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1,3-dipolar cycloaddition of diaryldiazomethanes Ar 2 C N 2 across Cl 3 C–CH N–CO 2 Et 1 yields Δ 3 -1,2,4-triazolines 2 . Thermolysis of 2 leads, via transient azomethine ylides 3 , to diaryldichloroazabutadienes [Ar(Ar')C N–CH CCl 2 ] 4 . Treatment of 4a (Ar = Ar' = C 6 H 5 ) and 4c (Ar = Ar' = p -ClC 6 H 4 ) with NaSR in DMF yields 2-azabutadienes [Ar 2 C N–C(H) C(SR) 2 ] 5 . In contrast, nucleophilic attack of NaS t Bu on 4 affords azadienic dithioethers [Ar 2 C N–C(S t Bu) C(H)(S t Bu)] ( 7a Ar = C 6 H 5 ; 7b Ar' = p -ClC 6 H 4 ). The reaction of 4a with NaSEt conducted in neat EtSH produces [Ph 2 C N–C(H)(SEt)–CCl 2 H] 8 , which after dehydrochloration by NaOMe and subsequent addition of NaSEt is converted to [Ph 2 C N–C(SEt) C(H)(SEt)] 7c . Upon the reaction of 4c with NaS i Pr, the intermediate dithioether [( p -ClC 6 H 4 ) 2 C N–CH C(S i Pr) 2 ] 5k is converted to tetrakisthioether [( p - i PrSC 6 H 4 ) 2 C N–CH C(S i Pr) 2 ] 6 . Treatment of 4a with the sodium salt of piperidine leads to [Ph 2 C N–CH C(NC 5 H 10 ) 2 ] 10 . The coordination of 6 on CuBr affords the macrocyclic dinuclear Cu(I) complex 11 . The crystal structures of 5i , 7a , b , 10 and 11 have been determined by X-ray diffraction. [ABSTRACT FROM AUTHOR]