Diorganotin( IV ) Complexes of a Cyclic Thiosemicarbazone Ligand: Crystal Structures of [SnPh 2 (C 15 H 10 N 3 S)Cl] and [SnMe 2 (C 15 H 10 N 3 S) 2 ]

Treatment of 5‐methoxy‐5,6‐diphenyl‐4,5‐dihydro‐2 H ‐[1,2,4]triazine‐3‐thione (LH 2 OCH 3 ) with compounds SnR 2 X 2 (R = Me and Ph; X = Cl and NO 3 ) afforded, for the first time, metal derivatives of a cyclic thiosemicarbazone. Treatment of LH 2 OCH 3 with the appropriate diorganotin( IV ) chloride in dichloromethane provided 1:1 complexes, but 1:2 derivatives were isolated when the nitrate salts in distilled water were used. The complexes were studied by mass spectrometry, IR and multinuclear ( 1 H, 13 C and 119 Sn) NMR in solution, and also by 119 Sn CP/MAS NMR spectroscopy and by X‐ray diffraction in the solid state. In all the complexes, the thiosemicarbazone had been modified by formation of a new C=N bond. In addition, the ligand LH had lost a hydrogen atom, acting as an anion. The crystal structures of [SnPh 2 (C 15 H 10 N 3 S)Cl] ( 1 ) and [SnMe 2 (C 15 H 10 N 3 S) 2 ] ( 4 ) each consist of discrete molecules with the tin atom bonded to the sulfur and amine nitrogen atoms to give a four‐membered chelate ring with the [1,2,4]triazine modified. For phenyl derivative 1 , the tin atom is in a trigonal‐bipyramidal environment with the phenyl rings in equatorial positions, and for complex 4 it is in an octahedral arrangement, with the methyl groups in axial positions. The 119 Sn CP/MAS NMR spectra of the complexes are in accordance with these structures. The values obtained indicate a five‐coordinate geometry for [SnMe 2 (C 15 H 10 N 3 S)Cl] ( 2 ) and suggest a coordination number of six for complex 3 . The 119 Sn spectra of complexes in solution depend on the coordinating capacity of the solvents. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)