Diiron and diruthenium aminocarbyne complexes containing pseudohalides: stereochemistry and reactivity

Acetonitrile is easily displaced from [Fe2{μ-CN(Me)(R)}(μ-CO)(CO)(MeCN)(Cp)2][SO3CF3] (R = 2,6-Me2C6H3 (Xyl) (1a); Me (1b)) upon stirring in THF at room temperature in the presence of [NBu4][SCN]. The resulting complexes trans-[Fe2{μ-CN(Me)(R)}(μ-CO)(CO)(NCS)(Cp)2] (R = Xyl (trans-2a); Me (trans-2b)) are completely isomerised to cis-[Fe2{μ-CN(Me)(R)}(μ-CO)(CO)(NCS)(Cp)2] (R = Xyl (cis-2a); Me (cis-2b)) when heated at reflux temperature. Similarly, the complexes cis-[M2{μ-CN(Me)(R)}(μ-CO)(CO)(NCO)(Cp)2] (M = Fe, R = Me (4a); M = Ru, R = Xyl (4b); M = Ru, R = Me (4c)) and cis-[M2{μ-CN(Me)(R)}(μ-CO)(CO)(N3)(Cp)2] (M = Fe, R = Xyl (5a); M = Fe, R = Me (5b); M = Ru, R = Xyl (5c)) can be obtained by heating at reflux temperature a THF solution of [M2{μ-CN(Me)(R)}(μ-CO)(CO)(MeCN)(Cp)2][SO3CF3] (M = Fe, R = Xyl (1a); M = Fe, Me (1b); M = Ru, R = Xyl (1c); M = Ru, R = Me (1d)) in the presence of NaNCO and NaN3, respectively. The reactions of 5 with MeO2CCtriple bond; length of mdashCCO2Me, HCtriple bond; length of mdashCCO2Me and (NC)(H)Cdouble bond; length as m-dashC(H)(CN) afford the triazolato complexes [M2{μ-CN(Me)(R)}(μ-CO)(CO){N3C2(CO2Me)2}(Cp)2] (M = Fe, R = Xyl (6a); M = Fe, R = Me (6b); M = Ru, R = Xyl (6c)), [M2{μ-CN(Me)(R)}(μ- CO)(CO){N3C2(H)(CO2Me)}(Cp)2] (M = Fe, R = Me (7a); M = Ru, R = Xyl (7b)) and [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO){N3C2(H)(CN)}(Cp)2] (8), respectively. The asymmetrically substituted triazolato complexes 7–8 are obtained as mixtures of N(1) and N(2) bonded isomers, whereas 6 exists only in the N(2) form. Methylation of 6–8 results in the formation of the triazole complexes [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO){N3(Me)C2(CO2Me)2}(Cp)2][CF3SO3] (9), [M2{μ-CN(Me)(R)}(μ-CO)(CO){N3(Me)C2(H)(CO2Me)}(Cp)2][CF3SO3] (M = Fe, R = Me (10a); M = Ru, R = Xyl (10b)) and [Fe2{μ-CN(Me)(Xyl)}(μ-CO)(CO){N3(Me)C2(H)(CN)}(Cp)2][CF3SO3], 11. The crystal structures of trans-2b, 4b · CH2Cl2, 5a, 6b · 0.5CH2Cl2 and 8 · CH2Cl2 have been determined.