Cl, BF4). Adjusting the metallation stoichiometry allowed the preparation of [(Ph2PPrPDI)Rh][(COD)RhCl2], as validated by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. The coordinative flexibility of newly prepared PDI ligands has been evaluated following their addition to [(COD)RhCl]2. Tailoring this chelate class to include donor atoms has allowed the preparation of complexes featuring tetradentate and pentadentate PDI coordination.

AB - The addition of aminoalkyl-substituted 2,6-bis(imino)pyridine (or pyridine diimine, PDI) ligands to [(COD)RhCl]2 (COD = 1,5-cyclooctadiene) resulted in the formation of rhodium monochloride complexes with the general formula (NPDI)RhCl (NPDI = iPr2 NEtPDI or Me2NPrPDI). The investigation of (iPr2NEtPDI)RhCl and ( Me2NPrPDI)RhCl by single-crystal X-ray diffraction verified the absence of amine arm coordination and a pseudo square-planar geometry about rhodium. Replacement of the chloride ligand with an outer-sphere anion was achieved by adding AgBF4 directly to ( iPr2NEtPDI)RhCl to form [(iPr 2NEtPDI)Rh][BF4]. Alternatively, this complex was prepared by chelate addition following the salt metathesis reaction between AgBF4 and [(COD)RhCl]2. Using the latter method, both [(NPDI)Rh][BF4] complexes were isolated and found to exhibit κ4-N,N,N,N-PDI coordination regardless of arm length or steric bulk. In contrast, the metallation of PPDI chelates featuring alkylphosphane imine substituents (PPDI = Ph 2PEtPDI or Ph2PPrPDI) resulted in the formation of cationic complexes featuring κ5-N, N,N,P,P-PDI coordination in all instances, [(PPDI)Rh][X] (X = Cl, BF4). Adjusting the metallation stoichiometry allowed the preparation of [(Ph2PPrPDI)Rh][(COD)RhCl2], as validated by multinuclear NMR spectroscopy and single-crystal X-ray diffraction. The coordinative flexibility of newly prepared PDI ligands has been evaluated following their addition to [(COD)RhCl]2. Tailoring this chelate class to include donor atoms has allowed the preparation of complexes featuring tetradentate and pentadentate PDI coordination.

KW - Coordination modes

KW - Electronic structure

KW - Ligand design

KW - Non-innocent ligands

KW - Rhodium

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