Di(imino)aryltin(iv) dichlorides as tectons for heterometallic coordination compounds

Abstract

Hydrolysis of [2-{(CH₂O)₂CH}C₆H₄]₂SnCl₂ (1) [prepared from 2-[(CH₂O)₂CH]C₆H₄MgBr and SnCl₄, in 2 : 1 molar ratio] gave [2-(OCH)C₆H₄]₂SnCl₂ (2). Treatment of 2 with the appropriate amine, in the absence of a solvent or catalyst, resulted in the isolation in high yields of [2-(RNCH)C₆H₄]₂SnCl₂ [R = 2′-C₁₀H₇ (3), 2′,4′,6′-Me₃C₆H₂ (4), PhCH₂ (5), Me₂NCH₂CH₂ (6), 2′-PyCH₂ (7)]. The reaction of 7 with [Pd(COD)Cl₂] provided the heterometallic species [Cl₂Pd{2-(2′-PyCH₂NCH)C₆H₄}₂SnCl₂] (8). The compounds were characterised by multinuclear NMR spectroscopy in solution, and mass spectrometry and IR spectroscopy in the solid state. The molecular structures of 1, 2, 4–7 and 8·CH₃CN were established by single-crystal X-ray diffraction. For all diorganotin(IV) dichlorides intramolecular O→Sn or N_imine→Sn coordination results in hypercoordinated species with a distorted octahedral (C,E)₂SnCl₂ core (E = O, N). The presence of intramolecular N→Sn interactions in solution, responsible for the restriction of free rotation of mesityl groups around the C–N(C) single bonds, is suggested by ¹H and ¹³C NMR data. In the heterometallic dinuclear complex 8 the octahedral coordination around tin is preserved as in 7 and the nitrogen atoms from the pyridyl groups in the pendant arms are coordinated to palladium, leading to a trans-square planar PdCl₂N₂ core.