Reactions of Cationic Bridging Carbyne Complexes of Bis(η-cyclopentadienyl)diiron Tricarbonyl with Nucleophiles. A Route to Diiron Bridging Carbene Complexes

Abstract

The reactions of the cationic carbyne complex of diiron, [Fe2(μ-CO)(μ-CPh)(CO)2(η-C5H5)2]BBr4 (3), with NaSMe, NaSEt, NaSPh, NaSC6H4Me-p, and NaSC6H4NO2-p in THF at low temperature afforded diiron bridging thiocarbene complexes [Fe2(μ-CO){μ-C(SR)Ph}(CO)2(η-C5H5)2] (5, R = Me; 6, R = Et; 7, R = Ph; 8, R = p-MeC6H4; 9, R = p-NO2C6H4). Complex [Fe2(μ-CO)(μ-CC6H4Me-p)(CO)2(η-C5H5)2]BBr4 (4) reacted similarly with NaSPh and NaSC6H4Me-p to give corresponding bridging carbene complexes [Fe2(μ-CO){μ-C(SR)C6H4Me-p}(CO)2-(η-C5H5)2] (10, R = Ph; 11, R = p-MeC6H4). Complex 3 also reacted with NaOPh and NaN(SiMe3)2 to yield bridging carbene complexes [Fe2(μ-CO){μ-C(OPh)Ph}(CO)2(η-C5H5)2] (12) and [Fe2(μ-CO){μ-C(N(SiMe3)2)Ph}(CO)2(η-C5H5)2] (13), respectively. Complexes 3 and 4 reacted with reactive salt [Et3NH][Fe2(μ-CO)(μ-SBun)(CO)6] to yield the bridging mercaptocarbene complex [Fe2(μ-CO){μ-C(SH)Ph}(CO)2(η-C5H5)2] (14) and the bridging butylthiocarbene complex [Fe2(μ-CO){μ-C(SBun)C6H4Me-p}(CO)2(η-C5H5)2] (15), respectively. The analogous reactions of [Et3NH][Fe2(μ-CO)(μ-SPh)(CO)6] with 3 and 4 afforded the thiolato-bridged iron carbonyl compound [Fe2(μ-SPh)2(CO)6] (16) and the bridging arylcarbene complexes [Fe2(μ-CO){μ-C(H)Ar}(CO)2(η-C5H5)2] (17, Ar = Ph; 18, Ar = p-MeC6H4), while [Et3NH][Fe2(μ-CO)(μ-SC6H4Me-p)(CO)6] reacted with 3 to yield 17 and [Fe2(μ-SC6H4Me-p)2(CO)6] (19). The reaction of metal carbonyl anion compounds Na2W(CO)5 and Na2Fe(CO)4 with 3 gave the same product, 17. The structures of 6, 7, 15, and 17 have been established by X-ray diffraction studies.

Syntheses, structures and reactivities of diindenyl-coordinated diiron bridging carbene complexes

“…The two Fe atoms are coordinated symmetrically (relative to the mirror) by the two indenyl groups, respectively. The Fe-Fe distance in 6 (2.5393(15) Å ) is essentially the same as that in the bridging alkoxy-carbene complex 4 (2.5392(9) Å ) and close to that of analogous cyclopentadienyl-coordinated complex {l-C(H)C 6 H 4 CH 3 -p}(CO) 2 -(g-C 5 H 5 ) 2 ] (2.523(2) Å ) [12], but is significantly shorter than that found in analogous COT-coordinated complex [Fe 2 {l-C(H)C 6 H 4 CF 3 -p}(CO) 4 (g 8 -C 8 H 8 )] (2.7069 (11) Å ) [11a]. In addition to the molecular configuration, an apparent difference in the structure of 4 and 6 is the shorter C(3)-C(5) bond in 6 (1.445(10) Å ), which is intermediate between C-C single and C@C double bond lengths, as compared to 4 (1.503(5) Å ).…”

“…The compound 5 would be a diindenyl-coordinated diiron cationic complex with a bridging carbyne ligand as inferred from its reactivity (below) and previously reported analogous compexes [12] as well as its IR and 1 H NMR spectra. Complex 5 is only sparingly soluble in polar organic solvents such as THF and CH 2 Cl 2 and very sensitive to air, moisture, and temperature and can be stored at low temperature (below À60°C) only for a short period of time.…”

“…However, this resonance has undergone a significant upfield shift, as compared to that of analogous cyclopentadienyl-coordinated bridging arylcarbene complex {l-C(H)C 6 H 4 CH 3 -p}(CO) 2 (g-C 5 H 5 ) 2 ] (d 12.40) [12], which probably is arising from that the H atom is influenced by the ring current of the dindenyl moiety.…”

“…For instance, dicyclopentadienyl-coordinated diiron cationic carbyne complexes [Fe 2 (l-CO)(l-CC 6 H 5 )-(CO) 2 (g 5 -C 5 H 5 ) 2 ]BBr 4 reacts with NaN(SiMe 3 ) 2 and Na[M(CO) 5 CN] (M = Cr, Mo, W) to give bridging carbene complex [Fe 2 (l-CO){(l-C(N(SiMe 3 ) 2 )C 6 H 5 )(CO) 2 (g 5 -C 5 H 5 ) 2 }] [12] and bridging carbyne complexes [Fe 2 (l-CO)-(l-CC 6 H 5 )(CO) 2 (g 5 -C 5 H 5 ) 2 NCM(CO) 5 ] [9], respectively, while the analogous reactions of dimethylsilane-bridged biscyclo-pentadienyl diiron cationic carbyne complexes [Fe 2 (l-CO)(l-CAr)(CO) 2 {(g 5 -C 5 H 4 ) 2 -Si(CH 3 ) 2 }]BBr 4 give benzonitrile-coordinated diiron complex [Fe 2 (l-CO) 2 (CO)-NC-C 6 H 5 {(g 5 -C 5 H 4 ) 2 Si(CH 3 ) 2 }] and bridging phenyl (pentacarbonylcyanometal)carbene complexes [Fe 2 [10], respectively.…”

Synthesis, structure and reactivity of novel pyridazine-coordinated diiron bridging carbene complexes

“…The 1 H NMR spectrum had a resonance at 10.11 ppm, characteristic for a l-CHR group. However, this resonance has undergone a significant upfield shift, as compared to that of an analogous cyclopentadienyl-coordinated bridging arylcarbene complex [Fe 2 (l-CO){l-C(H)C 6 H 4 CH 3 -p}(CO) 2 (g-C 5 H 5 ) 2 ] (d 12.40), 12 which probably arises from the fact that the H atom is influenced by the ring current of the N(1)N(2)C( 14)C( 15)C( 16)C( 17) moiety.…”