The influence of substituents (R) at N1 atom of thiophene-2-carbaldehyde thiosemicarbazones {(C4H3S)HC2N3–N(H)–C1(S)N1HR} on bonding, nuclearity and H-bonded networks of copper(I) complexes

The nuclearity, bonding and H-bonded networks of copper(I) halide complexes with thiophene-2-carbaldehyde thiosemicarbazones {(C4H3S)HC2N3–N(H)–C1(S)N1HR} are influenced by R substituents at N1 atom. Thiophene-2-carbaldehyde-N1-methyl thiosemicarbazone (HttscMe) or thiophene-2-carbaldehyde-N1-ethyl thiosemicarbazone (HttscEt) have yielded halogen-bridged dinuclear complexes, [Cu2(μ-X)2(η1-S-Htsc)2(Ph3P)2] (Htsc, X: HttscMe, I, 1; Br, 2; Cl, 3; HttscEt, I, 4; Br, 5; Cl, 6), while thiophene-2-carbaldehyde-N1-phenyl thiosemicarbazone (HttscPh) has yielded mononuclear complexes, [CuX(η1-S-HttscPh)2] (X, I, 7a; Br 8; Cl, 9) and a sulfur bridged dinuclear complex, [Cu2(μ-S-HttscPh)2(η1-S-HttscPh)2I2] 7b co-existing with 7a in the same unit cell. These results are in contrast to S-bridged dimers [Cu2(μ-S-Httsc)2(η1-Br)2(Ph3P)2] · 2H2O and [Cu2(μ-S-Httsc)2(η1-Cl)2(Ph3P)2] · 2CH3CN obtained for R = H and X = Cl, Br (Httsc = thiophene-2-carbaldehyde thiosemicarbazone) as reported earlier. The intermolecular CHPh⋯π interaction in 1–3 (2.797 Å, 1; 3.264 Å, 2; 3.257 Å, 3) have formed linear polymers, whereas the CHPh⋯X and N3⋯HCH interactions in 4–6 (2.791, 2.69 Å, 5; 2.776, 2.745 Å, 6, respectively) have led to the formation of H-bonded 2D polymer. The PhN1H⋯π, interactions (2.547 Å, 8, 2.599 Å, 9) have formed H-bonded dimers only. The Cu⋯Cu separations are 3.221–3.404 Å (1–6).

Graphical abstractRole of substituents (R) at N1 nitrogen of thiophene-2-carbaldehyde thiosemicarbazones {(C4H3S)HC2N3–N(H)–C1(S)N1HR} on bonding and nuclearity of copper(I) halide complexes has been described. For R = Ph, X = I, a three coordinate monomer and its S-bridged dimer co-exist in the same unit cell (1).Figure optionsDownload full-size imageDownload as PowerPoint slide