Synthesis Of Super-Large Silicon-Based Acetylene Molecules And Novel Phosphine-Based Compounds

Ultra-large silyl acetylene molecules are a class of compounds with special substituent effects,which are not only used as multi-purpose alkynyl nucleophiles in general organic synthesis,but also as alkyne polymers and precursors of silyne-acetylene copolymers.Molecular and acetylene-bridged silicon-protected intermediates of organometallic complexes.Its bulky silicon group can provide a good kinetic protection effect for the synthesis of novel heavy main group element compounds,and alkyne triple bonds can form unsaturated cyclic compounds with heavy group 14 elements.Trisubstituted phosphine compounds can be used as Lewis base ligands in transition metal chemistry for the synthesis of reducing metal complexes and the preparation of homogeneous catalysts,Tetrasubstituted quaternary phosphonium salts can be used as Lewis acid catalysts for C-C,C-O,and C-N bond formation and asymmetric transformations,and even as precursor materials for the synthesis of novel phosphino-stabilized carbene compounds.Such molecules are a highly challenging and academically valuable research topic in synthetic chemistry.This master’s work is mainly divided into the following parts:1.A series of phenylsilyl acetylene molecules 1-3 were synthesized from trichloroethylene and substituted alkynes,as well as two examples of acetylene compounds 5 and 6 substituted by super-large silyl groups.Bis（triisopropylsilyl）acetylene 5 and bis（tert-butyldimethylsilyl）acetylene 6 were prepared by salt elimination reaction using trichloroethylene preparation method,and their side chain groups have huge steric positions It can provide good kinetic protection for alkyne molecules and subsequent derivatives.¹H NMR and ¹³C NMR revealed their molecular composition and structure,which provided the possibility for the follow-up study of their reactivity and structural novel heavy main group element derivatives.2.Using Ph₃PCl₂,Ph₃PBr₂,and Ph₄PCl as reaction precursors,five samples with super-large anions were synthesized after salt elimination reaction with potassium trifluoromethanesulfonate and sodium tetrakis（pentafluorophenyl）borate in dichloromethane solution.The quaternary phosphonium salt compounds 18,19,21,23,and26 can be used as good precursors of phosphine compounds,which provide the possibility for further exploration of phosphine-coordinated low-valent main group element compounds.3.Using bromotriphenylphosphonium trifluoromethanesulfonate 19 as the precursor,two examples of novel phosphine coordination compounds 24a and 24b were obtained through the salt elimination reaction of anthracenyllithium substituted bromine atoms,and their crystals structure were completely characterized.The lithium atom on compound 24a has three coordination modes,and the whole presents a stepped spanning structure and contains a certain hole structure.Compound 24b exhibits a tetrahedral coordination configuration.Lithium atoms and sulfur atoms occupy four vertices of the tetrahedron,respectively,and the remaining vertices are occupied by O atoms.The discovery of this structure provides a reference for the subsequent exploration of quaternary phosphonium salts that remove lithium ions.4.In the hydrolysis reaction of chlorotriphenylphosphonium tetrakis（pentafluoropheny l）borate 21,an example of triphenylhydroxyphosphonium cationic compound 22 with novel structure was prepared.Compound 22 has higher ionic properties,and the b ond length of its P1-O1 bond is longer than the corresponding bond length reported in the literature.This is because the lone pair of electrons of the oxygen atom an d the phosphorus atom are fully bonded,and they are more prone to sp hybridizati on.P1-O1-H1 affecting the core region presents a certain curved V configuration.This master’s work has successfully prepared and characterized 10 cases of novel c ompounds within the expected task scope,and learned and mastered the syntheti c e xperimental research experience using anhydrous and oxygen-free Schlenk technolog y.Among them,the synthesis of two ultra-large silyl hexyne molecules laid the fou ndation for the subsequent research on reactivity and derivatives of heavy main gro up elements.Continued exploration of low-valent main-group element compounds cr eates favorable prospects.