Synthesis of new o-alkyl substituted arylalkylphosphanes: study of their molecular structure and influence on rhodium-catalyzed propene and 1-hexene hydroformylation

A set of new phosphane ligands designed to increase the branched-to-normal ratio of the hydroformylation reaction were prepared in the same way as the previously reported ortho-alkyl substituted arylphosphanes, which have shown increased i/n ratios in the hydroformylation of propene and 1-hexene. In order to determine the relationship between the catalytic behavior and stereoelectronic properties of the ligands, various functional alkyl groups (methyl, isopropyl, cyclohexyl) were placed on the phosphorus atom directly and in the ortho position of the phenyl ring connected to phosphorus. In the hydroformylation reaction of propene and 1-hexene a higher i/n ratio resulted with nearly all the ligands compared with that of triphenylphosphane. Additionally as the ortho-alkyl-substituent became larger, it had a favorable effect on the i-selectivity. Characterization of the ligands was carried out by NMR spectroscopy (mainly ¹H, ³¹P{¹H}, ¹³C{¹H}, HSQC/HETCOR and COSY-90). Properties of the ligands were also studied by quantum mechanical calculations and by synthesizing three Rh(acac)(CO)(PR₃) derivatives. The o-alkyl-substituent was orientated outside the ligands’ cone angle in the X-ray crystal structures of (2-cyclohexylphenyl)dicyclohexylphosphane and (2,5-dimethylphenyl)bis(4-pyridyl)phosphane, and Rh(acac)(CO)(PR₃) complex of (2-methylphenyl)dicyclohexylphosphane.     

双核茂金属催化剂的合成、表征与应用

使用桥连配体锂盐与MCl₄络合, 合成了4个不同结构的双核茂金属化合物[μ,μ-(CH₂)₃]{[C(H)·(η⁵-C₅H₄)(η⁵-C₁₃H₈)](MCl₂)}₂[M=Zr or Ti](4, 5)和[μ,μ-(CH₂)₃]{[C(H)(η⁵-C₅H₄)(η⁵-C₉H₆)]·(MCl₂)}₂[M=Zr or Ti](6, 7), 配体和化合物都经过核磁氢谱(¹H NMR)、 碳谱(¹³C NMR)、 红外光谱(IR)及元素分析等表征, 确认了化学结构. 以甲基铝氧烷(MAO)为助催化剂, 化合物4~7为催化剂催化丙烯聚合, 考察了聚合温度、 乙烯压力、 铝钛或铝锆比对催化剂活性及聚合物分子量的影响. 结果表明, 多亚甲基桥连双核茂金属是高活性乙烯和丙烯聚合催化剂, 乙烯聚合活性最高达到7.5× 10⁶ g PE/(mol Zr·h)(化合物6), 丙烯聚合活性达 10 × 10⁵ g sPP/(mol Zr·h)(化合物4). 所得间规聚丙烯(sPP)的间规度指数(SI, r) 达到90%. 在同样条件下, 双核化合物的催化活性、 聚合物分子量M_w(> 100000)以及分子量分布(MWD>2.5)均比相应的单核化合物高(M_w<70000, MWD≤2), 表明该体系中存在较强的核效应.     

Stabile Bis(η-alkin)MCl2-komplexe; Darstellung und reaktivität

The synthesis and reactivity of {(η⁵-C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂} MCl₂ (M = Fe: 3a; M = Co: 3b; M = Ni: 3c) is described. The complexes 3 are accessible by the reaction of (η⁵-C₅H₄SiMe₃) ₂Ti(CSiMe₃)₂ (1) with equimolar amounts of MCl₂ (2) (M = Fe, Co, Ni). 3a reacts with the organic chelat ligands 2,2′-dipyridyl (dipy) (4a) or 1,10-phenanthroline (phen) (4b) in THF at 25°C to afford in quantitative yields (η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂ (1) and [Fe(dipy)₂]Cl₂ (5a) or [Fe(phen)₂]Cl₂ (5b). 1/n[Cu^IHal]_n (6) or 1/n[Ag^IHal]_n (7) (Hal = Cl, Br) react with {(η⁵ -C₅H₄SiMe₃)₂Ti(CCSiMe₃)₂}FeCl₂ (3a), by replacement of the FeCl₂ building block in 3a, to yield the compounds {(η⁵-C₅H₄SiMe₃)₂Ti(C CSiMe₃)₂}Cu^IHal (8) or {(η⁵-C₅H₄SiMe₃)₂Ti(CSiMe₃)₂}Ag^IHal (9) (Hal = Cl, Br), respectively. In 8 and 9 each of the two Me₃SiCC-units is η²-coordinated to monomeric Cu^I Hal or Ag^IHal moieties. Compounds 8 and 9 can also be synthesized by the reaction of (η⁵-C₅H₄SiMe₃)₂ Ti(CSiMe₃)₂ (1) with 1/n[Cu^IHal]_n (6) or 1/n [Ag^IHal]_n (7) in excellent yields. All new compounds have been characterized by analytical and spectroscopic data (IR, ¹H-NMR, MS). The magnetic moments of compounds 3 were measured.     

The reaction of (μ-H)2Os3(CO)9(PPh3) with ethylene affords the ethylidene complex (μ-H)2Os3(CO)9(PPh3)(μ-CHCH3)

The product isolated from the reaction of (μ-H)₂Os₃(CO)₉(PPh₃) with ethylene is shown to be the ethylidene complex (μ-H)₂Os₃(CO)₉(PPh₃)(μ-CHCH₃) (1) rather than the ethylene complex (μ-H)(H)Os₃(CO)₉(PPh₃)(C₂H₄), as previously claimed. The characterization of 1 is based on a combination of ¹H and ¹³C NMR results. The ¹H NMR data (δ 6.84 (1 H_D), 2.53 (3 H_C), J(CD) = 7.4 Hz) establish the presence of the ethylidene moiety, whereas detailed analysis of the 1-D and 2-D ¹³C NMR spectra of ¹³CO-enriched 1 indicates the relative positions of the ethylidene, hydride, and phosphine ligands on the triosmium framework.     

The cyclopalladation of benzylidenebenzylamines

A number of isomeric N-benzylbenzalimine palladium(II) complexes of the type [P ·CH₂Ph]₂ (with C=N endo to the palladocycle) and [P =C(CH₃Ph]₂ (with C=N exo to the palladocycle), have been prepared and charcterised by ¹H and ¹³C NMR methods. The crystal structures of two analogous monomeric acac complexes, synthesized independently by oxidative addition of o-BrC₆H₄CH₂N=CH · Ph to Ph to Pd(dibenzylideneacetone)₂ have also been determined. These are [P · CH₂Ph)] (15a) and [P =CHPh)] (20a). Crystals of 15a are monoclinic, space group P2₁/a with Z = 4 in a cell of dimensions a 10.286(2), b 11.902(3), c 13.895(5) Å, β 93.52(2)° while 20a is monoclinic, space group P2₁/c with Z = 8 and a 10.353(3), b 20.600(5), c 16.545(7) Å, β 92.14(3)°. The structures 15a and 20a were refined to residuals R = 0.041 and 0.055 for 1661 and 2525 observed reflections respectively.     

Photochemical reactions of alkynyl iron (II) complexes with carbon disulfide. Insertion of CS2 into an iron-C(sp) bond

The novel alkynyldithiocarboxylate complexes [Fe(η⁵-C₅H₅)(S₂CCCR) (dppm-P)] (3a,b) and [Fe(η₅-C₅H₅)(S₂CCCR)(PPh₃)] (4a,b) were obtained through the insertion of CS₂ into the iron-akynyl bond in the complexes [Fe(η₅-C₅H₅)(CCR)(L)(L′] L, L′ = dppm R = Ph (1a), ^tBu(1b); L = (CO), L′ = (PPh₃) R = Ph (2a), ^tBu (2b). Variable-temperature ³¹P{¹H} NMR studies indicate the presence of two different isomers, [Fe(η⁵-C₅H₅)(η³-S,C,S′---S₂CCCR)(L)(L′)] and [Fe(η⁵-C₅H₅(η²-S,S′-S₂CCCR)(L)(L′)], which rapidly interconvert at room temperature. The synthesis of the precursor complex [Fe(η⁵-C₅H₅)(CC^tBu)(CO)(PPh₃)] is also described.     

H NMR Spectra and electronic structure of binuclear niobocene and titanocene containing fulvalene ligands

¹H NMR spectra of binuclear metallocene hydride complexes, (η⁵ : η⁵-C₁₀H₈)(C₅H₅)₂M₂(μ-H)₂ (M = Nb, 20°C and Ti, (−60 to +25°C), were studied. The Nb complex is diamagnetic and gives a high resolution spectrum. The coordination of bridging hydride H atoms provides Nb atoms with complete 18 electron configuration. In its ground state, the Ti complex is also diamagnetic (the spectrum at −60°C agrees to that) in spite of only 17 electron configuration of each Ti atom. However, the population of the excited triplet state in the case of the Ti complex is appreciable at temperatures higher than −30°C, the proton resonance lines being shifted downfield and significantly broadened as compared with the spectrum at −60°C.     

RCOO-取代的镍(Ⅱ)配合物单组分高效催化乙烯均聚和共聚反应

合成并表征了含RCOO-基团的单核(Ni¹~Ni²)及双核(Ni³)镍配合物[(2,6-R₂-C₆H₃)—N=C(H)—(3-Ph-5-PhCOO-2-O-C₆H₂)-κ²-N,O]Ni(CH₃)(pyridine)](R=iPr;3,5-tBu₂C₆H₃),并用于催化乙烯均聚和共聚反应。 作为单组分催化剂,这些配合物可以有效地催化乙烯聚合得到中等相对分子质量的支化聚乙烯(PE)。 供电性的PhCOO—基团促进了催化剂Ni¹的引发,从而在低温下比Ni⁰活性更高。 引入大位阻的2,6-(3,5-二叔丁基苯基)苯胺基团,催化剂Ni²在5×10⁵ Pa下的活性高达1.8×10⁶ g PE mol^-1·Ni^-1·h^-1,是活性最高的水杨醛亚胺中性镍催化剂之一。 与相应的单核催化剂相比,双核催化剂Ni³对三苯基膦具有更好的耐受性。 这些催化剂可催化乙烯与1,5-己二烯、1,7-辛二烯、6-溴-1-己烯或10-十一烯酸甲酯的共聚合,制备功能化聚乙烯。     

Preparation and structure of (η-cyclopentadienyl)(η-tetraphenylcyclobutadiene) cobalt coordinated by four Cr(CO)3 units at the phenyl rings

The reaction of (η⁵-cyclopentadienyl)(η⁴-tetraphenylcyclobutadiene)cobalt (1) with excess Cr(CO)₆ yielded several heterometallic compounds: 2, 3 (3′ and 3″), 4 and 5 with, respectively, one, two, three and four phenyl rings complexed with Cr(CO)₃ fragment(s). These compounds were characterized by mass, infrared, ¹H and ¹³C NMR spectra. The crystal structure of 5 was determined. In 5 the four Cr(CO)₃ fragments are on the same side of the CpCo fragment; whereas, the two Cr(CO)₃ fragments of 3′, the precursor of 5, are pointed in a different direction from the CpCo fragment. The cyclopentadienyl ring shows a static disorder around the axis that passes through the cobalt and the centre of the ring.     

Synthesis and characterization of hydroxo, pyrazolato and carboxylato derivatives of the PdR(PPh3)moiety (R = C6F5 or C6Cl5)

The hydroxo-complexes [{PdR(PPh₃)(μ-OH)}₂] (R = C₆F₅ or C₆Cl₅) have been obtained by reaction of the corresponding [{PdR(PPh₃)(μ-Cl)}2] complexes with NBu₄OH in acetone. In this solvent, the reaction of the hydroxo-bridged complexes with pyrazole (Hpz) and 3,5-dimethylpyrazole (Hdmpz) in 1:2 molar ratio leads to the formation of the new complexes [{Pd(C₅F₅)(PPh₃)(μ-azolate)}2] and [{Pd(C₆Cl₅)(PPh₃)}₂(μ-OH)(μ-azolate)] (azolate = pz or dmpz). The reaction of the bis(μ-hydroxo) complexes with Hpz and Hdmpz in acetone in 1:1 molar ratio has also been studied, and the resulting product depends on the organic radical (C₆F₅ or C₆Cl₅) as well as the azolate (pz or dmpz). The identity of the isomer obtained has been established in every case by NMR (¹H, ¹⁹F and ³¹P) spectroscopy. The reaction of the bis(μ-hydroxo) complexes with oxalic (H₂Ox) and acetic (HOAc) acids yields the binucle ar complexes [{PdR(PPh₃)}2(μ-Ox)] (R = C₆F₅ or C₆Cl₅) and [{Pd(C₆F₅)(PPh₃)(μ-OAc)}2], respectively. [{Pd(C₆F₅)(PPh₃)(μ-OH)}₂] reacts with PPh₃ in acetone in 1:2 ratio giving the mononuclear complex trans-[Pd(C₆F₅) (OH)(PPh₃)₂], whereas the pentachlorophenylhydroxo complex does not react with PPh₃, even under forcing conditions.     

Synthesis of new N-substituted imidazolyl and 1H-1,2,4-triazolyl derivatives of (η-arene)(η-cyclopentadienyl)iron(II) salts

A series of new imidazolyl and 1H-1,2,4-triazolyl derivatives of (η⁶-arene)(η⁵cyclopentadienyl)iron(II) salts have been prepared by reaction of the corresponding chloroarene complexes with the sodium salts of the heterocycles. Good yields of N-substituted products were obtained in all cases under very mild conditions. In contrast to substitution by primary and secondary amines, both chlorines were displaced from [(η⁵-1,2-dichlorobenzene)(η⁵-Cp)Fe][PF₆], indicating electron withdrawal by the imidazolyl and triazolyl groups. Detailed ¹H and ¹³C NMR analysis confirmed this point. NOE difference spectra were used for ¹³C assignments, and evidence for conformational isomers in the 1,2-disubstituted complexes is presented.     

Mononuclear manganese carboxylate complexes: Synthesis and structural studies

Several manganese carboxylates complexes having Pz^iPr2H (3,5-diisopropylpyrazole), Tp^Ph,Me (hydrotris(3-phenyl,5-methyl-pyrazol-1-yl)borate), Tp^ipr2 (hydrotris(3,5-diisopropyl-pyrazol-1-yl)borate) as supporting ligands have been synthesised and structurally characterized. Single-crystal X-ray diffraction studies suggest that the manganese center in complexes (Pz^iPr2H)₄Mn(NO₂–OBz)₂ (5) and (Pz^iPr2H)₄Mn(F–OBz)₂ (6) have same coordination environment and geometry whereas the complex [Tp^Ph,MeMn(OAc)Pz^Ph,MeH] (7) has a five coordinate manganese center. In all these complexes, the carboxylate groups are coordinated as monodentate and the uncoordinated oxygen atom of the carboxylate groups form intramolecular hydrogen bonds with the NH group of the corresponding coordinated pyrazole (Pz^iPr2H/Pz^Ph,MeH). The complexes 5–8 and 10 were tested for their superoxide dismutase activity and it was found that only complex 7 has SOD activity as its structure is very similar to the active site structure of the native Mn–SOD enzyme. The SOD activity studies on these carboxylate complexes suggest that any model compound with analogous active site structure and intramolecular hydrogen bonding may be a suitable mimic for the Mn–SOD enzyme.     

Matrix isolation infrared spectroscopic and theoretical study of noble gas coordinated dipalladium–dioxygen complexes

The reaction products of palladium atoms with molecular oxygen in solid argon have been investigated using matrix isolation infrared absorption spectroscopy and quantum chemical calculations. In addition to the previously reported mononuclear palladium–dioxygen complexes: Pd(η²–O₂) and Pd(η²–O₂)₂, dinuclear palladium–dioxygen complexes: Pd₂(η²–O₂) and Pd₂(η²–O₂)₂ were formed under visible light irradiation and were identified on the basis of isotopic substitution and theoretical calculations. In addition, experiments doped with xenon in argon coupled with theoretical calculations suggest that the Pd(η²–O₂), Pd₂(η²–O₂) and Pd₂(η²–O₂)₂ complexes are coordinated by two argon or xenon atoms in solid argon matrix, and therefore, should be regarded as the Pd(η²–O₂)(Ng)₂, Pd₂(η²–O₂)(Ng)₂ and Pd₂(η²–O₂)₂(Ng)₂ (NgAr or Xe) complexes isolated in solid argon.     

新型含N-杂环卡宾二硫化碳配体的锰铼金属双核化合物的合成、表征及电化学性质

合成了一系列含N-杂环卡宾二硫化碳加合物配体的锰铼金属有机化合物, 其中包括3种单核化合物和3种双核化合物, 对它们的结构进行了表征, 并研究其反应性和电化学性质. 与三烷基膦二硫化碳配体相比, 含N-杂环卡宾二硫化碳加合物配体的锰铼金属有机化合物展现出不同的反应特性. 研究结果表明, [MnRe(CO)₆(μ-H){μ-CH₃SC(S)IMes₂}]配合物具有催化质子还原成氢气的能力.     

Acyl complexes of molybdenum: structural and reactivity studies

The following structural peculiarities of the agostic acyl structure ₂R) (R = H, SiMe₃) and some characteristic chemical reactivity of the M-η²-acyl and iminoacyl linkage are described. (i) A structural comparison of the bonding parameters within three agostic acetyl Mo complexes containing the dithioacid ligand, indicates that the agostic interaction strengthens upon increasing the electron-releasing properties of the S-chelating ligand. (ii) The acyl-xanthate complex Mo(C(O)Me)(S₂COR)(CO)(PMe₃)₂ undergoes loss of a sulfur atom from the coordinated xanthate and coupling with the acyl ligand to form complexes containing coordinated alkoxythiocarbonyl and monothioacetate ligands. The latter can be metathetically replaced by KS₂COR. (iii) Upon heating at 70°C η²-acyl-dicarbonyl bispirazolilborate complexes of molybdenum of the type Mo(H₂B(pz^*)₂)(η²-C(O)Me)(CO)₂(PMe₃) (pz^* = 3,5-dimethyl-pyrazol-1-yl) yield functionalized acyl ligands derived from the stereo- and regioselective intramolecular addition of one of the B---H bonds of the H₂B(pz^*)₂ group across the C=O moiety of the η²-acyl group. (iv) The η²-acyl-isocyanide complexes {Mo}(η²-C(O)R)(CNR′) ({Mo} = Mo(H₂B(pz^*)₂)(CO)(PMe₃)) undergo irreversible thermal isomerization to the corresponding η²-iminoacyl-carbonyl derivatives {MO}(η²-C(NR′)R)(CO). This isomerization reaction follows first-order kinetics.     

Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen : XLIV. Synthesen von Hydrogensulfido- und Hydrogenselenido-Komplexen der Metalle Chrom, Molybdän und Wolfram

Hydrogenchalcogenido complexes of general composition (η⁵-C₅R₅)(CO)₃M(EH) (R = H, CH₃; M = Cr, Mo, W; E = S, Se) can be obtained by three different routes, sometimes in quite good yields. Thus, the sulfur and selenium derivatives can be synthesized by insertion of the respective elements into the metal-hydrogen bonds of the precursor compounds (η⁵-C₅R₅)(CO)₃MH. This species also reacts with potassium selenocyanate to yield the hydrogenselenido derivatives (η⁵-C₅R₅)(CO)₃M(SeH) which can also be obtained by treatment of the methyl complexes (η⁵-C₅R₅)(CO)₃M(CH₃ (M = Mo, W) with HBF₄ and Li[SeH]. The corresponding hydrogentellurido compounds are probably formed by these preparative methods but appear to be quickly converted into either the dinuclear tellurium bridge products (μ-Te)[(η⁵-C₅R₅)(CO)₃M]₂ (M = Mo) or into the hydrido complexes (η⁵-C₅R₅)(CO)₃MH (M= Mo, W) by release of elemental tellurium.     

Substituted metal carbonyls XXIII . Syntheses of unicoordinated diphosphine complexes of Cr and Mo and their entry into heterobimetallics MM′(CO)10(μ-P-P) [M, M′= Cr, Mo, W; P---P = Ph2P(CH2)nPPh2, n = 2–4] as metalloligands

A series of pentacarbonyl complexes of chromium and molybdenum with unicoordinated-diphosphines, M(CO)₅(η¹-P-P) (P-P = dppe, dppp, dppb) has been prepared by amine oxide-induced phosphine substitution of the binary carbonyls. The basicity of the pendant phosphine groups was demonstrated by their ready conversion to the diphosphine-bridged heterobimetallic complexes (OC)₅M(μ-P-P)M′(CO)₅ (M, M′= Cr, Mo, W; M ≠ M′) in the presence of MCO)₅(CH₃CN). The complexes were characterized by IR and NMR (¹H and ³¹P-{¹H}) spectroscopy.     

Synthesis, structure and hydrogenation catalytic activity of [Ru3(μ3,η-ampy)(μ,η:η-PhC=CHPh)(CO)6(PPh3) (Hampy = 2-amino-6-methylpyridine)

The compound [RU₃(μ₃,η²- -ampy)(μ₃η¹:η²-PhC=CHPh)(CO)₆(PPh₃)₂] (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU₃(η-H)(μ₃,η²- ampy) (μ,η¹:η²-PhC=CHPh)(CO)₇(PPh₃)] with triphenylphosphine at room temperature. However, the reaction of [RU₃(μ-H)(μ₃, η² -ampy)(CO)₇(PPh₃)₂] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU₃(μ₃,η²-ampy)(μ,η ¹:η² -PhC=CHPh)(μ,-PPh₂)(Ph)(CO)₅(PPh₃)] (2). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans -stilbene under mild conditions (80°C, 1 atm. of H₂), although progressive deactivation of the catalytic species is observed. The dihydride [RU₃(μ-H)₂(μ ₃,η²-ampy)(μ,η¹:η²- PhC=CHPh)(CO)₅(PPh₃)₂] (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction.     

Synthesis and characterization of planarly chiral nonbridged bis(1-R-indenyl) zirconium dichloride complexes and X-ray structure of rac-[(η-C9H6-1-C(CH3)2---o-C6H4---OCH3)2ZrCl2]·THF

Reactions of the lithium salts of 3-substituted indenes 1, 2 with ZrCl₄(THF)₂ gave two series of nonbridged bis(1-substituted)indenyl zirconocene dichloride complexes. Fractional recrystallization from THF–petroleum ether furnished the pure racemic and mesomeric isomers of [(η⁵-C₉H₆-1-C(R¹)(R²)---o-C₆H₄---OCH₃)₂ZrCl₂]·nTHF (R¹=R²=CH₃, n=1, rac-1a and meso-1b; R¹=CH₃, R²=C₂H₅; n=0.5 or 0, rac-2a and meso-2b), respectively. Complex 1a was further characterized by X-ray diffraction to have a C₂ symmetrically racemic structure, where the six-member rings of the indenyl parts are oriented laterally and two o-CH₃O---C₆H₄---C(CH₃)₂--- substituents are oriented to the open side of the metallocene (Ind: bis-lateral, anti; Substituent: bis-central, syn). The four zirconocene complexes are highly symmetrical in solution as characterized by room temperature ¹H-NMR, however ¹H–¹H NOESY of meso-1b shows that some of the NOE interactions arise from the two separated indenyl parts of the same molecule, which can only be well explained by taking into account the torsion isomers in solution.     

Acyl C---O bond cleavage in Cp2TiCOR compounds: formation of benzene derivatives by Cp-ring expansion involving incorporation of the acyl carbon atom (Cp = η-C5Me5)

Reaction of Cp^*₂TiR (R = CH₃, neo-C₅H₁₁) with CO gives labile acyl compounds Cp^*₂TiCOR. The latter react with (CpMo(CO)₃)₂ to yield complexes Cp^*₂Ti(η²-COR)(μ-OC)MoCp(CO)₂, which undergo acyl C---O band scission with concomitant formation of benzene derivatives at room temperature. The benzene derivatives are formed through ring expansion of the Cp^* ligand by incorporation of the R---C fragment of the acyl group. The acyl oxygen is incorporated into a dimeric titanium oxo complex.