Exceptionally effective catalysis of cyclopropanation reactions by the hexarhodium carbonyl cluster

Hexadecacarbonylhexarhodium exhibits exceptional activity as a cyclopropanation catalyst in reactions between ethyl diazoacetate and alkenes that are remarkably free of competing processes.     

Synthesis and some properties of heteronuclear platinum and palladium carbonyl clusters

Heteronuclear clusters of general formula [Pt_xPd_y(CO) _z] were synthesized by reaction of CO with PtCl₄ + PdCl₂ solutions in 95% ethanol at room temperature and atmospheric pressure. The products isolated were analyzed by IR spectroscopy, thermogravimetry, and X-ray powder diffraction.     

取代苄基瞵酸脂与取代苯甲醛反应的动力学研究

本文报导几种中等活性的瞵酸脂与各种取代苯甲醛反应的动力学研究, 并考查了中等活性的瞵酸脂组分及中等活性的醛组分上不同取代对反应速度的影响。     

Rate-structure studies of the carbonylation and decarbonylation of substituted metal carbonyl complexes

The rate of CO insertion for the following complexes have been determined: RCH₂Mn(CO)₅ where R  cyclohexyl, hydrogen, phenyl, methoxy, and carboxyl; RCH₂Fe(CO)₄^? where R  cyclohexyl, n-octyl, n-heptyl, and phenyl. It appears that a Taft σ? correlation can be established for this reaction. Rate data for the decarbonylation reaction of an analogous series of substituted manganese carbonyl complexes (RCH₂COMn(CO)₅) was also obtained. As in the case of the CO insertion reaction, the rates increase as the Taft σ for RCH₂ decreases.The linear free energy relationships (LFER) generated in this study have been used to predict the relative probability of several reaction steps that have been postulated for the conversion of carbon monoxide and hydrogen into ethylene glycol.     

Raman-spectrum investigation of the equatorial and axial carbonyl groups of some substituted cyclohexanes

Summary In the determination of conformations in accordance with the largest substituents it is found that compound (IV) has the conformations trans-ee and trans-aa and compound (V) the conformations cis-ae and cis-ea; none of these conformations predominates substantially, as with neither of the two possible conformations of the compound (III).     

Arsido iron carbonyl clusters

Summary The XAsFe₄(CO)₁₄ (X = Cl, Br) clusters have been prepared and characterised and a new synthesis under mild conditions has been found for As₂Fe₃(CO)₉. The latter complex has at least two isomeric structures in solution.A preliminary account of this work was given in a lecture.The terms pnicogen and pnictide have been introduced as group names for the group Va family of elements analogous to the use of chalcogen and chalcogenid as group names for the group VIa elements.     

The activation of transition-metal carbonyl clusters

Methods by which the reactivity of transition-metal osmium carbonyl clusters may be modified are explored.     

Spectroscopic studies on the carboxylic acids of some carbonyl fluoride telomers

The NMR and infrared spectra of a series of carboxylic acids of carbonyl fluoride telomers, CF₃O(CF₂O)_nCF₂COOH (with n = 1 through 7) are described and tentative assignments for the main vibrational modes proposed.     

Vibrational spectra of bridging carbonyl groups in transition metal carbonyl clusters

The spherical harmonic model (SHM), previously used for the analysis of the terminal nu(CO) vibrations of transition metal carbonyl clusters, is applied to the corresponding bridging CO modes. The model is applicable, although the spectra show a greater sensitivity to the molecular geometry than is the case for their terminal counterparts. The reasons for this sensitivity are discussed. When both micro(2) and micro(3) CO groups are present in a molecule, a spectral distinction may not be apparent.     

Spectral studies of some substituted arylthiobenzo[f]quinolines

Synthesis and spectral studies (ir, ¹H nmr, ms) of 1- and 3-substituted arylthiobenzo[f]quinolines (IIIa-IIIc, IVa-IVc) obtained through nucleophilic displacement of the corresponding halobenzo[f]quinoline by various thiols (a-c) were done.     

Syntheses and molecular structures of some compounds containing many-atom chains end-capped by tricobalt carbonyl clusters

Several complexes containing Co₃ carbonyl clusters end-capping carbon chains of various lengths are described. Pd(0)/Cu(I)-catalysed reactions between {Co₃{μ₃-C(CC)₂Au(PPh₃)}(μ-dppm)(CO)₇ and I(CC)₂SiMe₃ or FcCCI gave {Co₃{μ₃-C(CC)_xR}(μ-dppm)(CO)₇ [x = 4, R = SiMe₃3; x = 3, R = Fc 8]; treatment of 3 with NaOMe and AuCl(PPh₃) gave 4 [x = 4, R = Au(PPh₃)]. Related preparations of Co₃{μ₃-C(CC)₂[Ru(PP)Cp′]}(μ-dppm)_n(CO)_9−2n [PP = (PPh₃)₂, Cp’ = Cp, n = 1, 5; PP = dppe, Cp′ = Cp^∗, n = 1, 6; 0, 7] are also described. Syntheses of bis-cluster complexes {Co₃(μ-dppm)(CO)₇}₂(μ-C_x) (x = 14, 12; 16, 9; 18, 11; 26, 10) - the latter being the longest cluster-capped C_x chains so far described - and the mercury-bridged compounds Hg{(CC)_xC[Co₃(μ-dppm)(CO)₇]}₂ (x = 1, 13; 2, 14) are reported. The molecular structures of 7, 12, 13 and 14, as well as of Co₃(μ₃-CCCSiMe₃)(μ-dppm)(CO)₆(PPh₃) (15) and Co₃{μ₃-CC(O)OEt}(μ-dppm)(CO)₇ (16), are reported.     

Homogeneous catalysis by ruthenium carbonyl clusters

The historical background of and the incentive for using ruthenium carbonyl clusters as homogeneous catalysts are outlined. Keeping in view the possible solutions the uncertainties arising from declusterification and metal colloid formation are discussed. All ruthenium cluster-catalysed reactions are broadly classified as reactions with or without carbon monoxide as one of the reactants and the basic differences between such reactions are highlighted. Some of the factors of special relevance to cluster-catalysed reaction systems are mentioned. The reactions involving carbon monoxide are then discussed. These include water-gas-shift reaction, carbon monoxide hydrogenation, hydroformylation, reductive carbonylation of nitrobenzene and other carbonylation reactions. Hydrogenation, transfer hydrogenation, isomerisation and a few other reactions are then discussed. For all these reactions, special emphasis is laid on well-characterised cluster complexes that have been proposed as catalytic intermediates. Finally an attempt has been made to identify the path that future research in cluster catalysis is likely to follow.     

Fluxionality in mixed-metal osmium carbonyl clusters

The heteronuclear clusters [Os₁₀C(CO)₂₄(MPR_3n^m− (n = 1, m = 1; 2: M = Au; 3: M = Ag; 4: M = Cu; 5 n = 2, m = 0, M = Ag) have been prepared. These clusters undergo molecular rearrangements in solution, and two isomeric forms of 2, 3, 4, 5 and 6 have been identified. This interconversion is thought to involve a cap [lrarr2] edge bridge [lrarr2] cap pathway.     

Some substituted thiourea complexes of molybdenum carbonyl

Preparation of monosubstituted thiourea complexes of molybdenum carbonyl [Mo(CO)₅L] both by thermal and UV irradiation methods have been described. The ligands (L) used were N,N′-dimethylthiourea (DMTU), N,N′-diphenylthiourea (DPTU), tetramethylthiourea (TMTU) and tetraethylthiourea (TETU). The complexes [Mo(CO)₅(L)] were characterised by NMR, IR, UV-visible and elemental analyses.