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This study reports on the exploration of the phosphinoboration reaction with several thiosemicarbazones ([R.sup.5][R.sup.4]NC(S)N[R.sup.3]N=C[R.sup.1][R.sup.2]). Reactions between either [Ph.sub.2]PBpin (pin =1,2-[O.sup.2][C.sup.2][Me.sup.4]) or [Ph.sup.2]PBcat (cat =1,2-[O.sup.2][C.sup.6][H.sup.4]) with thiosemi-carbazones containing a terminal primary or secondary amine afforded boron-containing heterocyclic 1,3,4-thiadiazoline products in excellent yield. The addition of [Ph.sub.2]PBpin to thiosemicarbazones containing an [NMe.sub.2] group in the terminal position generated novel five-membered heterocycles in moderate yield, which included boron, sulfur, and nitrogen atoms. Heterocy-clization of the thiosemicarbazones occurs preferentially in the presence of functional groups such as acetyl and pyridyl groups. Key words: boron, borylation, phosphinoboration, 1,3,4-thiadiazoline, thiosemicarbazone, Introduction Historically, the reactivity of B--E-containing reagents has concentrated on hydroboration (E = H), (1-4) diboration (E = B), (5-7) and silylboration (E = Si (8-10) reactions, while the chemistry [...]

A series of germanium(II) and tin(II) bromide polyether complexes have been synthesized. Specifically, [GeBr([15]crown-5)] [Ge[Br.sub.3]], [GeBr([18]crown-6)][Ge[Br.sub.3]], [GeBr(triglyme)][Ge[Br.sub.3]], [GeBr(tetraglyme)][Ge[Br.sub.3]], [SnBr([18]crown-6)][Sn[Br.sub.3]], [Sn[([15]crown-5).sub.2]][Sn[[Br.sub.3]].sub.2], [SnBr(triglyme)][Sn[Br.sub.3]], and [SnBr(tetraglyme)][Sn[Br.sub.3]] have been fully characterized including by single crystal X-ray diffraction. The synthesis of [GeBr(dibenzo[24]crown-8)][Ge[Br.sub.3]] and [GeCl(dibenzo[24]crown-8)][Ge[Cl.sub.3]] are also reported, along with the crystal structure of the latter's water adduct, which features a water molecule adjacent to the Ge[Cl.sup.+] ion within the cavity of the crown ether. Key words: main group, polyether, crown ether, germanium and tin halides, group 14. Nous avons synthétisé une série de complexes de bromure de germanium(II) et d'étain(II) à base de polyéthers. En particulier, le [GeBit[15]couronne-5)][Ge[Br.sub.3]], le [GeBr([18]couronne-6)][Ge[Br.sub.3]], [GeBr(triglyme)][Ge[Br.sub.3]], le [GeBr(tétraglyme)][Ge[Br.sub.3]], le [SnBr([18]couronne-6)][Sn[Br.sub.3]], le [Sn([15]couronne-5)2][Sn[[Br.sub.3]].sub.2], le [SnBr(triglyme)][Sn[Br.sub.3]] et le [SnBr(tétraglyme)][Sn[Br.sub.3]] ont été soumis à une caractérisation complète, dont la diffraction des rayons X sur monocristal. Nous décrivons également la synthèse du [GeBr(dibenzo[24]couronne-8)][Ge[Br.sub.3]] et du [GeCl(dibenzo[24]couronne-8)][Ge[Cl.sub.3]], ainsi que la structure cristalline du dernier sous forme de produit d'addition avec l'eau, lequel présente une molécule d'eau adjacente à l'ion Ge[Cl.sup.+] à l'intérieur de la cavité de l'éther couronne. [Traduit par la Rédaction] Mots-clés: groupe principal, polyéther, éther couronne, halogénures de germanium et d'étain, groupe 14., Introduction The chemistry involving group 14 cations and polyether ligands has been an area of great interest over the last decade. (1) The complexation of lead(II) ions by macrocyclic polyethers [...]

Treatment of two equivalents of the triphosphenium zwitterion L with sources of Ni0 and Pd0 form the mononuclear η2‐diphosphoniodiphosphene complexes 1 and 2. The reaction between L and [FeCp(CO)2]2 results in the binuclear μ‐η1:η1‐diphosphoniodiphosphene iron complex 3, which features an alternative bonding motif of the diphosphoniodiphosphene unit. The formation of these species has been confirmed by spectroscopic methods and single‐crystal X‐ray diffraction analysis, and their electronic structures have been elucidated using computational methods. A diphosphoniodiphosphene is unexpectedly formed by insertion of Ni0, Pd0, and FeI into the P−P bonds of a triphosphenium zwitterion, giving rise to structurally confirmed μ2‐bound monometallic or μ‐η1:η1‐bimetallic species. [ABSTRACT FROM AUTHOR]

Conformationally flexible cores that generate large free volume when stacked and have an insufficient number of side-chains for filling the lateral space around each core have been proposed as design criteria for discotic liquid crystals that display nematic rather than columnar mesophases. Presented here are 1,3,5-triazines substituted with three thiophene carboxylate ester groups that fulfil these design criteria. Nine derivatives with linear, branched, and chiral ester chains were synthesised and their mesomorphism was studied by polarised optical microscopy, differential scanning calorimetry, and powder x-ray diffraction. Triazines with linear propyl to octyl chains display monotropic nematic discotic mesophases that crystallise within hours or days or when mechanically agitated. Packing structures for the nematic phases are proposed based on the single crystal structure of the ethyl ester. Their unusually slow nucleation and crystal growth can be attributed to the large number of possible low energy conformations that arise from the conformationally flexible core. Incorporation of racemic and chiral branched chains expectedly lowers the melting points of these derivatives but, unexpectedly, enhances nucleation and crystal growth well above the temperature ranges of their hypothetical nematic phases. Chiral nematic discotic mesophases were obtained for binary mixtures of derivatives with chiral branched and linear chains. [ABSTRACT FROM AUTHOR]

A convenient synthesis of dicyanophosphide and dicyanoarsenide anions is reported. These heavy homologues of the long-known and fundamentally important dicyanamide anion were formed through the nucleophilic displacement of bis(diphenylphosphino)ethane (dppe) from the pnictogen + transfer agents [dppePn][BPh 4 ] (Pn=P, As) by exposure to cyanide salts. The protocol requires three synthetic steps from commercially available materials and the [dppePn][BPh 4 ] salts are remarkably temperature, air, and moisture stable. All products have been fully characterized by spectroscopic methods and by single-crystal X-ray diffraction, and the electronic structures of the DCPn anions have been assessed computationally., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Reported are general synthetic approaches for the syntheses of asymmetrically substituted phosphorus(I) cations by P + transfer from [dppeP] + (dppe = 1,2-bis(diphenylphosphino)ethane). The first method grants access to acyclic derivatives and is accomplished by the sequential substitution of dppe using first a sterically encumbered ligand which cannot form a stable homoleptic complex, followed by a second equivalent of a less sterically demanding ligand. The second method grants access to cyclic derivatives and utilizes asymmetric hybrid phosphine/N-heterocyclic carbene ligands. Interplay between the different ligand types and their stoichiometries relative to those of [dppeP] + also allows for the isolation of symmetrical derivatives with pendant phosphines.

The isolation and full characterisation of a series of cationic metal-carbonyl complexes bearing an N-heterocyclic carbene stabilised phosphorus(I) ligand are reported. Specifically, the mononuclear coordination complexes [LM(CO) 5 ][BPh 4 ] (M=Cr, Mo, W), [LFe(CO) 4 ][BPh 4 ] and the dinuclear complexes [LMn 2 (CO) 8 ][BPh 4 ] and [LCo 2 (CO) 6 ][BPh 4 ], in which L=[bis(1,3,4,5-tetramethylimidazol-2-ylidene)phosphanide] + , have all been isolated in the solid state and structurally confirmed by single-crystal X-ray diffraction. The dicationic platinum complex trans-[L 2 PtCl 2 ][BPh 4 ] 2 is also reported and fully characterised. The donor ability of [L] + has been assessed by IR spectroscopy of its metal-carbonyl complexes and by using DFT calculations. The results suggest that [L] + is a weak π-acceptor with moderate donor strength and thus it bridges the gap that exists between phosphines and amines in terms of ligand properties. Collectively, these molecules represent the first crystallographically characterised cationic metal-carbonyl derivatives of a P I -centred ligand and are a rare collection of cationic metal-carbonyl complexes., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)