A new trinuclear mixed-valence Co(II)-Co(III) complex stabilized by a bis(salicylidene) based ligand

被引:49
作者
Banerjee, Suparna
Chen, Jiu-Tong
Lu, Can-Zhong
机构
[1] Univ Calcutta, Coll Sci & Technol, Dept Chem, Kolkata 700009, W Bengal, India
[2] Chinese Acad Sci, Fujian Inst Res Struct Matter, State Key Lab Struct Chem, Fujian 350002, Peoples R China
关键词
Co-III-Co-II-Co-III trinuclear complex; reaction stoichiometry; redox behaviour; magnetic properties; chemical reduction;
D O I
10.1016/j.poly.2006.08.035
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
The present work deals with a class I mixed valence trinuclear complex [Co-II(mu-OAc)(2)(mu-L)(2)CO2III (NCS)(2)] (1) formed by partial aerial oxidation (H2L = 1,7-bis(2-hydroxyphenyl)-2,6-diazahepta-1,6-diene). The terminal Co-III N3O3 centres exhibit a uniform facial arrangement of both N-3 and O-3 donor sets and the Co-II centre is coordinated to six oxygen atoms. Variable temperature magnetic susceptibility measurement reveals that the intermediate Co(II) paramagnetic centre undergoes a very weak spin exchange (theta = -6.39 K, antiferromagnetic) interaction with the two terminal Co(III) diamagnetic centres over the range 300-2 K. A three line EPR spectra at 4 K was characterized with highly anisotropic g tensors and the one line broad spectra at 300 K indicates the strong influence of temperature on the metal spin states, consistent with a high spin Co(II) complex. Two anodic responses appeared at +0.85 (Co2+ -> Co3+, reversible) and +1.7 V (Co3+-> Co4+, irreversible) corresponding to one and two electron transfer oxidation respectively. Another reversible signal attributed to Co3+ -> Co2+ reduction occurred at -0.5 V, associated with a two electron stoichiometry. Compound 1 reacted with hydrazinc to form a square planar orange-red [Co-II(L)] species, 2. Inter conversion between 1 and 2 involves electron exchange coupled with proton transfer. (c) 2006 Elsevier Ltd. All rights reserved.
引用
收藏
页码:686 / 694
页数:9
相关论文
共 34 条
[31]   Geometric and electronic structure/function correlations in non-heme iron enzymes [J].
Solomon, EI ;
Brunold, TC ;
Davis, MI ;
Kemsley, JN ;
Lee, SK ;
Lehnert, N ;
Neese, F ;
Skulan, AJ ;
Yang, YS ;
Zhou, J .
CHEMICAL REVIEWS, 2000, 100 (01) :235-349
[32]   UNUSUAL BOND LENGTHS, CONFORMATIONS, AND LIGAND-EXCHANGE RATES IN B-12 MODELS WITH THE BIS(SALICYLIDENE)-ORTHO-PHENYLENEDIAMINE EQUATORIAL LIGAND [J].
SUMMERS, MF ;
MARZILLI, LG ;
BRESCIANIPAHOR, N ;
RANDACCIO, L .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1984, 106 (16) :4478-4485
[33]   LIGAND-FIELD THEORY FOR 5-CO-ORDINATE MOLECULES .3. MAGNETIC PROPERTIES OF TRIGONAL BIPYRAMIDAL MOLECULES WITH A GROUND TERMS [J].
WOOD, JS .
JOURNAL OF THE CHEMICAL SOCIETY A -INORGANIC PHYSICAL THEORETICAL, 1969, (10) :1582-&
[34]   [N,N′-Bis(2-hydroxynaphthylmethylene)1,3-propanediaminato]cobalt(II) [J].
You, ZL ;
Zhu, HL ;
Liu, WS .
ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS, 2004, 60 :M654-M656