New four- and five-coordinated complexes of cobalt with sterically hindered o-iminobenzoquinone ligands: synthesis and structure

Poddel’sky, Andrey I.; Cherkasov, V. K.; Fukin, Georgy K.; Bubnov, M. P.; Abakumova, L. G.; Абакумов, Г. А.

doi:10.1016/j.ica.2004.04.013

Cited by 55 publications

(24 citation statements)

References 17 publications

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“…Earlier, 8 we have found that sterically hindered com plex 2 can react with chlorine containing solvents to form the chloride containing cobalt(III) bis o iminobenzo semiquinone complex Co(ISQ Me) 2 Cl (3) However, the reaction with the use of isopropyl sub stituted iminoquinone gives a mixture of five coordinate complex 4 and four coordinate complex 1 (see Scheme 2). The reaction products cannot be preparatively separated because of their similar solubility.…”

Section: Resultsmentioning

confidence: 99%

“…Complexes 1, 2, and 3 were synthe sized according to a procedure described earlier. 8 The thallium derivatives Tl(ISQ Me) (5) and Tl(ISQ Pr i ) (6) of o imino benzoquinones were synthesized according to a known pro cedure. 3 Bis [4,6 di tert butyl N (2,6 diisopropylphenyl) o imino benzosemiquinone]chlorocobalt(III), Co(ISQ Pr i ) 2 Cl (4).…”

Section: Methodsmentioning

confidence: 99%

“…5 In the square planar complexes Co(ISQ Pr i ) 2 (1) and Co(ISQ Me) 2 (2), the strong antiferromagnetic cou pling between the unpaired electrons of the ligands results in the doublet ground state (S = 1/2). 8 The bis o semi quinone complex Cu(3,6 DBSQ) 2 and the bis o imino semiquinone complex Cu(ISQ) 2 exist in the ground dou blet state with a low lying temperature accessible quadru plet (S = 3/2). 5, 15 The effective magnetic moment of manganese com plex 9 (2.77 µ B ) is similar to the spin only value (2.83 µ B ) for systems containing two unpaired electrons on one center (S = 1).…”

Section: Magnetic Propertiesmentioning

confidence: 99%

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Synthesis and structures of five-coordinate bis-o-iminobenzosemiquinone complexes M(ISQ-R)2X (X = Cl, Br, I, or SCN; M = CoIII, FeIII, or MnIII)

et al. 2006

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New five coordinate complexes Co(ISQ Pr i ) 2 Cl, Co(ISQ Me) 2 Cl, Co(ISQ Me) 2 I, Co(ISQ Me) 2 (SCN), Mn(ISQ Pr i ) 2 Cl, and Fe(ISQ Me) 2 Br (ISQ Pr i and ISQ Me are the 4,6 di tert butyl N (2,6 diisopropylphenyl) and 4,6 di tert butyl N (2,6 dimethylphenyl) o iminobenzosemiquinone radical anions, respectively) were synthesized. The complexes were characterized by UV Vis and IR spectroscopy and magnetochemistry. The molecular struc tures of the Fe(ISQ Me) 2 Br and Mn(ISQ Pr i ) 2 Cl complexes were established by X ray diffrac tion. The singlet ground state (S = 0) of the cobalt complexes is caused by antiferromagnetic coupling between the unpaired electrons of the radical ligands (S = 1/2) through the fully occupied atomic orbitals of low spin cobalt(III) (d 6 , S = 0). The effective magnetic moments of the complexes at 10 К are 0.18 µ B for Co(ISQ Pr i ) 2 Cl and 0.16 µ B for Co(ISQ Me) 2 I. The ground state of the manganese complex is triplet (S = 1). Two unpaired electrons of the o iminobenzosemiquinone ligands are strongly antiferromagnetically coupled with two of four unpaired electrons of high spin manganese(III) (d 4 , S = 2).Abundant data on o semiquinone complexes have been accumulated. 1,2 Studies of metal complexes with o imino benzoquinone ligands (analogs of o benzoquinones) are of considerable interest because o iminobenzoquinones have distinguishing features due to which such studies extend the range of related compounds and add to our knowledge of this class of complexes.Unlike o quinones, o iminoquinones are asymmetric, and the presence of the nitrogen atom allows one to in vestigate the spin density distribution in the chelate ring. The use of o iminosemiquinone as a spin labeled ligand in metal complexes helps in solving structural dynamic problems 3 and makes it possible to determine the spatial arrangement of ligands containing magnetic nuclei with respect to the plane of the o iminosemiquinone plane. 4 At the same time, o iminosemiquinones, like o semi quinones, serve as magnetic centers. From this stand point, investigation of spin couplings between ligands and/or between ligands and metals are of interest.The steric hindrance of the metal centers in com plexes can be varied over a wide range by introducing various substituents at the nitrogen atom. For example, o iminobenzoquinones containing the unsubstituted phe nyl substituent at the nitrogen atom form tris ligand tran sition metal complexes, which are very similar to o semi quinone derivatives. 5-7

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Magnetic Propertiesmentioning

confidence: 99%

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Synthesis and structures of five-coordinate bis-o-iminobenzosemiquinone complexes M(ISQ-R)2X (X = Cl, Br, I, or SCN; M = CoIII, FeIII, or MnIII)

et al. 2006

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“…Such complexes include the possibility to find: (i) heteroligand systems containing different types of radicals and (ii) linear molecular chains where X will be the connecting bridge between ML 2 fragments. Halogen-containing species ML 2 Hal are represented in the literature by cobalt, iron and manganese complexes [53][54][55][56].…”

Section: Pentacoordinate Bis-o-iminobenzoquinonato Complexes Of M(isqmentioning

confidence: 99%

Transition metal complexes with bulky 4,6-di-tert-butyl-N-aryl(alkyl)-o-iminobenzoquinonato ligands: Structure, EPR and magnetism

Poddel’sky

Cherkasov

Abakumov

2009

Coordination Chemistry Reviews

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317

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“…The two C-O stretch bands at 1200-1097 cm −1 in the spectrum of II are shifted toward lower frequencies in the spectrum of Cu(L II ) 2 , indicating Cu (II) coordinated to hydroxyls of II. The strong band at 1463 cm −1 in the Cu(L II ) 2 spectrum may be due to the radical-anionic ligand form [47] (see below).…”

Section: Infrared Spectramentioning

confidence: 99%

Copper (II) complexes of sterically hindered o-diphenol derivatives: synthesis, characterization and microbiological studies

et al. 2006

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Abstract:Cu (II) complexes with the sterically hindered diphenol derivatives 3,5-di(tertbutyl)-1,2-benzenediol (I), 4,6-di(tert-butyl)-1,2,3-benzenetriol (II) and the sulfur-containing 4,6-di(tert-butyl)-3-(2-hydroxyethylsulfanyl)-1,2-benzenediol (III) and 2-[4,6-di(tert-butyl)-2,3-dihydroxyphenylsulfanyl]acetic acid (IV) have been synthesized and characterized by elemental analysis, TG/DTA, FT-IR, ESR, XPS, XPD and conductivity measurements. Compounds I-III can coordinate in their singly deprotonated forms and act as bidentate ligands. These compounds yield Cu (II) complexes of the stoichiometry Cu(L) 2 , which have square planar geometry (g > g ⊥ >g e ). Unlike them, compound IV behaves as a terdentate ligand, and its complex Cu(L IV ) 2 has distorted octahedral geometry. According to ESR data, only the Cu(L II ) 2 complex contains a very small amount of phenoxyl radicals. Antimicrobial activities of these ligands and their respective Cu (II) complexes have been determined with respect to Gram-positive and Gram-negative bacteria, as well as on yeasts. Their phytotoxic properties against Chlorella vulgaris 157 were also examined.

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New four- and five-coordinated complexes of cobalt with sterically hindered o-iminobenzoquinone ligands: synthesis and structure

Cited by 55 publications

References 17 publications

Synthesis and structures of five-coordinate bis-o-iminobenzosemiquinone complexes M(ISQ-R)2X (X = Cl, Br, I, or SCN; M = CoIII, FeIII, or MnIII)

Synthesis and structures of five-coordinate bis-o-iminobenzosemiquinone complexes M(ISQ-R)2X (X = Cl, Br, I, or SCN; M = CoIII, FeIII, or MnIII)

Transition metal complexes with bulky 4,6-di-tert-butyl-N-aryl(alkyl)-o-iminobenzoquinonato ligands: Structure, EPR and magnetism

Copper (II) complexes of sterically hindered o-diphenol derivatives: synthesis, characterization and microbiological studies

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