Studies on the Properties of Organoselenium(IV) Fluorides and Azides

Abstract

The reaction of organoselenides and -diselenides (R2Se and (RSe)2) with XeF2 furnished the corresponding organoselenium(IV) difluorides R2SeF2 (R=Me (1), Et (2), iPr (3), Ph (4), Mes (=2,4,6-(Me)3C6H2) (5), Tipp (=2,4,6-(iPr)3C6H2) (6), 2-Me 2NCH2C6H4 (7)), and trifluorides RSeF3 (R=Me (8), iPr (9), Ph (10), Mes (11), Tipp (12), Mes* (=2,4,6-(tBu) 3C6H2) (13), 2-Me2NCH2C6H4 (14)), respectively. In addition to characterization by multinuclear NMR spectroscopy, the first molecular structure of an organoselenium(IV) difluoride as well as the molecular structures of subsequent decomposition products have been determined. The substitution of fluorine atoms with Me3SiN3 leads to the corresponding organoselenium(IV) diazides R2Se(N3)2 (R=Me (15), Et (16), iPr (17), Ph (18), Mes (19), 2-Me 2NCH2C6H4 (20)) and triazides RSe(N3)3 (R=Me (21), iPr (22), Ph (23), Mes (24), Tipp (25), Mes* (26), 2-Me2NCH2C6H4 (27)), respectively. The organoselenium azides are extremely temperature-sensitive materials and can only be handled at low temperatures.

Structural isomerism in (p-XC6H4)SeCl3 and (p-XC6H4)SeBr3 (X = F, Cl) compounds. Co-crystallisation of cis- and trans-dimeric forms of (p-ClC6H4)SeCl2(μ-Cl)2(p-ClC6H4)SeCl2. A new structural modification for the “PhSeBr” reagent, Ph2Se2Br2, containing an elongated Se–Se bond

“…This results in the shorter terminal Se-X bond being trans to the longer bridging Se-X bond, and vice versa. This type of trans-effect has long been established for main group halogen compounds, 31,32 and is particularly 5 pronounced for bridged systems where a lone pair is present, as is the case for selenium(IV) halide species. The structures are thus closely related to anionic systems such as [Se 2 X 10 ] 2-(X = Cl, Br).…”

“…35 RSeF compounds are highly unstable with respect to disproportionation to RSeF 3 and R 2 Se 2 , 4 and reactions of R 2 Se 2 with fluorinating agents such as XeF 2 usually result in the exclusive formation of RSeF 3 compounds. 4,5 Whilst both RSeX and RSeX 3 species can usually be formed when X = Cl and Br, 40 there are no reports of RSeI 3 compounds. Reactions of R 2 Se 2 with I 2 usually leads to products with an "RSeI" stoichiometry, although examples containing genuine covalent selenium-iodine bonds are rare.…”

“…A small number of RSeCl 3 compounds have been 5 structurally characterised and again show variations. The structure of PhSeCl 3 is polymeric, and consists of individual "saw-horse" shaped PhSeCl 3 units linked into a chain polymer by bridging chlorines, the overall geometry at selenium being square pyramidal, see Fig.…”

A Structural Comparison of Organoterminated Selenide, Diselenide, and Triselenide

“…The H atoms are drawn with arbitrary radii. (6) 1.893 (7) C(11)-Se(1)-Se (2) 99.08 (19) 98.9 (2) Se(1)-Se(2)-Se (3) 100.06 (4) 100.68 (4) C(31)-Se(3)-Se (2) 98.9 (2) 99.0 (23) C(11)-Se(1)-Se(2)-Se (3) 73.6 (2) 75.3 (2) Se(1)-Se(2)-Se(3)-C(31) −74.0 (2) −72.7 (2) triselenane-unit approach ±74 • ( Table 1). These geometric parameters are slightly different compared to open chain triselenanes 11 but quite similar to those obtained for the orthorhombic modification (1 ort ) of the same compound (Table 1).…”

Isolation of tetraphenylselenurane

“…According to its spectral data, it is identical to the material described before, where it has been prepared by fluorination of (C 6 H 5 ) 2 SeCl 2 [7]or (C 6 H 5 ) 2 Se [8] with XeF 2 .…”