The Influence of Substituents at C2 Carbon Atom of Thiosemicarbazones {R(H)C2=N3‐N2(H)‐C1(=S)‐N1H2} on their Dentacy in PtII/PdII Complexes: Synthesis,Spectroscopy, and Crystal Structures |
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Authors: | Tarlok S Lobana Prof Gagandeep Bawa Geeta Hundal M Zeller |
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Institution: | 1. Amritsar / India, Department of Chemistry, Guru Nanak Dev University;2. Youngstown/USA, Department of Chemistry, Youngstown Universitry |
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Abstract: | The coordination chemistry of platinum(II) with a series of thiosemicarbazones {R(H)C2=N3‐N2(H)‐C1(=S)‐N1H2, R = 2‐hydroxyphenyl, H2stsc; pyrrole, H2ptsc; phenyl, Hbtsc} is described. Reactions of trans‐PtCl2(PPh3)2 precursor with H2stsc (or H2ptsc) in 1 : 1 molar ratio in the presence of Et3N base yielded complexes, Pt(η3‐ O, N3, S‐stsc)(PPh3)] ( 1 ) and Pt(η3‐ N4, N3, S‐ptsc)(PPh3)] ( 2 ), respectively. Further, trans‐PtCl2(PPh3)2 and Hbtsc in 1 : 2 (M : L) molar ratio yielded a different compound, Pt(η2‐ N3, S‐btsc)(η1‐S‐btsc)(PPh3)] ( 3 ). Complex 1 involved deprotonation of hydrazinic (‐N2H‐) and hydroxyl (‐OH) groups, and stsc2? is coordinating via O, N3, S donor atoms, while complex 2 involved deprotonation of hydrazinic (‐N2H‐) and ‐N4H groups and ptsc2? is probably coordinating via N4, N3, S donor atoms. Reaction of PdCl2(PPh3)2 with Hbtsc‐Me {C6H5(CH3)C2=N3‐N2(H)‐C1(=S)‐N1H2} yielded a cyclometallated complex Pd(η3‐C, N3, S‐btsc‐Me)(PPh3)] ( 4 ). These complexes have been characterized with the help of analytical data, spectroscopic techniques {IR, NMR (1H, 31P), U.V} and single crystal X‐ray crystallography ( 1 , 3 and 4 ). The effects of substituents at C2 carbon of thiosemicarbazones on their dentacy and cyclometallation are emphasized. |
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Keywords: | Platinum Salicylaldehyde thiosemicarbazone Pyrrole‐2carbaldehyde thiosemicarbazone Benzaldehyde thiosemicarbazone Cyclometallation Deprotonation |
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