Organochromium(II) and Organonitridochromium(V) N‐Heterocyclic Carbene Complexes: Synthesis and Structural Characterization

The N‐heterocyclic carbene‐stabilized chromium(II) alkyl, aryl, and alkynyl complexes (IPM)₂CrR₂ [R = Me ( 2 ), Ph ( 3 ), C≡CPh ( 3 ); IPM = 1,3‐diisopropyl‐4,5‐dimethylimidazole‐2‐ylidene] were prepared by metathesis reactions of (IPM)₂CrCl₂ ( 1 ) with the corresponding organolithium reagents. Further reaction of 3 with an organic azide, 1‐azidoadamantane, yielded an organonitridochromium(V) compound (IPM)₂Ph₂Cr≡N ( 5 ). Compounds 2 – 5 are fully characterized by ¹H NMR and IR spectroscopy, X‐ray crystallography as well as by elemental analysis. The structural analysis shows that the metal atom adopts a nearly square‐planar arrangement in the respective 2 , 3 , and 4 and a square‐pyramidal one in 5 . The reaction of 3 with the organic azide to 5 appears a novel way to the organonitridochromium compound.     

Chelatkomplexe LM/n von Übergangsmetallen mit Iminophosphin-säureamidato-Liganden R2P(NR′)2– (= L)

Chelate Complexes LM/n of Transition Metals with Phosphinoimidic Amidato Ligands R₂P(NR′)₂^– (= L) Reaction of LLi with metal halides or metal halide complexes affords chelate complexes LM/n (L = R₂P(NR′)₂^–; M = Cr⁺⁺⁺, Co⁺⁺, Ni⁺⁺, Zn⁺⁺). With the bulky ligand t-Bu₂P(NSiMe₃)₂^– and Ni(PPh₃)₂Cl₂ or Ni(dme)Br₂ (dme = dimethoxyethane) only halide bridged chelates [LNiHal]₂ (Hal = Cl, Br) containing tetrahedral chromophors NiN₂Hal₂ were obtained. Main objects of investigation were the bischelates L₂Ni 2 . 2 a (R = i-Pr, R′ = Me) and 2 c (R = Ph, R′ = Et) are planar, 2 b (R = i-Pr, R′ = Et) and 2 d–g (R, R′ = i-Pr, i-Pr; Ph, i-Pr; Et, SiMe₃; Ph, SiMe₃) tetrahedral. In solutions of 2 b and 2 c a conformational equilibrium planar (diamagnetic) tetrahedral (paramagnetic) exists that is shifted to the right with increasing temperature and is dominated by the tetrahedral ( 2 b ) or planar conformer ( 2 c ) at room temperature. As is the case with the isovalence electronic compounds [R₂P(S)NR′]₂Ni small substituents R′ apparently favour the planar state and in contrast to some complexes [R₂P(O)NR′]₂Ni no paramagnetic planar species 2 have yet been observed. These findings that are derived from the results of magnetic measurements and of UV/VIS as well as NMR spectroscopy are confirmed by crystal structure determinations: 2 a was found to be planar (orthorhombic; a = 3382.8(11), b = 1124.0(4), c = 8874(3); P2₁2₁2; Z = 6), and 2 g to be tetrahedral (monocline; a = 1268.4(2), b = 1806.8(2), c = 1971.6(2), P2₁/n; Z = 4). The bite angle NNiN of the chelate ligand in 2 a (ca. 77°) is similar to those in paramagnetic planar complexes [R₂P(O)NR′]₂Ni (NNiO 74–77°) and shows that a small chelate bite does not necessarily imply paramagnetism of planar Ni(II) complexes.     

Syntheses and Structures of Zinc Bis(phosphinimino)methanide Complexes

Reactions of bis(phosphinimino)methanes H₂C(PPh₂NR)₂ [R = SiMe₃ (L¹H), Ph (L²H), 2,6‐iPr₂‐C₆H₃ (DIPP) (L³H)] with ZnR₂ (R = Me, Et) yielded the corresponding bis(phosphinimino)methanide zinc complexes LZnMe [L² ( 1 ), L³ ( 2 )] and LZnEt [L¹ ( 3 ), L² ( 4 ), and L³ ( 5 )]. Complexes 1 – 5 were characterized by heteronuclear NMR (¹H, ¹³C, ³¹P) and IR spectroscopy, elemental analysis, and single‐crystal X‐ray diffraction.     

STEREOCHEMISTRY OF (R)-2-METHYLAZIRIDINE COMPLEXES OF COBALT(III) AND DIMERIZATION OF THE LIGAND

Abstract

A cobalt(III) complex containing (R)-2-methylaziridine (R-meaz), [Co(R-meaz)(NH₃)₅]³⁺, was prepared and the two diastereomers arising from the presence of the chiral nitrogen atom (N(R) and N(S)) were separated by column chromatography. Molecular mechanics calculations estimated the N(R)-isomer to be more stable. This result was supported by the x-ray structure determination of the more abundant (ca. 94%) isomer, N(R)-[Co(R-meaz)(NH₃)₅]Br₃H₂O. Crystal data: monoclinic, P2₁, a = 7.357(1), b = 9.780(1), c = 10.426(1) Å, μ = 93.58(1)°, V= 748.7(3) ų, Z= 2. Kinetic studies of isomerization (epimerization) between the two isomers revealed that inversion at the nitrogen center was very slow (5 × 10^?2 M^?1 S^?1at 25 °C). The small rate constant seems to be related to the strained three-membered structure of the meaz ligand. The reaction of Na₃[Co(N0₂)6] and R-meaz yielded a complex containing two dimerized R-meaz chelates, trans-[Co(NO₂)2(di-R-meaz)₂] (di-R-meaz =RR)-α,2-dimethyl-l-aziridineethanamine). The crystal strucrure of trans-[Co(NO₂)₂ (di-R-meaz)₂]C1O₄H₂O was established by x-ray crystallography. Crystal data: orthorhombic, P2₁2₁2₁, a = 11.784(6), b = 21.023(9), c = 8.608(7) Å, V = 2133(2) ų, Z = 4.     

Synthesis and Structure of Novel Dimethylcobalt(III) Complexes Containing Trimethylphosphine and Salicylaldiminato(N:O) Ligands

Dimethyl(salicylaldiminato[N:O])cobalt complexes [CoMe₂(2‐O‐C₆H₁R¹R² R³‐CH=NR⁴)L₂] (L=PMe₃) ( 1 ‐ 6 ) have been prepared through the reaction of [CoMe₃(PMe₃)₃] with the corresponding substituted salicylaldimine. The complexes were characterized with IR, ¹H NMR, ¹³C NMR, ³¹P NMR and elemental analyses. The X‐ray crystal structure of complex 1 shows an octahedral coordination of cobalt, with two equatorial cis‐methyl groups opposite to the planar N:O‐chelate ring.     

Preparation of chiral diimino- and diaminodiphosphine ligands and their Cu and Ag complexes. X-ray crystal structures of [Cu(1S,2S-cyclohexyl-P2N2)][PF6] and [Ag(1R,2R-cyclohexyl-P2N2H4)][BF4]

The interaction of optically pure 1R,2R-diammoniumyclohexane mono-(+)-tartrate and 1S,2S-diammoniumcyclohexane mono-(−)-tartrate with 2 equiv. of o-(diphenylphosphino)benzaldehyde in the presence of 2 equiv. of potassium carbonate in a refluxing ethanol/water mixture gave the optically pure condensation products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diiminocyclohexane[1R,2R-cyclohexyl-P₂N₂, (R,R)-I] and N,N′-bis[o-(diphenylphosphino)benzylidene]-1S,2S-diiminocyclohexane [1S,2S-cyclohexyl-P₂N₂, (S,S)-I], respectively, in good yield. Reduction of optically pure (R,R)-I and (S,S)-I with NaBH₄ in ethanol gave the optically pure reduced products N,N′-bis[o-(diphenylphosphino)benzylidene]-1R,2R-diaminocyclohexane[1R,2R-cyclohexyl-P₂N₂H₄, (R,R)-II] and N,N′-bis[o-diphenylphosphine)benzylidene]-1S,2S-diaminocyclohexane[1S,2S-cyclohexyl-P₂N₂H₄, (S,S)-II], respectively, in good yield. The coordination behaviour of I and II toward salts of Cu^I and Ag^I have been examined. The interaction of [Cu(C)₃CN)₄][X] (X = ClO₄⁻, PF₆⁻) with 1 equiv. of optically pure L₄ [L₄ = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [CuL₄][X] complexes, III–VI IIIa, L₄ = (R,R)-I, X = PF₆⁻ IIIb, L₄ = (R,R)-I, X = ClO₄⁻ IV, X = PF₆⁻; Va, L₄ = (R,R)-II, X = PF₆⁻, Vb L₄ = (R,R)-II, X= ClO₄⁻, VI L₄ = (S,S)-II, X = PF₆⁻, in good yield. For the Cu^I complexes, the L₄ ligand acted as a tetradentate ligand. However, a variable-temperature ³¹P[¹H] NMR study of IIIb shows that at ambient temperature one of the imino groups of the tetradentate ligand undergoes rapid dissociation to form a tridentate ligand. The interaction of AgBF₄ with 1 equiv. of otpically pure L₄ [L₄ = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II gave the corresponding optically pure [AgL₄][BF₄] complexes, VII–X VII L₄ = (R,R)-I; VIII, L₄ = (S,S)-I; IX,L₄ = (R,R)-II; X, L₄ = (S,S)-II], in good yield. For the Ag^I complexes, the L₄ ligand acted as a tetradentate ligand with the two amino groups coordinated unsymmetrically to the silver. A variable temperature ³¹P [¹H] NMR study of VII suggests that at high temperature the complex exists as a tri-coordinated complex. The structurers of IV and IX were established by X-ray diffraction studies.     

Asymmetric Diels-Alder Reaction of 1-Methoxybuta-1,3-diene with (2R)-N-Glyoxyloylbornane-10,2-sultam

Starting from sultam 1 , the chiral dienophile (2R)-N-glyoxyloylbornane-10,2-sultam ( 4 ) was readily prepared. Non-catalyzed atmospheric- and high-pressure as well as [Eu(fod)₃]-promoted [4 + 2] cycloadditions of 1-methoxy-buta-1,3-diene ( 5 ) to chiral dienophile 4 , leading with high asymmetric induction to 6-methoxy-3,6-dihydro-2H-pyran-2-yl derivatives 6 – 9 , are described. The extent and direction of asymmetric induction in these reactions were established by ¹H-NMR analysis and chemical correlation, respectively. Stereochemical models for both non-catalyzed and [Eu(fod)₃]-promoted reactions are proposed.     

Molybdenum(VI) Bis(imido) Complexes: From Frustrated Lewis Pairs to Weakly Coordinating Cations

Molybdenum(VI) bis(imido) complexes [Mo(NtBu)₂(L^R)₂] (R=H 1 a ; R=CF₃ 1 b ) combined with B(C₆F₅)₃ ( 1 a /B(C₆F₅)₃, 1 b /B(C₆F₅)₃) exhibit a frustrated Lewis pair (FLP) character that can heterolytically split H−H, Si−H and O−H bonds. Cleavage of H₂ and Et₃SiH affords ion pairs [Mo(NtBu)(NHtBu)(L^R)₂][HB(C₆F₅)₃] (R=H 2 a ; R=CF₃ 2 b ) composed of a Mo(VI) amido imido cation and a hydridoborate anion, while reaction with H₂O leads to [Mo(NtBu)(NHtBu)(L^R)₂][(HO)B(C₆F₅)₃] (R=H 3 a ; R=CF₃ 3 b ). Ion pairs 2 a and 2 b are catalysts for the hydrosilylation of aldehydes with triethylsilane, with 2 b being more active than 2 a . Mechanistic elucidation revealed insertion of the aldehyde into the B−H bond of [HB(C₆F₅)₃]⁻. We were able to isolate and fully characterize, including by single-crystal X-ray diffraction analysis, the inserted products Mo(NtBu)(NHtBu)(L^R)₂][{PhCH₂O}B(C₆F₅)₃] (R=H 4 a ; R=CF₃ 4 b ). Catalysis occurs at [HB(C₆F₅)₃]⁻ while [Mo(NtBu)(NHtBu)(L^R)₂]⁺ (R=H or CF₃) act as the cationic counterions. However, the striking difference in reactivity gives ample evidence that molybdenum cations behave as weakly coordinating cations (WCC).     

Structural Studies on Dimethyltin(IV) Carboxylates

In order to correlate ¹¹⁹Sn Mössbauer parameters and structural data for dimethyltin(IV) derivatives, the molecular structures of bis(acetato)dimethyltin(IV) and bis(trifluoroacetato)dimethyltin(IV) were determined by single crystal X-ray diffration. Crystals of Me₂Sn(OOCCH₃)₂ are monoclinic, a = 26.282(4), b = 5.282(1), c = 14.434(3) Å, β = 101.17(2)°, Z = 8, space group C2/c, and those of [Me₂Sn(OOCCF₃)₂]_n are monoclinic, a = 8.444(1), b = 17.689(1), c = 15.368(1) Å, β = 93.013(9)°, Z = 8, space group Cc. The structures were solved by the Patterson method and were refined by full-matrix least-squares procedures to R = 0.025 and 0.027 (R_w = 0.023 and 0.030) for 2 298 and 4 182 reflections with I ≥ 3σ(F²), respectively.     

Alternating copolymerization of propylene oxide and carbon dioxide with highly efficient and selective (salen)Co(III) catalysts: Effect of ligand and cocatalyst variation

Synthetic routes to a series of new (salen)CoX (salen = N,N′-bis(salicylidene)-1,2-diaminoalkane; X = Br or pentafluorobenzoate (OBzF₅)) species are described. Several of these complexes are active for the copolymerization of propylene oxide (PO) and CO₂, yielding regioregular poly(propylene carbonate) (PPC) without the generation of propylene carbonate byproduct. Variation of the salen ligand, as well as the inclusion of organic-based ionic or Lewis basic cocatalysts, has dramatic effects on the resultant (salen) CoX catalytic activity. Highly active (R,R)-(salen- 1 )CoOBzF₅ (salen- 1 = N,N′-bis(3,5- di-tert-butylsalicylidene)-1,2-diaminocyclohexane) catalysts with [Ph₄P]Cl or [PPN]Y ([PPN] = bis(triphenylphosphine)iminium; Y = Cl or OBzF₅) cocatalysts exhibited turnover frequencies up to 720 h⁻¹ for rac-PO/CO₂ copolymerization, yielding PPC with greater than 90% head-to-tail connectivity. Additionally, the (R,R)-(salen- 1 )CoOBzF₅/[PPN]Cl catalyst system demonstrated a k_rel of 9.7 for the enchainment of (S)- over (R)-PO when the copolymerization was carried out at low temperatures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5182–5191, 2006     

Kristallstrukturen,Schwingungsspektren und Normalkoordinatenanalysen der Chloro-Iodo-Rhenate(IV) (CH2Py2)[ReCl5I], cis-(CH2Py2)[ReCl4I2] · 2 DMSO,trans-(CH2Py2)[ReCl4I2] · 2 DMSO und fac-(EtPh3P)2[ReCl3I3]

Crystal Structures, Vibrational Spectra, and Normal Coordinate Analyses of the Chloro-Iodo-Rhenates(IV) (CH₂Py₂)[ReCl₅I], cis -(CH₂Py₂)[ReCl₄I₂] · 2 DMSO, trans -(CH₂Py₂)[ReCl₄I₂] · 2 DMSO, and fac -(EtPh₃P)₂[ReCl₃I₃] [ReCl₅I]^2–, cis-[ReCl₄I₂]^2–, trans-[ReCl₄I₂]^2–, and fac-[ReCl₃I₃]^2– have been synthesized by ligand exchange reactions of [ReI₆]^2– with HCl and are separated by ion exchange chromatography on diethylaminoethyl cellulose. X-ray structure determinations have been performed on single crystals of (CH₂Py₂)[ReCl₅I] ( 1 ) (triclinic, space group P1 with a = 7.685(2), b = 9.253(2), c = 12.090(4) Å, α = 90.06(2), β = 101.11(2), γ = 95.07(2)°, Z = 2), cis-(CH₂Py₂)[ReCl₄I₂] · 2 DMSO ( 2 ) (triclinic, space group P1 with a = 8.662(2), b = 12.109(2), c = 12.9510(12) Å, a = 97.533(11), β = 96.82(2), γ = 89.90(2)°, Z = 2) , trans-(CH₂Py₂)[ReCl₄I₂] · 2 DMSO ( 3 ) (triclinic, space group P1 with a = 9.315(7), b = 9.663(3), c = 15.232(3) Å, α = 80.09(2), β = 81.79(4), γ = 83.99(5)°, Z = 2) and fac-(EtPh₃P)₂[ReCl₃I₃] ( 4 ) (monoclinic, space group P2₁/a with a = 17.453(2), b = 13.366(1), c = 19.420(1) Å, β = 112.132(8)°, Z = 4). The crystal structure of ( 1 ) reveals a positional disorder of the anion sublattice along the asymmetric axis. Due to the stronger trans influence of I compared with Cl on asymmetric axes Cl˙–Re–I′ is caused a mean lenghthening of the Re–Cl˙ distances of 0.020 Å (0.8%) and a shortening of the Re–I′ distances of 0.035 Å (1.3%) with regard to symmetrically coordinated axes Cl–Re–Cl and I–Re–I, respectively. Using the molecular parameters of the X-Ray determinations the low temperature (10 K) IR and Raman spectra of the (n-Bu₄N) salts of all four chloro-iodo-rhenates(IV) are assigned by normal coordinate analyses. The weakening of the Re–Cl˙ bonds and the strengthening of the Re–I′ bonds is indicated by a decrease or increase of the valence force constants each by 9%.     

含联吡啶，Eu(III)或Gd(III)的手性高分子配合物的合成及荧光性质研究

手性高分子P–1由(R)-5,5′-二溴-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘(R–M–1)和5,5′-二乙烯基-2,2′-联吡啶(M–2)通过Pd催化的Heck偶合反应合成得到,高分子配合物P-2和P-3由高分子P-1与Eu(TTA)3·2H2O和Gd(TTA)3·2H2O (TTA– = 2-噻吩甲酰三氟丙酮)反应生成。手性高分子P-1能发射强的蓝色荧光,这是由于手性重复单元(R)-6,6′-二(4-三氟甲基苯基)-2,2′-二正辛氧基-1,1′-联萘和单元2,2′-联吡啶通过亚乙烯基桥连形成共轭高分子结构造成的。在不同的激发波长激发下,含Eu(III)的高分子配合物P–2不仅显示高分子荧光,还可显示Eu(III) (5D0→7F2)特征荧光。含Gd(III)的高分子配合物P–3仅发射高分子荧光。基于高分子及含RE(III)的高分子配合物的荧光性质研究发现,共轭高分子并没有把能量转移到Eu(III)或Gd(III) 配合物部分,只发射它自身的荧光,含Eu(III)的高分子配合物P–2发射Eu(III) (5D0→7F2)特征荧光能量主要来源于配阴离子TTA–。     

REACTIONS OF CuX (X = SCN AND CN) WITH 2-BENZOYLPYRIDINE. SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF [9-OXO-INDOLO[1,2-a] PYRIDINIUM] DITHIOCYANATOCUPRATE(I) AND POLYMERIC μ-CYANO(2-BENZOYLPYRIDINE) COPPER(I)

Abstract

When a mixture of excess CuSCN and 2-benzoylpyridine (2-Bzpy) stands in an ethanolic medium for about ten days in contact with air, the intramolecular oxidative cyclization of 2-Bzpy occurs with formation of the ionic compound [9-oxo-indolo[1,2-a]pyridinium]⁺ [Cu(SCN)₂]^? (1). In contrast, interaction of CuCN and 2-Bzpy in ethanol leads to formation of the polymer [Cu(CN)(2-Bzpy)]_n (2). The reaction of Cu(II) and 2-Bzpy in presence of excess SCN^? in ethanol affords (1) and the green monomer [Cu(SCN)₂(2-Bzpy)₂] (4). These complexes, along with the 1:1 CuSCN complex of 2-Bzpy (3) are studied by IR, Raman and electronic spectroscopic methods and X-ray structural analysis of (1) and (2). Crystals of (1) are monoclinic, space group P2₁/n (No. 14), with a = 5.887(1), b = 36.142(7), c = 7.083(1) Å, B = 109.56(1)°, Z = 4, and R_F = 0.033 for 2487 observed MoKα data, (2) monoclinic, space group P2₁/c (No. 14), a = 14.393(3), b = 8.881(2), c = 9.287(2) Å, B = 103.80(3)°, Z = 4, and R_F = 0.036 for 2030 observed MoKα data. The structure of (1) consists of a packing of [9-oxo-indolo [1,2-a]pyridinium]⁺ cations and [Cu(SCN)₂]^? anions. Puckered layers are formed by the [Cu(SCN)₂]^? component with four-coordinate Cu(I) and one tridentate μ(N,S,S)-thiocyanato ligand. Complex (2) features distorted tetrahedral Cu(I) geometry, formed by a bidentate chelating 2-Bzpy and linear C- and N-bonded bidentate cyano groups, which link adjacent copper centers to form zigzag chains extending along the c axis. Complexes (1) and (2) do not fluoresce at room temperature.     

Metal derivatives of thiosemicarbazones: crystal structure of [chloro bis(triphenylphosphino) (thiophene-2-carbaldehyde thiosemicarbazone) copper(I)] complex

Reactions of copper(I) halides (X = Cl, Br, I) with thiophene-2-carbaldehyde thiosemicarbazone and triphenylphosphine in 1 : 1 : 2 molar ratio yield tetrahedral mononuclear complexes, [CuX(η¹-S-Httsc)(Ph₃P)₂] (X = Cl, 1; Br, 2; I, 3), characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P), and single crystal X-ray crystallography (1). The unit cell of 1 has two independent distorted tetrahedral molecules (1a and 1b) with different bond parameters. One acetonitrile is entrapped between them. Crystal data: C₈₆H₇₇Cl₂Cu₂N₇P₄S₄ 1: triclinic, P-1, a = 12.8810(9), b = 18.5049(13), c = 18.7430(13) Å, α = 63.7130(10), β = 89.0960(10), γ = 85.5010(10)°, V = 3992.4(5) ų, Z = 2, R _(int) = 0.0314. Bond parameters: 1a, Cu(1A)–Cl(1A), 2.3803(5); Cu(1A)–S(1A), 2.3822(5); Cu(1A)–P(1A), 2.2498(5) Å; P(1A)–Cu(1A)–P(2A), 124.294(19)°; 1b, Cu(1B)–Cl(1B), 2.3975(5); Cu(1B)–S(1B), 2.3756(5); Cu(1B)–P(1B), 2.2777(5) Å; P(1B)–Cu(1B)–P(2B), 127.156(19)°.     

Tin(IV) and organotin(IV) derivatives of novel β-diketones: Part IV. Triorganotin(IV) complexes of fluorinated 4-acyl-5-pyrazolones. Crystal structure of (1-(4-trifluoromethylphenyl)-3-methyl-4-acetylpyrazolon-5-ato)triphenyltin(IV)

The synthesis of three 1-(4-trifluoromethylphenyl)-3-methyl-4-R¹(C=O)-5-pyrazolone proligands LH (L¹H; R¹=C₆H₅: L²H; R¹=CH₃: L³H; R¹=CF₃) and their interaction with R₃Sn(IV) acceptors (R=Me, Buⁿ, Ph) are reported. When R=Me or Buⁿ, aquo (4-acylpyrazolonate)SnR₃(H₂O) derivatives are obtained and the anionic donors 4-acylpyrazolonate (L⁻) act in the O–monodentate form. These triorganotin complexes are not stable in chlorohydrocarbon solvents and decompose to R₄Sn and bis(4-acyl-5-pyrazolonate)₂SnR₂. When R=Ph, stable (4-acyl-5-pyrazolonate)SnPh₃ derivatives, both in solution and in the solid state, are obtained. The crystal structure of (1-(4-trifluoromethylphenyl)-3-methyl-4-acetylpyrazolon-5-ato)triphenyltin(IV) shows a five-coordinate tin atom in a strongly distorted cis-bipyramidal trigonal environment (axial angle=161.2(2)°) with the acylpyrazolonate donor acting as an asymmetric O₂–bidentate species (Sn–O(1)=2.081(6) Å: Sn–O(2)=2.424(5) Å). Electronic effects are responsible for the different behavior shown by these trialkyl and triphenyl derivatives.     

Darstellung der Halogeno-Pyridin-Rhenate(III), [ReX6−n (Py)n](3−n)− (X = Br,Cl; n = 1−3), sowie Kristallstrukturen von trans-[(C4H9)4N][ReBr4(Py)2], mer-[ReCl3(Py)3] und mer-[ReBr3(Py)3]

Preparation of Halogeno Pyridine Rhenates(III), [ReX_6?n(Py)_n]^(3?n)? (X = Br, Cl; n = 1?3) Crystal Structures of trans-[(C₄H₉)₄N][ReBr₄(Py)₂], mer-[ReCl₃(Py)₃], and mer- [ReBr₃(Py)₃] The mixed halogeno-pyridine-rhenates(III), [ReX_6?n(Py)_n]^(3?n)? (X = Br, Cl), n = 1?3, have been prepared for the first time by reaction of the tetrabutylammoniumsalts (TBA)₂[ReX₆] (X = Br, Cl) in pyridine with (TBA)BH₄ and separation by chromatography on Al₂O₃. Apart from the monopyridine complexes only the trans and mer isomers are formed from the bis-and tris-pyridine compounds. The X-ray structure determinations of the isotypic neutral complexes mer- [ReX₃(Py)₃] (monoclinic, space group P 2₁/n, Z = 4; for X = Cl: a = 9,1120(8), b = 12,5156(14), c = 15,6100(13) Å, β = 91,385(7)°; for X = Br: a = 9,152(5), b = 12,852(13), c = 15,669(2) Å, β = 90,43(2)°) reveal, due to the stronger trans influence of pyridine compared with Cl and Br, that the Re? X distances in asymmetric Py? Re? X3 axes with ReCl3 = 2,397 Å and ReBr3 = 2,534 Å are elongated by 1,3 and 1% in comparison with symmetric X1? Re? X2 axes with ReCl1 = ReCl2 = 2,367 Å and ReBr1 = 2,513 and ReBr2 = 2,506 Å, respectively. The Re? N bond lengths are roughly equal with 2,12 Å. Trans-(TBA)[ReBr₄(Py)₂] crystallizes triclinic, space group P1 , a = 9,2048(12), b = 12,0792(11), c = 15,525(2) Å, α = 95,239(10), β = 94,193(11), γ = 106,153(9)°, Z = 2. The unit cell contains two independent but very similar complex anions with approximate D_2h(mmm) point symmetry.     

Preparation of poly(biphenylene vinylene) type polymers by Ni‐promoted polycondensation and their basic optical properties

Ni(0)‐complex promoted dehalogenation polymerization of 1,2‐bis(4‐bromophenyl)ethylene derivatives gave poly(p‐biphenylene vinylene) type polymers, [—C₆H₂R—CR² = CR²—C₆H₂R—)_n (P(R¹,H) and P(H,R²) ], having substituents (R¹ = Me, Et, CHMe₂, and n‐C₈H₁₇, R² = Me, Et, n‐C₆H₁₃, n‐C₁₁H₂₃, and Ph) at the benzene ring or vinylene group in 90–99% yields. The polymers were soluble in organic solvents such as CHCl₃, dimethylformamide, and tetrahydrofuran, and gave M_n of 2.4–5.3 × 10³ in gel permeation chromatography analysis. The absorption peak of the polymers appeared at a longer wavelength than that of the corresponding monomers by about 30 nm due to the expansion of the π‐conjugation system. The polymers were photoluminescent in solutions and in their films, emitting blue or green light. P(R¹,H)s gave higher quantum yields (Φ = 0.35–0.51) than P(H,R²) s in CHCl₃. P(H,R²) s showed a large Stokes shift (9600–13,500 cm⁻¹) in their photoluminescence. Single‐layer and multilayer light emitting diodes using vacuum deposited thin film of P(H,Ph) were prepared. Polymers with long alkyl substituents formed an ordered structure in the solid state as judged from their XRD patterns. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1493–1504, 2000     

Rhenium(I) Tellurolate,Telluroether and Bidentate-Telluroether Complexes: Crystal Structures of Re(CO)3Br(PhTe(CH2)3TePh), PhTeRe(CO)5 Re2(μ-SePh)2(CO)8 and [(PhTeMe)Re(CO)5][BF4]

The monomeric rhenium(I) complex with bidentate telluroether ligand Re(CO)₃Br(PhTe(CH₂)₃TePh) (1) was accessible via reaction of the PhTe(CH₂)₃TePh with Re(CO)₅Br. This chelate complex crystallized in triclinic space group $ {\rm P}\bar 1 $ with a = 9.390(5) Å, b = 10.961(3) Å, c = 11.849(4) Å a = 63.30(3)°, β = 87.49(4)° γ = 69.31(4)°, V = 1009.5(7) ų Z = 2, R = 0.033, and R_w = 0.034. Reaction of Re(CO)₅Cl with NaTePh yielded the Re(I) specics PhTeRe(CO)₅ (2). This complex crystallized in triclinic space group $ {\rm P}\bar 1 $ with a = 7.085(1) Å, b = 9.203(1) Å, c = 11.341(1) Å, α = 107.24(1)°, β = 100.56(1)°, γ = 96.47(1)°, V = 683.2(2) ų, Z = 2, R = 0.027, R_w = 0.022. Reaction of PhTeRe(CO)₅ and (PhSe)₂ in THF at 65 °C yielded a product that was confirmed crystallographically to be the known species Re₂(μ-SePh)₂(CO)₈ (3), in which two phenylselenolate ligands bridge the two Re(I). Compound 3 crystallized in monoclinic space group P2₁/n with a = 7.210(2) Å, b = 18.862(6) Å, c = 9.083(3) Å, β = 107.48(3)° V = 1178.2(7) ų, Z = 2, R = 0.046, and R_w = 0.051. Methylation of PhTeRe(CO)₅ with [Me₃O][BF₄] afforded Re(I) product [(PhTeMe)Re(CO)₅][BF₄] (4). This monodentate telluroether species crystallized in monoclinic space group P2₁/n with a = 8.405(1) Å, b = 13.438(3) Å, c = 15.560(2) Å, β = 92.59(1)° V = 1755.5(5) ų, Z = 4, R = 0.035, and R_w = 0.035.     

Synthesis and properties of the chain-like polymeric copper (II) complexes bridged by bis(diphenylphosphino oxide)ethane

At room temperature, the chain-like polymeric copper (II) complexes bridged by bis (diphenylphosphino oxide) ethane (dppeO2), [Cu(dppeO2)X2]n[X=Cl(1), Br(2)] have been prepared and characterized by elemental analysis, 31P NMR, TG-DTA and X-ray analysis for [ CuBr2 (dppeO2) ] n The chain is composed of subunits containing tetrahedron coordinated copper (II) atoms. The four-coordinated copper (II) atom is ligated to another four-coordinated copper (II) atom through dppeO2. The coordination sphere of copper(II) atom is completed by two monodentate bromide and two oxygen atoms from bridging dppeO2. Crystal data are as follows: C26-H24CuP2BnO2, 0.50 mm× 0.40 mm×0.40 mm, monoclin-ic, space group: C2/c, λ= 0.07107 nm(Mo Ka), a = 1.2286(2) nm, b=2.0555(8) nm, c = 1.0652(2) nm, β = 97.366(9)°, V = 2.668nm3, Z = 4, Dcalc = 1.628 g·cm-3, R = 0.066; Rw = 0.091.     

Easily available niobium(V) mixed chloro‐alkoxide complexes as catalytic precursors for ethylene polymerization

The dinuclear [NbCl_n(OR)_(5‐n)]₂ (n = 4, R = Et, 1 ; n = 4, R = CH₂Ph, 2 ; n = 3, R = Et, 3 ; n = 2, R = Et, 4 ; n = 2, R = , 5 ), and [Nb(OEt)₅]₂, 6 , and the mononuclear niobium compounds NbCl₄[κ²? OCH₂CH(R′)OR] (R = Me, R′ = H, 7 ; R = Et, R′ = H, 8 ; R = CH₂Cl, R′ = H, 9 ; R = CH₂CH₂OMe, R′ = H, 10 ; R = R′ = Me, 11 ), NbBr₄[κ²? OCH₂CH₂OMe], 12 , and NbCl₃(κ²? OCH₂CH₂OMe)(κ¹? OCH₂CH₂OMe), 13 , were tested in ethylene polymerization. Optimized reaction conditions included the use of D‐MAO as co‐catalyst and chlorobenzene as solvent at 50 °C. Complex 7 , whose X‐Ray structure is described here for the first time, exhibited the highest activity ever reported for a niobium catalyst in alkene polymerization [151 kg_polymer × mol_Nb^?1 × h^?1 × bar^?1]. Compounds 1 , 3‐5 , 8 , 13 showed activities similar to that of 7 . Linear polyethylenes (characterized by FT‐IR, NMR, GPC, and DSC analyses) with a broad polydispersivity were obtained. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011