钛,锆和铪羰基化合物M(CO)_n(M=Ti,Zr,Hf;n=4～7)的理论研究

利用密度泛函方法对标题化合物的平衡几何、热化学及振动频率进行了理论预测,发现这3种金属原子都有相似的M(CO)n(n=4～7)结构.全局最低构型对M(CO)7都是单态C3v戴帽八面体7S-1,对M(CO)6都是三重态D3d畸变八面体6T(而对应的单重态M(CO)5仅比它低不到21 kJ·mol-1).对M(CO)n(n=5,4)都是三重态6S-1,其构型分别为从6T中移去1个或2个CO基的衍生物5T和4T.此外,五重态的D3h的三角双锥M(CO)5和单态的Td四面体M(CO)4以及能量更高的含有C和O同时与金属成键的独特配位CO基的M(CO)6和M(CO)3也被发现.最后,给出M(CO)7→M(CO)6+CO反应的离解能.并讨论了金属18价电子的Ti(CO)7存在的可能性.     

Übergangsmetall-substituierte acylphosphane und phosphaalkene : XX. Dipolare [3 + 2]-Cycloadditionen eines acetylendicarbonsäureesters an die metallophosphaalkene (η-C5Me5)(CO)2Fe---P=C(R)SiMe3 (R = Ph, SiMe3)

The metallo-phosphaalkenes (η⁵-C₅Me₅)(CO)₂FeP=C(R)(SiMe₃) (Ia: R = SiMe₃, Ib: R = Ph) and MeO₂C---CC---CO₂Me undergo a dipolar [3+2]-cycloaddition to afford the metallo-heterocycles [(η⁵-C₅Me₅)(CO)

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=C(R)SiMe₃] (IIIa,b) with exocyclic P=C double bonds.     

Substituted cyclopentadienyl ligands—10. Intramolecular steric interactions in [(η-C5H3(SiMe3)2)Mo(CO)2(L)I]

Reaction of C₅H₄(SiMe₃)₂ with Mo(CO)₆ yielded [(η⁵-C₅H₃(SiMe₃)₂)Mo(CO)₃]₂, which on addition of iodine gave [(η⁵-C₅H₃(SiMe₃)₂Mo(CO)₃I]. Carbonyl displacement by a range of ligands: [L = P(OMe)₃, P(OPrⁱ)₃,P(O-o-tol)₃, PMe₃, PMe₂Ph, PMePh₂, PPh₃, P(m-tol)₃] gave the new complexes [(η⁵-C₅H₃(SiMe₃)₂ MO(CO)₂(L)I]. For all the trans isomer was the dominant, if not exclusive, isomer formed in the reaction. An NOE spectral analysis of [(η⁵-C₅H₃(SiMe₃)₂)Mo(CO)₂(L)I] L = PMe₂Ph, P(OMe)₃] revealed that the L group resided on the sterically uncongested side of the cyclopentadienyl ligand and that the ligand did not access the congested side of the molecule. Quantification of this phenomenon [L = P(OMe)₃] was achieved by means of the vertex angle of overlap methodology. This methodology revealed a steric preference with the trans isomer (less congestion of CO than I with an SiMe₃ group) being the more stable isomer for L = P(OMe)₃.     

Reactivity of ZrCl4 and HfCl4 with silylamines and thermal decomposition of the compounds [MCl4{NH(R)(SiR′3)}] (M = Zr,Hf, R = tBu,R′ = Me; R = SiR′3 = SiMe3, SiMe2H)

The Lewis acid/base adducts [MCl₄{NH(R)(SiR′₃)}] (M = Zr, Hf; R = tBu, R′ = Me; R = SiR′₃ = SiMe₃, SiMe₂H) were synthesized by the 1:1 reaction of MCl₄ with NH(R)(SiR′₃) in dichloromethane solution at room temperature. The decomposition of [MCl₄{NH(R)(SiR′₃)}] proceeds with the elimination of R′₃SiCl, as shown by thermogravimetric analysis. Pyrolysis of the compounds at 620 °C under inert conditions (N₂, vacuum) afforded powders of composition [ClMN] or [Cl₂MNH]. Preliminary low pressure chemical vapour deposition experiments show that [MCl₄{NH(R)(SiR′₃)}] deposits thin films of metal nitride contaminated with metal oxide.     

Oxidative alkylation of (η-C5Me5)2TiR (R = Cl, Me, Et, CH=CH2, Ph, OMe, N=C(H)Bu) to (η-C5Me5)2Ti(Me)R by group 12 organometallic compounds MMe2

Oxidative alkylation of Cp^*₂TiX (Cp^*: η⁵-C₅Me₅; X = OMe, Cl, N=C(H)^tBu) and Cp^*₂TiMe by CdMe₂ or ZnMe₂ gives diamagnetic Cp^*₂Ti(Me)X and Cp^*₂TiMe₂ respectively, and cadmium or zinc. The reactions of Cp^*₂TiR (R = Et, CH=CH₂, Ph) with MMe₂ (M = Cd, Zn) give statistical mixtures of Cp^*₂Ti(Me)R, Cp^*₂TiMe₂ and Cp^*₂TiR₂. Dimethylmercury does not react with Cp^*₂TiX.     

MX~4(M=Ti,Zr,Hf;X=Cl,Br)的电子结构研究

本文利用单电子非相对论Hartree-Fock-Slater和完全相对论Dirac-Fock-Slater两种离散变分局域密度泛函方法(DV-Xα), 对MX~4(M=Ti,Zr,Hf;X=Cl,Br)的电子基态和相应于低能UV光谱的激发态进行了计算, 结果与实验符合得较好。用Mulliken布居分析方法研究了分子的共价性质, 发现除HfBr~4外,相对论效应对金属与配体之间的键级影响很小。     

The redox behaviour of ferrocene derivatives : III. Ferrocenylacyl complexes (η-C5H5) Fe(η-C5H4-COER3 E = C, Si or Ge; R = Me or Ph

The electrochemical behaviour of the ferrocenylacyl derivatives [FcCOER₃] (E = C, Si or Ge; R = Me or Ph) is examined. One-electron oxidations to the substantially stable monocations [FcCOER₃]⁺ occur at potentials significantly higher than that observed with ferrocene, but only minor differences hold within the series, independent of the nature of both E and R. In contrast the EPR spectra of the monocations for E = C show that the unpaired electron resides mainly on the iron, whereas for E = Si or Ge the electron density is essentially localized on the C₅H₄COER₃ fragment.     

Synthesis and structure of ansa-cyclopentadienyl pyrrolyl titanium complexes: [(η-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 and [1,3-{CH2(2-C4H3N)}2(η-C5H3)]Ti(NMe2)

Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C₅H₅)CH₂(2-C₄H₃NH) (2) with Ti(NMe₂)₄ affords bis(dimethylamido)titanium complex [(η⁵-C₅H₄)CH₂(2-C₄H₃N)]Ti(NMe₂)₂ (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH₂(2-C₄H₃NH)}₂C₅H₄ (4), undergoes an analogous reaction with Ti(NMe₂)₄ to give [1,3-{CH₂(2-C₄H₃N)}₂(η⁵-C₅H₃)]Ti(NMe₂) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies.     

Les phases Na4XO4 (X = Si,Ti, Cr,Mn, Co,Ge, Sn,Pb) et K4XO4 (X = Ti,Cr, Mn,Ge, Zr,Sn, Hf,Pb)

The isotypic Na₄XO₄ (X = Si, Ti, Cr, Mn, Co, Ge, Sn, Pb) and K₄XO₄ (X = Ti, Cr, Mn, Ge, Zr, Sn, Hf, Pb) phases crystallize in the triclinic system. Optical and magnetic properties of the chromium, manganese, and cobalt compounds show that the transition element has a tetrahedral surrounding.     

Synthesis and structures of crystalline lithium 1-azaallyls and a 1,3-diazaallyl derived from Li{CH(SiMe3)(SiMe3−n(OMe)n)} (n=1 or 2) and Li{CH(SiMe2OMe)2} and RCN (R=Bu, Ph, 2,5-Me2C6H3, or Ad)

Crystalline [Li{N(SiMe₂OMe)C(^tBu)C(H)(SiMe₃)}]₂ (5), [Li{N(SiMe₂OMe)C(Ph)C(H)(SiMe₃)}]₂ (6), [C(C₆H₃Me₂-2,5)C(H)(SiMe₃)}(TMEDA)](7), [Li{N(SiMe(OMe)₂)C(^tBu)C(H)(SiMe₃)}(THF)]₂ (8), Li{N(SiMe(OMe)₂)C(Ph)C(H)(SiMe₃)}(TMEDA) (9) and [Li{N(SiMe₂OMe)C(^tBu)C(H)(SiMe₂OMe)}]₂ (10) were readily obtained at ambient temperature from (i) [Li{CH(SiMe₃)(SiMe₂OMe)}]₈ (1) and an equivalent portion of RCN (R=^tBu (5), Ph (6) or 2,5-Me₂C₆H₃ (7)); (ii) [Li{CH(SiMe₃)(SiMe(OMe)₂)}]_∞ (2) and an equivalent portion of ^tBuCN (8) or PhCN (9); and (iii) [Li{CH(SiMe₂OMe)₂}]_∞ (3) and one equivalent of ^tBuCN (10). Reactions (i) and (ii) were regiospecific with SiMe_3−n(OMe)_n>SiMe₃ in 1,3-migration from C (in 1 or 2)→N. The 1-azaallyl ligand was bound to the lithium atom as a terminally bound κ¹-enamide (8 and 10), a bridging η³-1-azaallyl (6), or a bridging κ¹-enamide (5). The stereochemistry about the CC bond was Z for 5, 8 and 10 and E for 7. X-ray data are provided for 5, 6, 7, 8 and 10 and multinuclear NMR spectra data in C₆D₆ or C₆D₅CD₃ for each of 5-10.     

Reactions of the carbonyl complexes M(CO)3(L)3 (L = py,M = Mo,W; L = NH3, M = Mo) and M(CO)4(2-Mepy)2 (M = Mo,W) with HgX2 (X = Cl,CN, SCN)

The reactions of the substituted Group VI metal carbonyls of the type M(CO)₄(2-Mepy)₂ (M = Mo, w) and M(CO)₃(L)₃ (L = py, M = Mo, W; L = NH₃, M = Mo) with mercuric derivatives HgX₂ (X = Cl, CN, SCN) have given rise to three series of tricarbonyl complexes: M(CO)₃(py)HgCl₂ · 1/2HgCl₂ (M = Mo, W); 2[M(CO)₃(L)]Hg(CN)·nHg(CN)_x (L = py, M = Mo, W, n = $\text{1}\text{2}$, × = 2; L = 2- Mepy, × = 1; M = Mo, n = 3; M = W, n = 1); and [M(CO)₃(L)Hg(SCN)₂ · nHg(SCN)₂] (L = py, M = Mo,W, n = 0; L = 2-Mepy, M = Mo, W, n = $\text{1}\text{2}$; L = NH₃, M = Mo, n = 0) depending on which mercuric compound is employed. All the reactions with Hg(SCN)₂ give isolable products whereas those with Hg(CN)₂ and HgCl₂ did so far only the reactions with [M(CO)₄(2-Mepy)₂] and M(CO)₃(py)₃. The greater reactivity of Hg(SCN)₂ than of Hg(CN)₂ and HgCl₂ is consistent with the various acceptor capacities of the groups bonded to the mercury atom.The reactions studied always involve displacement of the N-donor ligand of the original complex and partial or total displacement of the halide or pseudohalide groups of the mercury compound to give in all cases compounds containing MHg bonds. In addition, elimination of a CO group in the tetracarbonyl complexes M(CO)₄(2-Mepy)₂occurs.     

Ketene organoelement derivatives. Synthesis of bis(l-R-2-oxovinyl)silanes and germanes (R = SiMe3, GeMe3, SnMe3)

Earlier unknown 1,3-bisketene organoelement derivatives RMeE(C(E ’Me₃)=C=O)₂ (E = Si, Ge; E’ = Si, Ge, Sn) have been synthesized by the reaction of bis(alkoxyethynyl)silanes and -germanes with Me₃E’Hal. Bis(1-trimethylsilyl-2-oxovinyl)silane is also formed by the reaction of trimethylsilyl- and (dimethylsilylene)bisketenes with dimethylsilylene bistriflate and trimethylsilyl triflate, respectively. Addition of nucleophiles to the ketene fragment of compounds synthesized has been studied.     

Bildung und Charakterisierung von Oberflächenverbindungen in den Systemen (C6H5CH2)4M/γ-Al2O3 (M = Ti,Zr)

Formation and Characterization of Surface Compounds in the Systems (C₆H₅CH₂)₄M/γ-Al₂O₅ (M = Ti, Zr) By O-bridges anchored surface-compounds are formed by protolytic splitting off of benzyl groups if tetrabenzyltitanium and -zirconium are added to γ-alumina. These compounds contain the metal in different oxidation states in dependence on the carrier/substrate ratio and the density of OH groups on the alumina surface. The different kinds of surface compounds are discussed. Furthermore, the products formed by thermal decomposition and hydrogenolysis of the surface compounds were analysed. With regard to catalytic conversion reactions of hydrocarbons systems of the type (C₆H₅CH₂)₄M/Pt/γ-Al₂O₃were involved in the investigations.     

Phosphido- und arsenido-verbrückte Zweikernkomplexe: Synthese und Struktur von (η5-C5H4R)2Zr{μ-P(SiMe3)2}2M(CO)4 (R = Me,M = Cr; R = H,M = Mo) sowie die Synthese von (η5-C5H5)2Zr{μ-As(SiMe3)2}2Cr(CO)4

Phosphido- and Arsenido-bridged Dinuclear Complexes. Synthesis and Molecular Structure of (η⁵-C₅H₄R)₂Zr{μ-P(SiMe₃)₂}₂M(CO)₄ (R = Me, M = Cr; R = H, M = Mo) and Synthesis of (η⁵-C₅H₅)₂Zr{μ-As(SiMe₃)₂}₂Cr(CO)₄ The reaction of (η⁵-C₅H₄R)₂Zr{E(SiMe₃)₂}₂ with M(CO)₄(NBD) (NBD = norbornadiene) yields the dinuclear phosphido- or arsenido-bridged complexes (η⁵-C₅H₄R)₂Zr{μ-E(SiMe₃)₂}₂M(CO)₄ (R = Me, E = P, M = Cr ( 1 ); R = H, E = P, M = Mo ( 2 ); R = H, E = As, M = Cr ( 3 )). No formation of dinuclear complexes was observed in the reaction of (η⁵-C₅H₄Me)₂Zr{P(SiMe₃)₂}₂ with Ni(PEt₃)₄, Ni(CO)₂(PPh₃)₂ or with NiCl₂(PPh₃)₂ in the presence of Mg. Complexes 1 – 3 were characterised spectroscopically (i. r., n. m. r., m. s.), and X-ray structure investigations were carried out on 1 and 2 . The central four-membered ZrP₂M ring is slightly puckered (dihedral angle between planes ZrP₂/CrP₂ 14.7°, ZrP₂/MoP₂ 14.2°). The Zr? P bond lengths are equivalent ( 1 : Zr? P1 2.654(4), Zr? P2 2.657(4) Å; 2 : Zr? P1 2.6711(9), Zr? P2 2.6585(7) Å), as are the M? P bond lengths (M = Cr ( 1 ): Cr? P1 2.513(4), Cr? P2 2.502(4) Å; M = Mo ( 2 ): Mo? P1 2.6263(7), Mo? P2 2.6311(10) Å). The long Zr ··· M distances of 3.414 Å (M = Cr ( 1 )) and 3.461 Å (M = Mo ( 2 )) indicate the absence of a metal-metal bond.     

Synthesis and structures of the 2-(dimethylsila)pyrimidine derivatives (Ar = Ph, C6H4Bu-4; X = H, SiMe3, Li(hmpa)2, K(thf)3; n = 1, 2)

Five crystalline 2-(dimethylsila)pyrimidine derivatives (Z) have been prepared in excellent 1–4 or satisfactory 5 yield and characterised. The source of each was ultimately Li[CH(SiMe₂R)(SiMe₂OMe)] [R = Me (B) or OMe (I)]. Compound 1 (Z with Ar = Ph, X = SiMe₃, n = 1) was obtained from Z [with Ar = Ph, X = Li(OEt₂), n = 4; previously isolated from B [P.B. Hitchcock, M.F. Lappert, X.-H. Wei, J. Organomet. Chem. 689 (2004) 1342]] and Me₃SiCl. The potassium salt 2 [Z with Ar = C₆H₄Bu^t-4; X = K(thf)₃, n = 2] was made from K[CH(SiMe₃)(SiMe₂OMe)] (C) (via B) and 4-Bu^tC₆H₄CN. Treatment of 2 with 1,2-dibromoethane afforded 3 (Z with Ar = 4-Bu^tC₆H₄; X = H, n = 1); which when reacted with successively n-butyllithium and Me₃SiCl produced 4 (Z with Ar = 4-Bu^tC₆H₄, X = SiMe₃, n = 1). Compound 5 [Z with Ar = 4-Bu^tC₆H₄, X = Li(hmpa)₂, n = 1] resulted from I with 4-Bu^tC₆H₄CN and then OP(NMe₂)₃ (≡ hmpa). Plausible reaction pathways from the appropriate alkali metal alkyl C or I to 2 or 5, respectively, are suggested; these involve regiospecific 1,3-migrations of SiMe₂OMe from C → N and electrocyclic loss of Me₃SiOMe or SiMe₂(OMe)₂, respectively. The X-ray structures of crystalline 1, 2 and 5 are presented.     

Metallorganische lewissäuren : XX. Reaktionen von (π-C5H5)(CO)2LM-X (L = CO, PR3; M = Mo, W; X = BF4, PF6, AsF6, SbF6) mit Schwefel-haltigen liganden

The compounds (π-C₅H₅)(CO)₂LM-X (L = CO, PR₃; M = Mo, W; X = BF₄, PF₆, AsF₆, SbF₆) react with H₂S, p-MeC₆H₄SH, Ph₂S and Ph₂SO(L′) to give ionic complexes [(π-C₅H₅)(CO)₂LML′]⁺ X⁻. Also sulfur-bridged complexes, [(π-C₅H₅)(CO)₃W---SH---W(CO)₃(π-C₅H₅)]⁺ AsF₆⁻ and [(π-C₅H₅)(CO)₃M-μ-S₂C=NCH₂Ph-M(CO)₃(π-C₅H₅)], have been obtained. Reactions with SO₂ and CS₂ have been examined.     

Pyrolysis of metallocene complexes (ηC5H4R)2MR: An organometallic route to metal carbide (MC) materials (M = Ti,Zr, Hf)

The following compounds were prepared and their pyrolysis in a stream of argon was studied: (η⁵-C₅H₅)₂Ti(C?CC₆H₅)₂, (η⁵-C₅H₄SiMe₃)₂-Ti(SH)₂, [(η⁵-C₅H₅)Ti(μ-CH₂)]₂, (η⁵-C₅H₅)₂ZrR₂-(R?CH₂, CH₂C₆H₅, N(CH₃)₂), (η⁵-C₅H₄CH₃)₂-Zr(C?CC₆H₅)₂, [(η⁵-C₅H₄SiMe₃)₂Zr(μ-S)]₂, [(η⁵-C₅H₄SiMe₃)₂Hf(μ-S)]₂ and (η⁵-C₅H₄SiMe₃)₂Hf-(C?CC₆H₅)₂. The products of bulk pyrolysis of these materials were formed in 20–40% yield, based on the charged sample weight, and consisted mainly of titanium carbide together with small amounts of amorphous carbon.     

Electrochemical and spectral properties of some tantalocene derivatives with one pentamethylated cyclopentadienyl ligand: Cp*(Cp-R)TaCl2 , R = H, SiMe3 or (CH2)3NC4H4

Three tantalocene dichloride complexes, Cp*(Cp-R)Ta(IV)Cl₂, with one pentamethylated cyclopentadienyl ligand, Cp* = η⁵–C₅Me₅, Me = CH₃, and one monosubstituted cyclopentadienyl ligand, Cp-R, Cp = η⁵–C₅H₅, R = H, SiMe₃ or (CH₂)₃NC₄H₄, have been studied in acetonitrile solutions with cyclic voltammetry in the ranges of the Ta(IV) oxidation to Ta(V) or of its reduction to Ta(III). The former transition is reversible, while the latter one gives an irreversible wave due to the dissociation of the reduced complex with the loss of one chloride ligand. The redox transformation from the initial state of complex Cp*CpSiMe₃TaCl₂ to its oxidized state, Cp*CpSiMe₃TaCl₂ ⁺, and back was monitored by spectroelectrochemical measurements in a thin-layer acetonitrile solution. Kinetic data for the evolution of the UV-visible spectrum of the system in the course of the double potential step experiment were treated on the basis of two theoretical models as the reactant diffusion across the solution layer without or with taking into account ohmic losses. The values of the diffusion coefficients of the complex in its initial and oxidized (cationic) states have been estimated. It was demonstrated that this complex in each of two oxidation states, Ta(IV) or Ta(V), is represented by a single molecular form. An attempt to deposit a conducting polymer film by oxidation of the tantalocene complex containing a pyrrole group attached to the Cp ring, Cp*Cp(CH₂)₃PyTaCl₂, led to a thin insulating layer at the electrode surface because of an inhibiting effect of chloride anions.

Synthesis and Anti-inflammatory Action of （η-C5H5 ）2Ti（ Sal）2 and （η-C5H5 ）2Ti（Clo）2

IntroductionSince K pf[1]discovered that dicyclopenta die-nyltitanium dichloride possesses antitumour action in1979,a large number of cyclopentadienyltitanium com-plexes with different substituents have been synthe-sized[2,3].The experimental data reveal …     

Ternary silicides M2Cr4Si5 (M=Ti, Zr, Hf): filled variants of the Ta4SiTe4 structure type

The isostructural ternary silicides M₂Cr₄Si₅ (M=Ti, Zr, Hf) were prepared by arc-melting of the elemental components. The single-crystal structure of Zr₂Cr₄Si₅ was determined by X-ray diffraction (Pearson symbol oI44, orthorhombic, space group Ibam, Z=4, a=7.6354(12) Å, b=16.125(3) Å, c=5.0008(8) Å). Zr₂Cr₄Si₅ adopts the Nb₂Cr₄Si₅-type structure, an ordered variant of the V₆Si₅-type structure. It consists of square antiprisms that have Zr and Cr atoms at the corners and Si atoms at the centers; they share opposite faces to form one-dimensional chains _∞¹[Zr_4/2Cr_4/2Si] surrounded by additional Si atoms and extending along the c direction. In a new interpretation of the structure, additional Cr atoms occupy interstitial octahedral sites between these chains, clarifying the relation between this structure and that of Ta₄SiTe₄. The formation of short Si-Si bonds in Zr₂Cr₄Si₅ is contrasted with the absence of Te-Te bonds in Ta₄SiTe₄. The compounds M₂Cr₄Si₅ (M=Ti, Zr, Hf) exhibit metallic behavior and essentially temperature-independent paramagnetism. Bonding interactions were analyzed by band structure calculations, which confirm the importance of Si-Si bonding in these metal-rich compounds.