Wolf W. Du Mont

Di(phosphavinyl) ethers (2,4-diphospha-3-oxapentadienes)

Hydrolytic cleavage of the P-chlorophosphaalkenes (RMe2Si)2C=PCl (R = Me: 1a; R = iPr: 1b) in the presence of triethylamine leads to di(phosphavinyl) ethers (2,4-diphospha-3-oxapentadienes) [(RMe2Si)2C=P]2O (2a, 2b) as main products, accompanied by alkylphosphinic acids (RMe2Si)2(H)CP(H)(O)OH (3a, 3b). The hydrolysis of (PhMe2Si)2C=PCl (1c) proceeds less selectively. Reactions with metal oxides under aprotic conditions provide 2a [impure, from 1a with (nBu3Sn)2O] and 2b [from iodophosphaalkene (iPrMe2Si)2C=PI with Ag2O] as oils. 1H, 13C, 29Si and 31P NMR spectra, however, allow unambiguous characterisation of 2a and 2b. Formation mechanisms, structure, and C=P-O π stabilisation of the oxabisphosphaalkene [(H3Si)2C=P]2O (2ʹ) were studied with DFT methods. The double [2+4] cycloaddition reaction of 2a with two equivalents of cyclopentadiene leads to the phosphinous anhydride 7 as a mixture of diastereomers whereas the addition of two equivalents of tetrachloro-o-benzoquinone proceeds in a diastereoselective fashion. An X-ray crystal structure determination of the resulting oxo-bridged bis(2-phospha-2,5-dioxa-3,4-benzophospholene) derivative 8 revealed the presence of a racemic mixture of (R,R)- and (S,S)-configurated molecules. The solid state structure of a by-product, bisylphosphonic tetrachlorocatechol monoester (Me3Si)2CH-P(=O)(OH)-o-OC6Cl4OH 9, was also determined crystallographically. Graphical Abstract Di(phosphavinyl) Ethers (2,4-Diphospha-3-oxapentadienes)

Approaching P -Indoxyle, P -Indigo and P -Vinylchalcogenides

A great challenge in the chemistry of π -conjugated organophosphorus compounds and dyestuffs remains the preparation of phosphoindigo, in which the nitrogen atoms of indigo are replaced by phosphorus. Indolerelated benzophosphole (phosphindole) derivatives are well known, but only scattered information is available on their 3-oxo derivatives,1 which would be related to precursors of indigo or thioindigo. On the way to phosphoindigo, we studied a number of reactions to find suitable reagents and conditions for the oxidative coupling of known 1-ethoxy1-oxophosphindoline-3-one (1)1,2 or new phosphindoline-3-one (2) [ phosphoindoxyle] leading to the first 1,1′-diphosphaindigo derivatives.

Phosphine Selenide Arenetellenyliodide Complexes and Telluroselenophosphonium Salts

Trialkylphosphine selenides tBu n iPr3− n PSe (n = 3, 2, 1, 0) and bidentate phosphine selenides (dppmSe2, dppeSe2) react with arenetellurenyl iodides (RTeI) furnishing complexes tBu n iPr3− n PSeTe(R)I (R = p-tolyl, p-anisyl, mesityl [Mes]), dppm[SeTe(Mes)I]2 and dppe[SeTe(Mes)I]2 that contain Se-Te(R)-I moieties (10-Te-3). Dppe[SeTe(Mes)I]2 exhibits supramolecular soft-soft interactions by “T-stacking” of the Se-Te(R)-I functions in the solid. When trialkylphosphine selenides tBu n iPr3− n PSe react with two equivalents of RTeI, novel trialkyl(aryltelluroseleno)phosphonium diiodotellurate(II) salts are formed. In solid [(tBu2iPrPSeTe-p-Tol)+(p-TolTeI2)−] the Te atom from the (p-TolTeI2)−anion behaves as soft donor towards the formally uncharged Te atom in the cation (tBu2iPrPSeTe-p-Tol)+exhibiting a novel type of Te…Te anion → cation donor-acceptor interaction (Te…Te 318 pm). Loss of mesityl groups in course of reactions with MesTeI led to a unique iodotelluroselenophosphonium salt {[(iPr3PSeTeI)+]2(TeI6)2−} with chelating cation-anion Te II …I-Te IV contacts, to the six-membered chelate complex dppmSe2TeI2 with a square planar cis-Se2TeI2 group, and to dppeSe2TeI2 with trans-Se2TeI2 groups in a helical chain structure.

Trichlorosilylation of Trialkylgermanium and -Tin Moieties to Unexpected Heteroneopentanes

Reactions of chlorogermanes and chlorostannanes with trichlorosilane / triethylamine and reactions of germyl- and stannylphosphanes with hexachlorodisilane lead to new compounds with Ge-Si and Sn-Si bonds, among them unexpected novel heteroneopentanes (R3M)2Si(SiCl3) (M = Ge, Sn; R = alkyl). Reaction sequences leading to these highly branched trialkylgermyl- or stannyloligosilanes were followed by heteronuclear n.m.r. spectroscopy.

Structures of Arylselenenyl Iodides: The Role of Aryl Stacking and “Soft-Soft” SE⋯I and I⋯I Interactions

The influence of packing effects and Se...I / I...I interactions on the stability of Iodoselanes are discussed.