Azo compounds as electron acceptor or radical ligands in transition metal species: spectroelectrochemistry and high-field EPR studies of ruthenium, rhodium and copper complexes of 2,20-azobis(5-chloropyrimidine)
نویسندگان
چکیده
Oxidative coupling of 2-aminopyrimidine with LiOCl produces 5-chloro-2,20-azobis(pyrimidine) and 2,20-azobis(5chloropyrimidine) (abcp), both of which were structurally characterized. The symmetrical abcp was used as strongly p-accepting monoand bis-chelate ligand in complexes with [(bpy)2Ru] 2þ, [(H6C6)ClRu] þ, [(Ph3P)2Cu] þ and (OC)3ClRe. The p-acceptor capability of abcp results in low-energy MLCT transitions and facile reduction to isolable radical complexes of which the DFT-calculated and structurally characterized dicopper(I) species {(m-abcp)[Cu(PPh3)2]2}(PF6) was studied by Xand W-band EPR and the complex {(m-abcp)[Ru(bpy)2]2}(PF6)3 at 9.6, 230 and 285 GHz EPR frequency. The results indicate considerable metal–ligand orbital mixing in the singly occupied molecular orbitals. q 2003 Elsevier B.V. All rights reserved.
منابع مشابه
STUDIES OF TRANSITION METAL COMPLEXES WITH 2N-QUINOLYL- AND 2N-ISOQUINOLYL- 1,1,3,3-TETRAMETHY LGUANIDINES
Ligands derived from 8-quinoline, 6-quinoline, 1 -isoquinoline, and 5-isoquinoline were synthesized. These compounds have been used as ligands for complexation of transition metals, such as copper(II) and nickel(II). According to the spectrosocopic data, copper(II) cation forms (I: 1) and (I:2) complexes with 2-(8-quinoly1)-l,l,3,3- tetramethylguanidine and 2- (I '-isoquinoly1)- 1,1,3,3-tetr...
متن کاملSynthesis and characterization of some transition metal complexes with new mixed-donor schiff base ligands derived from 2-hydroxynaphthaldehyde
2-[3-(2-Formylnaphthoxy)-2-hydroxypropoxy] naphthaldehyde (1) have been prepared by reaction of 2-hydroxynaphthaldehyde with 1,3-dichloro-2-propanol. New N2O3 macro-acyclic ligands (L1, L2) synthesized from the reaction of (1) with aniline or cyclohexylamine. Ni (II), Co (II) and Cu (II) complexes was prepared from reaction of Schiff-bases with metal chloride and nitrate salts. All of these com...
متن کاملSynthesis and characterization of some transition metal complexes with new mixed-donor schiff base ligands derived from 2-hydroxynaphthaldehyde
2-[3-(2-Formylnaphthoxy)-2-hydroxypropoxy] naphthaldehyde (1) have been prepared by reaction of 2-hydroxynaphthaldehyde with 1,3-dichloro-2-propanol. New N2O3 macro-acyclic ligands (L1, L2) synthesized from the reaction of (1) with aniline or cyclohexylamine. Ni (II), Co (II) and Cu (II) complexes was prepared from reaction of Schiff-bases with metal chloride and nitrate salts. All of these com...
متن کاملDifferent manifestations of enhanced π-acceptor ligation at every redox level of [Os(9-OP)L2]n, n = 2+, +, 0, - (9-OP- = 9-oxidophenalenone and L = bpy or pap).
The title complexes were isolated as structurally characterised compounds [OsII(9-OP)L2]ClO4, L = 2,2'-bipyridine (bpy) or 2-phenylazopyridine (pap), and were compared with ruthenium analogues. A reversible one-electron oxidation and up to three reduction processes were observed by voltammetry (CV, DPV) and spectroelectrochemistry (UV-vis-NIR, partially EPR). Supporting calculations (DFT, TD-DF...
متن کاملSynthesis, Spectroscopy and Magnetic Characterization of Five Dinuclear Copper(II) Complexes with 2, 3 or 4-Pyridinemethanol as the Ligand
The synthesis, spectroscopy and magnetic characterization of five new dinuclear copper(II) complexes are described. All five compounds have the general formula [Cu2(L)4(O-R)2](Cl)2 or [Cu2(L)2(Cl)2](Cl)2, in which R = CH3 or H, L=2, 3 or 4-pyridinemethanol as L2, L3 or L4, respectively. The title compounds consist of dinuclear units with bridging methoxo groups in [Cu2(L4)4(O-CH3)2](Cl)2, hydro...
متن کامل