• Rekha Sharma

      Articles written in Journal of Chemical Sciences

    • Synthesis and crystal structure of [chlorobis(triphenylphospino) (p-chlorobenzaldehyde thiosemicarbazone)] copper(I) complex

      Ashiq Khan Poonam Sharma Rajnikant Vivek K Gupta Naresh Padha Rekha Sharma

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      Reactions of copper(I) halides with p-chlorobenzaldehyde thiosemicarbazone (H1L) and triphenylphosphine in 1 : 1 : 2 molar ratio yielded complexes of stoichiometry, [CuX(𝜂1-S- H1L)(Ph3P)2] (X = I, 1: Br, 2; Cl, 3). All the three complexes were characterized using analytical (CHNS) and spectroscopic (IR, 1H NMR) techniques. The structure of complex 3 was confirmed by X-ray crystallography. It has been found to crystallize in the triclinic system with space group P-1 and unit cell parameters: a = 10.207(5) Å, b = 13.027(5) Å, c = 16.269(5) Å, 𝛼 = 100.054(5)°, 𝛽 = 99.228(5)° and 𝛾 = 97.234(5)°. This complex has distorted tetrahedral geometry with two phosphorus atoms from two triphenylphosphine ligands, thione sulfur of thiosemicarbazone ligand and chloride ion occupying the four corners of the tetrahedron. The structure of complex 3 was in contrast to sulfur-bridged dinuclear complex of copper(I) chloride with benzaldehydethiosemicarbazone, [Cu2Cl2(𝜇2-S-Hbtsc)2(Ph3P)2]·2H2O. The intermolecular H-bonding, Cl· · ·HCph, 2.733 Å and 𝜋 interactions, {CHph · · · 𝜋, 2.796; 2.776 Å} in this complex led to the formation of 1D chain. Two such 1D chains were cross-linked via, Cl· · ·HCph, 2.896 Å H-bonding to form a 2D network.

    • 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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