Synthesis and Reactivity of Selones and Dihaloselones: Complexation of Selones with d⁸‐ and d¹⁰‐Metal Ions

Abstract

The reactivities of the monodentate selone LSe (L = 1,3-dibutylbenzimidazol-2-ylidene; 10a), the bidentate pyridine-functionalized selone L′Se (L′ = 1-pyridyl-3-butylimidazol-2ylidene; 10b) and the multidentate ether-functionalized selone L′′Se {L′′ = 1,3-bis[2-(2-methoxyethoxy)ethyl]benzimidazol-2-ylidene; 10c} with soft transition-metal halides (PdX 2 , PtX 2 , ZnX 2 , CdX 2 and HgX 2 ; X = Cl, Br, I) are probed. Compounds 10a and 10c react with metal halides to give complexes of the type [Cu 2 (μ-X) 2 (LSe) 2 ] (X = Br, I; 11, 12), [MX 2 (LSe) 2 ] (13-22) or [M 2 X 2 (μ-X) 2 (L′′Se) 2 ] (X = Cl, Br, I; 26-32), whereas 10b and HgX 2 (X = Cl, Br, I) form 1:1 complexes HgX 2 (L′Se) (21-23), in which the pyridine moiety coordinates to the metal centre to form a [a] 2968 Scheme 2. Synthesis and reactivity of mono-, bi-and multidentate selone ligands (10a-10c).Compounds 8a and 8c were prepared in ca. 80 % yield through the N-alkylation reactions of benzimidazole (6) with n-butyl bromide (7a) and 1-bromo-2-(2′-methoxyethoxy)ethane (7c), respectively, in 30 % NaOH in the presence of a phase-transfer catalyst (tetrabutylammonium bromide, TBAB; Scheme 2) [7] Compounds 8a and 8c were purified by column chromatography (petroleum ether/ethyl acetate, 3:1) and characterized by NMR spectroscopic techniques. Compound 8b was prepared by the reported procedure. [17] Compounds 8a-8c were heated under reflux with alkyl bromides (7a-7c) in dry 1,4-dioxane under nitrogen for 12 h to produce white precipitates of the 1,3dialkylbenzimidazolium salts 9a-9c in yields of ca. 90 % (Scheme 2). [7,16] Compounds 9a-9c were collected by filtration, Eur.Compound 27: The reagents used were selone 10c (0.15 g, 0.37 mmol) and zinc chloride (0.05 g, 0.37 mmol). Yield: 0.21 g, (68 %). UV/Vis (CH 3 CN, 0.1 mmol dm -1 ): λ max = 263, 311, 321 nm. 1 H NMR (400 MHz, CDCl 3 ): δ = 7.54 (d, 4 H), 7.31 (d, 4 H), 4.71 (t,

Bis(selone) Complexes of Palladium(II), Platinum(II), and Gold(III): Synthesis and Structural Studies

“…The chemical shift of 17 is downfield of that of the bis(selone)-palladium(II) complex 13 (δ = 43 ppm) and the 5,6-membered C,C,Se-palladium(II) pincer complex 14 (δ = 98 ppm). [1d] The 77 Se NMR signal for 18 is slightly downfield of the signals for the platinum-selone adduct PtCl 2 (LSe) 2 (L = 1,3-dibutylbenzimidazol-2-ylidene) (δ = 121 ppm) [13] and [Pt(N-ethylimidazolidine-2-selone) 4 ]Cl 2 (δ = 61 ppm). [12] Complex 18 is sparingly soluble in common organic solvents.…”

“…Solvents (dichloromethane, methanol, and 1,4-dioxane) were dried as per standard methods. [23] The 1 H NMR (400 MHz, 500 MHz), 13 as the external standard for 77 Se NMR spectroscopy. The elemental analyses were carried out with a Carlo Erba Model 1106 elemental analyzer.…”

“…[12] Very recently, our group reported the platinum-selone adduct PtCl 2 (LSe) 2 azol-2-ylidene), formed by the reaction of monodentate selone with PtCl 2 . [13] In the present work, the possibility of the formation of a 7,7-membered palladium(II) pincer complex 16 by C-Br activation of 3,3′-[(2-bromo-1,3-phenylene)bis(methylene)]bis(1-mesityl-1,3-dihydro-2H-imidazole-2-selone) has been attempted (Scheme 1).…”

“…, 12 H, 13-H) ppm 13. C NMR (125 MHz, [D 6 ]DMSO): δ = 144.0, 139.7, 135.3, 134.6, 133.1, 129.2, 128.5, 128.4, 123.9, 123.5, 123.0, 53.8, 20.7, 17.6 ppm.…”

Luminescent zinc(ii) selone macrocyclic ring

“…Though the coordination chemistry of Zn(II)-IMSe is well established by Singh et al, 10,11 the potential of these Zn(II)-IMSe derivatives are yet to explore. 4,9 Continuing our interest in the related area, 9 herein we report a simple strategy to isolate the luminescent Zn(II)-IMSe derived from chromophore tagged IMSe.…”