Theoretical study of the intramolecular cis-trans isomerization mechanism in the chromium carbonyl complex, Cr(CO)5X (X = carbonyl, phosphine, triphenylphosphine)

Hansen, Lillian M.

doi:10.1021/ic00338a019

Cited by 13 publications

(3 citation statements)

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“…In agreement with this, DFT calculation shows that A is more stable than B by 6.6 kJ/mol. While the photoisomerization of 3a″ has been proposed to occur via migratory deinsertion of the acyl ligand back to a carbonyl and an alkyl ligand following CO loss, given the mild conditions (room temperature and no photochemical activation required), it is unlikely that the isomerization which we have observed follows an analogous mechanism; the well-studied Ray-Dutt twist is more likely. − …”

Section: Results and Discussionsupporting

confidence: 57%

Structural Mimics of the [Fe]-Hydrogenase: A Complete Set for Group VIII Metals

Barik

Ganguly

et al. 2018

Inorg. Chem.

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Section: Results and Discussionsupporting

confidence: 57%

Structural Mimics of the [Fe]-Hydrogenase: A Complete Set for Group VIII Metals

Barik

Ganguly

et al. 2018

Inorg. Chem.

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“…In order to understand the effects of CF 3 groups on the structure and bonding of manganese tris(pyrazolyl)borates, we have carried out a PRDDO/M calculation. This method, which is an approximate ab initio approach, has been shown to yield reasonable geometries in a wide variety of transition-metal complexes , and has proven useful in many problems involving structure and conformation in inorganic and organometallic systems. − In Table , we compare the calculated and experimental values for the important geometrical parameters of [PzB(Pz) 3 ]Mn(CO) 3 , [HB(3-(CF 3 )Pz) 3 ]Mn(CO) 3 , and [HB(3,5-(CF 3 ) 2 Pz) 3 ]Mn(CO) 3 . To compare our calculated geometries to experimental ones, in the manganese systems we chose [PzB(Pz) 3 ] - (rather than [HB(Pz) 3 ] - ) as the parent system ligand.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the Electronic and Geometric Effects of Trifluoromethyl Substituents on Tris(pyrazolyl)borate Ligands Using Manganese(I) and Copper(I) Complexes

et al. 1996

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Manganese tricarbonyl complexes of fluorinated tris(pyrazolyl)borate ligands [HB(3,5-(CF3)2Pz)3]- and [HB(3-(CF3)Pz)3]- (where Pz = pyrazolyl) were synthesized by treating BrMn(CO)5 with [HB(3,5-(CF3)2Pz)3]Ag(THF) or [HB(3-(CF3)Pz)3]Na(THF). The reaction of [HB(3-(CF3)Pz)3]Na(THF) with copper(I) trifluoromethanesulfonate under CO afforded [HB(3-(CF3)Pz)3]CuCO. Compounds [HB(3,5-(CF3)2Pz)3]Mn(CO)3 (5), [HB(3-(CF3)Pz)3]Mn(CO)3 (6), and [HB(3-(CF3)Pz)3]CuCO (7) were characterized by 1H NMR, 19F NMR, and IR spectroscopy and by X-ray crystallography. They have relatively high C−O stretching frequencies. However, the νCO values are much lower than that in free CO and the relative lowering is higher for manganese adducts. The CF3 substitution on the 5-position has a significant effect on the metal center. This is readily apparent from the infrared spectroscopic data. Theoretical calculations of the geometries of [tris(pyrazolyl)borato]manganese(I) and -copper(I) carbonyls are in excellent agreement with the experimental results. Increasing the degree of fluorination lengthens the metal−C and metal−N bonds and shortens the C−O distance. The metal−Pz bonding is essentially a pure σ-interaction. Cyclic voltammetry data for the copper complexes show high oxidation potentials for the fluorinated analogs. IR spectroscopic data of the [tris(pyrazolyl)borato]manganese and -copper carbonyls have also been compared to those of cyclopentadienyl analogs.

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“…This special class of H 2 ML 4 complexes undergo rearrangements with much lower activation barriers than those found for most other octahedral complexes. Several mechanisms 5,[13][14][15][16][17][18][19] have been proposed for the polytopal rear-rangements of d 6 octahedral transition metal complexes. These reactions have been studied primarily by Muetterties and coworkers 1,5,14,15 for a class of six-coordinate transition metal hydrides of the type H 2 ML 4 (where L is a phosphite, phosphine, phosphinite, or phosphonite).…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Rearrangements in Six-Coordinate Ruthenium and Iron Dihydrides

et al. 2001

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Molecular orbital calculations at the ab initio level are used to study polytopal rearrangements in H2Ru(PH3)4 and H2Fe(CO)4 as models of 18-electron, octahedral metal dihydrides. It is found that, in both cases, the transition state for these rearrangements is a dihydrogen species. For H2Fe(CO)4, this is a square pyramidal complex where the H2 ligand occupies an apical position and is rotated by 45 degrees from its original orientation. This is precisely analogous to the transition state for Fe-olefin rotation in (olefin)Fe(CO)4 complexes and has a very similar electronic origin. Another transition state very close in energy is found wherein the basic coordination geometry is a trigonal bipyramid and the H2 ligand is coordinated in the axial position. For H2Ru(PH3)4, the former stationary point lies at a much higher energy and the latter clearly serves as the transition state for hydride exchange. The reason for this difference is discussed along with the roles of electron correlation in the two compounds.

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Theoretical study of the intramolecular cis-trans isomerization mechanism in the chromium carbonyl complex, Cr(CO)5X (X = carbonyl, phosphine, triphenylphosphine)

Cited by 13 publications

References 0 publications

Structural Mimics of the [Fe]-Hydrogenase: A Complete Set for Group VIII Metals

Structural Mimics of the [Fe]-Hydrogenase: A Complete Set for Group VIII Metals

Investigation of the Electronic and Geometric Effects of Trifluoromethyl Substituents on Tris(pyrazolyl)borate Ligands Using Manganese(I) and Copper(I) Complexes

Intramolecular Rearrangements in Six-Coordinate Ruthenium and Iron Dihydrides

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