Tin(IV) and organotin(IV) complexes containing mono or bidentate N-donor ligands: III. 1-methylimidazole derivatives: synthesis, spectroscopic and structural characterization

Abstract

A series of adducts of the type [(L #) y R n SnX 4− n ]· zH 2O (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, 119Sn Mössbauer, and 1H, 13C and 119Sn 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) 3SnNO 3], yielding the 2:1 ionic complex [(L #) 2(CH 3) 3Sn]NO 3. The derivative [(L #) 2(CH 3) 2SnCl 2] reacts with NaClO 4, AgNO 3, NaBPh 4 and KSCN in ethanol and diethyl ether giving the complexes [(L #) 2(CH 3) 2Sn(ClO 4) 2], [(L #)(CH 3) 2Sn(NO 3) 2(H 2O)], [(L #)(CH 3) 2SnCl(H 2O) 2]BPh 4 and [(L #) 2(CH 3) 2Sn(NCS) 2], respectively, whereas when [(L #)(CH 3) 3SnCl] interacts with an equimolar quantity of NaClO 4, [(L #) 2(CH 3) 3Sn]ClO 4·1/2H 2O and (CH 3) 3Sn(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) 2SnBr 2] reacts with 1,10-phenanthroline (Phen), yielding immediately the complex [(Phen)(CH 3) 2SnBr 2], whereas from the reaction between [(L #) 2(CH 3) 2Sn(ClO 4) 2] and Phen, the mixed ligand complex [(L #)(Phen)(CH 3) 2Sn](ClO 4) 2 is obtained. A different behaviour has been shown from the diiodide complex [(L #) 2(C 2H 5) 2SnI 2] which reacts with Phen, yielding the compound with the 3:2 stoichiometry [(Phen) 3{(C 2H 5) 2SnI 2} 2]. Both the crystal structures of [(L #) 2(CH 3) 2SnBr 2] and [(L #) 2(C 2H 5) 2SnI 2] show the tin atom in an all- trans octahedral regular configuration, whereas in [(L #)(C 6H 5) 3SnCl] 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 3SnXN-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.