• Ray J Butcher

      Articles written in Journal of Chemical Sciences

    • Rhodium and iridium complexes of N-(2′-hydroxyphenyl)pyrrole-2-aldimine: Synthesis, structure, and spectral and electrochemical properties

      Semanti Basu Indrani Pal Ray J Butcher Georgina Rosair Samaresh Bhattacharya

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      Reaction of N-(2′-hydroxyphenyl)pyrrole-2-aldimine (H2L) with [M(PPh3)3Cl] (M = Rh, Ir) affords complexes of type [M(PPh3)2(L)Cl]. Structures of both complexes have been determined by X-ray crystallography. In both complexes, the N-(2′-hydroxyphenyl)pyrrole-2-aldimine ligand is coordinated to the metal centre, via dissociation of the acidic protons, as a dianionic tridentate N,N,O-donor. The M(L)Cl fragment constitutes an equatorial plane with the metal at the centre and the two PPh3 ligands occupying axial positions. The complexes are diamagnetic (low-spin d6, S = 0) and show intense MLCT transitions in the visible region. Cyclic voltammetry of the [M(PPh3)2(L)Cl] complexes shows reversible M(III)-M(IV) oxidation near 0·5 V vs SCE and quasi-reversible ligand-centred oxidative response near 1·0 V vs SCE.

    • Variable coordinating activity of sulfur in silver(I) complexes with thiophene based N¹ -substituted thiosemicarbazones: First case of thiopheneyl-thione sulfur bridging in a dinuclear complex


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      Thiophene-2-carbaldehyde / acetaldehyde-N¹-substituted thiosemicarbazones {R¹R²C² = N³ - N(H)- C¹(=S)N¹HR; R¹, R², R : C₄H₃S, H, Me, Httsc- NMe; C₄H₃S, H, Et, Httsc-NEt; C₄H₃S, H, Ph, Httsc-NPh; C₄H₃S, Me, Et, Hattsc-NEt} and furan-2-carbaldehyde-N-ethyl thiosemicarbazone (C₄H₃O, H, Et, Hftsc-NEt) were reacted with silver(I) halides/silver(I) acetate in presence of triphenylphosphine in organic solvents. These reactions yielded a series of dinuclear [Ag₂(μ-Br)₂ (κ-S-Httsc-NEt)2(PPh3)2]·2MeOH 1, [Ag2Cl2(κ1-SHttsc-NPh)2(μ-S,S-Httsc-NPh)2] 2, [Ag2Cl2(μ-S-Hftsc-NEt)2(κ1-S-Hftsc-NEt)2] 4, [Ag2(μ3-N3,S-ttsc-NMe)2 (Ph3P)2]·2(CH3)2CO 5, [Ag2 (μ3-N3,S-attsc-NEt)2(Ph3P)2]·0.5(CH3)2CO 6 and mononuclear [AgBr(κ1-SHttsc-NPh)(PPh3)2]· MeCN 3 complexes, all of which have been characterized using analytical techniques, IRand NMR spectroscopy, and X-ray crystallography. Thio-ligands bind in neutral form in complexes 1-4 and in anionic form in complexes 5-6. Further, the sulfur donor atoms have shown variable coordination modes incomplexes, namely, κ1-S in 1 and 3; κ1-S, μ-S in 4; κ1-S, μ-S,S (thiopheneyl-thione) in 2 and μ3- N3, S in 5 and 6. Tertiary-phosphine (PPh3) showed dual function of ligation/de-ligation towards silver(I) chloride during the synthesis of complexes 2 and 4. The bridge bonding of Httsc-NPh in 2 through thiopheneyl ring sulfur andthione sulfur is unprecedented in metal-thiosemicarbazone chemistry.

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