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A series of adducts of the type [(L # ) y R n SnX 4− n ]· z H 2 O (L # =1-methylimidazole, y =1 or 2, R=Me, Et, Bu n or Ph, n =1, 2 or 3, X=Cl, Br or I, z =0, 1/2 or 1) has been characterized in the solid state and in solution by analyses, spectral (IR, 119 Sn Mossbauer, and 1 H, 13 C and 119 Sn NMR) data and conductivity measurements. The molecular weight determinations and the NMR data indicate that these organotin(IV) complexes partly dissociate in chloroform and acetone solution. The donor L # interacts with [(CH 3 ) 3 SnNO 3 ], yielding the 2:1 ionic complex [(L # ) 2 (CH 3 ) 3 Sn]NO 3 . The derivative [(L # ) 2 (CH 3 ) 2 SnCl 2 ] reacts with NaClO 4 , AgNO 3 , NaBPh 4 and KSCN in ethanol and diethyl ether giving the complexes [(L # ) 2 (CH 3 ) 2 Sn(ClO 4 ) 2 ], [(L # )(CH 3 ) 2 Sn(NO 3 ) 2 (H 2 O)], [(L # )(CH 3 ) 2 SnCl(H 2 O) 2 ]BPh 4 and [(L # ) 2 (CH 3 ) 2 Sn(NCS) 2 ], respectively, whereas when [(L # )(CH 3 ) 3 SnCl] interacts with an equimolar quantity of NaClO 4 , [(L # ) 2 (CH 3 ) 3 Sn]ClO 4 ·1/2H 2 O and (CH 3 ) 3 Sn(ClO 4 ) in 1:1 ratio are obtained. The stability towards self-decomposition of the complexes obtained decreases with increasing number of the Sn-bonded aryl or alkyl groups. The derivative [(L # ) 2 (CH 3 ) 2 SnBr 2 ] reacts with 1,10-phenanthroline (Phen), yielding immediately the complex [(Phen)(CH 3 ) 2 SnBr 2 ], whereas from the reaction between [(L # ) 2 (CH 3 ) 2 Sn(ClO 4 ) 2 ] and Phen, the mixed ligand complex [(L # )(Phen)(CH 3 ) 2 Sn](ClO 4 ) 2 is obtained. A different behaviour has been shown from the diiodide complex [(L # ) 2 (C 2 H 5 ) 2 SnI 2 ] which reacts with Phen, yielding the compound with the 3:2 stoichiometry [(Phen) 3 {(C 2 H 5 ) 2 SnI 2 } 2 ]. Both the crystal structures of [(L # ) 2 (CH 3 ) 2 SnBr 2 ] and [(L # ) 2 (C 2 H 5 ) 2 SnI 2 ] show the tin atom in an all- trans octahedral regular configuration, whereas in [(L # )(C 6 H 5 ) 3 SnCl] the tin atom exhibits a distorted trigonal bipyramidal geometry, with the phenyl groups in the equatorial positions. A comparison was made with structural data of other R 3 SnXN-type derivatives. The molecular parameters of 1-methylimidazole in the tin(IV) complexes were used, together with other structural data in literature, to derive empirical rules concerning the imidazole donor.

Tin(IV) and organotin(IV) compounds containing hydridotris(3,4,5-trimethyl-1 H-pyrazol-1-yl)borate (L3), [RnSnCl4-n-1L3] (R=Me, n = 0–2) have been synthesised and studied by NMR (1H, 13C, 119Sn) spectroscopic techniques. The compounds are not fluxional and contain six-coordinate tin(IV) with a tridentate ligand. X-ray crystal structure of [MeSnCl2L3] is reported together with that of the parent potassium hydridotris(3,4,5-trimethyl-1 H-pyrazol-1-yl)borate, K(C18H28N6B) and comparisons are made.