Synthesis,structure and stereochemistry of diiodide complexes (E)[(η5-t-BuC5H3)Fe(CO)2I]2 (E = Me2Si,Me2SiSiMe2, and Me2SiOSiMe2)

Reactions of diiron complexes (E)[⁵-t-BuC₅H₃)Fe(CO)]₂(-CO)₂ [E = Me₂Si (1), Me₂SiSiMe₂ (2), and Me₂SiOSiMe₂ (3)] with iodine in CHCl₃ yielded diiodide complexes (E)[⁵-t-BuC₅H³)Fe(CO)₂I]₂ [E=Me₂Si (5), Me₂SiSiMe₂ (6), and Me₂SiOSiMe₂ (7)]. Like (1–3), complexes (5–7) also exists as mixtures of cis and trans isomers even though the Fe–Fe bond in (1–3) has been cleaved. When the pure isomers (1–3) reacted with iodine respectively in CHCl₃, the cis isomers (1c–3c) yielded only the cis products (5c–7c), whereas the trans isomers (1t–3t) yielded only the trans isomers (5t–7t). This indicates that iodination of bridged diiron complexes is stereospecific. Similar treatment of trans-(Me₂Si)[{⁵-t-(heptyl)C₅H₃}Fe(CO)]₂(-CO)₂ (4t) with iodine gave only the trans product (Me_2Si)[{⁵-t-(heptyl)C₅H₃}Fe(CO)₂I]₂ (8t). The molecular structure of (5t) was determined by X-ray diffraction.     

(Me3Si)2NBCl2和(Me3Si)2NB(Cl)NHSiMe3的合成及其成环反应

自从氮化硼陶瓷纤维用聚合物先驱体法[1]合成以后,硼氮六元环化合物越来越为人们所重视[2],文中在制备氮化硼纤维先驱体的过程中,合成了其中间产物,通过热缩合成环反应,合成了含有硼氮六员环的化合物,并采用色-质联用技术对其进行了表征。1　实验部分参照文献[3],改用液氮和丙酮为冷冻剂,控制温度在-50到-40℃,搅拌下向三氯化硼的正戊烷溶液中缓慢滴加三乙胺的正戊烷溶液,滴完后Ｎ2气氛下-50℃加丙酮冷凝回流2ｈ,慢慢由-50℃升至室温,抽滤即得到白色产物Ｅｔ3ＮＢＣｌ3(Ａ)。将Ａ溶于适量苯中[4,5],加入等物质的量的三乙胺,加热回流搅拌…     

Mixed-ligand guanidinate derivatives of rare-earth metals. Molecular structures of { (Me3Si)2NC(N-cyclo-Hex)2}Y[N(SiMe3)2]2, [{ (Me3Si)2NC(N-cyclo-Hex)2}YbI(THF)2]2, and [{(Me3Si)2N} Y(THF)(µ-Cl)]2 complexes

The insertion of N,N′-dicyclohexylcarbodiimide at one of the Y-N bonds of the [(Me₃Si)₂N]₃Y complex in toluene at 70 °C afforded the monoguanidinate diamide derivative { (Me₃Si)₂NC(N-cyclo-Hex)₂}Y[N(SiMe)₃]₂ (1) (cyclo-Hex is cyclohexyl) in 72% yield. The reaction of equimolar amounts of sodium N,N′-dicyclohexyl-N″-bis(trimethylsilyl)guanidinate, which was prepared in situ from {(Me₃Si)₂N}Na and N,N′-dicyclohexylcarbodiimide, and YbI₂(THF)₂ in THF gave the [{(Me₃Si)₂NC(N-cyclo-Hex)₂}YbI(THF)₂]₂ complex (2). An attempt to use this procedure for the synthesis of the yttrium compound { (Me₃Si)₂NC(NSiMe₃)₂}₂YCl containing the sterically more hindered guanidinate ligand unexpectedly led to the formation of the diamide chloride complex [{(Me₃Si)₂N}₂Y(THF)(µ-Cl)]₂ (3). The structures of complexes 1–3 were established by X-ray diffraction. Compound 1 is mononuclear. Complexes 2 and 3 are dinuclear and contain two µ²-bridging halide ligands.     

Synthesis and molecular structure of [1, 3-(Me3Si)2C5H3]2Lu(μ-Cl)2

Cp^* ₂Lu(-Cl)₂ (1) was isolated following the reaction of Cp^*Na (Cp^* = 1, 3-(Me₃Si)₂C₅H₃) with LuCl₃ in THF and subsequent treatment with toluene at 80°C. An X-ray structural investigation of1 was performed (MoK radiation, 2933 reflections,R = 0.020). The crystals are triclinic,a = 10.744(3) Å,b=11.821(2) Å, c=12.966(3) Å, a=71.54(1)°, =85.32(2)°, =74.83(1)°,Z = 2, space groupP-1. Two Lu atoms withdistorted tetrahedral coordination are linked by two chloride bridges with a mean Lu-Cl distance equal to 2.62 Å.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 568–570, March, 1993.     

Synthesis and properties of guanidinate derivatives of rare-earth metals. Molecular structures of the { (Me3Si)2NC(NPri)2}2Y(µ-Cl)2Li(THF)2, [{ (Me3Si)2NC(NPri)2}2SmCl]2 and {(Me3Si)2NC(NPri)2} Sm(µ3-BH4)2(DME) complexes

The reaction of anhydrous SmCl₃ with two equivalents of lithium N,N′-diisopropyl-N″-bis(trimethylsilyl)guanidinate in THF afforded the [{(Me₃Si)₂NC(NPrⁱ)₂}₂SmCl]₂ complex (1) in 82% yield. Analogous reactions with YCl₃ and GdCl₃ produced the ate-complexes { (Me₃Si)₂NC(NPrⁱ)₂}₂Ln(µ-Cl)₂Li(THF)₂ (Ln = Y (2) and Gd (3)). The structures of complexes 1 and 2 were established by X-ray diffraction. The reaction of complex 1 with NaBH₄ in hexane (20 °C) followed by treatment with dimethoxyethane yielded the unexpected product, { (Me₃Si)₂NC(NPrⁱ)₂}Sm(µ³-BH₄)₂(DME) (5). X-ray diffraction study showed that both borohydride ligands in complex 5 are tridentate.     

Synthesis, molecular structures, and properties of heterometallic cobalt tetramethylcyclobutadiene complexes (C4Me4)Co(CO)2TePh, (C4Me4)Co(CO)2TePh[W(CO)5], and Me4C4Co(μ3-S)2Cr2Cp2(μ-SC4H9)

The reaction of Cb*Co(CO)₂I (1) (Cb* is tetramethylcyclobutadiene) with sodium phenyltelluride afforded the mononuclesar complex Cb*Co(CO)₂TePh (2). The reaction of the latter with W(CO)₅(THF) produced the Cb*Co(CO)₂TePh[W(CO)₅] compound (4). The reaction of 1 with the Cp₂Cr₂(SCMe₃)₂S complex gave the heterometallic cluster Cb*Co(μ₃-S)₂Cr₂Cp2 (μ-SCMe₃) (5). Complexes 2, 4, and 5 are diamagnetic. Their structures were determined by X-ray diffraction. Complex 2 contains the Co-Te bond (2.585(1) Å); complex 4, the Co-Te (2.558(8) Å) and W-Te (2.8467(6) Å) bonds. Complex 5 has the stable triangular sulfide-and tert-butylmercaptide-bridged core Cr₂Co (Cr-Cr and Cr-Co bond lengths are 2.626(2) and 2.673(2) Å, respectively) with Cp ligands at the chromium atoms and a Cb* ligand at the cobalt atom. Complex 5 was characterized by cyclic voltammetry. The thermolysis of complex 4 was studied.     

Low-temperature thermodynamics of Ln(Me2dtc)3(C12H8N2) (Me2dtc = dimethyldithiocarbamate, Ln = La, Pr, Nd, Sm)

The heat capacities of Ln(Me₂dtc)₃(C₁₂H₈N₂) (Ln = La, Pr, Nd, Sm, Me₂dtc = dimethyldithiocarbamate) have been measured by the adiabatic method within the temperature range 78–404 K. The temperature dependencies of the heat capacities, C _p,m [La(Me₂dtc)₃(C₁₂H₈N₂)] = 542.097 + 229.576 X ? 27.169 X ² + 14.596 X ³ ? 7.135 X ⁴ (J K^?1 mol^?1), C _p,m [Pr(Me₂dtc)₃(C₁₂H₈N₂)] = 500.252 + 314.114 X ? 17.596 X ² ? 0.131 X ³ + 16.627 X ⁴ (J K^?1 mol^?1), C _p,m [Nd(Me₂dtc)₃(C₁₂H₈N₂)] = 543.586 + 213.876 X ? 68.040 X ² + 1.173 X ³ + 2.563 X ⁴ (J K^?1 mol^?1) and C _p,m [Sm(Me₂dtc)₃(C₁₂H₈N₂)] = 528.650 + 216.408 X ? 16.492 X ² + 12.076 X ³ + 4.912 X ⁴ (J K^?1 mol^?1), were derived by the least-squares method from the experimental data. The heat capacities of Ce(Me₂dtc)₃(C₁₂H₈N₂) and Pm(Me₂dtc)₃(C₁₂H₈N₂) at 298.15 K were evaluated to be 617.99 and 610.09 J K^?1 mol^?1, respectively. Furthermore, the thermodynamic functions (entropy, enthalpy and Gibbs free energy) have been calculated using the obtained experimental heat capacity data.     

Synthesis and Molecular Structure of Tris(pentamethylphenyl)aluminum, (C6Me5)3Al, and the Magnesium Cluster [Mg6(μ3-OH)2(μ3-Br)2(μ2-Br)8(OEt2)8]

The synthesis and molecular structures of tris(pentamethylphenyl)aluminum, (C₆Me₅)₃Al, (I), and the magnesium cluster [Mg₆( ₃-OH)₂( ₃-Br)₂( ₂-Br)₈(OEt₂)₈] (II), are reported. Both compounds were isolated from the same system. The aluminum atom in (I) resides in an almost idealized trigonal planar environment. The dihedral angles of the pentamethylphenyl rings relative to the AlC₃plane in (I) are 67.2, 62.4, and 61.2°. The neutral magnesium cluster, (II), is interesting in that contains six magnesium atoms each of which resides in octahedral environments.     

Synthesis and structures of bridged diruthenium complexes (E)[η5-C5H4)Ru(CO)]2(μ-CO)2 (E = Me2Ge,Me2SiOSiMe2, Me2SiOSiMe2OSiMe2)

A series of bridged diruthenium complexes (E)[(⁵-C₅H₄)Ru(CO)]₂(-CO)₂ (E = Me₂Ge (2); Me₂SiOSiMe₂ (3); Me₂SiOSiMe₂OSiMe₂ (4)) has been prepared by reacting Ru₃(CO)₁₂ with Cp₂E in refluxing heptane. The molecular structures of (2) and (4) have been determined by X-ray diffraction.     

Guanidinate borohydride derivatives of lanthanides: synthesis and molecular structures of the [(Me3Si)2NC(NCy)2]Gd(BH4)2DME and [{(Me3Si)2NC(NPri)2}2Sm(BH4)2]−[Li(DME)3]+ complexes. Catalytic activity of the [(Me3Si)2NC(NCy)2]2Ln(BH4)2Li(THF)2 complexes (Ln = Nd, Sm, or Yb) in methyl methacrylate polymerization

The reaction of Gd(BH₄)₃(THF)₂ with two equivalents of sodium N,N′-dicyclohexyl-N″-bis(trimethylsilyl)guanidinate in THF followed by the treatment of the reaction product with 1,2-dimethoxyethane produced the monoguanidinate bis(borohydride) complex [(Me₃Si)₂NC(NCy)₂]Gd(BH₄)₂DME (1) (Cy is cyclohexyl). The treatment of the heterobimetallic samarium complex {(Me₃Si)₂NC(NPrⁱ)₂}₂Sm(BH₄)₂Li(THF)₂, in which the lanthanide and lithium atoms are linked by two bridging borohydride groups, with 1,2-dimethoxyethane afforded the ionic complex [{(Me₃Si)₂NC(NPrⁱ)₂}₂Sm(BH₄)₂]^?[Li(DME)₃]⁺ (2). The structures of complexes 1 and 2 were established by X-ray diffraction. The [(Me₃Si)₂NC(NCy)₂]₂Ln(BH₄)₂Li(THF)₂ complexes (Ln = Nd (3), Sm (4), or Yb (5)) were found to catalyze methyl methacrylate polymerization.     

New Stable Germylenes,Stannylenes, and Related Compounds II. Bis(butylthio)tin(II) and ate-Complexes [(Me3Si)3CE(μ-SBu)2Li(THF)2] (E = Ge,Sn). Synthesis and Structure

By reaction of Me₃SiSBu with anhydrous tin(II) chloride bis(butylthio)tin was obtained that exemplified a coordination polymer [Sn(SBu)₂] _n , whose elementary unit contained according to X-ray diffraction study three independent four-membered rings Sn₂S₂ of unusual geometry. It was demonstrated that polymeric thiolates [E(SBu)₂] _n (E = Ge, Sn) readily reacted with TsiLi (Tsi = C(SiMe₃)₃) in a mixed solvent ether THF affording in a good yield ate-complexes [(Me₃Si)₃CE(-SBu)₂Li(THF)₂]. Both complexes contain a four-membered ring in a butterfly conformation where the lithium atom is symmetrically bonded to both sulfur atoms, and the coordination polyhedra of Ge and Sn atoms may be regarded as distorted tetrahedra AB₃X, where one of coordination places is occupied by unshared electron pair. The structure of the ate-complexes observed in a crystal is conserved also in solution of nonpolar solvents.     

Novel Low Dimensional Cluster Compounds: Syntheses and Crystal Structures of Cs[{Me3Sn}3{Re6Se8(CN)6}], [{Me3Sn(H2O)}2{Me3Sn}{Re6Se8(CN)6}] · H2O, and [(Me3Sn)3(OH)2][{Me3Sn}3{Re6Se8(CN)6}]. pH Control of the Structural Dimensionality

Three novel cluster complex compounds Cs[{Me₃Sn}₃{Re₆Se₈(CN)₆}] (1), [{Me₃Sn(H₂O)}₂{Me₃Sn}{Re₆Se₈(CN)₆}] · H₂O (2) and [(Me₃Sn)₃(OH)₂][{Me₃Sn}₃{Re₆Se₈(CN)₆}] (3) have been synthesized by reaction of Cs₃KRe₆Se₈(CN)₆ with SnMe₃Cl in aqueous solutions at different pH values (pH ～7 for 1, pH <7 for 2 and pH >7 for 3). The crystal structures of all compounds have low dimensional features (linear chains in 1, zig-zag chains in 2; layers in 3), they are polymeric ones based on ${-}{\rm Re}_{6}{-}{\rm CN}{-}{\rm SnMe}_{3}{-}{\rm NC}{-}{\rm Re}_{6}{-}$ bonding. The connectivity of these structures is determined strongly by reaction conditions, in particular, pH of reaction solutions.     

Triphospha-Ferrocenes as Ligands. Crystal Structures of [Fe(η5-C5Me5)(η5-C2 TBu2P3)M(CO)5)], (M= Cr,MO, W) and the Novel ruthenium and Nickel Complexes [Fe(η5-C5Me5) (η5-C2 TBu2P3)Ru3(CO)9] and [Fe(η5-C5Me5)(η5-C2 tBu2P3)Ni(Co)2]2

Abstract

Syntheses and structures of penta- and hexaphosphorus analogues of ferrocene have been described recently¹. Unlike their simple ferrocene analogues, these complexes have further ligating potential towards other transition metal centres by virtue of the availability of the ring phosphorus lone-pair electrons that are not involved in the η⁵-coordination. We now describe the first examples of coordination compounds of the triphospha-ferrocene [Fe(η⁵-C₅Me₅) (η⁵-C₂ ^tBu₂P₃]. In the ruthenium complex [Fe(η⁵-C₅Me₅)(η⁵-C₂ ^tBu₂P₃) Ru₃(CO)₉] ² two adjacent phosphorus atoms of the η⁵-C₂ ^tBu₂P₃ ring are interlinked by a ruthenium carbonyl cluster in which all three ruthenium atoms interact with the phosphorus atoms. The tetrametallic nickel complex [Fe(η⁵-C₅Me₅)(η⁵-C₂ ^tBu₂P₃)Ni(CO)₂]₂ ³ represents the first example of intermolecular interlinkage of two phospha-ferrocene systems by two metal centres.     

New polynuclear molecular ferromagnetic complex {Co3((η2-NH2)2C6H2Me2)2(μ-OOCCMe3)2(η1-OOCCMe3)2(η2-OOCCMe3)2(HOOCCMe3)2}{Co((η2-NH2)2C6H2Me2)2(η1-OOCCMe3)2}

Russian Chemical Bulletin -     

The all non-metal homodinuclear and heterodinuclear sandwich-like compounds C2(η3-L3)2 and BN(η3-L3)2 (L = BCO, BNN and CBO)

Density functional theory studies on the all non-metal homodinuclear and heterodinuclear sandwich-like compounds C(2)(η(3)-L(3))(2) and BN(η(3)-L(3))(2) (L = BCO, BNN and CBO) have been performed. The staggered conformations of both C(2)(η(3)-L(3))(2) and BN(η(3)-L(3))(2) are predicted to be stable. The non-metal direct C-C and B-N bonds are covalent with σ interactions, which are formed by the interactions of s and p(z) orbitals of the center atoms. Different from the ionic metal-ligand bond in the traditional metal center sandwich-like compounds, the C-L, B-L, and N-L bonds are covalent in these all non-metal sandwich-like compounds. The NICS values indicate that the ligands of C(2)(η(3)-L(3))(2) and BN(η(3)-L(3))(2), as well as their bare rings, display multiple aromaticity (σ and π aromaticity). Both σ and π aromaticity of the ring ligands towards the center atoms become stronger after complexation with the center atoms, while the π aromaticity against the center atoms is reduced. The π aromaticity of the ligands bonded to different center atoms follows a trend of B > C > N, and the (CBO)(3)(+) ligands bonded to B possess the strongest π aromaticity. The dissociation reactions and possible synthetic reactions analysis show that these all non-metal sandwich-like compounds are stable, and the homodinuclear species are more stable than the heterodinuclear ones. These all non-metal binuclear sandwich-like compounds can be regarded as potential synthetic targets according to the highly negative free energies of the possible synthetic reactions. The isomerization reactions demonstrate that the CBO-based compounds should be more possible to synthesize in experiments than their BCO-based isomers.     

Alkyne-vinylidene coupling in the reactions of the alkyne complex Os3(μ-CO)(CO)9(μ3-Me3C2Me) with Me3SiC≡CR (R=Me, Bun). The structure and stereodynamic behavior of clusters Os3(CO)9{μ3-C(SiMe3)=C(Me)C=C(SiMe3)=C(Me)C=C(SiMe3)R} containing an osmacyclobutene moietycontaining an osmacyclobutene moiety

Reactions of the alkyne cluster Os₃(μ-CO)(CO)₉(μ₃-Me₃C₂Me) with alkynes Me₃SiC≡CR (R=Me, Buⁿ) in refluxing hexane result in the formation of clusters Os₃(CO)₉{μ₃-C(SiMe₃)=C(Me)C=C(SiMe₃)=C(Me)C=C(SiMe₃)R} (2a: R=Me;3a: R=Buⁿ). The dienediyl ligand in these complexes is formed by alkyne-vinylidene coupling, with vinylidene generated in the course of reaction from the alkyne molecule by the acetylene-vinylidene rearrangement involving a 1,2-shift of the Me₃Si group. The structure of cluster3a was determined by X-ray structural analysis. The dienediyl ligand is coordinated to three metal atoms of the cluster framework by two π-ethylene bonds with two osmium atoms and two σ-bonds with the third osmium atom with the formation of the osmacyclobutene moiety. The¹H and¹³C NMR study of¹³CO-enriched samples of clusters2a and3a revealed the stereochemical nonrigidity of these molecules due to the exchange of the hydrocarbon and carbonyl ligands.     

(Me3Si)2CH]2(i)PrSi(NHC)Si═Si(Me)Si(i)Pr[CH(SiMe3)2]2]+: a molecule with disilenyl cation character

Reaction of the disilyne-NHC complex 1 [RLSi═SiR: (R = Si(i)Pr[CH(SiMe(3))(2)](2), L = NHC)] with MeOTf gave the cation 2 [RLSi═SiRMe](+), which is the first example of a base-stabilized heavy group 14 element analogue with vinyl cation character. Cation 2 has been fully characterized by multinuclear NMR spectroscopy and X-ray diffraction analysis. The molecular structure indicates that there are significant contributions from the NHC-stabilized cationic resonance structure 2A, the disilene-like structure 2B, and even some contribution from the silylene-like structure 2C.     

Mixed-ligand cluster [Mo3S4(Dtp)2(μ-AcO)Cl(Me2Bipy)]: Synthesis and structure

Mixed-ligand cluster [Mo₃S₄(Dtp)₂(μ-AcO)Cl(Me₂Bipy)] · CHCl₃ (I · CHCl₃), where Dtp is (EtO)₂PS₂, was synthesized by the reaction of the molybdenum aqua complex [Mo₃S₄(H₂O)₉]⁴⁺ with 4,4′-dimethyl-2,2′-bipyridine (Me₂Bipy) and phosphorus sulfide (P₄S₁₀) in ethanol followed by chromatographic separation on silica gel and crystallization in the presence of acetic acid. The crystal structure of I · CHCl₃ was determined by X-ray diffraction analysis. The synthesized compound was characterized by the IR and NMR spectra and elemental analysis. The electronic structure of the synthesized compound was established, and its electrochemical behavior in a solution was studied.     

Photochemistry of (Me3P)4Mo(η-CO2)2: Deoxygenation of coordinated carbon dioxide and phosphine oxidation

Irradiation of the title compound 1 through quartz in toluene solution at − 20°C produces cis-Mo(CO)₂(PMe₃)₄ and OPMe₃ as the major products along with lesser amounts of mer- and _fac-Mo(CO)₃(PMe₃)₃ and Mo(CO)PMe₃) ₅. Irradiation of 1 through Pyrex produces in addition substantial amounts of an unstable species formulated as trans-Mo (CO)₂(PMe₃)₄.