Thermolytic Products Derived from Thermolysis of Cycloolefin-Coordinated Diiron Bridging Carbene Complexes

Abstract

Heating a benzene solution of the COT-coordinated diiron bridging alkoxycarbene complexes [Fe2{μ-C(OC2H5)Ar}(CO)4(η8-C8H8)] (1, Ar = C6H5; 2, Ar = p-CH3C6H4; 3, Ar = p-CF3C6H4) in a sealed tube at 85−90 °C for 72 h gave the bicycloolefin-coordinated tricarbonyliron dimers [Fe{η4-C9H8(Ar}(CO)3]2 (10, Ar = C6H5; 12, Ar = p-CH3C6H4; 14, Ar = p-CF3C6H4) and bridging arylcarbene complexes [Fe2{μ-C(H)Ar}(CO)4(η8-C8H8)] (11, Ar = C6H5; 13, Ar = p-CH3C6H4; 15, Ar = p-CF3C6H4). A similar thermolysis of 7H-indene-coordinated diiron bridging alkoxycarbene complex [Fe2{μ-C(OC2H5)C6H5}(CO)4(η4,η4-C9H8)] (4) yielded the ring addition product [Fe2{C(OC2H5)C6H5(η2,η5-C9H8)}(CO)5] (16). The 7H-indene-coordinated diiron bridging arylthiocarbene complexes [Fe2{μ-C(Ar)SC6H4CH3-p}(CO)4(η4,η4-C9H8)] (8, Ar = C6H5; 9, Ar = p-C6H5C6H4) were heated similarly to afford the isomerized 7H-indene-coordinated diiron bridging carbene complexes with a μ-SC6H4CH3-p ligand, [Fe2{μ-C(Ar)(η2,η5-C9H8)}(μ-SC6H4CH3-p)(CO)3] (17, Ar = C6H5; 19, Ar = p-C6H5C6H4), and the acyliron compounds [Fe(CO)2(CO){C(H)Ar(η5-C9H8)}] (18, Ar = C6H5; 20, Ar = p-C6H5C6H4). The structures of complexes 14, 16, 17, and 18 have been established by X-ray diffraction studies.

CC Bond Formation in Diiron Complexes

“…Interestingly, some of these bridging alkoxycarbene complexes undergo thermal rearrangement involving the coupling of carbene with bridging olefins (7 H ‐indene or cyclooctatetraene (COT)) 51a. 52 One example is shown in Scheme .…”

Advances in the synthesis and reactivity of 2-pyranylidene carbene complexes

“…Fischer-type carbene complexes are among the most important organometallic compounds, and these have experienced a considerable surge in recent times because of their widespread application in synthetic organic chemistry since the first carbene complex was reported by Fischer and coworkers in 1964 [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. During the course of the development of Fischer-type carbene complexes, unsaturated Fischer carbene complexes, in which unsaturated substituents are attached to the carbene carbon center, occupy an important status owing to their good reactivity in Michael-type reactions, cycloaddition reactions, transmetalation reactions.…”

“…During the course of the development of Fischer-type carbene complexes, unsaturated Fischer carbene complexes, in which unsaturated substituents are attached to the carbene carbon center, occupy an important status owing to their good reactivity in Michael-type reactions, cycloaddition reactions, transmetalation reactions. The strong electron-withdrawing property of the pentacarbonyl metal moiety and the electron-deficient property of the β-position carbon resulting from electron-transfer from the carbene center play a cooperative effect on the versatile reactivity of unsaturated Fischer carbene complexes [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. 2-Pyranylidene metal carbene complexes bearing a pyran ring carbene ligand are a special kind of unsaturated Fischer carbene complex, that has received much less attention probably because of their limitation of the synthetic methodology.…”

Organometallic chemistry of bi- and poly-metallic complexes

“…66 The photochemical reaction between [(Z 5 -C 5 H 5 )Fe(CO) 2 -SiMe 3 ] and (Me 3 Si) 2 NSiH 3 gave the unprecedented complexes [(Z 5 67 The thermolytic reactions of cyclooctatetraene-(COT) and 7H-indene-coordinated diiron bridging carbene complexes have been investigated and found to be greatly influenced by the different cycloolefin and bridging carbene units. 68 A new route to the m-vinyliminium complexes (15) involving alkyne-isocyanide coupling in [(Z 5 -C 5 H 5 ) 2 Fe 2 (CNMe)(CO) 3 {m-CQN(Me)R}] has been developed. The reactivity of the m-vinyliminium species towards unsaturated hydrocarbons and diazoalkanes has been investigated and found to involve facile addition to the nitrogen atom of the bridging ligand.…”