Thiosemicarbazones as co-ordinating agents. Part 3. Synthesis, spectroscopic characterization, and X-ray structure of methyl pyruvate thiosemicarbazone hemihydrate, chloro(ethyl pyruvate thiosemicarbazonato)copper(II)(green form), and chloro(pyruvic acid thiosemicarbazonato)copper(II) dihydrate (blue form)

Abstract

Three new compounds, methyl pyruvate thiosemicarbazone hemihydrate Hmpt·0.5H₂O (1), chloro(ethyl pyruvate thiosemicarbazonato)copper(II), [{Cu^II(ept)Cl₂}](2), and chloro(pyruvic acid thiosemicarbazonato)copper(II) dihydrate, {[Cu^II(Hpt)Cl]·2H₂O}_n(3), have been synthesized and characterized using single-crystal X-ray diffraction methods. The following results were obtained: (1); space group C2/c, a= 12.406(1), b= 10.838(1), c= 12.845(1)Å, β= 97.79(1)°, Z= 8, R0.040, R′ 0.048. (2), P2₁/n, a= 11.785(1), b= 8.202(1), c= 11.057(1)Å, β= 95.70(1)°, Z= 4, R0.042, R′ 0.045. (3); P2₁/c, a= 8.496(1), b= 18.046(2), c= 7.184(1)Å, β= 109.90(1)°, Z= 4, R0.031, R′ 0.033. In (1) the compound is in the fully extended conformation showing an E configuration about both the C(2)–N(3) and C(1)–N(2) bonds, but a Z configuration about C(2)–C(3)[with respect to donating centres S, N(3), and O(1)]. In (2) the organic molecule is hydrolyzed and transesterificated to form chloro(ethyl pyruvate thiosemicarbazonato)copper(II)(green form)(dimeric), while in (3) it is hydrolyzed only to form chloro(pyruvic acid thiosemicarbazonato)-copper (II) dihydrate (blue form)(polymeric). The main vibrational bands are also reported and discussed.