Activation of Isocyanides and Hydrosilanes by a Cationic [CCH] Subunit in a Tetrairon–Tetracarbon Cluster

Abstract

Abstract The reactivity of [(η5-C5H4Me)4Fe4(HCCH)(HCC-NC4H4N)](PF6)2 (1) toward isocyanides and hydrosilanes was examined. The reaction of 1 with tert-butyl isocyanide led to C(sp3)-N(sp) bond cleavage to give [(η5-C5H4Me)4Fe4(HCCH)(HCC-CN)](PF6) (2), 1-tert-butylpyrazinium salt, and isobutene. In the reactions with cyclohexyl and benzyl isocyanides, isocyanide adducts [(η5-C5H4Me)4Fe4(HCCH)(HCC-CNR)](PF6)2 (R = Cy (5), CH2Ph (6)) were obtained and further transformed to 2 (70 °C, 10 h for 5; RT, 120 h for 6). The reactions of 1 with aryl isocyanides such as 2,6-dimethylphenyl and 2,4,6-tri-tert-butylphenyl isocyanides yielded thermally stable [(η5-C5H4Me)4Fe4(HCCH)(HCC-CNAr)](PF6)2 (Ar = 2,6-Me2C6H3 (8), 2,4,6-tBu3C6H2 (9)). The Si–H bonds of R3SiH (R = Et, Ph), Ph2SiH2, and PhSiH3 were activated to give [(η5-C5H4Me)4Fe4(HCCH)2](PF6) together with the corresponding fluorosilanes. Coordination of the substrates with a cationic [CCH] subunit promoted the cleavage of the carbon–nitrogen and silicon–hydrogen bonds to give the products.