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

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.

Norbornadiene as a Building Block for the Synthesis of Linked Benzazocinones and Benzazocinium Salts through Tetranuclear Carbopalladated Intermediates

“…Under these conditions, derivative 8a was obtained (Scheme ), which apparently resulted from the C–C reductive coupling of a cyano-palladium­(II) complex that could have formed after the dealkylation of the coordinated t BuNC ligand in intermediate I (Scheme ). There are numerous examples of t BuNC ligand dealkylation reactions, which happen to be relatively easy in cationic complexes. , Moreover, we have found similar results in the decomposition of cationic alkenyl complexes of Pd­(II) containing coordinated t BuNC …”