Isolation and Computational Studies of a Series of Terphenyl Substituted Diplumbynes with Ligand Dependent Lead-Lead Multiple-Bonding Character.

A series of formally triply bonded diplumbyne analogues of alkynes of the general formula ArPbPbAr (Ar = terphenyl ligand with different steric properties) was synthesized by two routes. All diplumbyne products were synthesized by a simple reduction of the corresponding Pb(II) halide precursor ArPb(Br) by DIBAL-H with yields in the range 8-48%. For one of the diplumbynes ArPbPbAr (Ar = CH-2,6-(CH-2,6-Pr)) it was shown that reduction of ArPb(Br) using a magnesium(I) beta-diketiminate afforded a much improved yield in comparison (29 vs 8%) to that obtained by reduction with DIBAL-H.

Convenient Preparation and Detailed Analysis of a Series of NHC-Stabilized Phosphorus(I) Dyes and Their Derivatives.

A safe, convenient, and P-atom-efficient synthesis of N-heterocyclic-carbene- (NHC-) stabilized phosphorus(I) bromide salts is reported that involves P(+) transfer from an easily prepared triphosphenium precursor. The resulting family of phosphamethine cyanine dyes featuring N,N'-dialkyl-substituted 4,5-dimethylimidazole-2-ylidenes ((R)NHC(Me)) and benzimidazole-2-ylidenes ((R)NHC(B)) (R = Me, Et, iPr) have been fully characterized. We found that increasing N-alkyl group size causes increased twisting of the carbene fragments from the C-P-C plane, which decreases the magnitude of hyperconjugation between the π-type lone pair on phosphorus and the carbene fragments.

Low-valent chemistry: an alternative approach to phosphorus-containing oligomers.

A convenient preparative approach to low-valent phosphorus-rich oligomers is presented. Ligand substitution reactions involving anionic diphosphine ligands of the form [(PR2)2N](-) and [(PPh2)2C5H3](-) and a triphosphenium bromide P(I) precursor result in the formation of phosphorus(I)-containing heterocycles, several of which are of types that have never been prepared before. The methodology described also allows for the preparation of the known heterocycle cyclo-[P(PPh2)N(PPh2)]2 in better yields and purity than the synthetic approach reported previously.

1,1,1-Tris(di-methyl-amino)-2-[tris-(di-methyl-amino)-phospho-ranyl-idene]diphosphinium tetra-phenyl-borate tetra-hydro-furan monosolvate.

In the tetra-hydro-furan solvate of the title salt, C12H36N6P3 (+)·C24H20B(-)·C4H8O, the cation features short P-P bond lengths [2.1111 (11) and 2.1364 (10) Å] and a distinctly bent P-P-P angle [104.

Aza-Diels-Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome.

The synthesis of 5-substituted 6,6a-dihydroisoindolo[2,1-a]quinolin-11(5H)-ones via [4 + 2] imino-Diels-Alder cyclization from N-aryl-3-hydroxyisoindolinones and N-vinyl lactams under Lewis acid-catalysed anhydrous conditions is reported. Reactions of N-(2-substituted-aryl)-3-hydroxyisoindolinones with N-vinylpyrrolidone under identical conditions resulted in the formation of 2-(2-substitued-aryl)-3-(2-(2-oxopyrrolidin-1-yl)vinyl)isoindolin-1-one analogues indicating steric hinderance as the cause of deviation. The probable mechanism of the reaction based on the results from X-ray crystallography and molecular modelling is discussed.

Synthesis of zwitterionic triphosphenium transition metal complexes: a boron atom makes the difference.

A collection of zwitterionic phosphanide metal carbonyl coordination complexes has been synthesized and fully characterized, representing the first isolated series of metal complexes for the triphosphenium family of compounds. The dicoordinate phosphorus atom of the zwitterion is formally in the +1 oxidation state and can coordinate to one metal, 2M (M = Cr, Mo, W) and 2Fe, or two metals, a Co2(CO)6 fragment 4, depending on the starting reagents. All complexes have been isolated in greater than 80% yield, and structures were confirmed crystallographically.

Synthesis and thermolytic behavior of tin(IV) formates: in search of recyclable metal-hydride systems.

The synthesis and characterization of the series of organotin formates together with their thermolytic behavior are described. The diformate Bu(n)(2)Sn{OC(O)H}(2) (1) was synthesized by the reaction of Bu(n)(2)SnH(2) with formic acid. The triorganotin monoformate compounds R(3)SnOC(O)H (R = Cy (cyclohexyl)) 3, Mes, (mesityl, 2,4,6-trimethylphenyl) 4, and Dmp (2,6-dimethylphenyl 5) were obtained by the reaction of R(3)SnOH with formic acid.

Synthesis and characterization of the M(II) (M = Ge, Sn, or Pb) phosphinidene dimers {M(μ-PAr')}2 (Ar' = C6H3-2,6-(C6H3-2,6-Pr(i)2)2).

Reaction of M{N(SiMe(3))(2)}(2) (M = Ge, Sn, or Pb) with the sterically encumbered primary phosphine Ar'PH(2) (2), Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-Pr(i)(2)), at ca. 200 °C afforded the highly colored phosphinidene dimers {M(μ-PAr')}(2), M = Ge(3), Sn(4), or Pb(5), with disilylamine elimination. The compounds were characterized by single-crystal X-ray crystallography and heteronuclear NMR spectroscopy.

Recycle of tin thiolate compounds relevant to ammonia-borane regeneration.

The use of benzenedithiol as a digestant for ammonia-borane spent fuel has been shown to result in tin thiolate compounds which we demonstrate can be recycled, yielding Bu(3)SnH and ortho-benzenedithiol for reintroduction to the ammonia-borane regeneration scheme.

Reaction of hydrogen or ammonia with unsaturated germanium or tin molecules under ambient conditions: oxidative addition versus arene elimination.

The reactions of hydrogen or ammonia with germylenes and stannylenes were investigated experimentally and theoretically. Treatment of the germylene GeAr(#)(2) (Ar(#) = C(6)H(3)-2,6-(C(6)H(2)-2,4,6-Me(3))(2)) with H(2) or NH(3) afforded the tetravalent products Ar(#)(2)GeH(2) (1) or Ar(#)(2)Ge(H)NH(2) (2) in high yield. The reaction of the more crowded GeAr'(2) (Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-(i)Pr(2))(2)) with NH(3) also afforded a tetravalent amide Ar'(2)Ge(H)NH(2) (3), whereas with H(2) the tetravalent hydride Ar'GeH(3) (4) was obtained with Ar'H elimination.

Reversible reactions of ethylene with distannynes under ambient conditions.

Ethylene's cycloadditions to unsaturated hydrocarbons occupy well-established ground in classical organic chemistry. In contrast, its reactivity toward alkene and alkyne analogs of carbon's heavier-element congeners silicon, germanium, tin, or lead has been little explored. We show here that treatment of the distannynes Ar(iPr4)SnSnAr(iPr4) [Ar(iPr4) = C6H3-2,6(C6H3-2,6-iPr2)2, 1] or Ar(iPr8)SnSnAr(iPr8) [Ar(iPr8) = C6H-2,6(C6H2-2,4,6-iPr3)2-3,5-iPr2, 2] with ethylene under ambient conditions affords the cycloadducts Ar(iPr4) Sn(mu2:nu1:n1-C2H4)2Sn Ar(iPr4 (3) or Ar(iPrs) Sn(mu2:nu1:nu1-C2H4)2Sn AriPrs (4) that were structurally and spectroscopically characterized.

Reduction of terphenyl iron(II) or cobalt(II) halides in the presence of trimethylphosphine: an unusual triple dehydrogenation of an alkyl group.

The reduction of {ArFeBr}(2) (Ar = terphenyl) with KC(8) in the presence of excess PMe(3) afforded the Fe(i) complex 3,5-Pr(i)(2)-Ar'Fe(PMe(3)) (1) (Ar'-3,5-Pr(i)(2) = C(6)H-2,6-(C(6)H(3)-2,6-Pr(i)(2))-3,5-Pr(i)(2)), which has a structure very different from the previously reported, linear Cr(i) species 3,5-Pr(i)(2)-Ar*Cr(PMe(3)) (3,5-Pr(i)(2)-Ar* = C(6)H-2,6-(C(6)H(2)-2,4,6-Pr(i)(3))(2)-3,5-Pr(i)(2)) and features a strong Fe-eta(6)-aryl interaction with the flanking aryl ring of the terphenyl ligand. In sharp contrast, the reduction of {ArCoCl}(2) (Ar = 3,5-Pr(i)(2)-Ar' and Ar') afforded the allyl complexes Co(eta(3)-{1-(H(2)C)(2)C-C(6)H(3)-2-(C(6)H(2)-2,4-Pr(i)(2)-5-(C(6)H(3)-2,6-Pr(i)(2)))-3-Pr(i)})(PMe(3))(3) (4) and Co(eta(3)-{1-(H(2)C)(2)C-C(6)H(3)-2-(C(6)H(4)-3-(C(6)H(3)-2,6-Pr(i)(2)))-3-Pr(i)})(PMe(3))(3) (5) formed by an unusual triple dehydrogenation of an isopropyl group. It is proposed that the reduction initially generates an intermediate 3,5-Pr(i)(2)-Ar'Co(PMe(3)), which is similar in structure to , followed by 3,5-Pr(i)(2)-Ar'Co(PMe(3)) decomposition to a cobalt hydride intermediate and dehydrogenation of the isopropyl group via remote C-H activation induced by PMe(3) complexation.

Reactions of Ar'CrCrAr' with N2O or N3(1-Ad): complete cleavage of the Cr-Cr quintuple interaction.

Reaction of Ar'CrCrAr' (Ar' = C(6)H(3)-2,6-(C(6)H(3)-2,6-Pr(i)(2))(2)) with heterocumulene reagents N(2)O or N(3)(1-Ad) resulted in Ar'Cr(micro-O)(2)Cr(O)Ar' or Ar'Cr(micro(2):eta(1),eta(3)-N(3)(1-Ad))CrAr' which have no metal-metal bonding.

Synthesis, characterization and real molecule DFT calculations for neutral organogallium(I) aryl dimers and monomers: weakness of gallium-gallium bonds in digallenes and digallynes.

A series of stable aryl gallium(I) terphenyl derivatives was synthesized and characterized spectroscopically, structurally and by density functional calculations. Dimeric structures with trans-bent planar CGaGaC core arrangements were observed for [(GaAr*-4-tBu)(2)] (7, Ar*-4-tBu = C(6)H(2)-2,6(C(6)H(2)-2,4,6-iPr(3))(2)-4-tBu) and [(GaAr*-4-CF(3))(2)] (8, Ar*-4-CF(3) = C(6)H(2)-2,6(C(6)H(2)-2,4,6-iPr(3))(2)-4-CF(3)), whereas monomeric structures featuring one coordinate gallium were observed for the more crowded complexes [:GaAr*-3,5-iPr(2)] (10, Ar*-3,5-iPr(2) = C(6)H-2,6(C(6)H(2)-2,4-6-iPr(3))(2)-3,5-iPr(2)) and [GaAr'-3,5-iPr(2)] (11, Ar'-3,5-iPr(2) = C(6)H-2,6(C(6)H(3)-2,6-iPr(2))(2)-3,5-iPr(2)). Complexes 7 and 8 dissociate to monomers in hydrocarbon solution and their electronic spectra closely resemble those of 10 and 11 as well as those of [Ar'GaGaAr'] (Ar' = C(6)H(3)-2,6(C(6)H(3)-2,6-iPr(3))(2)) and [(GaAr*)(n)] (Ar* = C(6)H(3)-2,6(C(6)H(2)-2,4,6-iPr(3))(2)).

Addition of H2 to distannynes under ambient conditions.

Dihydrogen reacts directly with a range of distannynes at ca. 25 degrees C under one atmosphere pressure to afford symmetric hydrogen bridged or unsymmetric stannylstannane products in high yield.

An arene-stabilized cobalt(I) aryl: reactions with CO and NO.

The half-sandwich cobalt(I) complex (eta (6)-C 7H 8)CoAr*-3,5- ( i )Pr 2 (Ar*-3,5- ( i )Pr 2 = -C 6H-2,6-(C 6H 2-2,4,6- ( i )Pr 3) 2-3,5- ( i )Pr 2) was synthesized by reduction of [3,5- ( i )Pr 2Ar*Co(mu-Cl)] 2 in toluene. It reacts with CO or NO to afford the unusual complexes [3,5- ( i )Pr 2Ar*C(O)Co(CO)] or [3,5- ( i )Pr 2Ar*N(NO)OCo(NO) 2].

Diarylstannylene activation of hydrogen or ammonia with arene elimination.

Treatment of the stannylenes SnAr'2 (Ar' = C6H3-2,6(C6H3-2,6-Pri2)2), SnAr2# (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2, or Sn{N(SiMe3)2}2 with H2, D2, or NH3 under identical, mild (1 atm, 65 degrees C) conditions showed that SnAr2' reacted readily to afford the products {Ar'Sn(mu-H)}2, {Ar'Sn(mu-D)}2, or {Ar'Sn(mu-NH2)}2 with elimination of Ar'H or Ar'D. The less crowded stannylenes SnAr2# and Sn{N(SiMe3)2}2 were recovered unreacted. The differences in reactivity were accounted for in terms of the n-p energy separations which is lowest in the case of AnAr2'.

Univalent transition metal complexes of arenes stabilized by a bulky terphenyl ligand: differences in the stability of Cr(I), Mn(I) or Fe(I) complexes.

Two univalent transition metal complexes, (micro-eta6:eta6-C7H8){MnAr*-3,5-Pri2}2 () and (eta6-C6H6)FeAr*-3,5-Pri2 () (Ar*-3,5-Pri2=C6H-2,6-(C6H(2)-2,4,6-Pri3)(2)-3,5-Pri2), that have eta6 arene coordination were synthesized by reduction of the corresponding metal halides. The complexes are thermally stable in contrast to the corresponding Cri complexes of benzene or toluene which decompose at room temperature.

Solid-state (63)Cu and (65)Cu NMR spectroscopy of inorganic and organometallic copper(I) complexes.

Solid-state 63Cu and 65Cu NMR experiments have been conducted on a series of inorganic and organometallic copper(I) complexes possessing a variety of spherically asymmetric two-, three-, and four-coordinate Cu coordination environments. Variations in structure and symmetry, and corresponding changes in the electric field gradient (EFG) tensors, yield 63/65Cu quadrupolar coupling constants (CQ) ranging from 22.0 to 71.

Phosphorus(I) iodide: a versatile metathesis reagent for the synthesis of low oxidation state phosphorus compounds.

An improved method for the synthesis of cyclic low oxidation state P cations is presented. The only byproducts of the reaction of phosphorus triiodide with chelating phosphines are readily removed, resulting in an easily accessible P(I) reagent with an anion that can be readily replaced through salt metathesis chemistry. These P(I) salts are surprisingly stable, even in O2 and moisture, and the origin of this unusual stability is elucidated using density functional theory calculations.

The synthesis, characterisation and electronic structure of N-heterocyclic carbene adducts of P(I) cations.

Two different syntheses of N-heterocyclic carbene complexes of P(I) cations are presented; the structural features of these phosphamethine cyanine salts, in conjunction with the results of computational investigations, provide insight into the nature of the bonding of these heavy allene analogues.

Computational insights into the acceptor chemistry of phosphenium cations.

Phosphines are traditionally considered as Lewis bases or ligands in transition metal and main group complexes. Despite their electron-rich (lone pair-bearing) nature, an extensive coordination chemistry for Lewis acidic phosphorus centers is being developed; such chemistry provides a new synthetic approach for phosphorus-element bond formation, leading to new types of structures and modes of bonding. Complexes of Ph2P+ with a variety of donor elements (P, N, C) give experimentally short donor-acceptor bond lengths, when compared to other cationic phosphorus Lewis acid complexes.

Stabilized arsenic(i) iodide: a ready source of arsenic iodide fragments and a useful reagent for the generation of clusters.

The new stable low oxidation state arsenic(I) iodide reagent [(dppe)As][I] (dppe = 1,2-bis(diphenylphosphino)ethane) exhibits chemistry that is considerably different from its AsIII analogues. While [(dppe)As][I] is not crystalline, the crystal structure of the derivative salt [(dppe)As][(dppe)As2I7] is reported and is compared to that of [(dppe)As]2[SnCl6] x 2CH2Cl2. The air oxidation of [(dppe)As][I] produces crystals of the salt [Ph2P(O)CH2CH2P(OH)Ph2]2[As6I8] x 2CH2Cl2 and suggests that, in contrast to previous studies, the reaction of the univalent arsenic iodide salt with certain oxidants results in the oxidation of the dppe ligand and the release of "AsI-I" fragments that oligomerize to form AsI clusters.

Indium(I) trifluoromethanesulfonate and other soluble salts for univalent indium chemistry.

Herein we report the synthesis, structure and preliminary reactivity studies of a series of unusually soluble indium(i) salts that are improved alternatives to indium(i) halide reagents.