Macrocyclic oxovanadium(IV) complexes: structure, magnetochemistry and electrochemistry

Autor:	Alok K. Mukherjee, Madeleine Helliwell, Kausik K. Nanda, Monika Mukherjee, Kamalaksha Nag, Ramprasad Das
Rok vydání:	1993
Předmět:	Denticity Stereochemistry Vanadium chemistry.chemical_element Protonation General Chemistry Crystal structure chemistry.chemical_compound Crystallography chemistry Magnetochemistry Saturated calomel electrode Macrocyclic ligand Cyclophane
Zdroj:	Journal of the Chemical Society, Dalton Transactions. :2241
ISSN:	1364-5447 0300-9246
DOI:	10.1039/dt9930002241
Popis:	The oxovanadium(IV) complexes, [VO(L)]·H2O 1, [VO(H2L)(SO4)]·3H2O 2, [(VO)2L(µ-SO4)]·MeOH·3H2O 3 and [Zn(L)VO(SO4)]·4H2O 4 have been synthesised from the dinucleating tetraaminodiphenol macrocyclic ligand H2L. The ESR and IR spectra of 1 have indicated stacking of the molecules due to ⋯ VO ⋯ VO ⋯ interactions. In complexes 2 and 4 the unidentate sulfate is bound to the octahedral vanadium and two of the secondary amino groups in 2 are protonated. Both of these complexes undergo oxidation to produce oxovanadium(V) species with E½= 0.40 V (2), 0.455 V (4)vs. saturated calomel electrode (SCE). Fairly strong antiferromagnetic exchange interaction has been found in 3 from variable-temperature susceptibility measurements, J=–128 cm–1. The crystal structure of 3 has been determined; tetragonal, space group P4122, a=b= 12.252(2), c= 40.819(5)A and Z= 8; refinement led to R= 0.053 and R′= 0.055 using 1825 unique reflections with I > 3σ(I). The two octahedral vanadium centres in the complex, separated by 3.077 A, are bridged by sulfate and have syn oxo configuration.
Databáze:	OpenAIRE
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