Diiron and diruthenium aminocarbyne complexes containing pseudohalides: stereochemistry and reactivity

Acetonitrile is easily displaced from [Fe-2{mu-CN(Me)(R)}(mu-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-[Fe-2{mu-CN(Me)(R)}(mu-CO)(CO)(NCS)(CP)(2)] (R = Xyl (trans-2a); Me (trans-2b)) are completely isomerised to cis-[Fe-2{mu-CN(Me)(R)}(mu-CO)(CO)(NCO)(Cp)(2)] (R = Xyl (cis-2a); Me (cis-2b)) when heated at reflux temperature. Similarly, the complexes cis-[M-2{mu-CN(Me)(R)}(mu-CO)(CO)(NCO)(Cp)(2)] (M = Fe, R = Me (4a); M = Ru, R = Xyl (4b); M = Ru, R = Me (4c)) and cis-[M-2{mu-CN(Me)(R)}(mu-CO)(CO)(N-3)(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 [M-2{mu-CN(Me)(R)}(mu-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 MeO2CC&3bond; CCO2Me, HC&3bond; CCO2Me and (NC)(H)C=C(H)(CN) afford the triazolato complexes [M-2{mu-CN(Me)(R)}(mu-CO)(CO){N3C2(CO2Me)(2)}(Cp)(2)] (M = Fe, R = Xyl (6a); M = Fe, R = Me (6b); M = Ru, R = Xyl (6c)), [M-2{mu-CN(Me)(R)}(mu-CO)(CO){N3C2(H)(CO2Me)}(Cp)(2)] (M = Fe, R = Me (7a): M = Ru, R = Xyl (7b)) and [Fe-2{mu-CN(Me)(Xyl)}(mu-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 [Fe-2{mu-CN(Me)(Xyl)}(mu-CO)(CO){N-3(Me)C-2(CO2Me)(2)}(Cp)(2)][CF3SO3] (9). [M-2{mu-CN(Me)(R)}(mu-CO)(CO){N-3(Me)C-2(H)(CO2Me)}(Cp)(2)][CF3SO3] (M = Fe, R = Me (10a); M = Ru, R = Xyl (10b)) and [Fe-2{mu-CN(Me) (Xyl)}(mu-CO)(CO){N-3(Me)C-2(H)(CN)}(Cp)(2)][CF3SO3], 11. The crystal structures of trans-2b, 4b center dot CH2Cl2, 5a, 6b center dot 0.5CH(2)Cl(2) and 8 center dot CH2Cl2 have been determined.