Unprecedented Zwitterionic Iminium−Chalcogenide Bridging Ligands in Diiron Complexes

Abstract

The diiron vinyliminium complexes [Fe2{μ-η1:η3-C(R‘)CHCN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] [R = Xyl, R‘ = Me, 1a; R = Xyl, R‘ = Tol, 1b; R = Xyl, R‘ = CO2Me, 1c; R = Xyl, R‘ = CH2OH, 1d; R = Xyl, R‘ = Bun, 1e; R = Me, R‘ = Me, 1f; R = Me, R‘ = Tol, 1g; R = Me, R‘ = CO2Me, 1h; R = Me, R‘ = Bun, 1i; R = Me, R‘ = CH2OH, 1l; R = p-C6H4-CN, R‘ = Tol, 1m; R = p-C6H4-OMe, R‘ = Me, 1n; Tol = 4-C6H4-Me; Xyl = 2,6-Me2C6H3] react with elemental sulfur or selenium, in the presence of NaH, to give the zwitterionic vinyliminium compounds [Fe2{μ-η1:η3-C(R‘)C(E)CN(Me)(R)}(μ-CO)(CO)(Cp)2] [R = Xyl, R‘ = Me, E = S, 2a; R = Xyl, R‘ = Tol, E = S, 2b; R = Xyl, R‘ = CO2Me, E = S, 2c; R = Xyl, R‘ = CH2OH, E = S, 2d; R = Xyl, R‘ = Bun, E = S, 2e; R = Xyl, R‘ = Me, E = Se, 3a; R = Xyl, R‘ = Tol, E = Se, 3b; R = Me, R‘ = Me, E = Se, 3c; R = Me, R‘ = Tol, E = Se, 3d; R = Me, R‘ = CO2Me, E = Se, 3e; R = Me, R‘ = Bun, E = Se, 3f; R = Me, R‘ = CH2OH, E = Se, 3g]. Similarly, the reaction of 1a with Me3NO/NaH results in the formation of [Fe2{μ-C(Me)C(O)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (4), in which the bridging ligand is better described as a bis-alkylidene. The reactions of 1a,c with S8/NaH afford also the five-membered metallacycles [Fe(Cp)(CO){Cα(NMe(Xyl))Cβ(H)Cγ(R‘)S}] [R‘ = Me, 6a; R‘ = CO2Me, 6b], as secondary products, in about 15% yield. Conversely, complexes [Fe2{μ-η1:η3-C(R‘)CHCN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3], 1f−h,m,n, react with S8/NaH, giving selectively the five-membered metallacycles [Fe(Cp)(CO){C(R‘)C(H)C{N(Me)(R)}S}] [R = Me, R‘ = Me, 7a; R = Me, R‘ = Tol, 7b; R = Me, R‘ = CO2Me, 7c; R = p−C6H4−CN, R‘ = Tol, 7d; R = p-C6H4-OMe, R‘ = Me, 7e]. The molecular structures of 2b·CH2Cl2, 3a, 4, 6a, and 7b have been determined by X-ray diffraction studies.

Coupling of Allenes with μ‐Alkylidyne Ligands in Diiron Complexes: Synthesis of Novel Bridging Thio‐ and Aminobutadienylidene Complexes

“…The peculiar character of the bridging C 3 ligands formed in these assembly reactions is due to the pres- Scheme 1. ence of heteroatoms (N or S) derived from the amino-and thiocarbyne precursors, which exert a relevant influence on the properties and reactivity of the complexes. [12] Scheme 2.…”

Bridging Vinyliminium‐ and Enaminoalkylidenediiron Complexes as Organometallic Ligands

“…[26] All reagents were commercial products (Aldrich) of the highest purity available and were used as received. Compounds 2a [8] and 3a-d [9] were prepared by published methods. Complexes 5b-d were obtained by the same procedure described for 5a, by treating 3b (150 mg), 3c (120 mg), and 3d (150 mg), respectively, with NaBH 4 .…”

“…[7] Our interest in the field of organometallic complexes containing highly functionalized ligands has been focused on the chemistry of bridging vinyliminiumdiiron complexes 1 [8] and on the transformations which can be performed on the bridging ligand (Scheme 1). These include functionalization with sulfur and thiolates (Scheme 1, complexes 2 [9] and 3 [10] ). In particular, zwitterionic complexes of type 2 contain an S functionality which is potentially able to coordinate unsaturated metal fragments, as evidenced by coordination of the Fp + group [Fp = Fe(CO) 2 Cp] [11] to form the trinuclear compound 4 (Scheme 1).…”

C–H Activation in Diiron Bridging Vinyliminium Ligands: Reaction with CS2 to Form New Zwitterionic Complexes Acting as Organometallic Ligands

“…Examples of both possibilities are shown in Scheme 1: reactions with aryl isocyanides (CNR) [6] or diazoacetates [7] lead to bis-alkylidene complexes (V and VII, respectively) bearing a double bond at C 2 . On the other hand, intermediates can be oxidized by treatment with S 8 [8] or PhSSPh [9] to afford vinyliminium complexes (VI and IV, respectively) with a C 2 -S single bond. In the light of these results and with the aim of finding new possibilities for forming C-C bonds at the bridging frame, we have extended our investigations to C-H activation in the presence of heteroallenes (CS 2 , CSNR).…”