초록 ▼

본 연구에서는 반응성이 매우 큰 divalent 규소화합물인 silylene 중간체에 관한 연구로, 상호 연관성을 가지는 4가지 세부과제로 나뉘어져서 수행되었다. 수행된 연구결과들은 각 세부과제별로 요약하면 다음과 같다.
제 1 세부과제에서는 여러가지 치환체를 가지는 silole 유도체를 합성하고 이 화합물들을 chromium carbonyl 과 반응시켜 silol 의 phenyl 기에 chromium carbonyl 이 배위된 η? π-착물을 얻었고 iron pentacarbonyl 과의 반응으로부터는 η? π-착물

본 연구에서는 반응성이 매우 큰 divalent 규소화합물인 silylene 중간체에 관한 연구로, 상호 연관성을 가지는 4가지 세부과제로 나뉘어져서 수행되었다. 수행된 연구결과들은 각 세부과제별로 요약하면 다음과 같다.
제 1 세부과제에서는 여러가지 치환체를 가지는 silole 유도체를 합성하고 이 화합물들을 chromium carbonyl 과 반응시켜 silol 의 phenyl 기에 chromium carbonyl 이 배위된 η? π-착물을 얻었고 iron pentacarbonyl 과의 반응으로부터는 η? π-착물을 얻었다. chromium 과 iron 이 silole 과 착물을 이룰때 chromium에서는 η?을-착물을 이루고 iron에서는 η?로 착물을 형성하는 차이를 관찰할 수 있었다. 이러한 겨로가는 규소기를 치환체로 갖는 silole의 전이금속착물로는 처음보고된 것으로 silicon-착화합물의 합성에 대한 기초연구로써 그 의의가 크다고 할 수 있다. 이러한 결과를 바탕으로 반응성이 큰 중간체인 diisopropoxysilylene과 전이금속과의 착물 합성을 시도하여 새로운 donor-stabilized silylene complex인 tetracarbonyl(diisopropoxysilanediyl)iron(0)-hexamethyl-phosphoamide를 합성하여 분광학적 방법으로 확인하고 single crystal structure determination을 수행한 결과 complex 의 구조가 apical 구조임을 알았다. 또한 variable temperature ?H-NMR spectra 의 line shape 분석을 통해 (Si<-HMPA) 결합이 끊어질때의 free energy △G? = 22 ㎉/mol 임을 알았다. 이는 척번째 정량적인 값으로 큰 의의가 있다. 또 다른 iron-substituted silylene의 전구체인 ［1,4,5,6 -tetraphenyl-2,3-benzo-7-ethyl-7-silanorbornadienyl］-cyclopentadienyldicarbonyliron 과 ［1,4,5,6-tetraphenyl-2,3-bis-(methoxy-carbonyl)-7-ethyl-7-silanorbornadienyl］cyclopentadienyldicar-bonyliron은 반응성이 너무 커서 이 전구체가 생성되자마자 iron-ethlsilyelene이 extrusion됨을 counter part인 tetraphenylphthalte 와 tetraphenylnaphthalene의 확인으로 간접적으로 확인하였다.
제 2 세부과제에서는 새로운 ethylphenylsilylene의 열 또는 광분해 전구체를 합성하고 분자내와 분자간 반응 조건에서 ethylphenylsilylene을 생성시켰다. 열분해 조건에서는 β C-H 삽입반응이 일어나 silacyclopropane이 중간체로 형성되고 이어서 ring extrusion과 ring cleavage 반응이 일어나 phenylsilane, phenylvinylsilane 그리고 phenylethylsilane 등이 생성됨을 알았고 광분해 조건에서는 분자내 β C-H 삽입 반응보다는 분자간 반응이 훨씬 더 유리하게 일어났음을 관찰하였다. β C-H 삽입 반응과 π-부가반응의 두가지 가능한 분자내 반응성을 가진 ethylvinylsilylene의 열분해 전구체를 합성하고 분자내 및 분자간 반응조건에서 각각 열분해반응을 수행하였다. 열분해 조건에서는 2,3-dimethyl-1,3-butadiene의 존재 하에서 분자간 반응을 시킨 결과 ethyl group으로의 β C-H 삽입 반응에 기인한 1-hydrido-1-vinyl-3,3-dimethyl-1-sila-cyclopent-3-ene(71%)이 주생생물로 얻어졌고, vinyl group으로의 π-부가 반응에 기인하는 1-ethyl-1-hydrido-3,4-dimethyl-1-silacyclo-pent-3-ene(2%)은 소량 얻어졌다. 이는 β C-H 삽입 반응이 π-부가 반응보다 훨씬 유리하게 진행되었음을 의미했다. 광분해 전구체인 methylbis(trimethylsilyl)(methylphenylphosphoryl)silane을 neat, triethylsilane 또는 diphenylacethylene 존재 하에서 광분해 시킨 결과, Si-P 결합의 homolytic cleavage 에 기인한 radical 반응생성물이 주로 생성되었고, 각각의 경우 생성된 α-phosphorylsilylene이 직접 trap된 생성물은 확인하지 못하였으나 간접적으로 확인할 수 있는 근거를 뒷받침하는 1,2,3,4,5-pentaphenylphosphole을 확인하였다. 이는 α-phosphorylsilylene이 intramolecular β C-H 삽입 반응을 통하여 silaphosphorane이 중간체로 생성되고 이어서 extrusion이 일어나 phosphinidine이 생성되며 이 중간체가 2 mole의 diphenylacethylene에 trap되어 생성된 것으로 생각되었다. 이 결과는 현재까지 알려지지 않은 α-phosphorylsilylene의 생성, silaphosphorane의 생성과 free phosphinidine 생성의 첫번째 경우가 된다. Diphenylphosphoryl-trimethylsilane의 분자 이온 (m/z 258)의 MIKE spectrum에서 benzene이 제거된 m/z 180의 metastable ion이 가장 크게 확인 되었으며, 분자 이온에서 trimethylsilyl cation의 생성은 매우 미미하였다. 이는 현재까지 알려지지 않은 매우 흥미있는 mechanistic 결과로 생각된다. 또한 phosphoryl group의 phenyl기와 silyl group의 methyl기가 서로 위치를 바꾸는 (transposition)것임을 확인하였으며, 이 재배열은 ［M-CH?］? ion에서 부터 일어나는 것을 MIKE spectrum으로 확인하였다. 이런 재배열 현상이 Si-P 결합 사이에서 확인된 것을 처음있는 일이다.
제 3 세부과제에서는 선형 및 고리 polysilane이 광반응에 의해 silylene, disilene 및 silyl 라디칼을 형성하였다. MeSi(SiMe?)?는 자외선광분해에 의해 Me-Si-SiMe?, :SiMe? SiMe? 및 (Me?Si)?MeSi 세가지 고반응성 생성물 과 안정한 포화생성물인 Me?SiSiMe? 및 Me?Si(SiMe?)?이 형성되었다. Octakis(trimethylsilyl)-cyclotetrasilane은 자외선에 의해 disilene으로 분해되었다. 여기에서 생성되는 고반응성 규소화학종은 알코올, diene 및 silane에 포착되었다. Diphenylsilane은 Rh 촉매와 상호작용하여 diphenyl-silylene-Rh 착체를 형성하는 반응이 관측되었다. Octaphenyl-cyclotetrasilane에서 1578 ㎝? 영역에서 nonsymmetric benzene ring stretching, 980-990 ㎝? 영역에서 symmetric benzene ring stretching이 일어났다. 690 ㎝?의 IR 스펙트럼에서 out-of plane C-H bending, 470 ㎝?? 부근에서 nonsymmetric Si-skeletal ring stretching, 430 ㎝?? 부근에서 symmetric Si-skeletal ring stretching이 일어났다. Octakis(trimethylsilyl)cyclotetrasilane은 740㎝?? 부근에서 non-symmetric SiC? stretching, 470㎝?? 부근에서 nonsymmetric skeletal stretching, 400㎝?? 부근에서 symmetric Si-skeletal ring stretching이 나타남을 알 수 있었다. Cyclotetrasilane에서 tetra-ring의 치환기가 Si-skeletal ring stretching에 큰 영향을 끼치지 않음을 알 수 있었다. Octaphenylcyclotetrasilane을 290 nm에서 여기시켰을 때 319 및 410nm에서 emission bands를 보여주었다. 319 nm의 형광수명은 4.2 나노초였고, 410 nm emission band의 형광은 세 개의 decay mode를 나타내었는데, 하나는 short component 인 390 피코초이고 나머지는 2.3 나노초 와 17.9 나노초의 형광세기가 약하며 수명이 긴 형광이었다. 17.9 나노초의 성분은 310 nm의 band와 overlap되어 나오는 것으로 해석되었다. 또한 고온펄수분자빔노즐을 이용하여 bis(9-fluorenyl)methane의 레이저유발형광여기수펙트라를 얻었다. Fluorene 단분자에 해당하는 날카로운 vibronic band 들이관측되었다. 이 구조로 부터 bis(9-fluorenyl)methane은 sanwich 형의 excimer 형태가 바닥상태의 구조가 아님을 알 수 있었다. 반실험적 연구방법인 AMl, MNDO, MINDO/3, PM3 방법 등을 이용하여 광반응 및 빛반응의 반응물 및 생성물의 열역학적 성질, 전자 및 입체구조 등을 예측하였고 반응메카니즘 등도 제시하였다.
제 4 세부과제에서는 2,3-dimethyl-1,3-butadiene 존재하에서 1,1-dimethoxy-1-phenyl-2,2,2-trimethyldisilane (Ⅲ)을 고온(500, 600, 700℃)에서 진공 열분해 반응시켰다. 그 결과 두가지 주요 생성물인 1-methoxy-1-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (XX)과 1-phenyl-3,4-dimethyl-1-silacyclopent-3-ene (XIX) 를 얻었으며 아울러 methoxytrimethylsilane도 생성되었다. 생성물 XIX는 phenylsilylene이 trapping agent와 반응에 의해서 얻어졌다고 본다. 이 phenylsilylene은 중간체로써 처음 생성된 methoxyphenylsilylene이 분자내 β C-H 삽입반응이 일어나 2-phenyloxasilacyclopropane 중간체가 생성된 후 이것이 ［3→2+1］cycloelimination으로부터 나왔다고 제안하였다. 본 반응을 온도변화에 따라 생성물비 (XIX/XX)를 조사하였다. 반응온도가 증가함에 따라 그 생성물비도 증가하였다. 이는 methoxyphenylsilylene이 phenylsilylene과 HCHO로 분해되는 과정이 activate process임을 의미한다. 2-Allyl-2-methyl-2-sila-1,2-dihydronaphthalene (XⅢ)과 과량의 MeOH 또는 MeOD를 혼합한 용액을 N?기체를 통과시키면서 copyrolysis (600℃) 시켰다. -원문참조-

Abstract ▼

This study has been directed toward highly reactive divalent organosilicon species such as silylene intermediaties. This work has been carried out in four separate subjects which are closely related to each other. The results obtained in this research project are summarized as follows:
In

This study has been directed toward highly reactive divalent organosilicon species such as silylene intermediaties. This work has been carried out in four separate subjects which are closely related to each other. The results obtained in this research project are summarized as follows:
In the first project, the siloles with various substituents synthesized were reacted with chromium hexacarbonyl to give new η? π-complexes of chromium tricarbonyls. On the other hand, the reaction of iron pentacarbonyl with siloles gave the η? π-comlexes. It was first found that when carbonyl compounds of chromium and iron were reacted with the tetraphenylsiloles, chromium prefered to form η? complexes whereas iron prefered to form η? compleses. The new donor-stabilized silylene complex, tetracarbonyl(diisopropoxysilane-diyl)iron(0)-hexa-methylphosphoamide, was synthesized through the reaction of dichloroisopropoxysilane and disodium tetracarbonylferrate sesquidioxanate. On the basis of spectroscopic studies, the synthesized complex was characterized as an apical isomer rather than as equatorial isomer which is one of the possible structures. The single crystal X-ray structure determination was also conducted. A line-shape analysis of variable temperature ?H NMR spectra afforded to get the free enery of activation for the bond cleavage of Si<-HMPA, △G? = 22 ㎉/mol. An attempt to synthesize ［1,4,5,6-tetraphenyl-2,3-benzo-7-ethyl-7-sila-norbornadi-enyl］cyclopentadienyldicarbonyliron and ［1,4,5,6-tetra-phenyl-2,3-bis-(methoxycarbonyl)-7-ethyl-7-sila-norborna-dienyl］cyclo-pentadienyldicar-bonyliron as an iron-substituted silylene-precursor has not been successful, because the precursors synthesized were unstable at the synthetic conditions to give tetraphenylphthalate and tetrapheyl-naphthalene which are counter parts of the generated iron-substituted silylenes.
In the second project, the thermal and photochemical precursors of the ethylphenylsiylene were synthesized. The ethylphenylsilylene was generated through intramolecular and intermolecular reaction conditions, respectively. The ethylphenylsilylene generated from flow vacuum pyrolysis condition was converted to silacyclopropane through a β C-H insertion and subsequent ring extrusion and ring cleavage reactions occured to give phenylsilane, phenylvinylsilane and phenylethylsilane. The results of photolysis reaction indicated that the intermolecular reaction was more favorable pathway than the intramolecular β C-H insertion reaction. The ethylvinylsilylene which has two possible intramolecular reactions to ethyl and vinyl group was thermally generated through intermolecular and intramolecular reaction conditions. Flow vacuum pyrolysis of thermal precursor in the presence of trapping agent, 2,3-dimethyl-1,3-butadiene gave 1-hydrido-1-vinyl-3,3-dimethyl-1-silacyclopent-3-ene(71%) formed through an intramolecular β C-H insertion to ethyl group and 1-ethyl-1-hydrido-3,4-dimethyl-1-silacyclopent-3-ene(2%) formed through as intermolecular π-addition to vinyl group. Theses result strongly indicated indicated that the intramolecular β C-H insertion was much preferred to the intramolecular π-addition reaction. The photolysis of methlbis(trimethlsilyl)(methylphenyl-phosphoryl)silane, which is α-phosphorylsilylene-precursor, was carried out in the absence of trapping agent and presence of trapping agents, such as triethylsilane and diphenylacetylene. A samll amount of hexamethyldisilane which led us to assume the generation of α-phosphorylsilylene was formed. But most of the photolysates were identified as the products formed in the radical process through the homolytic cleavage of Si-P bond. In the presence of diphenylacetylene, 1,2,3,4,5-pentaphenylphosphole was observed as the trapping adduct of phosphinidine. This result may suggest that phosphinidine was generated by extrusion reaction from the silaphosphorane intermediate which was formed by intramolecular C-H insertion of α-phosphorylsilylene, silaphosphorane and free phosphinidine. In the mass analyzed ion kinetic energy spectrum study on phosphorylsilane, the MIKE spectrum of the molecular ion (m/z 258) of diphenylphosphoryltrimethylsilane showed metastable ion (m/z 180) with the highest intensity formed through the elimination of bnezene and showed the trimethylsilyl cation as a tiny peak, which is unusual and interesting mechanistic result. Transposition rearrangement between the phenyl group on phosphorus atom and methyl group on silicon atom was observed. MIKE spectrum strongly suggested that this rearrangment was initiated from the fragment ［M-CH?］. ?
In the third project, UV photolysis of linear and cyclo polysilanes produces several reactive silicon species, silylene, disilene and silyl radical. These reactive species are trapped with appropriate trapping agents. UV photolysis of MeSi(SiMe?)? is carried out in the presence of trapping agents to yield Me-Si-SiMe?, :SiMe? and (Me?Si)?MeSi whose trapping adducts are observed. Octakis(trimethyl-silyl) cyclotetrasilane is photolyzed to give rise to disilene which undergoes a Diels-Alder reaction with 2,3-dimethyl-1,3-butadiene. Pyrolysis of diphenylsilane is carried out over Rh catalysts to know whether or not the reaction system may produce a silylene-metal complex which could be formed via consecutive oxidative additions of the dihydride to the Rh surface. In the presence of 2,3-dimethyl-1,3-butadiene, the hydride is pyrolyzed over the Rh catalyst at 150℃. The hydride may dissoicate into silylene-surface complex which may react with the diene to produce 1,1-diphenyl-1-silacyclopent-3-ene. In a labelling experiment employing diphenyldideuteride, a possible deuterium incorporated cycloadduct is not observed in the mass spectra. This could support the mechanistic interpretation for the formation of the trapping products. Vibrational absorptions due to nonsymmetric and symmetric benzene ring stretches are observed in the regions of -(top)(～) 1578 ㎝?? and 980-990 ㎝??. Out-of-plane C-H bending, nonsymmetric Si-skeletal ring stretching and symmetric Si-skeletal ring stretchings are oberved near 690㎝??, 470㎝?? and 430㎝??, respectively. In the vibrations of octakis(trimethylsilyl)cyclotetrasilane, the absorptions for nonsymmetric SiC? stretchings, the nonsymmetric skeletal stretching and symmetric Si-skeletal ring stretchings are also observed in the similar rnages, near 740㎝??, 470㎝?? and 400㎝??, respectively. Bulky groups on the skeletal Si atom are not observed to affect the position of the ring stretching. When octaphenylcyclotetrasilane is laser-excited at 290 nm, two emission bands are observed with λ(sub)(max) = 319 and 410 nm. The life-time of the 319nm species is observed to be 4.2ns. The 410 nm emission band has three decay components. One of the species has a short life-time of 390 ps and the others are decayed with life-times of 2.3 ns and 17.9 ns. A laser induced fluorescence excitation spectra are obtained in a supersonic expansion of bis(9-fluorenyl)methane. We have employed a high temperature pulsed nozzle to check whether or not a molecular beam is to produce an internally "cold' molecule. Very sharp vibronic bands are observed corresponding with the monomer bands. This indicates that the ground-state configuration could be a trans-trans or trans-gauche configuration in which the fluorenyl subgroup is independent with the other. Semiemprirical studies using the AM1, MNDO, MINDO/3, PM3 programs are performed to infer the geometric and electronic structures of various reactive species involved in the photolytic and pyrolytic systems. -continue-

목차 Contents

• 1. 서론...21
• 2. 방법...26
• 3. 결과 및 고찰...27
• 4. 결론...47
• 5. 참고문헌...57