Stable Divalent Triarylstannates R3SnLi Derived from 2-[(Dimethylamino)methyl]phenyllithium and SnCl2 or R2Sn

作者：Jastrzebski Johann T B H; van Klaveren Mayra; van Koten Gerard^*

来源：Organometallics, 2015, 34(11): 2600-2607.

DOI：10.1021/om5012215

The triarylstannate lithium Compound [{kappa(1)-C-(2-Me2NCH2C6H4)(2)}{kappa(2)-C, N-(2-Me2NCH2C6H4)}SnLi-(THF)(2)] (3a) was obtained in 63% yield from the reaction of 2-Me2NCH2C6H4Li (1) with SnCl2 in THF. Quantitative formation of 3a was also observed on reacting 1 with [kappa(2)-C, N-(2-Me2NCH2C6H4)(2)Sn] (2). Removal of one THF molecule Occurred when 3a was kept in vacuo; this process afforded [{kappa(1)-C-(2-Me2NCH2C6H4)}{kappa(2)-C, N-(2-Me2NCH2C6H4)(2)}-SnLi(THF)(2)] (3b). Also, THF-free (2-Me2NCH2C6H4)(3)SnLi (3c) is likewise accessible. In the solid state (X-ray) both 3a and 3b are monomeric; notable structural features are the Sn-Li distances (2.860(6) and 2.72(2) angstrom, respectively) and the distortion of the tetrahedral geometry at Sn in the direction of a trigonal pyramidal one. In 3a, one of the 2-Me2NCH2C6H4 anions is C-bonded to Sn, while N-coordination occurs to Li; in 3b, two of the three 2-Me2NCH2C6H4 anions are kappa(2)-C,N bonded, H-1, C-13, Sn-119, and Li-7 NMR spectroscopic studies of the species 3 in toluene showed that both 3a and 3b are monomeric in solution; at temperatures below 253 K, via both the Sn-119 and Li-7 NMR spectra (toluene-d(8)), the Sn-119-Li-7 coupling (289 Hz) is nicely resolved. The exchange of aryl groupings (vide infra) as Well as between: coordinated and free-NMe2 substituents remains fast on the NMR time scale at 183 K. 2D H-1-H-1 EXSY spectroscopy confirmed that the 2-Me2NCH2C6H4 groups present in stannate 3b and bisaryltin(II) 2 undergo chemical exchange. The 2D Li-7-Li-7 EXSY Spectrum points to the occurrence of chemical exchange of the lithium atoms of stannate 3b and aryllithium 1.

• 出版日期2015-6-8