Abstract
The crystal and molecular structures of three new thiosemicarbazones, 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide monohydrate (1), 2-[1-(2-hydroxy-5-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide (2) and 2-[1-(2-hydroxy-4-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide acetonitrile solvate (3), are reported and confirmed by single crystal X-ray diffraction, NMR and UV-vis spectroscopic data. Compound (1), C11H15N3O2S·H2O, crystallizes in the monoclinic with space group P21/c, with cell parameters a = 8.2304(3) Å, b = 16.2787(6) Å, c = 9.9708(4) Å, and β = 103.355(4)°. Compound (2), C12H17N3O2S, crystallizes in the C2/c space group with cell parameters a = 23.3083(6) Å, b = 8.2956(2) Å, c = 13.5312(3) Å, β = 91.077(2)°. Compound (3), C11H15N3O2S·C2H3N, crystallizes in the triclinic P-1 space group with cell constants a = 8.9384(7) Å, b = 9.5167(8) Å, c = 10.0574(8) Å, α = 110.773(7)°, β = 92.413(6)°, and γ = 90.654(7)°. DFT B3LYP/6-31(G) geometry optimized molecular orbital calculations were also performed and frontier molecular orbitals of each compound are displayed. The correlations between the calculated molecular orbital energies (eV) for the surfaces of the frontier molecular orbitals to the electronic excitation transitions from the absorption spectra of each compound have been proposed. Additionally, similar correlations observed among three closely related compounds, (4), 2-[1-(2-hydroxy-4-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide, (5), 2-[1-(2-hydroxy-6-methoxyphenyl)ethylidene]-N-methyl-hydrazinecarbothioamide acetonitrile monosolvate and (6), 2-[1-(2-hydroxy-6-methoxyphenyl)ethylidene]-N-ethyl-hydrazinecarbothioamide, examining structural differences from the substitution of the methoxy group from the phenyl ring (4, 5, or 6 position) and the substitution of the terminal amine (methyl or ethyl) to their frontier molecular orbital surfaces and from their Density Functional Theory (DFT) molecular orbital energies provide further support for the suggested assignments of the title compounds.
Highlights
Thiosemicarbazones are a versatile class of ligands that bind a metal through a nitrogen and sulfur atom
There is an interest in developing novel thiosemicarbazone compounds and their metal complexes
A comparison of the angles between mean planes of the indole and phenylsulfonyl rings in the crystal and with the Density Functional Theory (DFT) geometry optimized calculation in concert with strong and weak intermolecular hydrogen bond interactions has been included in a discussion of the structural aspects for each molecule
Summary
Thiosemicarbazones are a versatile class of ligands that bind a metal through a nitrogen and sulfur atom. Due to these areas, there is an interest in developing novel thiosemicarbazone compounds and their metal complexes. We interest report novel the and crystal and Hartwig couplings [11]. Due to these areas, thereareas, is an interest in thiosemicarbazone structure of three new complexes [13],published and similar structure, methyl group on terminal amine as shown in Scheme below. Are similar in but vary in the position a methoxy the aryl ring, group and either a but varyor inethyl thestructure, position of athe methoxy group onnitrogen, theofaryl ring, andgroup either aonmethyl or ethyl on the methyl or ethyl group on the terminal amine nitrogen, as shown in Scheme below.
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