Růzicka Ales, Jambor Roman, Císarová Ivana, Holecek Jaroslav
Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 95, 532 10, Pardubice, Czech Republic.
Chemistry. 2003 Jun 6;9(11):2411-8. doi: 10.1002/chem.200304572.
The four organotin (IV) compounds (2,6-bis(dimethylaminomethyl)phenylR(1)R(2)stannane, with R(1)=R(2)=nBu (1), R(1)=nBu, R(2)=Cl (2), R(1)=nBu, R(2)=Br (3) and R(1)=R(2)=Br (4)), have been prepared and their structures have been investigated in various solvents and at various temperatures (NMR). The structures of these compounds in solution are solvent- and temperature-dependent. The solid state structures of 2 and 3 were studied using CP/MAS NMR spectroscopy and Xray diffraction techniques. The tetraorganotin compound 1 exhibits tetrahedral geometry with very weak Sn-N coordination. The dynamic process of Sn-N bond(s) association/dissociation was observed using low-temperature NMR measurements. The tin central atom in 2 and 3 is [4+2]-coordinated in toluene solutions and the NMR low-temperature measurements reveal the same dynamic behavior as for 1 in this solution, with retention of the covalent halogen-tin bond. However, this bond is dissociated in methanol solutions, yielding ionic species, where the tin atom is only [3+2]-coordinated, and the halogen atom lies outside of the primary coordination sphere of the tin atom. In addition, while the same ionic structure as in methanol was found in the whole measured temperature range in the chloroform solution of 3, the structure of 2 varies in this solvent. In this compound, the covalent Sn-Cl bond (similar structure as in toluene solution), which is retained at room temperature in chloroform solution, is continuously dissociated with a decrease in temperature, leading to ionic bonding (a similar structure as in methanol solution). All the above-mentioned processes are reversible in all the solvents and at all temperatures. In the solid state, the covalent Sn-Cl bond is observed for 2, while an ionic bond was found in 3.
已制备出四种有机锡（IV）化合物（[2,6 - 双（二甲基氨基甲基）苯基]（正丁基）R₁R₂锡烷，其中R₁ = R₂ = 正丁基（1），R₁ = 正丁基，R₂ = 氯（2），R₁ = 正丁基，R₂ = 溴（3）以及R₁ = R₂ = 溴（4）），并在各种溶剂和不同温度下（通过核磁共振）对它们的结构进行了研究。这些化合物在溶液中的结构取决于溶剂和温度。使用交叉极化/魔角旋转核磁共振光谱法和X射线衍射技术研究了2和3的固态结构。四有机锡化合物1呈现四面体几何构型，具有非常弱的Sn - N配位。通过低温核磁共振测量观察到了Sn - N键缔合/解离的动态过程。2和3中的锡中心原子在甲苯溶液中是[4 + 2]配位的，核磁共振低温测量显示在该溶液中与1具有相同的动态行为，同时保留了共价卤 - 锡键。然而，该键在甲醇溶液中会解离，产生离子物种，其中锡原子仅为[3 + 2]配位，且卤原子位于锡原子的一级配位球之外。此外，虽然在3的氯仿溶液中在整个测量温度范围内发现了与甲醇中相同的离子结构，但2在该溶剂中的结构有所不同。在该化合物中，在氯仿溶液中室温下保留的共价Sn - Cl键（与甲苯溶液中的结构相似）会随着温度降低而持续解离，导致形成离子键（与甲醇溶液中的结构相似）。上述所有过程在所有溶剂和所有温度下都是可逆的。在固态中，观察到2存在共价Sn - Cl键，而在3中发现了离子键。
