Chalcogen-substituted carbenes: a density functional study of structure, stability, and donor ability.

Chalcogen-substituted carbenes are examined computationally using density functional theory. Several approaches are used to assess the stability and reactivity of chalcogenazol-2-ylidene carbenes (NEHCs; E = O, S, Se, Te). The known unsaturated species 1,3-dimethylimidazol-2-ylidene is studied at the same level of theory as the NEHC molecules, as a reference.

Crystal structure and computational study of an oxo-bridged bis-titanium(III) complex.

The solid-state structure of the new compound μ-oxido-bis[dichloridotris(tetrahydrofuran-κO)titanium(III)], [TiClO(CHO)], at 150 K has been determined. The crystal has monoclinic (C2/c) symmetry and the complex features C symmetry about the bridging O atom. Positional disorder is evident in one of the three tetrahydrofuran environments.

A new polymorph of phenylselenium trichloride.

A second polymorph of phenylselenium trichloride, PhSeCl or CHClSe, is disclosed, which is comprised of asymmetric chlorine-bridged noncovalent dimer units rather than polymeric chains. These dimers are each weakly bound to an adjacent dimer through noncovalent Se..

A structural study of 2,4-di-methyl-aniline derivatives.

Crystallographic studies of nitro-gen-containing small mol-ecules aid in the elucidation of their structure-activity relationships and modes of aggregation. In this study, two previously synthesized mol-ecules are crystallographically characterized for the first time. Reaction of 2,4-di-methyl-aniline with -bromo-succinimide affords the -brominated derivative 2-bromo-4,6-di-methyl-aniline (; CHBrN), which sublimates to afford crystals featuring hydrogen-bonded chains as well as Type I halogen-halogen inter-actions.

Diverse silver(i) coordination chemistry with cyclic selenourea ligands.

The coordination chemistry of two selenourea ligands (SeIMes and SeIPr) towards silver(i) triflate and silver(i) nitrate was investigated. Two aggregation modes were observed in the solid state, strongly influenced by the size of the aromatic substituents on the ligand. With mesityl groups, selenium-bridged bimetallic motifs [AgX(SeIMes)] were obtained, while for the bulkier diisopropylphenyl groups ion-separated species of formulae [Ag(SeIPr)][X] were obtained.

A Selenium-Containing Diarylamido Pincer Ligand: Synthesis and Coordination Chemistry with Group 10 Metals.

The synthesis of new bifunctional organoselenium diarylamine compounds RN(4-Me-2-SeMe-C6H3)2 (R = Me: 1; R = tert-butoxycarbonyl (Boc): 2; R = H: 3-H) via aryllithium chemistry is disclosed. Compound 1 serves as a Se,Se-bidentate neutral ligand toward Pd(II), forming the coordination complex {PdCl2[MeN(4-Me-2-SeMe-C6H3)2-κ(2)Se)]} (1-Pd) in reaction with [PdCl2(COD)] (COD = 1,5-cyclooctadiene), while the protio ligand 3-H forms tridentate pincer complexes [MCl(N(4-Me-2-SeMe-C6H3)2)] (M = Pd: 3-Pd; M = Pt: 3-Pt) with [MCl2(COD)] (M = Pd, Pt) in the presence of triethylamine. Complex 1-Pd does not undergo N-C cleavage at high temperature, unlike related alkylphosphine-bearing complexes.

A square-planar tellurium(II) complex with Te,Te'-chelating ligands.

While exploring the chemistry of tellurium-containing dichalcogenidoimidodiphosphinate ligands, the first all-tellurium member of a series of related square-planar E(II)(E')4 complexes (E and E' are group 16 elements), namely bis(P,P,P',P'-tetraphenylditelluridoimidodiphosphinato-κ(2)Te,Te')tellurium(II) (systematic name: 2,2,4,4,8,8,10,10-octaphenyl-1λ(3),5,6λ(4),7λ(3),11-pentatellura-3,9-diaza-2λ(5),4λ(5),8λ(5),10λ(5)-tetraphosphaspiro[5.5]undeca-1,3,7,9-tetraene), C48H40N2P4Te5, was obtained unexpectedly. The formally Te(II) centre is situated on a crystallographic inversion centre and is Te,Te'-chelated to two anionic [(TePPh2)2N](-) ligands in an anti conformation.

Crystal structure of 1-bromo-2-(phenyl-selen-yl)benzene.

In the title compound, C12H9BrSe, the Se atom exhibits a bent geometry, with a C-Se-C bond angle of 99.19 (6)°. The ortho Se and Br atoms are slightly displaced from opposite faces of the mean plane of the benzene ring [by 0.

Secondary diphosphine and diphosphido ligands: synthesis, characterisation and group 1 coordination compounds.

Two types of secondary diphosphines, 1,8-(ArPH)2C14H8 (1a: Ar = Tripp, 2,4,6-triisopropylphenyl; 1b: Ar = Mes, 2,4,6-trimethylphenyl) and 1,3-((t)BuPHCH2)2C6H4 (2), based on rigid 1,8-anthracene and flexible m-xylyl frameworks, respectively, have been synthesized using different strategies. Compounds 1a and 1b were formed by nucleophilic aromatic substitution of a potassium organophosphido salt onto 1,8-difluoroanthracene, while compound 2 was obtained by addition of the Grignard reagent [1,3-(ClMgCH2)2C6H4]x to a dichloroorganophosphine, followed by reduction to the diphosphine. These compounds were isolated as ca.

Thermally stable rare earth dialkyl complexes supported by a novel bis(phosphinimine)pyrrole ligand.

A novel bis(phosphinimine)pyrrole based ligand (HL) and its synthesis are reported. Rare earth dialkyl complexes of the ligand, LLn(CH(2)SiMe(3))(2) (Ln = Er, Lu, Sc), have been prepared and found to exhibit high thermal stability in solution. The protio-ligand and dialkyl lanthanide complexes (Ln = Er, Lu) have been characterised by single crystal X-ray diffraction studies.

Ring-opening polymerisation of rac-lactide mediated by cationic zinc complexes featuring P-stereogenic bisphosphinimine ligands.

The diastereomerically pure P-stereogenic bis(phosphinimine) ligands 4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf [Ar = 4-isopropylphenyl (Pipp): rac-4, meso-4; Ar = 2,6-diisopropylphenyl (Dipp): rac-4a; dbf = dibenzofuran] were synthesised and complexed to zinc using a protonation-alkane elimination strategy. The cationic alkylzinc complexes thus obtained, RZn[4,6-(ArN[double bond, length as m-dash]PMePh)(2)dbf][B(Ar')(4)] [Ar = Pipp, Ar' = C(6)H(3)(CF(3))(2): rac-6 (R = Et), meso-6 (R = Et), rac-7 (R = Me) meso-7 (R = Me); Ar = Dipp: rac-6a (R = Et, Ar' = C(6)H(3)(CF(3))(2)), rac-6b (R = Et, Ar' = C(6)F(5))] were investigated for their competency as initiators for the ring-opening polymerisation of rac-lactide. The formation of polylactide was achieved under relatively mild conditions (40 °C, 2-4 h) and the microstructures of the resulting polymers exhibited a slight heterotactic bias [polymer tacticity (P(r)) = 0.

Toward stereoselective lactide polymerization catalysts: cationic zinc complexes supported by a chiral phosphinimine scaffold.

The P-stereogenic phosphinimine ligands (dbf)MePhP═NAr (7: Ar = Dipp; 8: Ar = Mes; dbf = dibenzofuran, Dipp = 2,6-diisopropylphenyl, Mes = 2,4,6-trimethylphenyl) were synthesized as racemates via reactions of the parent phosphines (rac)-(dbf)MePhP (6) with organoazides. The ligands 7 and 8 were protonated by Brønsted acids to afford the aminophosphonium borate salts [(7)-H][BAr(4)] (9: Ar = C(6)F(5); 11: Ar = Ph) and [(8)-H][BAr(4)] (10: Ar = C(6)F(5); 12: Ar = Ph). The protonated ligands 9 and 10 were active toward alkane elimination reactions with diethylzinc and ethyl-[methyl-(S)-lactate]zinc to give the heteroleptic complexes [{(dbf)MePhP═NAr}ZnR][B(C(6)F(5))(4)] (Ar = Dipp, 13: R = Et; 15: R = methyl-(S)-lactate; Ar = Mes, 14: R = Et; 16: R = methyl-(S)-lactate).

A sulfur(II) complex of a dithioimidodiphosphinate.

The structure of bis[P,P-di-tert-butyl-N-(di-tert-butylphosphorothioyl)phosphinimidothioato-κS]sulfur(II) toluene solvate (systematic name: 5,13-dibutyl-7,7,11,11-tetramethyl-8,9,10-trithia-6,12-diaza-5λ(5),7λ(5),11λ(5),13λ(5)-tetraphosphaheptadeca-6,11-diene-5,13-dithione toluene solvate), C(32)H(72)N(2)P(4)S(5)·C(7)H(8), at 173 K has monoclinic (C2/c) symmetry. The S(II) centre of (SP(t)Bu(2)NP(t)Bu(2)PS-)(2)S is coordinated in an S-monodentate fashion to two [(SP(t)Bu(2))(2)N](-) monoanions. The molecule resides on a twofold axis which bisects the central S atom.

Thallium(I) complexes of dichalcogenido imidodiphosphinates {Tl[(EP(i)Pr(2))(2)N]}(n) (E = Te, Se, S): Synthesis, NMR spectra and a structural comparison.

The homoleptic thallium(i) complexes {Tl[(EP(i)Pr(2))(2)N]}(n) (, E = Te; , E = Se; , E = S) have been obtained in 70-86% yields from the reaction of TlOEt with (TMEDA)Na[(EP(i)Pr(2))(2)N] in CH(2)Cl(2) or Et(2)O. Complexes were structurally characterised in the solid state by single crystal X-ray diffraction and in solution by multinuclear NMR spectroscopy ((31)P, (77)Se, and (125)Te). The solid-state structures of , and are comprised of one-dimensional coordination polymers.

Synthesis, multinuclear NMR spectra, and X-ray structures of tBu2PNP(I)tBu2 and EPR2NP(I)R2 (E = Se, Te; R = iPr, tBu).

Two synthetic routes to bifunctional P(V)/P(V) compounds of the type EPR(2)NP(I)R(2) have been developed. The reaction of Li[EP(i)Pr(2)NP(i)Pr(2)] with one molar equivalent of I(2) produces EP(i)Pr(2)NP(I)(i)Pr(2) (3a-I, E = Se; 3b-I, E = Te). Alternatively, the oxidation of Na[N(P(t)Bu(2))(2)] with I(2) in tetrahydrofuran (THF) generates the P(III)/P(V) compound (t)Bu(2)PNP(I)(t)Bu(2) (6'-I) which, on treatment with elemental selenium or tellurium in THF, yields EP(t)Bu(2)NP(I)(t)Bu(2) (3a'-I, E = Se; 3b'-I, E = Te).

New insights into the chemistry of imidodiphosphinates from investigations of tellurium-centered systems.

Dichalcogenido-imidodiphosphinates, [N(PR(2)E)(2)](-) (R = alkyl, aryl), are chelating ligands that readily form cyclic complexes with main group metals, transition metals, lanthanides, and actinides. Since their discovery in the early 1960s, researchers have studied the structural chemistry of the resulting metal complexes (where E = O, S, Se) extensively and identified a variety of potential applications, including as NMR shift reagents, luminescent complexes in photonic devices, or single-source precursors for metal sulfides or selenides. In 2002, a suitable synthesis of the tellurium analogs [N(PR(2)Te)(2)](-) was developed.

Epitaxial CdTe rods on Au/Si islands from a molecular compound.

Formation of unusual CdTe rods on Si/SiO(2) and gold coated Si/SiO(2) surfaces is reported from chemical vapor deposition of Cd[(TeP(i)Pr(2))(2)N](2).

Synthesis, structures, and multinuclear NMR spectra of tin(II) and lead(II) complexes of tellurium-containing imidodiphosphinate ligands: preparation of two morphologies of phase-pure PbTe from a single-source precursor.

Group 14 metal complexes of heavy chalcogen-centered anions, M[(TeP(i)Pr(2))(2)N](2) (5, M = Sn; 6, M = Pb) and M(TeP(i)Pr(2)NP(i)Pr(2)Se)(2) (7, M = Sn; 8, M = Pb), were synthesized in 64-89% yields by metathesis of alkali-metal salts of the ligands with group 14 metal dihalides. Crystallographic characterization of the complexes revealed that 5, 6, and 8 engage in metal..

Palladium and platinum complexes of tellurium-containing imidodiphosphinate ligands: nucleophilic attack of Li[(P(i)Pr2)(TeP(i)Pr2)N] on coordinated 1,5-cyclooctadiene.

Homoleptic group 10 complexes of ditellurido PNP (PNP = imidodiphosphinate), heterodichalcogenido PNP and monotellurido PNP ligands, M[(TeP(i)Pr2)2N]2 (1: M = Pd; 2: M = Pt), M[(EP(i)Pr2)(TeP(i)Pr2)N]2 (3: M = Pd, E = Se; 4: M = Pt, E = Se; 5: M = Pd, E = S; 6: M = Pt, E = S) and M[(P(i)Pr2)(TeP(i)Pr2)N]2 (7: M = Pd; 8: M = Pt), respectively, were prepared by metathesis between alkali-metal derivatives of the appropriate ligand and MCl2(COD) in THF. Complexes 1-8 were characterised in solution by multinuclear (31P, 77Se, 125Te and 195Pt) NMR spectroscopy and, in the case of 1, 2, trans-7, cis-7 and trans-8, in the solid state by X-ray crystallography. The square-planar complexes 3-6 are formed as a mixture of cis- and trans-isomers on the basis of NMR data.

Group 11 complexes of the P,Te-centered ligand [TeP(i)Pr2NP(i)Pr2]-: synthesis, structures, and insertion reactions of the copper(I) complex with chalcogens.

The lithium reagent [LiTeP(i)Pr(2)NP(i)Pr(2)] undergoes metathetical reactions with group 11 chlorides to give the complexes {M(TeP(i)Pr(2)NP(i)Pr(2))}(3) (6: M = Cu; 7: M = Ag) and (Ph(3)P)Au(TeP(i)Pr(2)NP(i)Pr(2)) (8) as yellow crystalline solids. These new complexes were characterized by single crystal X-ray diffraction and multinuclear NMR spectroscopy. The tellurium atoms in the trimeric complexes 6 and 7 occupy bridging positions to give a Cu(3)Te(3) ring in a twist-boat conformation with short M.

Coordination chemistry of a new P,Te-centred ligand: synthesis, NMR spectra and X-ray structures of M(TePPri2NPPri2)2 (M = Zn, Cd, Hg).

The lithiation of the monotelluride TePPri2NP(H)Pri2 (2) with BunLi at -78 degrees C results in the formation of the reagent [LiTePPri2NPPri2] (5), which was characterized by 31P NMR spectroscopy but not isolated due to disproportionation upon solvent removal. Salt metathesis reactions of 5, generated in situ, with group 12 metal chlorides produce the complexes M(TePPri2NPPri2)2 (6, M = Zn; 7, M = Cd; 8, M = Hg), which were characterized by single crystal X-ray diffraction, multinuclear NMR spectroscopy and thermal analyses. The X-ray structures reveal distorted tetrahedral structures with two P,Te-chelating anionic ligands [TePPri2NPPri2](-).

The single molecular precursor approach to metal telluride thin films: imino-bis(diisopropylphosphine tellurides) as examples.

Interest in metal telluride thin films as components in electronic devices has grown recently. This tutorial review describes the use of single-source precursors for the preparation of metal telluride materials by aerosol-assisted chemical vapour deposition (AACVD) and acquaints the reader with the basic techniques of materials characterization. The challenges in the design and synthesis of suitable precursors are discussed, focusing on metal complexes of the recently-developed imino-bis(diisopropylphosphine telluride) ligand.

Experimental and theoretical investigations of structural isomers of dichalcogenoimidodiphosphinate dimers: dichalcogenides or spirocyclic contact ion pairs?

A synthetic protocol for the tert-butyl-substituted dichalcogenoimidodiphosphinates [Na(tmeda){(EPtBu(2))(2)N}] (3 a, E=S; 3 b, E=Se; 3 c, E=Te) has been developed. The one-electron oxidation of the sodium complexes [Na(tmeda){(EPR(2))(2)N}] with iodine produces a series of neutral dimers (EPR(2)NPR(2)E--)(2) (4 b, E=Se, R=iPr; 4 c, E=Te, R=iPr; 5 a, E=S, R=tBu; 5 b, E=Se, R=tBu; 5 c, E=Te, R=tBu). Attempts to prepare 4 a (E=S, R=iPr) in a similar manner produced a mixture including HN(SPiPr(2)).

A new route to antimony telluride nanoplates from a single-source precursor.

Aerosol-assisted chemical vapor deposition (AACVD) of Sb[(TePiPr2)2N]3 results in pure hexagonal Sb2Te3 nanoplates between 375 and 475 degrees C on glass substrates, with a potential for enhanced thermoelectric properties for novel nanodevices.