Study On Reactivity Of Amidinatosilylene And The N/Al FLP Aluminum Hydride

The divalent silylenes with small HOMO-LUMO energy gap have lone pair electrons and empty p orbital,so they act as Lewis acid and base as well as the two-electron reducing agent in many reactions.In this thesis,studies on the reactivities of amidinatochlorosilylene,amidinatophosphanylsilene,and amino group linked Si(Ⅱ)/B frustrated Lewis pair(FLP)will be carried.Aluminum hydride is an important hydrogenation reagent widely employed in the organic reactions.The reactivity of the N/Al FLP aluminum hydride toward the C-N multiple bond organics will be studied as well.The research content includes three chapters detailed as follows.1.Study on synthesis and reactions of amidinatochlorosilylene and amidinatophosphanylsilene.Amidinatochlorosilylene LSiCl(la,L=PhC(NtBu)2)was synthesized and employed to study on reactions with C-N multiple bond molecules and group XVI elements Se and Te.When la was reacted with pyridinyl imine PyCH=N-2,6-iPr2C6H3,compound LSi(Cl)(C5H5NCHN(2,6-iPr2C6H3)(1-la)was obtained through oxidative cycloaddition of the C5H5NC=N part at the Si(Ⅱ)center.Compound 1a reacted with arylphosphanyl-pyrolyl imine o-Ph2PC6H4N=CH(C4H3NH)to give compound[LSiNC4H3-o-CH(SiLCl2)N](o-Ph2PC6H4)(1-2a),which proceeded through complex process probably involving oxidative addition of the pyroyl NH at the Si(Ⅱ)center,reduction of the C=N bond,C-H activation,and coordination of the P,N,N-chelate.Furhter reaction of la with dicyclohexyl carbon diimide to produce the Si-centered spiral-ring compound[LSi(Cl)N(Cy)C(=NCy)](NCy)(1-3a),finalizing the combined oxidative cycloaddition of the N=C bond at the Si(Ⅱ)and the NCy-insertion。The reaction of la with trifluoromethyl benzonitrile resulted compound(LClSi)2(NCC6H4-o-CF3)(1-4a)by means of double consecutive cycloadditions into the C≡N triple bond.Finally,lareacted with cyclohexyl isonitrile to yield a C2NSi-ring compound[LSi(Cl)C(=NCy)N(Cy)][CSiL(Cl2)](1-5a),undergoing a process with a probable Si-.C=N state followed by rearrangement and isonitrile insertion.Amidinatophosphanylsilene LSiPPh2(1f)was also prepared,which reacted with Se and Te to result in the Si=Se bond LSi(=Se)PPh2(1-6a)and Si=Te bond LSi(=Te)PPh2(1-6b).All of the above compounds were characterized by Xcrystallography,and compounds 1-1a,1-2a,1-5a,1-6a,and 1-6b were analyzed by NMR spectroscopy.These reaction mechanisms have been discussed.2.Study on synthesis and reaction of the amino group linked Si(Ⅱ)/B frustrated Lewis pair(FLP).The amino group linked Si(Ⅱ)/B FLP compound LSiN(2,6-iPr2C6H3)(9BBN)(2-2a)has been prepared as a new species.The synthetic route included an H2-elimination reaction of H2N-2,6-iPr2C6H3 and(9BBN)H to afford compound(9BBN)NH-2,6-iPr2C6H3,and then the further deprotonation using nBuLi followed with LiCl-elimination with LSiCl(la).First reaction was carried out with dimethyl ketone and the COSi-three membered ring compound[LSiOC(Ph2)](N-2,6-iPr2C6H3)(9BBN)(2-3a)was obtained through[1+2]oxidative cycloaddition.Second reaction by using 2-2a was accomplished with the respective Se and Te,generating the Si=Se bond LSi(=Se)N(2,6-iPr2C6H3)(9BBN)(2-4a)and the Si=Te bond LSi(=Te)N(2,6-iPr2C6H3)-9BBN(2-4b).These results show a reaction focus on the silylene functionality and no influence by the lewis acid boryl group was found on the formation of the products.Compounds 2-2a-2-4a and 2-4b were all characterized by NMR spectroscopy and X-crystallography.3.Study on reaction of the N/Al FLP-based aluminum dihydride toward the C-N multiple bond molecules.The reactions of the N/Al FLP-based aluminum dihydride[(o-TMP-C6H4)AlH(μ-H)]2(TMP=N(CMe2CH2)2CH2,3-1a)with several C-N multiple bond molecules were studied.3-1a reacted with the respective imides PhCH=N-2,6-iPr2C6H3 and PhCH=N-2,4,6-Me3C6H3 to afforded compounds(o-TMP-C6H4)AlHN(CH2Ph)(2,6-iPr2C6H3)(3-2a)and(o-TMP-C6H4)AlHN(CH2Ph)(2,4,6-Me3C6H3)(3-2b)both as a monomer as a result by monohydroalumination.The reaction of 3-1a with phenylacetonitrile gave an Al2N2-four membered ring compound[(o-TMP-C6H4)AlH(N=CH2Ph)]2(3-3a).This reaction proceeded through monohydroalumination followed by dimerization due to the strong Lewis acidity of the Al nucleus.However,the reaction with dicyclohexyl carbon diimide yielded eight-membered ring product[(o-TMP-C6H4)AlHN(Cy)CHN(Cy)]2(3-4a),in which besides monohydroalumination and dimerization an additional N-donor coordination at the Al atom was occurred.All of these compounds were characterized by the NMR spectroscopy,of which compounds 3-2a,3-2b and 3-4a were further confirmed by X-ray crystallography.