Unsaturation in binuclear cyclopentadienylchromium carbonyl thiocarbonyls: Viability of (η-C5H5)2Cr2(CS)2(CO)3 in contrast to (η-C5H5)2Cr2(CO)5

The cyclopentadienylchromium carbonyl thiocarbonyls Cp₂Cr₂(CS)₂(CO)_n (n = 4, 3, 2, 1) have been studied by density functional theory using the B3LYP and BP86 functionals. The lowest energy Cp₂Cr₂(CS)₂(CO)₄ structure can be derived from the experimentally characterized unbridged Cp₂Cr₂(CO)₆ structure by replacing the two terminal carbonyl groups furthest from the Cr-Cr bond with two terminal CS groups. The two lowest energy Cp₂Cr₂(CS)₂(CO)₃ structures have a single four-electron donor η²-μ-CS group and a formal Cr-Cr single bond of length ∼3.1 Å. In contrast to the carbonyl analogue Cp₂Cr₂(CO)₅ these Cp₂Cr₂(CS)₂(CO)₃ structures are viable with respect to disproportionation into Cp₂Cr₂(CS)₂(CO)₄ and Cp₂Cr₂(CS)₂(CO)₂ and thus are promising synthetic targets. The lowest energy Cp₂Cr₂(CS)₂(CO)₂ structures have all two-electron donor CO and CS groups and short CrCr distances around ∼2.3 Å suggesting the formal triple bonds required to give the chromium atoms the favored 18-electron configurations. These Cp₂Cr₂(CS)₂(CO)₂ structures are closely related to the known structure for Cp₂Cr₂(CO)₄. In addition, several doubly bridged structures with four-electron donor η²-μ-CS bridges are found for Cp₂Cr₂(CS)₂(CO)₂ at higher energies. The global minimum Cp₂Cr₂(CS)₂(CO) structure is a triply bridged triplet with a CrCr triple bond (2.299 Å by BP86). A higher energy singlet Cp₂Cr₂(CS)₂(CO) structure has a shorter Cr-Cr distance of 2.197 Å (BP86) suggesting the formal quadruple bond required to give each chromium atom the favored 18-electron configuration.     

Cyclopentadienyl chromium and tungsten complexes with halide, methyl and σ-phenylethynyl ligands: Structures of (η-C5H5)Cr(NO)2(-CC-C6H5), (η-C5H5)Cr(NO)2I and [(η-C5H4)-COOCH3]W(CO)3Cl

With copper(I) iodide as catalyst, σ-alkynyls, compounds (η⁵-C₅H₅)Cr(NO)₂(CC-C₆H₅) (5), [(η⁵-C₅H₄)-COOCH₃]Cr(NO)₂(CC-C₆H₅) (10), and [(η⁵-C₅H₄)-COOCH₃]W(CO)₃(CC-C₆H₅) (13), were prepared from their corresponding metal chloride 1, 6 and 12. Structures of compound 3, 5 and 12 have been solved by X-ray diffraction studies. In the case of 5, there is an internal mirror plane passing through the phenylethynyl ligand and bisecting the Cp ring. The phenyl group is oriented perpendicularly to the Cp with an eclipsed conformation. The twist angle is 0° and 118.4° for -CC-Ph and two NO ligands, respectively. The orientation is rationalized in terms of orbital overlap between ψ₃ of Cp, dπ of Cr atom, and π^∗ of alkynyl ligand, and complemented by molecular orbital calculation. The opposite correlation was observed on the chemical shift assignments of C(2)-C(5) on Cp ring in compounds 6 and 12, using HetCOR NMR spectroscopy. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of ¹³C NMR data and compared with the calculations via density functional B3LYP correlation-exchange method.     

双核Fe配合物[(η5-C5H4)C6H10(C4H3S)Fe(CO)2]2的合成和晶体结构

由侧链带有噻吩的环戊二烯基配体C5H5C6H10C4H3S与Fe(CO)5在二甲苯中加热回流,合成了1个新颖的四羰基二铁配合物[(η5-C5H4)C6H10(C4H3S)Fe(CO)2]2。通过元素分析、IR、1H NMR对其结构进行了表征,用X-射线单晶衍射确定了其结构。X-射线单晶衍射表明配合物中有2个桥羰基和2个端羰基,Fe-Fe的键长为0.25465(10)nm。     

Dynamic behavior of [(η-C5H4CH3)Cr(CO)2(μ-SBu)Pt(PPh3)2] in solution

The structure and dynamic behavior of complex [(η⁵-C₅H₄CH₃)Cr(CO)₂(μ-SBu)Pt(PPh₃)₂] in solution was studied by multinuclear (¹H, ¹³C, ³¹P) NMR spectroscopy including a phase-sensitive NOESY experiment. Increasing temperature causes rupture of the Cr-Pt bond in the three-membered ring of the complex and rotation of the S-Pt(PPh₃)₂ unit around the Cr-S bond line, followed by formation of a new Cr-Pt bond to close the ring. All activation parameters for this dynamic process have been determined.     

Lanthanide nitrate complexes of the redox active ligand (ηC5H4P(O)Ph2)2Fe

The synthesis of complexes of (η⁵C₅H₄P(O)Ph₂)₂Fe = L with lanthanide nitrates is described. The single crystal X-ray structures for La(NO₃)₃L(μ-L)La(NO₃)₃L (1), [Eu(NO₃)₂L₂]₂[Eu(NO₃)₅] (2), [Ho(NO₃)₂L₂]₂[Ho(NO₃)₅] (3) and [Lu(NO₃)₂L₂] NO₃ (4) are reported. Trends in Ln–O bond distances cannot be explained by the lanthanide contraction alone. The cyclic-voltammetric (CV) oxidation–reduction behaviour of 1, 2, 4 and Dy(NO₃)₃L₂ · 2H₂O is described. This was reversible on a timescale of a few seconds in all cases. In our hands the CV behaviour of L also seemed reversible on this timescale, although attempted chemical oxidation of L led to the isolation of [FeL₂(NO₃)₂]NO₃ (5) which was characterised by X-ray crystallography.     

Synthesis, spectroscopic characterization and reactivities of linear and butterfly chromium/selenium complexes containing substituted cyclopentadienyl ligands: crystal structures of [{η-MeC5H4Cr(CO)2}2Se] and [{η-EtO2CC5H4Cr(CO)2}2Se2]

The Cr-Cr singly-bonded dimers [{η⁵-RC₅H₄Cr(CO)₃}₂] (1, R=Me; 2, R=CO₂Et) reacted with an equivalent of elemental selenium in THF at room temperature to give the linear Cr₂Se complexes [{η⁵-RC₅H₄Cr(CO)₂}₂Se] (3, R=Me; 4, R=CO₂Et), whereas the linear Cr₂Se complex (5, R=MeCO) reacted with excess NaBH₄, Ph₃PCHPh or 2,4-dinitrophenylhydrazine under respective conditions to afford the linear Cr₂Se derivatives [{η⁵-RC₅H₄Cr(CO)₂}₂Se] (6, R=MeCH(OH); 7, R=PhCHCMe; 8, R=2,4-(NO₂)₂C₆H₃NHNCMe). Similarly, while the butterfly Cr₂Se₂ complexes [{η⁵-RC₅H₄Cr(CO)₂}₂Se₂] (9, R=Me; 10, R=CO₂Et) could be produced either by reaction of dimers 1 and 2 with an excess amount of elemental selenium, or by reaction of the linear complexes 3 and 4 with an equivalent of elemental selenium, the butterfly Cr₂Se₂ derivatives [{η⁵-RC₅H₄Cr(CO)₂}₂Se₂] (12, R=MeCH(OH); 13, R=PhCHCMe; 14, R=2,4-(NO₂)₂C₆H₃NHNCMe) were yielded by reaction of the butterfly Cr₂Se₂ complex (11, R=MeCO) with an excess quantity of NaBH₄, Ph₃PCHPh and 2,4-dinitrophenylhyazine. Both the linear complexes 3, 4, 6-8 and the butterfly complexes 9, 10, 12-14 are new, which have been fully characterized by elemental analysis, spectroscopy and X-ray crystallography.     

Functionalization of linear and cyclic siloxanes and a dendritic carbosilane with (η-C5H5)Fe(CO)2Si(CH3)2CHCH2 via hydrosilylation reaction

A series of multimetallic systems containing silicon-linked cyclopentadienyl dicarbonyl iron moieties including carbosilane dendrimers and cyclic and polymeric siloxanes have been prepared using hydrosilylation reactions. For this purpose the vinyl-substituted silyliron complex (η⁵-C₅H₅)Fe(CO)₂Si(CH₃)₂ CHCH₂ (1) was prepared by salt elimination reaction between Na[(η⁵-C₅H₅)Fe(CO)₂] and ClSi(CH₃)₂CHCH₂ and fully characterized. Hydrosilylation reaction of 1 with the appropriate Si-H functionalized molecules in the presence of Karstedt catalyst afforded the novel silyl carbonyl iron-functionalized cyclotetrasiloxane 2, dendrimer 3 and copolymer 4, in which the organometallic units are attached to the silicon-based frameworks through a two-methylene flexible spacer. The electrochemical behaviour of compounds 1-4 has been examined in dichloromethane, tetrahydrofuran and acetonitrile solutions using cyclic voltammetry.     

Reactions of diferrocenyl dichalcogenides with [W(CO)5(THF)]: X-ray crystal structures of Fc2Te2 and [W2(μ-SeFc)2(CO)8] (Fc = [Fe(η-C5H5)(η-C5H4)])

Treatment of [W(CO)₅THF] with diferrocenyl diselenide, Fc₂Se₂, yielded the novel metal-metal bonded tungsten(I) complex, [W₂(μ-SeFc)₂(CO)₈] (1: Fc = ferrocenyl, [Fe(η⁵-C₅H₅)(η⁵-C₅H₄)]), which was characterised by NMR and IR spectroscopy, mass spectrometry, and X-ray crystallography. The corresponding tellurium derivative could not be prepared by an analogous route. The X-ray crystal structure of Fc₂Te₂ has also been determined.     

Photochemistry of β-(4-sydnonyl)-o-divinylbenzene: competitive cis-trans isomerization and photolysis

New cis- and trans-3-aryl-4-[2-(2-vinylphenyl)ethenyl]sydnones 2, aryl = phenyl, p-tolyl were prepared and transformed on irradiation in the presence of acrolein to a pyrazoline derivative that aromatized during isolation to trans-1-tolyl-3-[2-(2-vinylphenyl)ethenyl]pyrazole 7 and trans-5-formyl-1-tolyl-3-[2-(2-vinylphenyl)ethenyl]pyrazole 8.     

Synthesis of Mo(CO)2(η-PPh2(o-C6H4)C(O)H)2 and its reaction with C60

Reaction of Mo(CO)₃(NCMe)₃ and PPh₂(o-C₆H₄)C(O)H (abbreviated as PCHO) at room temperature affords Mo(CO)₂(η³-PCHO)₂ (1), while compound 1 and the phosphine-imine complex Mo(CO)₄(η²-PPh₂(o-C₆H₄)CHNMe) (2) are obtained by using Mo(CO)₃(η³-(MeNCH₂)₃) as the reactant. Thermal reaction of 1 with C₆₀ products Mo(CO)₂(η⁴-(PPh₂(o-C₆H₄)CH)₂)(η²-C₆₀) (3) in low yield, apparently through coupling of the formyl moieties. The structures of 1 and 3 have been determined by an X-ray diffraction study. The two aldehyde groups of 1 and C₆₀ ligand of 3 are coordinated to the molybdenum atom in a π-fashion.     

Synthesis and X-ray investigation of novel Fe and Mn phenyltellurenyl-halide complexes: (CO)3FeBr2(PhTeBr), (η-C5H5)Fe(CO)2(PhTeI2) and CpMn(CO)2(PhTeI)

New complexes of transition metals with organotellurium halide ligands are reported. Iodination of [CpMn(CO)₂]₂(μ-Ph₂Te₂) leads to the Te-Te bond cleavage and formation of CpMn(CO)₂(PhTeI). Oxidative addition of PhTeBr₃ to Fe(CO)₅ gives the monomeric complex (CO)₃FeBr₂(PhTeBr) which is isostructural with the recently reported (CO)₃FeI₂(PhTeI). Insertion of phenyltellurenyl iodide (PhTeI) into the Fe-I bond of CpFe(CO)₂I forms CpFe(CO)₂(TeI₂Ph). Molecular structures of the reported complexes were determined by single-crystal X-ray diffraction analysis (XRD). A considerable shortening of metal-tellurium distances is observed.     

The preparation and crystal structure of (η-C5H5)(OC)3Mo(CH2)3C6H5

The reaction of with p-CH₃C₆H₄S(O)₂O(CH₂)₃C₆H₅ produces (η⁵-C₅H₅)(OC)₃Mo(CH₂)₃C₆H₅. This is only the second structurally characterized organometallic species in which an aromatic moiety is separated by three or more methylene groups. The alkyl chain adopts a staggered conformation, the Mo-C(1)-C(2)-C(3)-C(4) unit is nearly coplanar, and the alkyl chain eclipses the trans-carbonyl group on Mo. NMR evidence indicates that this conformation is preserved in solution.     

Photochemical reactions of W(CO)6 with hydrosilanes: synthesis, spectroscopic characteristic, and crystal structure of W(CO)3(η-PhSiHPh2)

Photolysis of W(CO)₆ in the presence of Ph₃SiH in n-heptane leads to the formation of the first tricarbonyl(η⁶-triphenylhydrosilane)tungsten complex W(CO)₃(η⁶-PhSiHPh₂) (1) in good yield (ca. 70%). The molecular structure of the new tungsten-silane compound was established by single-crystal X-ray diffraction studies and characterized by IR, UV-Vis, ¹H, ¹³C{¹H}, and ²⁹Si{¹H} NMR spectroscopy.     

Allyl complexes of molybdenum with Schiff base ligands. The crystal structures of [MoCl(CO)2{N(C6H4-2-OMe)C(Me)C5H4N}(η-C3H5)] and [MoCl(CO)2{N(Me)C(Ph)C5H4N}(η-C3H5)] are described

Treatment of the molybdenum tetracarbonyl complexes of [Mo(CO)₄L₂] (L₂=pyridyl amine Schiff base ligands) with allyl chloride in refluxing THF afforded η³-allyl complexes [MoCl(CO)₂L₂(η³-allyl)] (1-9). These complexes have been characterised by various techniques including ¹H-NMR, IR and FABMS spectroscopies and the single crystal X-ray structure determinations of the complexes [MoCl(CO)₂{N(C₆H₄-2-OMe)C(Me)C₅H₄N}(η³-C₃H₅)] (3) and [MoCl(CO)₂{N(Me)C(Ph)C₅H₄N}(η³-C₃H₅)] (4).     

Solid-state isomerisation reactions of (η-C5H4R)M(CO)2(PR3)I (M=W, Mo; R=Bu, Me; R=Ph, OPr3)

The cis and trans monosubstituted cyclopentadienyl tungsten and molybdenum complexes (η⁵-C₅H₄R)M(CO)₂(L)I (1) (M=W, R=Me, ^tBu, L=P(OⁱPr)₃, PPh₃; M=Mo, R=Me, L=PPh₃) have been synthesised and fully characterised by elemental analysis and IR and NMR spectroscopy. It was found that 1 underwent a thermal solid-state ligand isomerisation reaction and that the favoured direction of the isomerisation reaction is related to the melting points of the cis and trans isomers, i.e., with intermolecular forces in the solid state. No obvious relationship between the melting point and the metal, the ring-substituent or the ligand was observed. Crystal structure determinations of the cis and trans isomers of (η⁵-C₅H₄Me)W(CO)₂(PPh₃)I reveal that a limited amount of isomer conversion can be accommodated in the unit cell of the trans isomer, prior to crystal fragmentation. The rearrangement of the molecules within the unit cell, during isomerisation, also leads to disorder in the crystal.     

Soft activation of the C-S bond: X-ray diffraction and spectroscopic study of the cluster Ru4(μ4-S)(μ,η3-C3H5)2(CO)12

The complex Ru₄(μ₄-S)(μ,η³-C₃H₅)₂(CO)₁₂ is prepared and examined by IR and NMR spectroscopy; its crystal structure is determined (an automatic Bruker-Nonius X8 Apex four-circle diffractometer equipped with a 2-D CCD-detector, 100 K, graphite-monochromated molybdenum source, λ = 0.71073 ?). The crystal belongs to the orthorhombic crystal system with unit cell parameters a = 19.3781(9) ?, b = 12.2898(7) ?, c = 10.1726(4) ?, V = 2422.6(2) ?³, space group Pnma, Z = 4, composition C₁₈H₁₀O₁₂Ru₄S, d _x = 2.343 g/cm³. The molecule of point symmetry C ₁ is situated on the mirror plane of the space group Pnma, two carbonyl groups at Ru2 and Ru3 atoms overlapping with the allylic ligand with a weight of 50% so that carbon atoms coincide. Thus, we have a racemic structure with two overlapping enantiomers of the molecule of Ru₄(μ₄-S)(μ,η³-C₃H₅)₂(CO)₁₂. Original Russian Text Copyright ? 2008 by I. Yu. Prikhod’ko, V. P. Kirin, V. A. Maksakov, A. V. Virovets, and A. V. Golovin __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 49, No. 4, pp. 748–752, May–June, 2008.     

Synthesis and reactions of cycloheptadienyl and cyclooctadienyl tungsten complexes: X-ray crystal structure of [W(CO)2(PPh3)2(η-C7H9)][BF4]

Protonation of the cycloheptatriene complex [W(CO)₃(η⁶-C₇H₈)] with H[BF₄] · Et₂O in CH₂Cl₂ affords the cycloheptadienyl system [W(CO)₃(η⁵-C₇H₉)][BF₄] (1). Complex 1 reacts with NaI to yield [WI(CO)₃(η⁵-C₇H₉)], which is a precursor to [W(CO)₂(NCMe)₃(η³-C₇H₉)][BF₄], albeit in very low yield. The dicarbonyl derivatives [W(CO)₂L₂(η⁵-C₇H₉)]⁺ (L₂=2PPh₃, 4, or dppm, 5) were obtained, respectively, by H[BF₄] · Et₂O protonation of [W(CO)₂(PPh₃)(η⁶-C₇H₈)] in the presence of PPh₃ and reaction of 1 with dppm. The X-ray crystal structure of 4 (as a 1/2 CH₂Cl₂ solvate) reveals that the two PPh₃ ligands are mutually trans and are located beneath the central dienyl carbon and the centre of the edge bridge. The first examples of cyclooctadienyl tungsten complexes [WBr(CO)₂(NCMe)₂(1-3-η:5,6-C₈H₁₁)] (6) and [WBr(CO)₂(NCMe)₂(1-3-η:4,5-C₈H₁₁)] (7) were synthesised by reaction of [W(CO)₃(NCR)₃] (R=Me or Prⁿ) with 3-Br-1,5-cod/6-Br-1,4-cod or 5-Br-1,3-cod/3-Br-1,4-cod (cod=cyclooctadiene), respectively. Complexes 6 and 7 are precursors to the pentahapto-bonded cyclooctadienyl tungsten species [W(CO)₂(dppm)(1-3:5,6-η-C₈H₁₁)][BF₄] and [W(CO)₂(dppe)(1-5-η-C₈H₁₁)][BF₄] · CH₂Cl₂.     

Transformation of C2 units on a bimetallic tetranuclear cluster.: Reactivity of [Ru3Mo(μ3-η-CC)(μ-CO)3(CO)2(η-C5H4R)3(η-C5H5)] (R = H, Me)

The reactivity of [Ru₃Mo(μ₄-η²-CC)(μ-CO)₃(CO)₂(η-C₅H₄R)₃(η-C₅H₅)] (R = H; Me) have been investigated, initially to elucidate the nature of the starting material, and, latterly, to define the reactivity of an interesting ethane-1,2-bis(ylidyne) species. While the mixed RuMo clusters were unreactive towards simple electrophiles and carbonyl substitution by phosphine ligands they did react with atmospheric oxygen or carbon monoxide to give substantially different products. In all instances oxygen was incorporated either at the metal centre or at the C₂ fragment. High-pressure carbonylations yielded [Ru₃(μ-CO)₃(η-C₅H₅)₃(μ₃-C-C(O)O{Ru(CO)₂(η-C₅H₅)})] and [{Ru₂(μ-CO)(CO)₂(η-C₅H₄Me)₂}(μ₄-η²-CC){Ru(CO)(η-C₅H₄Me)Mo(η-C₅H₅)(=O)(μ-O)}], an ethane-1,2-bis(ylidene) complex, this exemplifying a relatively rare raft geometry which further reacted with Cl₂CCCl₂ to give [Mo₃(μ₄-C₂(Ru(CO)₂(η-C₅H₄Me))(CO)(μ-CO)(η-C₅H₅)₃(Cl)₂] having a similar geometry and undergone halogenation. In order to extend the extant examples of these raft clusters we explored the reaction of [{Ru(CO)₂(η-C₅H₄R)₂}₂(μ-C₂)] with [{Ru(CO)₂(η-C₅H₅)₂}₂] to provide a rational synthetic pathway leading to very reactive [Ru(μ₄-η²-CC)(μ₂-CO)₂(CO)₄(η-C₅H₄Me)₂(η-C₅H₄R)₂] rafts.     

配合物{(n-Bu)2Sn[(η5-C5H5)Fe(η5-C5H4)COO]2}2的合成、谱学表征及晶体结构

合成了新型配合物{(n-Bu)₂Sn[(η⁵-C₅H₅)Fe(η⁵-C₅H₄)COO]₂}₂，用元素分析、红外光谱和核磁共振谱( ¹H、¹³C、¹¹⁹Sn)进行了表征，并用X-射线单晶衍射分析法测定其晶体结构。晶体属单斜晶系，空间群P2₁/c，晶胞参数a=11.753(4)?，b=21.133(7)?，c=23.374(9)?，β=101.62(3)°，V=5687(4)?³，Z=4，D_c=1.614Mg·m^-3，μ(MoKα)=1.912mm^-1，F(000)=2800，最终可靠因子R₁=0.0827，wR₂=0.2085。配合物分子呈中心对称，是具有Sn₂O₂中心内环的二聚体结构;每个锡原子与5个O原子和2个C原子形成扭曲的五角双锥几何构型，其中5个O原子为赤道配位原子，而C-Sn-C为配合物的轴。     

Pyrolysis of [Ru3(CO)10(dppe)]: activation of CH and PPh bonds.: The crystal structure and dynamical behavior of [Ru4(CO)9(μ-CO){μ4-η-PCH2CH2P(C6H5)2}(μ4-η-C6H4)]

The pyrolysis reaction of [Ru₃(CO)₁₀(dppe)], compound 1, in toluene yields as the main product [Ru₄(CO)₉(μ-CO){μ₄-η²-PCH₂CH₂P(C₆H₅)₂}(μ₄-η⁴-C₆H₄)], compound 2. The X-ray structure of 2 shows a benzyne group coordinated to a square of ruthenium atoms and a μ₄-η²-PCH₂CH₂PPh₂ fragment. Variable-temperature NMR experiments showed three independent dynamic processes: a rotation of the benzyne group, CO migration and a twisting movement of the CH₂CH₂ fragment. The thermolysis of [Ru₃(CO)₁₀(dfppe)], compound 3, (dfppe=1,2-bis(dipentafluorophenylphosphino)ethane, carried out under the same conditions, showed 3 to be stable.