Physical Chemistry Of Pseudohalogen NSO And Its Conjugated Derivatives

Pseudohalogens paly an important role in organic synthesis,materials science,biochemistry and atomospheric chemistry.NSO,as a new species of pseudohalogen,however,has rarely been investigated.Therefore,it has been of great necessity to study the physical chemistry of NSO and its conjugated derivatives.In this thesis,the sulfinyl pseudohalogen compounds decomposed by flash vacuum pyrolysis(FVP),and matrix-isolation technique is used to capture the nitrenes,OSN radical as well as its derivatives.Besides,quantum chemical calculations and isotope labelling are exploited to analyze corresponding spectroscopy,molecule structure,electronic structure and reaction mechanism.The main results of this study are as follow:1.normally,the a-oxo nitrenes,as organic activity intermediates,are triplet,but the sulfinyl nitrenes are singlet.Upon flash vacuum pyrolysis of trifluoromethane sulfinyl azide CF3S(O)N3 at 350 ?,an elusive trifluoromethane sulfinyl nitrene CF3S(O)N was generated in the gas in its singlet ground state and was characterized by matrix-isolation IR spectroscopy.Further fragmentation of CF3S(O)N at 600 ? produced CF3 and a novel pseudohalogen radical OSN,an SO2 analogue,which isomerized to SNO radical upon 266 nm irradiation.Both experimental and computational results support a stepwise decomposition mechanism of CF3S(O)N3.This work is the first time generated the sulfinyl nitrene and OSN radical,which stimulates further studies on their structure and reactivity.2.The decomposition of CH3OS(O)N3 has been studied by combining flash vacuum pyrolysis and matrix-isolation IR spectroscopy,the singlet methoxysulfinyl nitrene CH3OS(O)N in two conformations(syn and anti)has been identified.No Curtius-rearrangement but further fragmentation of the nitrene into H2CO and HNSO was observed upon pyrolysis at 500 ?.Irradiation of HNSO produced HOSN.This work provides a new way to generate unstable HNSO.3.Due to the low bond dissociation energy,the novel cumulene radical OCNSO has been generated by flash vacuum pyrolysis CF3S(O)NCO at 900? and characterized matrix-isolation IR spectroscopy.The reversible interconversion between the anti and the more stable syn conformation were observed by controling the temperature and visible light irradiation.Upon laser irradiation,the OSN radical was detected and further isomerized to SNO radical.Both the experimental and computational results support its existence as a sulfinyl isocyanate radical with the dominant spin on the sulfinyl moiety.This work not only enriches the interpseudohalogen family,but also stimulates new experimental efforts on the search of other elusive cumulenes formally consisting of two pseudohalogens by sharing the central nitrogen atom.4.As a reactive sulfur species,OSCN radical has been generated in the gas phase through the flash vacuum pyrolysis of CF3S(O)CN.Upon UV light(365 nm)irradiation OSCN in cryogenic matrices isomerizes to OSNC and SOCN,and the reverse conversion occurs under purple light irradiation(400 ± 20 nm),their characterization were accomplished by combining matrix-isolation IR spectroscopy and quantum chemical calculations.The bonding analysis of these isomers suggests the unpaired electron distribution over the SO moiety in OSCN and OSNC,whereas,the spin densities in SOCN,SONC,and SNCO predominantly localize at sulfur atom.