| Recognizing and manipulating patterns are an important means through which human beings understand and rebuild the world.In this manuscript,we explore patterns in a series of tetrazolate and tetrazolate-free Tp*-W-Cu-S cluster-based discrete clusters and coordination polymers which are obtained by the reaction of[Et4N][Tp*WS3](1),[Cu(CH3CN)4]BF4,NaN3 with alkyl-or aryl-nitriles under solvothermal conditions.The study of alkyl-nitriles.Six analogous 2D(6,3)networks,namely,｛[(Tp*WS3CU3)2(Mtta)3](μ3-N3))n(2;Mtta = 5-methyltetrazolate),{[(Tp*WS3Cu3)2(Etta)3](μ3-N3)}n(3a),{[(Tp*WS3Cu3)2(Etta)3]BF4).(3b;Etta ＝5-ethyltetrazolate),{[(Tp*WS3Cu3)2(Ptta)3]BF4}｝(4;Ptta = 5-propyltetrazolate),{[(Tp*WS3Cu3)2(Btta)3]BF4}"(5;Btta = 5-butyltetrazolate)and｛[(Tp*WS3CU3)2(Petta)3]BF4}｝(6;Petta = 5-pentyltetrazolate)were synthesized by one-pot reactions of[Et4N][Tp*WS3](1),Cu(MeCN)4BF4,NaN3 and NH4BF4 in alkyl-nitrile solvents CH3(CH2)fnCN(n = 0,1,2,3 and 4)under solvothermal reaction conditions.In the structures of 2-6,each alkyl tetrazolate was generated in situ from the "click" reaction between NaN3 and nitrile.A tetrahedron cage-like cluster[Tp*W(μ3-S)3(μ3-S’)Cu3]4(7)was also formed in some of the above reactions and can be readily separated by solvent extraction.The proportion of 7 increased with the elongation of the alkyl chains,and finally became the exclusive product when CH3(CH2)5CN was employed.After comparing the similarities and differences amongst 2-6,we were able to deduce patterns from these structures.The study of aryl-nitriles.Three cyanopyridine-based W-Cu-S clusters,namely,{[Tp*WS3Cu3(Cypy)3](BF4)2}.CH2Cl2-0.5MeCN(8.CH2Cl2.0.5MeCN;Cypy ＝4-cyanopyridine),{[Tp*WS3Cu3(Pybn)3]2(BF4)4}-3MeCN(9-3MeCN;Pybn =4-(pyridin-4-yl)benzonitrile)and {[Tp*WS3Cu3(Pyvbn)3]2(BF4)4}-2MeCN(10-2MeCN;Pyvbn = 4-(2-pyridin-4-yl-vinyl)-benzonitrile)were formed via a one-pot assembly of 1,Cu(MeCN)4BF4 and aryl-nitriles(Cypy,Pybn and Pyvbn).Our further attempts employing 8-10 as precursors to react with NaN3 under solvothermal conditions failed to gave either the tetrazolate-based coordination polymer or the discrete cluster of 7.In addition,when 1 was reacted with Cu(MeCN)4BF4,NaN3 and Cypy in DMF,a 3D coordination polymer of[Cu(Pytta)].(11;Pytta = 4-pyridyltetrazolate)was obtained.Furthermore,when 1 was mixed with an excess amount of CuCN in PhCH2CN,a CN bridged compound{[Et4N]{(Tp*WS3Cu3)[Cu2(CN)45]}2-2PhCH2CN}n(12*2PhCH2CN)was isolated.It can be concluded that the steric hindrance of nitriles plays an important role in guiding the formation of products.Compounds 5-10 and 12 have been investigated as the third-order nonlinear optical materials and exhibit much higher hyperpolarizability y values than that of the starting material 1. |
