Unusual reactions of cationic bridging carbyne complexes of dimethylsilane-bridged bis(η 5-cyclopentadienyl)diiron tricarbonyl with carbonylmetal anions

Abstract

The reactions of the dimethylsilane-bridged cationic carbyne complexes of diiron, [Fe 2(μ-CO)(μ-CAr)(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}]BBr 4 ( 1, Ar=C 6H 5; 2, Ar= p-CF 3C 6H 4), with carbonylmetal anionic compounds Na[M(CO) 5CN] ( 4, M=Cr; 5, M=Mo; 6, M=W) in THF at low temperature afford diiron bridging carbene complexes [Fe 2(μ-CO){μ-C(Ar)NCM(CO) 5}(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}] ( 9, M=Cr, Ar=C 6H 5; 10, M=Mo, Ar=C 6H 5; 11, M=W, Ar=C 6H 5; 12, M=Cr, Ar= p-CF 3C 6H 4; 13, M=Mo, Ar= p-CF 3C 6H 4; 14, M=W, Ar= p-CF 3C 6H 4). In contrast to the reaction of 1 and 2, cationic carbyne complex [Fe 2(μ-CO)(μ-CC 6H 4CH 3- p)(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}]BBr 4 ( 3) reacts with 4– 6 under the same conditions to produce novel cationic bridging carbyne complexes [Fe 2(μ-CO)(μ-CC 6H 4CH 3- p)(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}] +[M(CO) 5CN] − ( 15, M=Cr; 16, M=Mo; 17, M=W). Analogous cationic bridging carbyne complex [Fe 2(μ-CO)(μ-CC 6H 4CH 3- p)(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}] +[Fe(CO) 4CN] − ( 18) can also be obtained from the reaction of 3 with Na[Fe(CO) 4CN] ( 7). Complex 15 or 16 reacts with NaSR (R=CH 3, C 6H 5, p-CH 3C 6H 4) to give bridging mercaptocarbene complexes [Fe 2(μ-CO){μ-C(SR)C 6H 4CH 3- p}(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}] ( 19, R=CH 3; 20, R=C 6H 5; 21, R= p-CH 3C 6H 4) in high yields. The related reaction of 1 with NaN(SiMe 3) 2 affords a novel benzonitrile-coordinated diiron complex [Fe 2(μ-CO) 2(CO)NCC 6H 5{(η 5-C 5H 4) 2Si(CH 3) 2}] ( 22). Unexpectedly, the reactions of 1 and 2 with 7 yield diiron bridging arylcarbene complexes [Fe 2(μ-CO){μ-C(H)Ar}(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}] ( 23, Ar=C 6H 5; 24, Ar= p-CF 3C 6H 4). The products 23 and 24 and bridging p-tolyl-carbene complex [Fe 2(μ-CO){μ-C(H)C 6H 4CH 3- p}(CO) 2{(η 5-C 5H 4) 2Si(CH 3) 2}] ( 25) were also obtained from the reactions of 1– 3 with [(PPh 3) 2N][Cr(CO) 4NO] ( 8). The structures of 14, 15, 22, and 23 have been established by X-ray crystallography.