CO_2(CO)_8-Ru_3(CO)_(12)体系对乙烯氢甲酰化反应的双金属协同效应

本文介绍了Ru_3(CO)_(12)-Co_2(CO)_8混合体系对乙烯氢甲酰化反应的双金属协同效应。实验系用一定量的Co_2(CO)_8和Ru_3(CO)_(12)混合在一起为催化剂体系,以乙烯、合成气(H_2/CO=1)为原料,在110℃,7.6MPa压力下研究了对乙烯氢甲酰化反应的活性,并和相应的Co_2(CO)_8和Ru_3(CO)_(12)的单组分体系作了对比。结果表明Co-Ru双组分体系的活性远高于相应的单组分体系的活性。红外光谱考察表明,Co_2(CO)_8-Ru_3(CO)_(12)在用于烯烃氢甲酰化反应后,Co_2(CO)_8Ru_3(CO)_(12)之间没有因相互作用而产生新化合物。过去对氢甲酰化反应的催化循环,是基于在单一的络合物金属中心上讨论的。基于本文结果,可以设定在双金属体系存在下,烯烃氢甲酰化反应的催化循环有可能在双金属中心上实现。     

加压原位红外光谱法研究YCCo_3(CO)_9的热稳定性及其对1-己烯的醛化机理

用加温加压原位红外光谱法研究了YCCo_3(CO)_(?)(Y=H,C_3H_7,Ph,Cl)在低压醛化条件下的热稳定性及对1-己烯的醛化机理。升温过程中的光谱变化指出,这些簇在130℃,4.0MPa的合成气压力下至少部分分解生成Co_2(CO)_(?),最后降解为HCo(CO)_4。通过对1-己烯的醛化反应研究发现,该簇络合物对1-己烯的醛化反应机理相应於Co_2(CO)_(?)的反应机理。Y的电子效应对簇的稳定性有一定影响并进而影响其催化活性。     

羰基钴催化烯烃醛化反应中氢活化作用的理论研究——Ⅰ.氢在RCOCo(CO)_3上的氧化加成反应

本文运用ASED-MO理论计算了羰基钴催化烯烃醛化反应中氢的氧化加成反应(CH_3COCo(CO)_3 H_2→CH_3COCo(H)_2(CO)_3)的反应物,产物构型和反应过程的能量变化。得到了反应物、产物的稳定构型。由计算结果,提出了两种可能的反应途径,并分别获得了两种途径的位能面图。由此求出反应的活化能和反应热并根据计算结果对反应过程进行了讨论。     

羰基钴催化烯烃醛化反应中氢活化作用的理论研究——Ⅰ.氢在RCOCo(CO)3上的氧化加成反应

本文运用ASED-MO理论计算了羰基钴催化烯烃醛化反应中氢的氧化加成反应(CH_3COCo(CO)_3+H_2→CH_3COCo(H)_2(CO)_3)的反应物, 产物构型和反应过程的能量变化。得到了反应物、产物的稳定构型。由计算结果, 提出了两种可能的反应途径, 并分别获得了两种途径的位能面图。由此求出反应的活化能和反应热并根据计算结果对反应过程进行了讨论。     

制备trans-Fe(CO)_3(PR_3)_2的新的取代过程

报道了用H_2Fe(CO)_4制备trans-Fe(CO)_3(PR_3)_2的新的羰基取代反应。在 过量质子存在下，H_2Fe(CO)_4中的羰基被活化，中心铁原子对膦的亲核进攻更为 敏感。在这种条件下H_2Fe(CO)_4与膦反应时，首先失去氢生成Fe(CO)_4(PR_3), Fe(CO)_4-(PR_3)再与第二个膦反应可高产率的得到trans-Fe(CO)_3(PR_3)_2。用 PPh_3与Fe(CO)_4(PPh_3)在过量质子存在下反应生成trans-Fe(CO)_3(PR_3)_2，证 实了上述过程。     

金属簇络合物YCCo3(CO)9的合成与醛化性能的研究

本文提出一种常压下由硝酸钴和三卤化物经相转移催化合成钴簇络合物YCCo_3(CO)_9的新方法,并用该法合成了HCCo_3(CO)_9,ClCCo_3(CO)_9,PhCCo_3(CO)_9和EtOOCCo_3(CO)_9等四种络合物。考察了这些络合物对己烯的酸化活性和PhCCo_3(CO)_9对各种烯烃醛化时结构与活性的关系,以及它们的异构化和加氢活性。实验结果表明它们是一类在较缓和条件下具有较高活性和选择性的醛化催化剂。当反应温度130℃和压力40公斤/厘米~2时,己烯转化率达90％以上,选择性在80％以上。     

双核钴配合物(ROCH2C≡CCH2OR)Co2(CO)6的合成

Co_2(CO)_3中两个桥连的羰基很容易被一个炔键取代,生成羰基配合物(ROCH_2C)_2Co_2(CO)_6。此类配合物既可以催化炔烃三聚成苯,也可以作为炔烃的保护基团,还可以用它进行其它的合成。为此,我们用下述反应合成了这类配合物:     

介绍几种简便的制备水合氯化铑(RhCl_3·3H_2O)的方法

许多金属铑的络合物,如Wilkinson催化剂——RhCl(PPh_2)_3、Rh_2Cl_2(CO)_4、RhH(CO)(PPh_3)_3,等都是重要的有机反应(醛化反应、羰基化反应和加氢反应等)的有效催化剂,而水合氯化铑则是制备各种铑络合物的理想起始物质。因为金属铑不溶于沸腾的王水,而由氯气直接与金属铑在高温下反应得到的无水氯化铑不溶于水及无机酸从而无法利用,所以水合氯化铑     

铁—钴异核金属簇的催化作用——Ⅰ.[R_4N][FeCo_3(CO)_(12)]在溶液中的热分解反应

本文报导用加温加压原位红外光谱法在1:1的CO+H_2气氛中跟踪铁—钴异核金属簇催化剂[K_4N][FeCo_3(CO)_(12)](R=乙基、丁基、十六烷基、苄基三甲基、苄基三乙基等)在三种不同极性的溶剂(甲醇、甲苯、正庚烷)中的热分解反应。实验证明,在烯烃醛化条件下(120—150℃,4.0MPa),这些金属簇合物均分解生成Fe(CO)_5、Co_2(CO)_3、HCo(CO)_4和Co(CO)_4~-的盐。HCo(CO)_4和Co(CO)_4~-均为醛化活性物种。在甲苯中升温不超过150℃,并增加CO分压,再降至室温时,发现簇的吸收复出。R_4N~+的存在对催化剂体系有稳定作用。     

三核锇原子簇中μ,η~2-乙烯配位基顺反异构化及其反应动力学研究

含氢原子簇化合物H_2Os_3(CO)_(10)与乙炔反应生成顺式加成物[Os_3H(μ,η~2-CH=CH_2)(CO)_(10)]。本文首次报道高含量氘代原子簇D_2Os_3(CO)_(10)与乙炔反应生成合乙烯配位基的氘代原子簇[Os_3D(μ,η~2-CH=CHD)(CO)_(10)],H_2Os_3(CO)_(10)与氘代乙炔反应生成[Os_3H(μ,η~2-CD=CDH)(CO)_(10)],它们在微量亲核试剂吡啶作用下发生μ,η~2-乙烯配位基的顺反异构反应。本文用同位素氘代和~1H,~2H NMR动态波谱联用方法,研究了上述反应和异构化过程,提出了顺反异构化的核磁共振动态波谱证据、反应机理和动力学数据。     

Oxidative addition of 2,2′-dipyridyl disulfphide to the cluster [Os3(CO)10(MeCN)2]

The cluster [Os₃(CO)₁₀(MeCN)₂] reacts with 2,2′-dipyridyl disulphide (1, pySSpy) to give a range of oxidative addition products which were separated by TLC on silica and crystallization : [Os₃(pyS)₂(CO)₁₀] (2), [Os₃(pyS)₂(CO)₉] (3), [Os₂(pyS)₂(CO)₆] (4) and [Os(pyS)₂(CO)₂] (5), together with some of the hydride [Os₃H(pyS)(CO)₉] (6), which is not an expected oxidative addition product. The X-ray crystal structures of compounds 2, 3, 4 and 6 (compounds 2 and 6 occurring within a single crystal), together with the known structure of compound 5, reveal several modes of pyS bonding : chelating pyS, μ₂-pyS (both sulphur-bonded and nitrogen, sulphur-bonded) and μ₃-pyS.     

Phenylbis(2- pyridyl)phosphine: P- vs. N,N′-coordination in carbonylmolybdenum-(O) and -(II) complexes

The first carbonyl molybdenum-(O) and -(II) complexes with phenylbis(2-pyridyl)phosphine (PPhpy₂) have been synthesized. PPhpy₂ reacts with [Mo(CO)₅(NCMe)] to give [Mo(CO)₅(PPhpy₂-P)]. With [Mo(CO)₄(NBD)] (NBD = norbornadiene) it gives [Mo(CO)₄(PPhpy₂-P)₂] when a 2 : 1 ratio is used, or [MO(CO)₄(py₂PhP---N,N′)] for a 1 : 1 ratio. Decarbonylation of any of these pyridylphosphine complexes leads to an oligomer of formula {MO(CO)₃(μ-PPhpy₂)}_n, which is also obtained after heating [MO(CO)₆] in solution with an equimolar amount of PPhpy₂. The oligomer undergoes oxidative addition by iodine or allylbromide to give [MoI₂(CO)₃(py₂PhP---N,N′)], or [MoBr(η³-CH₂CHCH₂)(CO)₂(py₂PhP---N,N′)], respectively. These complexes are also obtained by addition of equimolar amounts of PPhpy₂ to solutions of [MoI₂(CO)₃(NCMe)₂] and MoBr(η³-CH₂CH CH₂)(CO)₂(NCMe)₂, respectively. The ligand tends to act as a P-donor towards molybdenum(O) substrates, and as a chelating N,N′-donor in molybdenum (II) complexes.     

Synthesis, structure and reactions of seven-coordinate, phosphine-supported, halide-activated carbonyl- and alkyne-complexes of niobium(I)

The complexes (Hal)Nb(CO)₃(PR₃)₃ (PR₃ = PEt₃, Hal = I; PR₃ = PMe₂Ph, Hal = Cl, Br, I) and (Hal)Nb(CO)_4/2(dppe)_1/2 (Hal = Br, I) have been prepared by oxidative halogenation of carbonylniobate with pyridinium halides (Hal = Cl, Br) or iodine (Hal = I). In the tricarbonyls, one CO and one PR₃ are labile and can be displaced by a four-electron donating alkyne to give all-trans-[(Hal)Nb(CO)₂(RCCR′)(PR₃)₂] (PR₃ = PMe₂Ph; Hal = Cl, Br, I: R, R′ = H, Et, Ph; R = H, R′ = Ph. PR₃ = PEt₃, Hal = I: R, R′ = Pr; R = H, R′ = Bu, Ph; R = Me, R′ = Et). In the case of acetylene, INb(CO)(HCCH)₂(PEt₃)₂ is also formed. PR₃ can be displaced by P(OMe) ₃. In the tetracarbonyls, two CO ligands are replaced by two isonitriles to form INb(CO)₂(CNR)₂dppe (R = ^tBu, Cy), or by one alkyne to form (Hal)Nb(CO)₂(PhCCPh)dppe (Hal = Br, I). In these complexes, the remaining CO ligands occupy cis positions. The structure of BrNb(CO)₂(dppe)₂·THF, INb(CO)₂(dppe)₂·hexane and INb(CO)₂(PEt₃)₂(MeCCEt) have been determined by a single crystal X-ray diffraction study. The alkyne complexes are best regarded as octahedral with the centre of the alkyne ligand occupying the positions trans to the halide and the CC axis aligned with the OC---Nb---CO axis. The complexes (Hal)Nb(CO)₂(dppe)₂ adopt a trigonal prismatic structure with the halide capping the tetragonal face spanned by the four phosphorus functions. The crystal structure of a by-product, Br₂Nb(CO)(H₂CPhPCH₂CH₂PPh₂)₂·1/2THF has also been determined. The geometry is pentagonal bipyramidal, with one of the bromine atoms and the CO on the axis. Some ⁹³ Nb NMR data for the Nb^I complexes are presented, and preliminary observations on the reactions between the π-alkyne complexes and H₂ or H⁻ are reported.     

Heterobimetallic Mo---Sn complexes. Reactions of [Mo(CO)3(CH3CN)2(Cl)(SnRCl2)] (R = Me, Ph) with 4(4-XC6H4)3 (X = Cl, F, H, Me, MeO)

Three families of heterobimetallic compounds were obtained by reaction of [Mo(CO)₃(CH₃CN)₂(Cl)(SnRCl₂)] (R = Ph, Me) with P(4-XC₆H₄)₃ (X = Cl, F, H, Me, MeO). The type of compound obtained dependent on the solvent and concentration of the starting compound. So, [Mo(CO)₂(CH₃COCH₃)₂(PPh₃)(Cl)(SnRCl₂)]·nCH₃COCH₃ (R = Ph, n = 0.5; R = Me, n = 1) (type I) and [Mo(CO)₃{P(4-XC₆H₄)₃}(μ-Cl)(SnRCl₂)]₂ (R = Ph, X = Cl, F, H, Me, MeO; R = Me, X = Cl, F) (type II) were isolated from acetone solution in ca 0.05 M and 0.1 M concentrations, respectively. However, [Mo(CO)₃(CH₃CN) {P(4-XC₆H₄)₃}(Cl)(SnRCl₂)] (R = Ph, X = H; R = Me, X = Cl, F, H) (type III) were obtained from dichloromethane solution independently of the concentration used. All new complexes showed a seven-coordinate environment at molybdenum, containing Mo---Cl and Mo---Sn bonds. Mössbauer spectra indicated a four-coordination at tin for type III complexes.     

Perfluormethyl-element-liganden : XXXI. Ligandeneigenschaften von Me2PP(CF3)2 und Me2AsP(CF3)2

The coordinating properties of the trifluoromethyl elemental compounds Me₂PP(CF₃)₂ and Me₂AsP(CF₃)₂ have been studied by the synthesis and spectroscopic investigations (IR, NMR, MS) of their complexes cis-M(CO)₄L₂ (A), [(CO)₄ML]₂ (B) and [(CO)₅M]₂L (C) (M = Cr, Mo, W). Complexes of type A with L = Me₂PP(CF₃)₂ are obtained in good yield by reaction with M(CO)₄NBD (NBD = norbornadiene), whereas with L = Me₂AsP(CF₃)₂ the homobinuclear compounds B are formed. The attempt to prepare the cis-M(CO)₄[Me₂AsP(CF₃)₂]₂ complexes by treating M(CO)₄(Me₂AsH)₂ with P₂(CF₃)₄ is successful only for M = W. Binuclear compounds of type B or C, in general, can be prepared by stepwise reaction of the ligands with either M(CO)₄NBD or M(CO)₅THF.     

Attempts at stepwise reduction of the carbon-nitrogen triple bond of a nitrile at two metal centres: study of the reactivity of [(CO)(PPh3)2Re( (μ-NCHPh)Ru(PPh3) 2(PhCN)] towards tetrafluoroboric acid and dihydrogen

The reaction of [(CO)PPh₃)₂Re(μ-H)₂(μ-NCHPh)Ru(PPh₃)₂(PhCN)] (2) with HBF₄-Me₂O generates [(CO)PPh₃)₂Re(μ- H)₂(μ,η¹,η²HNCHPh)Ru(PPh₃)₂(PhCN)][BF₄] (3). Monitoring the reaction by NMR spectroscopy shows the intermediate formation of [(CO)(PPh₃)₂ HRe(μ-H)₂(μ-NCHPh)Ru(PPh₃)₂(PhCN)][BF₄] (4). Attempted reduction of the imine ligand by a nucleophile (H⁻ or CN⁻) failed, regenerating 2. Under dihydrogen at 50 atm, 3 is slowly transformed into [(CO)(PPh₃)₂HRe(μ-H)₃Ru(PPh₃)₂(PhCN)][BF₄] (5) with liberation of benzyl amine.     

P and C NMR investigation of the system tetracarbonyldi-μ-chlorodirhodium(I) — tertiary phosphine

¹³C and ³¹P{¹H} NMR data at low temperature prompted us to characterize cis-[Rh(CO)₂(PR₃)Cl] (3) (3a, PR₃ = PPh₃; 3b, PR₃ = PMe₂Ph), as surprisingly stable products of the reaction between [{Rh(CO)₂(μ-Cl)}₂] (1) and tertiary phosphines in toluene (P : Rh = 1). Every attempt to isolate solid 3a led to the cis- and trans- halide-bridged dimers [{Rh(CO)₂(μ-Cl)}₂] (5a) and 6a which are formed from 3a by slow decarbonylation, a process which is greatly accelerated by the evaporation of the solvent under vacuum.

The analogous reaction of 1 with dimethylphenylphosphine follows a similar pathway; in this case, however, low temperature NMR spectra allowed us to characterize the pentacoordinated dinuclear species [{Rh(CO)₂(μ-Cl)}₂] (2b) as the unstable intermediate of the bridge-splitting process.

The reaction of 3 with a second equivalent of phosphine (P : Rh = 2) leads, at room temperature, to the well known product trans-[Rh(CO)(PR₃)₂Cl] (8) accompanied by evolution of CO; however our data show that when the reaction is performed at 200 K, decarbonylation is prevented and spectroscopic evidence of trigonal bipyramidal pentacoordinate [Rh(CO)₂(PR₃)₂Cl] (7), stable only at low temperature, can be obtained.     

Organonickel chemistry in the catalytic hydrodechlorination of polychlorobiphenyls (PCBs): ligand steric effects and molecular structure of reaction intermediates

Soluble homogeneous organophosphorus—nickel complexes have been used to detoxify polychlorinated biphenyls (PCBs) by catalyzed hydrodechlorination using NaBH₂(OCH₂CH₂OCH₃)₂ as the hydrogen source. The reactions appear to proceed by NiL₃ oxidative addition into C---Cl bonds followed by hydrogenolysis of the metal---carbon bond. In model experiments with decachlorobiphenyl, the cone angle of the organophosphorus ligand L was shown to be a key factor controlling the magnitude and position of chlorine displacement. Hence, ligands leading to para displacement (e.g. (o-MeC₆H₄O)₃P), meta—para displacement (e.g. (EtO)₃P and (PhO)₃P), and ortho—meta—para displacement (e.g. Me₃P and Et₃P) were found. Significantly, the highly toxic, coplanar dioxin precursor 3,3′,4,4′-tetrachlorobiphenyl, a meta—para chlorine-substituted congener, was dechlorinated quantitatively with the Et₃P catalyst system. Evidence for the presence of organonickel intermediates in the reaction mixtures was obtained by mass spectroscopic and X-ray diffraction studies. Of particular interest is the isolation of square planar complexes p-C₆Cl₅C₆Cl₄Ni(PEt₃)₂Cl from the reaction of decachlorobiphenyl with NaBH₂(OCH₂CH₂OCH₃)₂—(Et₃P)₂NiCl₂ as the catalyst precursor and m-C₆Cl₅C₆Cl₄Ni(PEt₃)₂Cl from decachlorobiphenyl—Ni(1,5-C₈H₁₂)₂—PEt₃ at room temperature. All are oxidative addition intermediates and precursors for decachlorobiphenyl hydrodechlorination.     

Synthesis and reactions of 4-vinyl pyridine derivatives of ruthenium(II)

4-Vinyl pyridine (4-Vp) reacts with RuHClCO(PPh₃)₃ (I) in THF to give RuHClCO(PPh₃)₂(4-Vp) (II, which reacts with sodium derivatives of bidentate chelating ligands to afford substitution products, [RuH(CO)(PPh₃)₂(L)]. The bindentate ligands used are 2-hydroxybenzaldehyde, 2-hydroxy-3-methoxybenzaldehyde, trifluorothenoylacetone and 8-hydroxyquinoline. Insertion reactions of the Ru---H bond of II with activated olefins such as acrylonitrile [giving RuCl(CO)(CH₃CHCN)(PPh₃)₂(4-Vp)], 2-vinyl pyridine, dimethyl fumarate and monobromodiethyl fumarate have been carried out to obtain chelated Ru---C bonded complexes. RuCl₂(PPh₃)₃ reacts with an excess of 4-Vp to give an octahedral ruthenium addition complex containing two vinyl pyridine ligands. The dimer [RuClCO(CH₃CHCN)(PPh₃)(4-Vp)]₂ is obtained by the reaction of [RuClCO(CH₃CHCN)(PPh₃)₂]₂ with an excess of 4-Vp. Stereochemical assignments have been made for these new complexes on the basis of IR and ¹H NMR data.     

Synthesis of aromatic acids via catalysed methyl formate-chloroarene reactions

Chlorobenzene and more generally, chloroarenes, can be converted into aromatic acids via catalytic reaction with aqueous methyl formate under biphasic conditions. The only efficient catalyst is [PdCl₂(PCy₃)₂] (Cy = cyclohexyl). [RU₃(CO)₁₂] and ammonium formate improve yield and selectivity. The mechanism should involve oxidative addition of the C---Cl bond to a zero-valent Pd species followed by CO insertion. The palladium catalyst may also directly activate methyl formate. The procedure is convenient (no solvent, no initial pressurization) and at least as efficient as previously described methods.