Synthesis, structure and physical properties of (.mu.-oxo)(.mu.-carboxylato)bis{(tris(2-pyridylmethyl)amine)chromium(III)} complexes

Gafford, B. G.; Marsh, Richard E.; Schaefer, William P.; Zhang, J. H.; O'Connor, C. J.; Holwerda, Robert A.

doi:10.1021/ic00348a014

Cited by 35 publications

(14 citation statements)

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“…37 Nearest neighbour magnetic exchange is dominated by the twisting of the -N-Omoiety of the phenolic oxime and the sign and magnitude of the pairwise exchange can be controlled via chemical substitution at the oximic C-atom. An excellent candidate in this regard is the tripodal tetradentate ligand tris(2-pyridylmethyl)amine (tpa) which has been used extensively to obtain dimers and trimers of Cu II , [43][44][45] Fe III , 46,47 Cr II and Cr III , [48][49][50][51] Co II , Ni II , 52,53 Mn II and Mn III . [40][41][42] Our most recent research attempts have therefore focused on deliberately targeting Mn III clusters with the R-saoH 2 family of ligands whose building blocks are not [Mn III 3 O(R-sao) 3 ] + triangles.…”

Section: Introductionmentioning

confidence: 99%

“…42 A simple method for favouring the formation of smaller clusters is through the use of polydentate chelating ligands which occupy the majority of coordination sites on the metal centre, leaving only one or two vacant sites for bridging ligands. An excellent candidate in this regard is the tripodal tetradentate ligand tris(2-pyridylmethyl)amine (tpa) which has been used extensively to obtain dimers and trimers of Cu II , [43][44][45] Fe III , 46,47 Cr II and Cr III , [48][49][50][51] Co II , Ni II , 52,53 Mn II and Mn III . [54][55][56] This ligand contains a tertiary N-atom bonded to three arms, each of which contains an N-donor atom from a pyridine ring (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

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From antiferromagnetic to ferromagnetic exchange in a family of oxime-based MnIII dimers: a magneto-structural study

et al. 2013

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The reaction of Mn(ClO4)2·6H2O, a derivatised phenolic oxime (R-saoH2) and the ligand tris(2-pyridylmethyl)amine (tpa) in a basic alcoholic solution leads to the formation of a family of cluster compounds of general formula [Mn(III)2O(R-sao)(tpa)2](ClO4)2 (1, R = H; 2, R = Me; 3, R = Et; 4, R = Ph). The structure is that of a simple, albeit asymmetric, dimer of two Mn(III) ions bridged through one μ-O(2-) ion and the -N-O- moiety of the phenolic oxime. Magnetometry reveals that the exchange interaction between the two Mn(III) ions in complexes 1, 3 and 4 is antiferromagnetic, but that for complex 2 is ferromagnetic. A theoretically developed magneto-structural correlation reveals that the dominant structural parameter influencing the sign and magnitude of the pairwise interaction is the dihedral Mn-O-N-Mn (torsion) angle. A linear correlation is found, with the magnitude of J varying significantly as the dihedral angle is altered. As the torsion angle increases the AF exchange decreases, matching the experimentally determined data. DFT calculations reveal that the dyz|π*|dyz interaction decreases as the dihedral angle increases leading to ferromagnetic coupling at larger angles.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

From antiferromagnetic to ferromagnetic exchange in a family of oxime-based MnIII dimers: a magneto-structural study

et al. 2013

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“…The metal-oxo distance -see Tables 1 and 2 -is significantly shorter than the other metal-ligand distances which are found in the range 2.03-2.21 Å [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Section: Model Parametersmentioning

confidence: 71%

Average One-Center Two-Electron Exchange Integrals and Exchange Interactions

Mossin

Weihe

2004

Structure and Bonding

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We show how the introduction of the average one-center two-electron exchange integral, which is closely related to Jørgensens spin-pairing energy parameter, facilitates comparison of the Heisenberg-Dirac-van Vleck exchange parameter for different transition metal dimers. The formalism is illustrated on m-oxo-dimanganese(III) and m-oxo-dichromium(III) complexes in which the oxo bridge is the important exchange pathway.

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“…We implemented the derived formulae as a program suite accepting standard quantum chemical input (molecular composition and geometry) using the GEOMO package [51] (QCPE No 290) as a source of the subroutines for performing the calulations of the molecular integrals and performing semi-empirical SCF MO LCAO procedures for the l -system. The package has been tested agaist the compounds of the Cr(III)OCr(III) family [52,53,54,55] known as «basic rhodo» compounds which have been synthetized by S.M. Jorgensen 130 years ago.…”

Section: Details Of Implementation and Calculation Resultsmentioning

confidence: 99%

Effective Hamiltonian Crystal Field for Magnetic Interactions in Polynuclear Transition Metal Complexes. Sequential Derivation and Exemplary Numerical Estimates

Tchougréeff¹

2013

Preprint

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By this we extend our work of the year 1992 devoted to calculating the intrashell excitations in the d-shells of coordination compounds of the first transition metal row, which resulted in the Effective Hamiltonian Crystal Field (EHCF) method, to their polynuclear analogs in order to assure the description of several open d-shells and of magnetic interactions of the effective spins residing in these shells. This is a challenging task since it requires improving the precision of ca. 1000 cm −1 (that of describing the excitation energies of the single dshells by the already well successful EHCF method) to the that of ca. 10 ÷ 100 cm −1 characteristic for the energies required to reorient the spins i.e. eventually by two orders of magnitude. This is performed within the same paradigm as used for the EHCF method: the concerted usage of the McWeeny's group-function approximation and the Löwdin partition technique. These are applied to develop the effective description of the d-system of the polynuclear complexes, composed of several d-shells, including the working formulae for the exchange parameters between the d-shells belonging to different transition metal ions. These formulae are implemented in the package MagAîxTic and tested against a series of binuclear complexes of trivalent Cr and Fe cations featuring µ-oxygen superexchange paths in order to confirm the reproducibility of the trends in the series of values of exchange parameters for the compounds differing by the chemical substitutions and other details of composition and structure. The results of calculations are in a reasonable agreement with available experimental data and other theoretical methods.

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Synthesis, structure and physical properties of (.mu.-oxo)(.mu.-carboxylato)bis{(tris(2-pyridylmethyl)amine)chromium(III)} complexes

Cited by 35 publications

References 3 publications

From antiferromagnetic to ferromagnetic exchange in a family of oxime-based MnIII dimers: a magneto-structural study

From antiferromagnetic to ferromagnetic exchange in a family of oxime-based MnIII dimers: a magneto-structural study

Average One-Center Two-Electron Exchange Integrals and Exchange Interactions

Effective Hamiltonian Crystal Field for Magnetic Interactions in Polynuclear Transition Metal Complexes. Sequential Derivation and Exemplary Numerical Estimates

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