New Tin‐Oxometallates from the Hydrolysis of SnEt 2 2+ in the Presence of 2,6‐Lutidine‐α 2 ,3‐Diol and different Anions

The reaction of the diethyltin(IV) cation with 2,6‐lutidine‐α 2 ,3‐diol (Lut, 2‐hydroxymethyl‐3‐hydroxy‐6‐methylpyridine) has been investigated in ethanol‐water (80:20 v/v) containing Cl – and NO 3 – , NO 3 – and OAc – or Cl – and OAc – ions in various molar ratios. The existence of complex equilibria in solution was confirmed by NMR spectroscopy and mass spectrometry. From this reaction several tin‐oxometallates were isolated and characterized by IR, Raman, 1 H, 13 C and 119 Sn solution NMR spectroscopy and also by mass spectrometry. The crystal structures of the compounds [(SnEt 2 ) 4 O 2 (CH 3 O) 2 Cl 2 ] ( 2 ), [SnEt 2 (Lut‐H)Cl] ( 3 ), [(SnEt 2 ) 4 O 2 (Lut‐H)Cl 3 ]⋅H 2 O ( 4 ⋅H 2 O) and [(SnEt 2 ) 4 O 2 (Lut‐H) 2 (NO 3 ) 2 ] ( 5 ) were determined by X‐ray diffractometry. The structure of the compound [SnEt 2 (Lut‐H)Cl)] contains dimeric [SnEt 2 (Lut‐H)Cl)] 2 units in which the Lut ligand is deprotonated and both of the tin atoms are hexacoordinated. All of the other compounds are tetranuclear and, with the exception of 2 , also contain the deprotonated Lut ligand and have the tin atoms in hexa‐ or pentacoordinated environments. The in vitro antitumour activities against the HeLa‐229, A2780 and A2780 cis cell lines were determined for the compounds, which proved to be significantly active compared with cisplatin against the two last lines– in particular against the A2780 cis cell line – thus showing a high ability to circumvent the cellular resistance to this drug.