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.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1002/chem.201701881 | DOI Listing |
ACS Appl Mater Interfaces
November 2024
College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China.
LiGaTe is a promising nonlinear optical crystal with a large figure of merit (/), but it is difficult to grow the LiGaTe single crystal due to its extreme instability. In this work, we used Ag to replace Li and successfully grew a LiAgGaTe crystal by the modified Bridgman method for the first time. We found it has thermal stability below 200 °C in an atmospheric environment, and the thermal expansion coefficient is positive.
View Article and Find Full Text PDFPhys Chem Chem Phys
August 2024
Department of Chemistry and Ames National Laboratory, Iowa State University, Ames, Iowa, 50011, USA.
The bonding structures of COLi and CSLi are studied by means of oriented quasi-atomic orbitals (QUAOs) to assess the possibility of these molecules being planar hexacoordinated carbon (phC) systems. CHLi and CO are employed as reference molecules. It is found that the introduction of Li ions into the molecular environment of carbonate has a greater effect on the orbital structure of the O atoms than it does on the C atom.
View Article and Find Full Text PDFChemistry
August 2024
LCC-CNRS, Université de Toulouse, CNRS, UPS, 31077, Toulouse, France.
The particular reactivity of the recently discovered class of the main group element polyhedral clusters, pyramidanes, remains largely unexplored. In this communication, we report the reaction of the germapyramidane with tert-butyllithium leading to the rather unusual organogermanium compound [Li(thf)]⋅2, as the product of the formal insertion of a Ge-apex into the C-Li bond. This reactivity mode exemplifies unusual electrophilic behaviour of a pyramidane, which is a priori considered as a nucleophilic reagent.
View Article and Find Full Text PDFChemistry
October 2023
Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
The reported tetracoordinate dilithio methandiide complex from Liddle and co-workers (1) is investigated from a coordination chemistry perspective, to probe the origin of its intriguing geometry. Through the application of a variety of computational techniques, non-covalent (steric, electrostatic) interactions are found to be dominant. Further, we arrive at a bonding description which emphasizes the tricoordinate sp -hybridized nature of the central methandiide carbon, differing somewhat from the original proposal.
View Article and Find Full Text PDFPhys Chem Chem Phys
June 2023
High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai, India.
With state-of-the-art density functional theory and molecular dynamics, we explored the BN-analog of a recently synthesized 2D biphenylene sheet. Its dynamical, thermal, and mechanical stability has been confirmed with phonon spectrum calculations, molecular dynamics (AIMD), and Born criteria, and its synthesis feasibility has been ascertained in terms of cohesive energy. The phonon spectrum and AIMD results show all positive frequencies and negligible variations in structure (bond length), kinetic and total energy for 5 ps, respectively.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!