Growing the Molecular Architecture at Alkynyl(amino)carbene Ligands in Diiron µ‐Aminocarbyne Complexes

The diiron µ‐aminocarbyne imidoyl complexes [Fe 2 {µ‐CN(Me)(R)}(µ‐CO)(CO){C(C≡CR′)=NXyl}Cp 2 ] [R = Xyl, R′ = Ph ( 1a );[1] R = Xyl, R′ = Tol ( 1b );[1] R = Me, R′ = Ph ( 1c ); R = Me, R′ = SiMe 3 ( 1d ); Xyl = 2,6‐C 6 H 3 Me 2 , Tol = 4‐C 6 H 4 Me] have been prepared by the addition of lithium acetylides to precursors containing a terminal isocyanide ligand. The treatment of 1a – c with CF 3 SO 3 CH 3 afforded the alkynyl(amino)carbene derivatives [Fe 2 {µ‐CN(Me)(R)}(µ‐CO)(CO){C(C≡CR′)N(Me)(Xyl)}Cp 2 ][SO 3 CF 3 ] [R = Me, R′ = Ph ( 2a ); R = Xyl, R′ = Ph ( 2b ); R = Xyl, R′ = Tol ( 2c )] in high yields. The reactions of 2b , c with CH 3 OH/NaBF 4 , NH 2 R and NaBH 4 led to [Fe 2 {µ‐CN(Me)(Xyl)}(µ‐CO)(CO){C(CH=C(Ph)OMe)N(Me)(Xyl)}Cp 2 ][BF 4 ] ( 3 ), [Fe 2 {µ‐CN(Me)(Xyl)}(µ‐CO)(CO){C(CH=C(Tol)NHR)N(Me)(Xyl)}Cp 2 ][SO 3 CF 3 ] [R = Et ( 4a ); R = Ph ( 4b )], and [Fe 2 {µ‐CN(Me)(Xyl)}(µ‐CO)(CO){C(CH=CHTol)N(Me)(Xyl)}Cp 2 ][SO 3 CF 3 ] ( 5 ) in yields of 65–80 %. Complexes 3 – 5 were formed by the selective functionalization of the alkynyl group in 2b , c . Complex 2c reacted with NaCH(CN) 2 /CH 2 (CN) 2 and NaCH(CO 2 Me) 2 to yield [Fe 2 {µ‐CN(Me)(Xyl)}(µ‐CO)(CO){C{N(Me)(Xyl)}CH=C(Tol)C(CN)C(NH 2 )C(CN) 2 }Cp 2 ] ( 6 ) and [Fe 2 {µ‐C(NXyl)C(C(Tol)=C(CO 2 Me) 2 )CN(Me)(Xyl)}(µ‐CO) 2 Cp 2 ] ( 7 ) in yields of 65 and 60 %, respectively. All the products were purified by alumina chromatography, alumina being presumably involved in the formation of 3 , and characterized by elemental analysis and IR and NMR spectroscopy. The structures of 2b , 3 , 5 , and 6 were ascertained by single‐crystal X‐ray diffraction analysis.