Giesen Alexander Walter, Raabe Gerhard, Runsink Jan, Gais Hans-Joachim
Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany.
Merianstrasse 16, 41749, Viersen, Germany.
Chemistry. 2017 Oct 12;23(57):14231-14247. doi: 10.1002/chem.201701881. Epub 2017 Sep 12.
tBuCH=C(Li)S(O)(NSO Tol)Ph⋅L (L=2THF, TMEDA) (1⋅L) in THF solution is a monomer with a C-Li bond according to NMR spectroscopy and cryoscopy. It was identified as CIP through the scalar C, Li coupling and Li,{ H} NOE experiments. The CIP has a six-membered C-Li-O-S-N-S chelate ring structure. Li, H FUCOUP and Li, H HMQC NMR experiments of 1⋅TMEDA revealed a scalar Li, H coupling across the Li-C=C-H bonds. According to the NMR data the π-bond of 1⋅L is polarized by the negative charge of the anionic C atom. tBuCH=C(Li)S(O)(NMe)Ph (2⋅L) is most likely also a monomer with a C-Li bond. According to Li,{ H} NOE experiments it has a four-membered C-Li-N-S chelate ring structure. C NMR spectroscopy showed the C-Li bonds of 1⋅L and 2⋅L to be fluxional. H NMR spectroscopy and 1D TOCSY experiments of Ph C=C(Li)S(O)(NSO Tol)Ph revealed topomerization of the phenyl groups, which is attributed to a fast positional exchange of the Li atom and the sulfonimidoyl group. The fluxionality of the C-Li bond and the interchange of the Li atom and the sulfonimidoyl group at the anionic C atom of sulfonimidoyl vinyllithiums, which result in a low configurational stability, most likely involve the formation of O,Li and N,Li CIPs through heterolysis of the C-Li bond. Ab initio calculation of MeCH=C(Li)S(O)(NMe)Ph yielded an energy minimum structure with a C-Li bond, a four-membered C-Li-N-S chelate ring and a strongly expanded C=C-Li bond angle. According to calculation of MeCH=C(Li)S(O)(NMe)Ph, [MeCH=CS(O)(NMe)Ph] and MeCH=C(H)S(O)(NMe)Ph deprotonation is not accompanied by a shortening of the C-S bond. Ab initio calculation of MeCH=C(Li)S(O)(NSO Me)Ph gave a structure with a C-Li bond and a six-membered C-Li-O-S-N-S chelate ring. Li, H NOE experiments and cryoscopy of LiCH S(O)(NSO Tol)Ph (3) revealed a monomeric CIP with a C-Li bond. The CIP has a six-membered C-Li-O-S-N-S chelate ring structure found in polymeric 3 in the crystal.
根据核磁共振光谱法和冰点降低法，四氢呋喃溶液中的tBuCH=C(Li)S(O)(NSO Tol)Ph⋅L（L = 2THF，TMEDA）（1⋅L）是一种具有C-Li键的单体。通过标量C，Li偶合和Li，{H} NOE实验将其鉴定为CIP。该CIP具有六元C-Li-O-S-N-S螯合环结构。1⋅TMEDA的Li，H FUCOUP和Li，H HMQC NMR实验揭示了Li-C = C-H键之间的标量Li，H偶合。根据NMR数据，1⋅L的π键被阴离子C原子的负电荷极化。tBuCH=C(Li)S(O)(NMe)Ph（2⋅L）很可能也是一种具有C-Li键的单体。根据Li，{H} NOE实验，它具有四元C-Li-N-S螯合环结构。C NMR光谱表明1⋅L和2⋅L的C-Li键是可流动的。Ph C = C(Li)S(O)(NSO Tol)Ph的H NMR光谱和1D TOCSY实验揭示了苯基的拓扑异构化，这归因于Li原子和磺酰亚胺基的快速位置交换。磺酰亚胺基乙烯基锂阴离子C原子上C-Li键的流动性以及Li原子和磺酰亚胺基的交换导致构型稳定性较低，最有可能涉及通过C-Li键的异裂形成O，Li和N，Li CIP。对MeCH = C(Li)S(O)(NMe)Ph进行从头算得到了一个能量最低结构，该结构具有C-Li键、四元C-Li-N-S螯合环和强烈扩展的C = C-Li键角。根据对MeCH = C(Li)S(O)(NMe)Ph、[MeCH = CS(O)(NMe)Ph]和MeCH = C(H)S(O)(NMe)Ph的计算，去质子化不会伴随C-S键的缩短。对MeCH = C(Li)S(O)(NSO Me)Ph进行从头算得到了一个具有C-Li键和六元C-Li-O-S-N-S螯合环结构。LiCH S(O)(NSO Tol)Ph（3）的Li，H NOE实验和冰点降低法揭示了一种具有C-Li键的单体CIP。该CIP具有在晶体聚合物3中发现的六元C-Li-O-S-N-S螯合环结构。
