X-ray structural study of the first bicluster π-arene complex [η6-PhCo4(CO)9]2CH2 and binuclear complex [η6-PhCr(CO)3]2CH2

It has been established by X-ray structural study that the bicluster cobalt -arene complex of diphenylmethane [⁶-PhCo₄CO₉]₂CH₂ and binuclear complex [⁶-PhCr(CO)₃]₂CH₂ have ans-trans-s-trans conformation in their crystals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1111–1117, June, 1995.This work was supported by the Russian Foundation for Basic Research (Projects No. 93-03-4028 and 94-03-08338).     

Planar chiral (η5-cyclohexadienyl)- and (η6-arene)-tricarbonylmanganese complexes: synthetic routes and application

Planar chiral arenetricarbonylchromium complexes have been intensively investigated and they have been applied as valuable building blocks for asymmetric synthesis and as ligands for asymmetric catalysis. In contrast, in the field of the isoelectronic cationic [(η(6)-arene)Mn(CO)(3)](+) complexes, until these last 10 years, very few studies were published involving nonracemic planar chiral cationic complexes and their potential applications, certainly because of the difficult access to enantiopure starting material. In 2009, however, the discovery of the first resolution of such compounds opened a new area for their application in the field of organic as well as of organometallic enantioselective syntheses. We felt it important to write a review on this subject to give an up-to-date summary of the methodologies used to prepare enantiomerically pure planar chiral neutral [(η(5)-cyclohexadienyl)Mn(CO)(3)] and cationic [(η(6)-arene)Mn(CO)(3)](+) complexes as well as their potential in enantioselective synthesis.     

Thermal isomerization of η6-arene ferradicarbolllides. Experimental proof for isolobal relation between (η6-arene)Fe and (η5-cyclopentadienyl)Co cluster units

The heating of selected [1-(η(6)-arene)-closo-1,2,3-FeC(2)B(9)H(11)] complexes resulted in the thermal rearrangement and isolation of the corresponding 1,2,4-, 1,2,7-, and 1,2,8-cage isomers. Demonstrated here is a similar rearrangement and the NMR behaviour for isostructural [1-(η(5)-cyclopentadienyl)-closo-1,2,3-CoC(2)B(9)H(11)] compounds.     

Preparative chemistry with [Ru(η6-arene)(H2O)3]2+: bis-arene and monobenzene complexes with O,N and S donors

The preparation, and electronic, ¹H and ¹³C NMR spectra of the complex ions [Ru(η⁶-C₆H₆)L₃]²⁺ (L = acetonitrile, dimethylsulphoxide, dimethylsulphide or tetrahydrothiophene) from [Ru(η⁶-C₆H₆)(H₂O)₃]²⁺ are reported. The NMR data of coordinated benzene are discussed in terms of the π-backbonding capacity of the monodentate ligand.     

Phosphine-centred resolution of (η4-diene)Fe(CO)3 complexes: (η4-tropone)Fe(CO)2L and (η4-isoprene)Fe(CO)2L [L = (+)-(neomenthyl)PPh2]

(η⁴-Tropone)Fe(CO)₃ and (η⁴-isoprene)Fe(CO)₃ form separable diastereoisomers on substitution of CO by (+)-(neomenthyl)PPh₂. In the tropone complex, diastereoisomer interconversion occurs by a 1,3-metal shift. The absolute configuration of the isoprene complex has been determined crystallographically.     

Electrochemical reductive acylation of (η6-arene)Cr(CO)3 complexes and (benzophenone)[Cr(CO)3]2

The electrochemical reductive acylation of (benzophenone)Cr(CO)₃ and (benzophenone) [Cr(CO)₃]₂ has been performed in DMF, by electrochemical reduction of complexed ketones in the presence of acetic and benzoic anhydride in excess. Three complexed benzhydryl esters ArCH(OCOR)PhCr(CO)₃, (Ar = Ph, R = Me: Ar = PhCr(CO)₃, R = Me; Ar = PhCr(CO)₃, R = Ph) were obtained in 46–57.5% yields after purification. Electrochemical reduction of (diphenylmethane)Cr(CO)₃ in the presence of acetic anhydride in excess leads to m-benzyl acetophenone.     

The synthesis and reactivity of the heptanuclear dianion [Os7(CO)20]2− including the synthesis and structural characterizations of the compounds [Os7(CO)20(AuPEt)3 2] and [Os8(CO)20(η6-C6H6]

Reduction of the heptaosmium cluster [Os₇(CO)₂₁] With [Et₄N][NH₄) gives the cluster dianion [Os₇(CO)₂₀]^2–,1, in high yield. The reaction of the dianion with [AuPR ₃Cl] (R=Et or Ph) in the presence of TlPF₆ forms [Os₇((CO)₂₀(AuPR ₃)₂] [R=Et (2a);R = Ph(2b)] in 80% yield, while the corresponding reaction with (Os(C₆H₆)(CH₃CN)₃]²⁺ gives [Os₈(CO)₂₀ ( ⁶-C₆H₆)] (3) in reasonable yield (ca. 30%). The dianion,1, and the clusters2 and3 have been fully characterized by bout spectroscopic and crystallographic methods. The crystal structure of the [Ph₄P]⁺ salt of1 shows that the metals in the anion adopt a capped octahedral geometry, with all twenty carbonyl ligands in terminal sites. The metal core geometry in2a is best described as a tricapped octahedron, and is based on the structure of the dianion1 with two adjacent octahedral faces capped by the Au atoms of the two AuPEt₃ groups. In a similar fashion, the geometry of3 is related to that of1 with the addition of an Os(C₆H₆) unit capped to a triangular face, to give a bicapped octahedral framework.     

New one-pot methods for the synthesis of metallonium dications [1,2-(η5:σ:σ-C5Me3(CH2)2)(η5-Cp*)Os]2+ and [1,1"-(η5:σ-C5Me4CH2)2Os]2+ based on decamethylosmocene or its derivatives

The reaction of Cp*₂Os or [Cp*₂OsH]⁺PF₆ ^– with oleum on heating or UV photolysis of Cp*₂Os in oleum under an inert atmosphere afforded two metallonium dications, viz., [1,2-(⁵::-C₅Me₃(CH₂)₂)(⁵-Cp*)Os]²⁺ and [1,1"-(⁵:-C₅Me₄CH₂)₂Os]²⁺. The structures of these dications were confirmed by the results of their alkoxylation. The [Os(H)₂(Cp*)₂]²⁺ and [Os(H)(Cp*)(C₅Me₄CH₂)]²⁺ dications were detected as intermediates in the above syntheses. All compounds were characterized by NMR spectroscopy. Calculations of the dications were carried out using the density functional theory (DFT).     

Nucleophilic substitution reactions of acetylides on substituted tricarbonyl(η6-fluoroarene)chromium and reactions of tricarbonyl[η6-(2-trimethylsilylethynyl)toluene]chromium and tricarbonyl[η6-(p-ethynyl-phenylethynyl)benzene]chromium with dicobalt octacarbonyl

Nucleophilic substitution reactions of various acetylides on substituted tricarbonyl(η⁶-fluoroarene)chromiums were pursued. The reaction presumably underwent a more complicated mechanism rather than the direct substitution on the fluorine-bearing carbon. The organometallic compounds (η⁶-C₆H₃R¹R²R³)Cr(CO)₃ (R¹: CC–C₆H₄CH₃, R²: o-Me, R³: H (5a), R¹: CC–C₆H₄CH₃, R²: o-OMe, R³: H (6a), R¹: CC–C₆H₄CH₃, R²: m-OMe, R³: H (6b), R¹: CCPh, R²: o-Me, R³: o-OMe (8b), R¹: CCPh, R²: m-Me, R³: m-OMe (8c), R¹: CCSiMe₃, R²: o-Me, R³: H (9a), R¹: CC–C₆H₄CCH, R²: H, R³: H (12), R¹: CC–C₆H₄CCH, R²: o-Me, R³: H (13)) as well as the organometallic dimmer [{(η⁶-o-Me-C₆H₄)Cr(CO)₃(di-ethynyl)] (di-ethynyl: CC–C₆H₄CC (14)) have been synthesized from nucleophilic substitution reactions of tricarbonyl(η⁶-fluoroarene)(chromium) compounds with suitable acetylides. The products have been characterized by spectroscopic means. In addition, (8b) and (8c) were characterized by X-ray diffraction studies. Further reactions of (9a) and (12) with appropriate amount of Co₂(CO)₈ yielded μ-alkyne bridged bimetallic complexes, Co₂(CO)₆{μ-Me₃SiCC–(o-tolueneCr(CO)₃} (10) and (Co₂(CO)₆)₂{μ-HCC–C₆H₄–CC–(benzene)Cr(CO)₃)}(15), respectively. Both (10) and (15) were characterized by spectroscopic means as well as single crystal X-ray crystallography. The core of these molecules is quasi-tetrahedron containing a Co₂C₂ unit. A two-dicobalt-fragments coordinated di-enyls complex, (Co₂(CO)₆)₂{μ-HCC–C₆H₄–CC–H} (17), was synthesized from the reaction of 1,3-diethynylbenzene with Co₂(CO)₈. Crystallographic studies of (17) also show that it exhibits a distorted Co₂C₂ quasi-tetrahedral geometry.     

Total synthesis of (±)-hirsutine: application of phosphine-catalyzed imine-allene [4 + 2] annulation

The total synthesis of the indole alkaloid hirsutine has been achieved, with a key step being the application of our phosphine-catalyzed [4 + 2] annulation of an imine with ethyl α-methylallenoate. From commercially available indole-2-carboxaldehyde, the target was synthesized in 14 steps and 6.7% overall yield.     

Crystal structure and magnetic properties of a three-dimensional complex constructed from [CuL]2+ and [Fe(CN)6]3− precursors

Self-assembly of the precursor [Cu(L)]²⁺ (L = 3,10-dipropyl-1,3,5,8,10,12-hexaazacyclotetradecane) with hexacyanometalate [Fe(CN)₆]³⁻ produces a 3-D cyano-bridged Cu(II)–Fe(III) bimetallic assembly, [CuL]₂[Fe(CN)₆]ClO₄ · H₂O (1), characterized by single-crystal X-ray diffraction studies, and magnetic measurements. The crystallographic determination reveals that each hexacyanoferromate(III) ion connects four copper(II) ions using four co-planar CN⁻ groups which axially coordinate to the copper ion in a trans fashion forming trans-CuL(N≡C)₂ moieties in (1). Magnetic studies reveal that (1) displays a ferromagnetic interaction between Cu(II) and Fe(III) through the CN linkage.     

The reactions of [Fe2(η-Cp)2(CNAr)4] complexes with halogens and tin(II) halides

Summary [Fe₂(-Cp)₂(CNAr)₄] (2) (540-01, C₆H₄Me-2, C₆H₄Et-2, C₆H₃Me₂-2,4, C₆H₃Me₂-2,6, C₆H₃(Me)Et-2,6, C₆H₃Et₂-2,6 or C₆H₃ i-Pr₂-2,6) react with I₂ to give [Fe(-Cp)(CNAr)₂I], but with Br₂[Fe(-Cp) (CNAr)₃]⁺ salts are the only products; IBr gives a mixture of the two. With SnX₂ (X = F, Cl, Br or I) in refluxing n-butanol, (2) gives isolable [{Fe(-Cp)(CNAr)₂}₂SnX₂] only when the CNAr ligands have two ortho substituents, otherwise decomposition occurred. When X = F, [Fe(-Cp) (CNAr)₂SnF₃] was also obtained from this reaction. Attempts to prepare [Fe(-Cp)(CNAr)₂X] (X = Cl or Br) by reaction of (2) with HX in the presence of air gave rather unstable products which with SnX₂ formed [Fe(-C₅H₅)-(CNAr)₂SnX₃]. Similar compounds, [Fe(-Cp) (CNAr)₂ SnX₂I], were obtained from [Fe(-Cp)-(CNAr)₂I] and SnX₂ (X = Cl or Br but not I). All of these complexes are much less stable than their Fe(-Cp)(CO)₂ counterparts; all decompose in solution to [Fe(-Cp)(CNAr)₃]⁺ which then break down to unidentified species. X-ray diffraction studies show that in [Fe(-Cp)(CNC₆H₃-i-Pr₂-2,6)₂I] and [{Fe(-Cp)(CNC₆H₃Me₂-2,6)₂}₂SnBr₂] there is pseudo-octahedral coordination about Fe. In the latter there is also distorted tetrahedral coordination about Sn so that its structure is very similar to that of [{Fe(-Cp)(CO)₂}₂SnCl₂]. Spectroscopic studies show that in all complexes rotation of the aryl rings of the CNAr ligands cannot be slowed in solution, and that there is free rotation about all 540-02 bonds.     

Some reactions of [(η6-C6Me6)Ru(η6-[2.2]paracyclophane)]-[BF4]2 with nucleophiles

Single addition of the nucleophiles X⁻ (X = H, CN, OH) to the less sterically hindered ring in [(η⁶-C₆Me₆)Ru(η⁶-C₁₆H₁₆)][BF₄]₂ (1) proceeds smoothly to produce, as the sole product, [(exo-η⁵-C₆Me₆X)Ru(η⁶-C₁₆H₁₆)][BF₄]. Use of Na[BD₄] in place of Na[BH₄] gives the expected shift in ν(C-H_exo) in the infrared spectrum.     

Dissociation kinetics of [Fe(phen)3]2+, [Fe(bipy)3]2+ and [Fe-(4,4′-Me2bipy)3]2+ in the presence of cyanide ion in aqueous solution at pressures up to 1 kilobar

Summary Rate constants for dissociation, in aqueous solution at 25° C, of [Fe(phen)₃]²⁺, [Fe(bipy)₃]²⁺, and [Fe(4,4-Me₂bipy)₃]²⁺ in the presence of cyanide, and of the last-named complex also in the presence of hydroxide, are significantly decreased by the application of pressure (up to 1 kbar). Kinetic measurements were carried out using a high pressure cell of improved design to that used in our earlier investigations. Volumes of activation, V ^*, are scarcely sensitive to ligand or to attacking nucleophile, being in the range of 10–12 cm³ mol^–1. An explanation of these results resides in an associative mechanism, a scheme invoked for similar reactions reported previously.     

A doubly deprotonated form of calix[6]arene: Crystal and molecular structure of (calix[6]arene-2H)2−·(HNEt 3 + )2

The doubly deprotonated form of calix[6]arene, with two protonated triethylamines as counter-ions, crystallizes in the monoclinic system: space groupP2₁/n,a=8.465(4),b=17.822(8),c=15.182(6) Å,=90.18(4)°,V=2291(2) ų,Z=2. Refinement led to a final conventionalR value of 0.063 for 1046 reflections. The macrocycle conformation is not apinched cone, usual for freeR-calix[6]arene, but a distorted 1,2,3-alternate cone, since the molecule lies on a symmetry center. Furthermore, one of the torsion angles defined by the methylene bridges is near to zero, which is unusual in calixarene structures. Supplementary Data relating to this article (atomic coordinates for hydrogen atoms, anisotropic displacement parameters for oxygen and nitrogen atoms, and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82182 (7 pages).     

Reaction of 2-(diphenylphosphino)-pyridine and -thiazole organoiron(0) polydentate ligands with iron(III) salts: X-ray structures of [η2-Ph2P(O)py]2Fe(μ-Cl)2FeCl2 and Fe(NCS)2[η2-Ph2P(O)taz]2 (taz=thiazole)

The reaction of trans-Fe(CO)₂(CS₂)(Ph₂Ppy-P)₂ (Ph₂Ppy=2-(diphenylphosphino)pyridine) with FeCl₃ resulted in the formation of the binuclear complex [η²-Ph₂P(O)py]₂Fe(μ-Cl)₂FeCl₂ (1), while the reaction of trans-Fe(CO)₃(Ph₂Ptaz-P)₂ (Ph₂Ptaz=2-(diphenylphosphino)thiazole) with Fe(NCS)₃ gave Fe(NCS)₂[η²-Ph₂P(O)taz]₂ (2). The crystal structures of (1) and (2)·C₆H₆ have been determined using X-ray crystallography.     

Synthesis, properties, and thermal decomposition of compounds [Co(En)3][Fe(CN)6] · 2H2O and [Co(En)3]4[Fe(CN)6]3 · 15H2O

Binary complex salts, [Co(En)₃][Fe(CN)6] · 2H₂O and [Co(En)₃]₄[Fe(CN)₆]₃ · 15H₂O, are synthesized. The properties of the salts and their thermolysis in air, dihydrogen, and argon are studied. Oxides of the central ions of the binary complex salts are found to be the thermolysis products in an oxidative atmosphere. Solid solutions (intermetallic compounds) CoFe are the thermolysis products in the reductive atmosphere, whereas intermetallides containing considerable amounts of C and N and an impurity of Co and Fe oxides are the thermolysis products in an inert atmosphere. Gaseous thermolysis products in dihydrogen and argon are NH₃, hydrocarbons, and ethylenediamine.     

A Study on Thermal Decomposition of K_3[Fe(CN)_6] and KFe[Fe(CN)_6] in Helium

K3 [Fe(CN)6] and KFe[Fe(CN)6] are classical coordination compounds. However, the mechanism of decomposition reactions has not been well expounded. The gas products of thermal decomposition were examined by gas chroma tography (GC) , and the structure of the solid products by Mossbauer spectroscopy(MS) and X-ray diffraction(XRD). The findings are explained in terms of the theory of coordination chemistry and a decomposition mechanism is proposed in this study. On the basis of various experimental results, the first stage of the decomposition of K3[Fe(CN)6] in He was found to be the evolution of(CN)2 resulting in the reduction of Fe(Ⅲ)12K3 [Fe(CN)6]→9K4[Fe(CN)6] + Fe2 [Fe(CN)6] + 6 ( CN )For KFe [Fe(CN) 6 ], the first stage of decomposition man be represented as6KFe[Fe(CN)6]→3K2Fe[Fe(CN)6] + 2Fe2[Fe(CN)6 + 3(CN)2At higher temperatures, the decomposition of both K3[Fe(CN)6) andKFe[Fe(CN)6] to form KCN and Fe2C was accomplished by the release of(CN)2 and N2.     

The Thermolysis of [Ru3(CO)12] in Cyclohexene: Synthesis and Charaterisation of the New Clusters [Ru3H2(CO)9(μ3-η1:η2:η1-C6H8)] and [Ru5(CO)12(μ4-η2-C6H8)(η4-C6H8)]

Thermolysis of [Ru₃(CO)₁₂] in cyclohexene for 24 h affords the complexes [Ru(CO)₃(η⁴-C₆H₈)] (1), [Ru₃H₂(CO)₉(μ₂-η¹:η²:η¹-C₆H₈)] (2), [Ru₄(CO)₁₂(μ₄-C₆H₈)] (3) [Ru₄(CO)₉(μ₄-C₆H₈)(η⁶-C₆H₆)] (4a and 4b, two isomers) and [Ru₅(CO)₁₂(μ₄-η²-C₆H₈)(η⁴-C₆H₈)] (5), where 1, 3, 4a and 4b have been previously characterised as products of the thermolysis of [Ru₃(CO)₁₂] with cyclohexa-1,3-diene. The molecular structures of the new clusters 2 and 5 were determined by single-crystal X-ray crystallography, showing that two conformational polymorphs of 5 exist in the solid state, differing in the orientation of the cyclohexa-1,3-diene ligand on a ruthenium vertex.     

Heterobimetallic Cyclosiloxanolate Sandwich Clusters: Na[η6-cyclo(PhSiO2)6]2[Fe(OR)]2Ni4(μ6-Cl) (R = H, Me)

The heterobimetallic cyclosiloxanolate sandwich clusters Na[⁶-cyclo (PhSiO₂)₆]₂[Fe(OR)]₂Ni₄(₆-Cl) (R = H, Me) (1) were prepared from Na₂[(PhSiO₂)₆]₂Na₄Ni₄(OH)₂ in the form of solvates. The new clusters 1 were characterized by spectra (UV-VIS, IR, ¹H-NMR), cyclic voltammetry. conductivity, magnetic susceptibility, and single-crystal X-ray diffraction.