Synthesis, NMR, and X-ray Molecular Structure of a Butadienesulfinate Iridium Dimer and Its Transformation into a Mononuclear Cp*IrCl[(1,2,5-η)-SO₂CHCRCHCHR] Complex

Abstract

A metathesis reaction of [Cp*IrCl2]2 with butadienesulfinate lithium (SO2CHCRCHCHR)Li (R = H, 1Li; Me, 2Li) affords the dinuclear compounds [Cp*Ir(Cl)2{(5-η)-SO2CHCRCHCHR}(Li)(THF)]2 (R = H, 3; Me, 4), respectively. The single-crystal X-ray analysis of 3 and 4 reveals the presence of metallacyclic, five- and eight-membered rings, which easily break to afford compounds Cp*IrCl[(1,2,5-η)-SO2CHCRCHCHR] [R = H, (5), Me (6)], upon displacement of THF and LiCl. The 1H and 13C NMR data are consistent with the single-crystal X-ray diffraction structures of 3 and 4. Compounds 5 and 6 showed that the butadienesulfonyl ligands are coordinated through the sulfur atoms and the terminal double bonds, according to the X-ray study of compound 5 and NMR spectroscopy. Immediate formation of compound 5 can be achieved in 83% yield from [Cp*IrCl2]2 and 1K, showing that the alkaline metal is crucial in the isolation of the lithium derivatives 3 and 4.

Chemistry of Iridium(I) Cyclooctadiene Compounds with Thiapentadienyl, Sulfinylpentadienyl, and Butadienesulfonyl Ligands

“…There was a preferred coordination mode in the chemistry of the adducts 14−19, where the butadienesulfonyl ligand was coordinated through the sulfur atom η 1 and η 2 with the terminal double bond (C1−C2) to the iridium atom. This type of bonding has been previously observed for several butadienesulfonyl iridium 15,16 and rhodium 16,35 compounds, as well as for thiapentadienyl and sulfinylpentadienyl compounds, vide supra.…”

“…Previous studies show that [Cp*IrCl 2 ] 2 , according to the size of the cation in M[CH 2 CHCHCHSO 2 ] (M = Li, 3Li; M = K, 3K), yields dinuclear [Cp*Ir(Cl) 2 {(5-η-CH 2 CHCHCHSO 2 )}(Li)(THF)] 2 or mononuclear [Cp*IrCl(1-2,5-η-CH 2 CHCHCHSO 2 )] compounds, respectively. 15 A strong dependence of reaction efficiency on the nature of the phosphine has been observed in Cp*IrCl(5-η-CH 2 CHCHCHSO 2 )PR 3 , (R = Me, Ph) from addition reaction of Cp*IrCl[1-2,5-η-CH 2 CHCHCHSO 2 ] with PR 3 (R = Me, Ph) or through the metathesis reaction of Cp*Ir(Cl) 2 PR 3 with the potassium butadienesulfinate. 16 The butadienesulfonyl ligand has shown different coordination modes, chemical versatility, and stability, as observed by its isomerization 16−18 and inter-and intramolecular hydrogen interactions.…”

“…Particularly, only a couple of examples in iridium chemistry have been reported related with the metathesis reaction of [Cp*IrCl 2 ] 2 with butadienesulfinate salts. Previous studies show that [Cp*IrCl 2 ] 2 , according to the size of the cation in M[CH 2 CHCHCHSO 2 ] (M = Li, 3Li ; M = K, 3K ), yields dinuclear [Cp*Ir(Cl) 2 {(5-η-CH 2 CHCHCHSO 2 )}(Li)(THF)] 2 or mononuclear [Cp*IrCl(1-2,5-η-CH 2 CHCHCHSO 2 )] compounds, respectively . A strong dependence of reaction efficiency on the nature of the phosphine has been observed in Cp*IrCl(5-η-CH 2 CHCHCHSO 2 )PR 3 , (R = Me, Ph) from addition reaction of Cp*IrCl[1-2,5-η-CH 2 CHCHCHSO 2 ] with PR 3 (R = Me, Ph) or through the metathesis reaction of Cp*Ir(Cl) 2 PR 3 with the potassium butadienesulfinate …”

A combined experimental and theoretical study of metallic salts of thiapentadienyl, sulfinylpentadienyl and butadienesulfonyls

“…The reactions of 3Li and 9Li with [Cp * IrCl 2 ] 2 have been shown the interesting formation of the dinuclear intermediates [Cp * Ir(Cl) 2 {(5-g)-SO 2 CH@CRCH@CHR} (Li)(THF)] 2 (R = H, Me), while 3K, 9K with [Cp * IrCl 2 ] 2 afford the mononuclear complexes Cp * IrCl[(1,2,5-g)-SO 2 CH@CRCH@CHR] (R = H, Me), which are the first examples with a butadienesulfonyl ligand coordinated to a transition metal [22].…”

Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent

“…However, most commercially available sulfinates are quite expensive. It was reported in the literature that compound 7 may be easily generated from sulfolene by treatment with n -butyllithium [ 35 ]. This compound is further oxidized by DIB in the presence of n -butanol to yield sulfonate 8a in 72% yield.…”