Heteroleptic tris-complexes of ruthenium(II/III) containing one bidentate Schiff base: Synthesis, characterisation and link-up of oxidation levels

1239-1244A series of mixed-tris chelates of ruthenium(II) and -(III) of general formula [RuLʹL2]z+ [Lʹ = N-((pyridin-2-yl)formylidene)aniline (pfan ), N-((pyridin-2-y l)benzylidene)aniline (pban), N((pyridin-2-yl)formylidene)benzylamine (pfba) or N-((pyridin-2-yl)benzylidene)benzylamine (pbba): L = 2,2ʹ-bipyridine (bpy), z = 2 or 3; L = 2-(m -tolylazo)pyridine (tap), z = 2] have been prepared, isolated as their perchlorates and characterised by physicochemical, magnetic and spectroscopic methods. The ruthenium (II) and rutheniun(III ) complexes, respectively exhibit several MLCT and LMCT charge- transfer transitions in the 200-900 nm region . In MeCN solutions all the compounds exhibit ruthenium(III)ruthenium(II) couple, and additionally bpy complexes show ruthenium(IV)-ruthenium(III) response. The stability of metal oxidation levels is discussed in terms of the electrochemical results and correlated to the π-acceptor properties of these ligands. On the negative side of SCE successive ligand reductions are observable involving diimine/azoimine group

Synthesis, structure and properties of [Cu(L)(NCO)]X (L = tetradentate schiff bases; X = ClO₄, PF₆)

1901-1905Four copper(II) complexes of the type [Cu(L)(NCO)]X (1-4) [L=N,N' -(bis(pyridin-2-yl)formylidene)butane-1 ,4-diamine (bpfd) or N,N'-(bis(pyridin-2-yl)benzylidene)butane-1 ,4-diamine (bpbd); X = ClO4, PF6] have been synthesised and characterised on the basis of microanalytical, spectroscopic, magnetic, electrochemical and other physicochemical properties. X-ray diffraction study of complex 1 (L= bpfd, X = ClO4 ) reveals copper(II) ion in a distorted trigonal bipyramidal environment through coordination of the metal centre by two pyridine N atoms and two imine N atoms of the schiff base with the fifth position occupied with N atom of terminal NCO'. The tetradentate chelator is folded in the butylenic part. I R spectra of the complexes show asymmetric and symmetric stretching vNCO vibrations at ~ 2250 and ~1320 cm-1 respectively indicating N-bonding of NCO'. Electrochemi cal electron transfer study reveals CUII-CUI reduction in methanolic solutions

Wilson’s disease: a cognitive neuropsychological perspective

Background: Wilson’s disease manifests as neuro-psychological or psychiatric symptoms along with neurological and liver disease. The present study aimed to probe into the declarative and non-declarative memory profile of Wilson’s disease patients from a neurocognitive perspective. Methods: The study involved a sample of 12 Wilson’s disease patients and 12 matched non-patient individuals who were assessed on Global Assessment Scale for Wilson’s disease, the Edinburgh handedness inventory, memory scales from PGI Battery of Brain Dysfunction, Rey Auditory Verbal Learning Test, and mirror tracing task. Results: The overall result indicated that the Wilson’s disease patient group differed with their non-patient counterparts with respect to immediate memory, recall, recognition, semantic memory, and procedural learning. Conclusion: The neural substrates related to the neuro-psychological symptoms of Wilson’s disease patients are found to be a neural network involving basal ganglia, fronto-striatal circuits, and cerebellar region

Synthesis, characterisation and redox behaviour of mixed ligand complexes of osmiurn(II/III/IV)

2772-2777A group of mixed-tris chelates of osmium(II), (III) and (IV) of the general formula [OsL'L2]z+ [L' = N-((pyridin-2-yl )formylidene) aniline (pfan) or N-((pyridin-2-yl)benzylidene)aniline (pban); L = 2,2'-bipyridyl (bipy), 2-(III-tolylazo)pyridine (tapy) or quinolin-8-olate (oxin); z = 1-3] have been prepared, isolated as their perchlorates and characterised by physicochemical, magnetic and spectroscopic methods. The complexes exhibit several spinallowed and spin-forbidden charge-transfer transitions in the 1000-200 nm region. In MeCN solutions the chelates display osmium(IV)-osmium(III) and osmium(III)-osmium(II) couples in the range -0.4 to 1.6 V vs SCE. The stability of metal oxidation levels is discussed in terms of the electrochemical result s and correlated to the π-acceptor properties of these ligands. On the negative side of SCE, successive ligand reductions in bipy/tapy complexes are observed involving diimine (-N=C-C=N-)/ azoimine (-N=N-C=N-) group

Synthesis, characterisation and redox behaviour of mixed ligand complexes of osmium(II/III/IV)-phosphines

1112-1118The reaction of [OsX2 L2] [X = Cl or Br; L = 2-(m-tolylazo)pyridine (tapy), 1; L = quinolin-8-olate (oxin), 2] with tertiary phosphine (PR3 = PPh3 or PPh2Me) bases in boiling aqueous alcohol affords complexes of the types [OsX(PR3)L2]z + (L = tapy, Z = 1, 3; L = oxin, Z = 0, 5) and [Os(PR3)2 L2]n+ (L =tapy,n = 2, 4;L = oxin, n = 0, 6), which when charged isolated as their perchlorates. The osimum(IV) counterparts [OsX(PR3)-(oxin2)1+ (7) and osimum(III) species [Os(PR3)2 (oxin)2]1+ (8) of [OsX(PR3)(oxin)2] (5) and [Os(PR3)(oxin)2] (6), respectively are also stable enough for isolation by oxidation with cerium(IV). The new complexes have been characterized by spectroscopic, magnetic, electrochemical and other physicochemical results. Using 1H NMR results (δMe of tapy/PPh2Me) in selected cases the stereochemistry of OsL2 fragment in these mixed L-PR3 complexes has been proposed. The diamagnetic osmium(II) complexes display a number of spin -allowed and spin -forbidden MLCT transitions whereas LMCT bands are seen in paramagnetic osmium (III) and osmium(IV) compounds. All the complexes are electroactive and exhibit osmium (III) - osmium (II) response in MeCN solutions; additionally, oxin complexes show osmium(IV)osmium(III) couple within accessible potential window. The stability of metal oxidation levels is discussed in terms of the electrochemical results and correlated to the π-acceptor strengths of these ligands

Synthesis, characterization and redox behaviour of camphorquinone monooximate complexes of osmium(II), -(III) and -(IV)

774-779A group of dihalogenobis complexes of the type [OsX2(HA)(A)] (1) and mixed-tris chelates of types [Os(A)(L)2] - CIO4.H2O (<b style="mso-bidi-font-weight: normal">2), Os(A)(Q)2 (3) and [Os(A)(Q)2]CIO4.H2O (<b style="mso-bidi-font-weight: normal">4) [where X=CI or Br; HA=camphor-quinone monooxime; L = 2-(arylazo)pyridines and HQ=quinolin-8-ol and its derivative] have been prepared by distinctly different synthetic routes and characterized by microanalytical, IR, EPR, UV-Vis and electrochemical results. Reversible/nearly- reversible osmium(III)-osmium(II) and osmium(IV)-osmium(III) couples are invariably seen in all the complexes. </span

Isomeric mixed dioxolene 2-(arylazo)pyridine complexes of osmium(II): Synthesis, spectra and electrochemistry

1374-1379The complexes blue-violet (3) and red-violet (4) isomers of [OsX2L2] [X = Cl or Br; L (2) = 2-(phenylazo)pyridine (L1 and 2-(m -tolylazo)pyridine (L2)] react smoothly with catechol and its substituted derivative [H2Q; (1)] in boiling aqueous ethanol affording mixed tris complexes of the type [OsQL2] [(5) and (6), respectively]. The new complexes have been characterized by physicochemical, spectroscopic and magnetic methods. From 1H NMR spectra (taking δMe of L2 as diagnostic probe), the stereoretentivity of the reactions is proposed. The diamagnetic complexes display a number of spinal lowed and spin-forbidden charge-transfer transitions in the 1200-200 nm range. Both (5) and (6) are electroactive and display six voltammetric responses - two oxidati ons and four reductions. EPR study of the coulometrically generated one electron oxidation product suggests the involvement of semiquinone radical formation

Synthesis, characterisation and X-ray structure of a mononuclear zinc(II)azido complex containing tetradentate schiff base

1119-1122The synthesis, characterisation and single crystal&nbsp; X-ray structural analysis of [Zn(bnbzpy)(N3)]ClO4 (1) [bnbzpy = N,N'(bis(pyridin-2-yl)benzylidene)butane- 1,4-diamine] have been described. X-ray diffraction study has been made for the exact definition of the coordination sphere. Structural analysis reveals that the zinc(II) centre in mononuclear 1 is in a distorted trigonal bipyramidal ZnN5 environment ligated by four N atoms of the organic blocker and the terminal azide. The tetradentate chelator is folded in the butylenic part