Synthesis And Study Of Paddlewheel Dibismuthanes(?)and Diarsines(?)Complexes

The aromatic five-membered N-heterocyclic free radicals have draw great interest in radical chemistry,physical chemistry as well as in functional materials.Among the radicals of interest are those derived from triazolyl,pyrazolyl,imidazolyl,tetrazolinyl,dithiadiazolyl and diselenadiazolyl derivatives.Aromatic N-heterocycles,especially the triazolyl radicals,have been the subject of numerous redox reaction studies.However,very few neutral triazolyl radical species have been isolated.Recently,we discovered that neutral N-pyrazolyl free radicals[3,5-R₂pz]·,1,2,4-diazaphospholyl free radicals[3,5-R₂dp]·,and a series of stable paddlewheel dibismuthanes(?)complexes with shorter Bi(?)-Bi(?)single bond that coordinated by pyrazole and 1,2,4-diazaphospholide were generated by one-electron oxidization of the corresponding 1,2,4-diazaphospholide anion[3,5-R₂dp]-and 3,5-disubstituted pyrazolato anions[3,5-R₂pz]-with BiCl3,respectively.We have always been interested in triazole free radicals,but the triazole anions are very stable and difficult to be oxidized.Therefore,we try to oxidize it with high-valent,oxidizing metal ions,and expect to obtain triazole free radicals and paddlewheel triazole dibismuthanes(?)complexes.The main work was summarized as follows:Synthesis and study of paddlewheel triazole dibismuthanes(?)complexes.K[3,5-R₂tz][R=Ph,iPr]was reacted with BiCl3 in THF,and synthesized a stable paddlewheel triazole Bi(?)-Bi(?)complex[{?¹,?¹-3,5-R₂tz}₂(Bi-Bi){?¹,?¹-3,5-R₂tz}₂][R=Ph,iPr],they are the first paddlewheel bimetallic complexes coordinated by triazole.The Bi-Bi single bonds in the paddlewheel phenyltriazole dibismuthane(?)and isopropyltriazole dibismuthane complexes were 2.8721(3)A and 2.8650(4)A,respectively.After analysis and calculation,the reaction between BiCl3 and K⁺[3,5-Ph2tz]^-/K⁺[3,5-iPr₂tz]^-was confirmed to be a one-electron redox reaction,and Bi3+successfully oxidized the triazole anion to a triazole radical.And we performed EPR detection,as a result,triazole radical[3,5-R₂tz]·[R=Ph,iPr]was successfully captured,and got its adduct with DMPO[3,5-R₂tz].DMPO[R=Ph,iPr],Their spectra show strong EPR signals,which display the hyperfine structure of well-resolved coupling peaks.However,[3,5-Ph2tz]·DMPO spectrum is more complicated,The spectra data demonstrates that two resonant structures of 3,5-diphenyltriazolyl radicals might be trapped and stabilized by DMPOIn addition,we have found that bismuth(?)in the P-region metal can oxidize 1,2,4-diazaphospholide anion[3,5-R₂dp]-,and stibium(?)can also oxidize 1,2,4-diazaphospholide anion[3,5-R₂dp]-,so we guessed and tried to use arsenic(?)to oxidize the 1,2,4-diazaphospholide anion[3,5-R₂dp]-.It is also desirable to obtain a paddlewheel bimetal complex coordinated by diazaphospholide.The specific work is as followsSynthesis of paddlewheel dibismuthane(?)and diarsine(?)complexes bearing cyclohexyl diazaphospholide ligangd.K[3,5-Cy₂dp]was reacted with BiCl3 or AsBr3 in THF,and we obtained a paddlewheel cyclohexyl diazaphospholide dibismuthane(?)and diarsine(?)complex[{?¹,?¹-3,5-Cy₂dp}2(M-M){?¹,?¹-3,5-Cy₂dp}2][M=As,Bi].In addition,we found that the isopropylphosphine pyrazonium(I)complex can activate small molecular oxygen,we obtained a stable isopropyl diazaphospholide arsine-oxygen eight-membered ring complex[{?¹,?¹-3,5-iPr₂dp}₂(As-O)₄{?¹,?¹-3,5-iPr₂dp}₂].