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The new heterobimetallic complexes [(η5-C5H5)(CO)3W(CH2)nMo(CO)3(η5-C5H5)] n=3 to 6; [(η5-C5H5)(CO)3W(CH2)nMo(CO)3(η5-C5(CH3)5)] n=3, 4; [(η5-C5H5)(CO)3W(CH2)nMo(CO)2(PPhiMe3 − i)(η5-C5H5)] and [(η5-C5H5)(CO)2Fe(CH2)nMo(CO)2(PPhiMe3 − i)(η5-C5H5)] (n=3,4 and i=0 to 3) were synthesized by direct displacement of the iodide of a metallo-iodoalkyl complex with the appropriate anion. The complexes have been fully characterised by IR, 1H NMR, 13C NMR, COSY, HETCOR, HSQC and elemental analyses. X-ray diffraction studies were done on the complexes [(η5-C5H5)-(CO)3W(CH2)3Mo(CO)2(PPh3)(η5-C5H5)] and [(η5-C5H5)(CO)2(PPh3)Mo(CH2)3Fe-(CO)2(η5-C5H5)]. Both compounds form monoclinic crystals in the space group P21/c. The former has a W–C(alkyl) bond length of 2.316(7) A˚ and Mo–C(alkyl) bond length of 2.357(7) A˚ and the latter a Mo–C(alkyl) bond length of 2.374(2) A˚ and Fe–C(alkyl) bond length of 2.076(2) A˚. [Copyright &y& Elsevier]

Reaction of WH(CO)3(η-C5Me5) with IrCl(CO)2(4-H2NC6H4Me) affords WIr3(μ-CO)3(CO)8(η-C5Me5) in low yield. A structural study reveals a WIr2-centred plane of bridging carbonyls, in contrast to the crystal structure of WIr3(CO)11(η-C5H5) (all-terminal carbonyl distribution). DFT calculations reveal an increasing proclivity to adopt an all-terminal CO disposition for clusters MIr3(CO)11(η-C5H5) in the gas phase on proceeding from M=Cr to Mo and then W, consistent with structural studies in the solid state for which the tungsten-containing cluster is the only all-terminal example. Increasing electron donation from the ligands in the tungsten system (either from phosphine substitution or cyclopentadienyl permethylation) suffices to impose a plane of bridging carbonyls in the ground state structure. 13C NMR fluxionality studies reveal that CO exchange mechanism(s) for WIr3(CO)11(η-C5H5) and the related tetrahedral cluster W2Ir2(CO)10(η-C5H5)2 are very fast and involve all carbonyls on the clusters. DFT calculations on MIr3(CO)11(η-C5H5) (M=Cr, Mo) substantiate a ‘merry-go-round’ mechanism for carbonyl scrambling in these systems, a result which is consistent with the scrambling behaviour seen in the NMR fluxionality studies on the W-containing congener. [Copyright &y& Elsevier]

(C5Me4H)SiMe2Cl reacts with (THF)KCH2CH&z.dbnd6;CHCH&z.dbnd6;CH2 to form (C5Me4H)SiMe2(CH2CH&z.dbnd6;CHCH&z.dbnd6;CH2) (1). Compound 1 reacts with KH and n-BuLi to make M(C5Me4)SiMe2(CH2CH&z.dbnd6;CHCH&z.dbnd6;CH2), M=K, 2; Li, 3, respectively. Carbon–silicon cleavage occurs when 1 reacts with K to form (C5Me4H)K, which crystallizes from dimethoxyethane as [(C5Me4H)K(DME)]x. This potassium salt has an extended structure which generates bent metallocene (C5Me4H)2K(DME) sub-structures which have 133.9° ring centroid&z.sbnd;K&z.sbnd;ring centroid angles. Compound 1 reacts with TiCl4 to make (C5Me4H)TiCl3 (5), which has a piano stool structure. [Copyright &y& Elsevier]

A series of iron–olefin complexes of the type [CpFe(CO)2(η2-CH2&z.dbnd6;CHR)]+ (R=CH3 to n-C14H29) have been prepared using various synthesis methods. In addition, the complexes [Cp*Fe(CO)2(η2-CH2&z.dbnd6;CHR)]+ (Cp*=η5-C5(CH3)5; R=CH3, n-C3H7 and n-C14H29) and [CpRu(CO)2(η2-CH2&z.dbnd6;CHR)]+ (R=CH3, n-C3H7 and n-C14H29) have been synthesized by reacting the iron–alkyl complexes Cp*Fe(CO)2(CH2CH2R) or ruthenium–alkyl complexes CpRu(CO)2(CH2CH2R) with Ph3CPF6. A number of these complexes are new and have been fully characterized by analytical and spectroscopic methods. The reaction of [CpFe(CO)2(η2-CH2&z.dbnd6;CHR)]+ with the isopropoxide ion gave the new ether derivatives [CpFe(CO)2(CH2CH{OCH(CH3)2}R)] (R=CH3, n-C2H5, n-C4H9 and n-C13H27). [Copyright &y& Elsevier]

N,N′-Bis(2,6-diisopropylphenyl)(tert-butyl)amidine and N,N′-bis(2,4,6-trimethyl-phenyl)(tert-butyl)amidine were prepared and treated with [CpMgMe(Et2O)]2 in diethyl ether or tetrahydrofuran to afford the monomeric amidinate complexes [CpMg(η2-tBuC(N(2,6-iPr2C6H3))2] (87%) and [CpMg(η2-tBuC(N(2,4,6-Me3C6H2))2)(THF)] (76%). The solid-state structures of the amidines and resultant magnesium complexes were determined by X-ray diffraction methods. In the solid-state, the magnesium complexes are monomeric and contain one η5-cyclopentadienyl ligand and one η2-amidinate ligand, as well as one tetrahydrofuran ligand for the latter. [CpMg(η2-tBuC(N(2,6-iPr2C6H3))2)] can be sublimed unchanged with 80% recovery at 180 °C/0.05 torr, while [CpMg(η2-tBuC(N(2,4,6-Me3C6H2))2)(THF)] decomposes to Cp2Mg (77%) and [Mg(η2-tBuC(N(2,4,6-Me3C6H2)))2] (83%) under similar conditions. [Mg(η2-tBuC(N(2,4,6-Me3C6H2)))2] was prepared independently through treatment of dibutylmagnesium with two equivalents of N,N′-bis(2,4,6-trimethylphenyl)(tert-butyl)amidine in toluene at ambient temperature. [Copyright &y& Elsevier]

The organometallic zwitterion (n[SUP5]-C[SUB5]H[SUB4]MeBCl[SUB3])Fe(CO)[SUB3] (2) is isolated as a minor product from the reaction between the sodium salt of the anion [n[SUP5]-C[SUB5]H[SUB4]Me)Fe(CO)[SUB2][SUP-] and boron trichloride. The crystal structure of 2 [P2[SUB1]/n, a = 7.3927(5) Å, b = 13.8027(9) Å, c = 12.2759(9) Å, α = γ = 90°, β = 92.5 17(3)°] features discrete molecules in which the coordination sphere of the iron center comprises three carbonyls and a novel (n[SUP5] - C[SUB5]H[SUB3]MeBCl[SUB3]) ligand, derived from attack of BCl[SUB3] on the (n[SUP5]-C[SUB5]H[SUB4]Me) moiety of the parent compound. The isolation of 2 confirms that the nucleophilic properties of organometallic anions of the type [(n[SUP5]-C[SUB5]R[SUB5])M(CO)[SUBn][SUP-] (M = Fe, Ru, n = 2; M = Mo, W, n = 3) are not confined to the metal center, or to the carbonyl oxygens (examples of which have previously been reported) but also encompass the cyclopentadienyl ligand. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of polymetallic complexes in which two or three Group 4 metals are linked to a benzene core through oxo groups. Four methods have been evaluated for the synthesis of such derivatives: from the appropriated alcohol with (a) methyl complexes via methane elimination, (b) chloride compounds in the presence of a Lewis base, or (c) a zirconium hydride, and (d) from the lithium salt of the alcohol and chloride complexes. Method a has been used for the synthesis of bimetallic and trimetallic (pentamethylcyclopentadienyl)titanium(IV) complexes [{Ti(C5Me5)Cl2}2{μ-1,4-O(C6H2XY)O&z.sbnd;}] (X=Y=H (1); X=H, Y=Me (2); X=Y=Me (3)), [{Ti(C5Me5)Me2}2{μ-1,4-O(C6H2Me2)O&z.sbnd;}] (4), and [{Ti(C5Me5)X2}3(μ3-1,3,5-C6H3O3&z.sbnd;)] (X=Cl (7), Me (8)) from the corresponding hydroquinones 1,4-HO(2,3-C6H2XY)OH (X=Y=H, Me; X=H, Y=Me) or 1,3,5-trihydroxibenzene and [Ti(C5Me5)Cl2Me] or [Ti(C5Me5)Me3], respectively. Bis(cyclopentadienyl)titanium bimetallic complex [{Ti(C5H5)2Cl}2{μ-1,4-O(C6H2Me2)O&z.sbnd;}] (5) is better prepared by method d by treatment of the dilithium salt Li2[1,4-O(2,3-C6H2Me2)O&z.sbnd;] with [Ti(C5H5)2Cl2] whereas the trimetallic compound [{Ti(C5H5)2Cl}3(μ3-1,3,5-C6H3O3&z.sbnd;)] (9) can be prepared directly from 1,3,5-trihidroxybenzene in the presence of NEt3 (method b). Finally, bis(cyclopentadienyl)zirconium complexes [{Zr(C5H5)2Cl}2{μ-1,4-O(C6H2Me2)O&z.sbnd;}] (6) and [{Zr(C5H5)2Cl}3(μ3-1,3,5-C6H3O3&z.sbnd;)] (10) are obtained from [Zr(C5H5)2ClH] (method c). The structure of complex 3 has been determined by X-ray diffraction methods. [Copyright &y& Elsevier]

Synthesis and characterization of a new class of ion-pairs complexes [Ln2(PhMe2CC5H4)4(μ-X)2][Li(DME)3]2 (Ln=Sm, X=I; Ln=Yb, X=Cl) are described. The reaction of SmI2(THF)2 (THF=tetrahydrofuran) with two equivalents of PhMe2CC5H4Li(DME) in THF affords the Sm(II) complex [Sm2(PhMe2CC5H4)4(μ-I)2][Li(DME)3]2 (1), while the Na–K alloy reduction of (PhMe2CC5H4)2YbCl, which was formed in situ by the reaction of YbCl3 and PhMe2CC5H4Li in 1:2 molar ratio, gives Yb(II) complex [Yb2(PhMe2CC5H4)4(μ-Cl)2][Li(DME)3]2 (2). The single-crystal structural analyses of 1 and 2 reveal that they both comprise two Li+(DME)3 cations and a new class of dianion, {[C5H4(CMe2Ph)]4Ln2(μ-X)2}2−, in which two [C5H4(CMe2Ph)]2Ln were bridged together by two iodine atoms for Sm and two chlorine atoms for Yb. The coordination geometry of the central metal is best described as a distorted tetrahedral. [Copyright &y& Elsevier]

In this article a summary is given of developments in the synthetic, structural and reaction chemistry of complexes containing boryl- and borate-substituted cyclopentadienyl ligands [(η5-C5R4BX2)− and (η5-C5R4BX3)2−]. [Copyright &y& Elsevier]

Reactions of MoIr3(μ-CO)3(CO)8(η-C5H5) (1) with stoichiometric amounts of isocyanides afford the ligand-substituted clusters [MoIr3(μ-CO)3(CO)8−n(L)n(η-C5H5)] (L=CNBut, n=1 (3), 2 (4), 3 (5); L=CNC6H3Me2-2,6, n=1 (6), 2 (7), 3 (8)) in moderate to excellent yields (13–75%). Single-crystal X-ray studies of 3 and 6 reveal that the isocyanides occupy coordination sites on an apical cluster core metal atom, a first for ligand-substituted derivatives of 1. In contrast, reaction of Mo2Ir2(μ-CO)3(CO)7(η-C5H5)2 (2) with one or two equivalents of CNBut affords Mo2Ir2(μ-CO)2(CNBut)2(CO)6(η-C5H5)2 (9) as the only major product. A single-crystal X-ray study of 9 reveals an unprecedented carbonyl configuration about the pseudotetrahedral cluster core. [Copyright &y& Elsevier]

The reaction of [Ru(η3:η3-C10H16)Cl2]2 (1) with the Cp-linked phosphine ligands Ln (C5H5&z.sbnd;CH2CHRPR′2; R=H, R′=Ph, n=1; R=Ph, R′=Ph, n=2), in a 5:1 mixture of acetonitrile–ethanol and in the presence of Li2CO3 and KPF6 affords the cationic half-sandwich ruthenium(II) complexes [{η5-C5H4&z.sbnd;CH2CHRPR′2-κP}Ru(CH3CN)2]·[PF6] (4) and (5). Both complexes have been characterized in the solid state by an X-ray structure analysis. In contrast, the reaction between 1 and L3 (R=Ph, R′=o-xylyl) affords the cationic sandwich compound [{η5:η6-C5H4&z.sbnd;CH2CHPhPR′2}Ru]·[PF6] (7), in which one arene substituent of the phosphine is η6-coordinated to the metal and the phosphorus remains pendant. Treatment of 5 with tertiary phosphines (PR″3, R″=i-Pr, Ph, Cy) affords a mixture of the diastereomers [L2Ru(CH3CN)PR″3]+. The diastereoselectivity observed depends on the steric bulkiness of the phosphines and on the reaction conditions. [Copyright &y& Elsevier]

The η3:η4-allyldiene-(η5-cyclopentadienyl)titanium(II) complex [Ti(η5-C5Me5){η3:η4-C5Me3(CH2)2}] (1) reacts with three molar equivalents of substituted propargylic alcohols FcC&z.tbnd6;CCMe2(OH) (2a) and PhC&z.tbnd6;CCH2OH (2b) at elevated temperature to give (η5-pentamethylcyclopentadienyl)titanium(IV) alkoxides [Ti(η5-C5Me5)(FcC&z.tbnd6;CCMe2O-κO)3] (3a) and [Ti(η5-C5Me5)(PhC&z.tbnd6;CCH2O-κO)3] (3b), respectively. The crystal structure of 3a has been determined by single-crystal X-ray diffraction. [Copyright &y& Elsevier]

A synthetic route for 1,4-dimethyl-6-phenylfulvene (4) and 1,4-dimethyl-6,6-diphenylfulvene (5), which are characteristic in that they have substituents only on 1-, 4-, and 6-positions, is developed. The synthetic route is straightforward from 2-bromo-3-methyl-2-cyclopenten-1-one ethylene ketal (1), which can be easily synthesized in 100-g scale. Overall yield from 1 is 50 and 47% for 4 and 5, respectively. Synthesis of an ansa-metallocene complex, [Ph(H)C(fluorenyl)(1,3-Me2Cp)]ZrCl2 (7), is demonstrated using 4. Much higher comonomer incorporation in ethylene/1-hexene copolymerization and dramatic increase of molecular weight in 1-hexene polymerization are observed with 7 when the reactivity compared with that of the one not having methyl substituents, [Ph(H)C(fluorenyl)(Cp)]ZrCl2. [Copyright &y& Elsevier]

Examination of the chemistry of sterically crowded (C5Me4R)3Ln complexes has provided access to a series of [(C5Me4R)2Ln]2(μ-O) complexes: [(C5Me5)2La]2(μ-O), [(C5Me5)2Nd(NC5H4NC4H8)]2(μ-O), [(C5Me4iPr)2Sm]2(μ-O), [(C5Me4Et)2Gd]2(μ-O), and [(C5Me5)2Sm(NC5H5)]2(μ-O). X-ray crystallographic data on these complexes provide information on the effect of metal and cyclopentadienyl ring size on Ln&z.sbnd;O bond distances and Ln&z.sbnd;O&z.sbnd;Ln angles, which vary between 173 and 180° in these complexes. [Copyright &y& Elsevier]

Substitution of cyclopentadiene by one to three Me3Si or t-Bu groups allows the formation of mono- and biscyclopentadienylmono-, di-, and triselanes. [(Me3Si)3C5H2]2Se2 is the first biscyclopentadienyldiselane characterized by single crystal X-ray diffraction. Crystal structures are also presented to show that such compounds can function as ligands via selenium or the cyclopentadienyl moieties. [Copyright &y& Elsevier]

Reaction of [CpOs(PPh3)2Br] (1) with acetonitrile ligand or monodentate anions yielded complexes of the type [CpOs(PPh3)2(CH3CN)]+ (2), [CpOs(PPh3)2X], X=CN (3) and NCS (4). Treatment of 1 with NaNO2–HCl in the presence of NH4BF4 yielded the dicationic complex [CpOs(PPh3)2(NO)](BF4)2 (5). Reactions of the complex [CpOs(PPh3)2(CH3CN)]BF4 (2) with chelating ligands L2 yielded cationic complexes of the type [CpOs(L2)(PPh3)]BF4, where L2=2,2′-bipyridine (bipy) (6), 1,10-phenanthroline (phen) (7). These compounds were characterized by 1H NMR, 31P NMR and IR spectral data. The X-ray crystal structure of the complex [CpOs(PPh3)(phen)]BF4 has been determined. [Copyright &y& Elsevier]

The synthesis and structures of three new lanthanide complexes incorporating tetra-substituted guanidinate ligand [iPrN∴C(NiPr2)∴NiPr] are described. Treatment of Cp2LnNiPr2(THF) (Ln=Yb, Dy, Gd) with N,N′-di-isopropyl-carbodiimide results in mono-insertion of carbodiimide into the Ln&z.sbnd;N σ-bond to yield Cp2Ln[iPrN∴C(NiPr2)∴NiPr] (Ln=Yb(1), Dy(2), Gd(3)), providing an efficient method for the synthesis of organolanthanide guanidinate complexes. It was found that an excess of N,N′-di-isopropyl-carbodiimide did not affect the nature of the final product. Complexes 1–3 were characterized by elemental analysis, IR and mass spectroscopies. Complexes 1 and 2 were determined by the X-ray single crystal diffraction analysis. [Copyright &y& Elsevier]

Fully methylated η3:η4-allyldiene(η5-cyclopentadienyl)titanium(II) (1) reacts with alkynylketones RC&z.tbnd6;CC(O)Me (R=SiMe3 (3a) and ferrocenyl (3b)) to give the expected products of the C&z.dbnd6;O group insertion into one Ti–CH2 bond 4a and 4b, respectively. Compound 4a could not be isolated in pure form due to its high solubility; a minor product of two-fold addition (5) was isolated instead. Complex 5, formally [1+2 3a], was characterized as a monocyclopentadienyl bis(alkoxy)organyl complex, where the alkoxyorganyl ligand arises from C&z.dbnd6;O insertion into one Ti–CH2 and the Ti–C(cyclopentadienyl) bonds. The structures of compounds 4b and 5 were determined by single-crystal X-ray diffraction. [Copyright &y& Elsevier]

Treatment of Cp2Mg with 2-methyl-2-propanethiol, cyclohexanethiol, and 2-propanethiol in toluene at ambient temperature afforded the tetrameric cyclopentadienyl thiolato complexes [(η5-Cp)Mg(μ3-StBu)]4 (97%), [(η5-Cp)Mg(μ3-S(C6H11))]4 (92%), and [(η5-Cp)Mg(μ3-SiPr)]4 (83%) as colorless crystalline solids. Treatment of [(η5-Cp)Mg(μ3-StBu)]4 with tetrahydrofuran or tert-butylpyridine in dichloromethane/hexane afforded the dimeric solvated complexes [(η5-Cp)Mg(μ2-StBu)(THF)]2 (78%) or [(η5-Cp)Mg(μ2-StBu)(tBupy)]2 (60%) as colorless crystals. The crystal structures of [(η5-Cp)Mg(μ3-StBu)]4, [(η5-Cp)Mg(μ2-StBu)(THF)]2, and [(η5-Cp)Mg(μ2-StBu)(tBupy)]2 were determined by X-ray diffraction methods. In the solid-state structure, [(η5-Cp)Mg(μ3-StBu)]4 contains one η5-cyclopentadienyl ligand per magnesium and one cubic core of Mg4S4 that features a mirror plane of symmetry along one diagonal Mg2S2 plane. [(η5-Cp)Mg(μ2-StBu)(THF)]2 contains one η5-cyclopentadienyl ligand per magnesium and one bent Mg2S2 core with a mirror plane along thiolato bridges. [(η5-Cp)Mg(μ2-StBu)(tBupy)]2 contains one η5-cyclopentadienyl ligand per magnesium and a planar Mg2S2 core with a center of symmetry. [Copyright &y& Elsevier]

We describe the synthesis of hydrochlorides of [TiCp{(C5H4(CH2)nNMe2}Cl2] (n=2 or 3) via [TiCpCl3] and the lithiated (cyclopentadienylalky)lamine. The –NHMe2 groups in these complexes are not coordinated to the titanium, and probably not in the parent amines either, the metal stereochemistry being the same in each group of compounds. The structure of [TiCp(η5-C5H4CH2CH2CH2NHMe2)Cl2]Cl is described in detail. [Copyright &y& Elsevier]

The dianions {[p-(CO)3MC5H4C(O)]2C6H4}2− reacted with Ph2SnBr2 in a 1:2 or 1:1 ratio to give tetranuclear heterodimetallic complexes p-[(Ph2BrSn)(CO)3MC5H4C(O)]2C6H4 (M=Mo (1) or W (2), respectively), and with CH2(SnPhBr2)2 to yield tetranuclear heterodimetallic metallamacrocycles {p-[(CO)3MC5H4C(O)]2C6H4}{(Ph2−nBrnSn)2CH2} (n=1, M=Mo (5) and W (6); n=0, M=Mo (7) and W (8), respectively). Only one bromide on the tin atom was replaced by the metallic anions owing to the electron-withdrawing groups on the cyclopentadienyl rings greatly decreasing the nucleophilicity of the metallic anions. Treatment of complexes 1 and 2 with Na2S·9H2O yielded the novel metallamacrocyclic complexes {p-[(CO)3MC5H4C(O)]2C6H4}{(Ph2Sn)2S} (M=Mo (3) and W (4), respectively). All compounds have been characterized by elemental analyses, IR and 1H-NMR spectra. The crystal structures of complexes 3 and 7 determined by X-ray crystallography indicate a novel 14-membered organometallic metallamacrocyclic ring system in which two Mo–Sn units are linked by the bridging cyclopentadienyl ligand and the sulfur or carbon atom. In addition, the carbonyl group π-system is coplanar with the adjacent cyclopentadienyl ring system, but markedly deviates from the bridging phenyl plane. [Copyright &y& Elsevier]

Organoterbium compounds TbBr2CpHPz and TbBr2CpPPh3 were obtained by reaction of pyrazole or triphenylphosphine ligands with cyclopentadienylterbium dibromide. These compounds were characterized by elemental analysis, complexometric titration with EDTA, thermal analysis, vibrational spectra in the infrared region and 1H NMR. In a preliminary catalytic study, these compounds were active in ethylene polymerization when MAO was used as cocatalyst, producing low crystalline polyethylene. [Copyright &y& Elsevier]

The photochemical reaction of (η5-C5H5)Fe(CO)2I (FpI) with 2′,3′,5′-tri-O-acetyluridine (1a), 3′,5′-di-O-acetylthymidine (1b) and 5′-O-(4,4′-dimethoxytrityl)thymidine (1c) in benzene containing excess of diisopropylamine afforded corresponding Fp-complexes of N(3)-deprotonated nucleosides, 2a–c in moderate (45–75%) yields. Attempted removal of acetyl groups from 2a–b (K2CO3, MeOH–H2O, rt, 1 h or 25% NH3 aq., MeOH, rt, 2 h) gave unseparable mixtures of 3-Fp-uridine or 3-Fp-thymidine (3a–b) with uridine or thymidine. On the other hand, removal of the 4,4′-dimethoxytrityl groups from 2c proceeded smoothly in 80% acetic acid affording 3-Fp-thymidine (3b) in quantitative yield. [Copyright &y& Elsevier]

Deprotonation of the phenol-imines 2-But-6-(RNCH)C6H3OH (R=2,4,6-Me3C6H2 (1a), C6F5 (1b), C6H11 (1c) and phenol-amines 2,4-But2-6-(R′NCH2)C6H2OH (R′=C4H8 (1d), C5H10 (1e)) with n-BuLi gives the corresponding lithium phenoxides. The reaction with MCl4 in THF solution leads to the bis(ligand) complexes {2-But-6-(RNCH)C6H3O}2MCl2 and {2,4-But2-6-(R′NCH2)C6H2O}2MCl2 (M=Ti: 2a, 2d, 2e, Zr: 3a, 3d and 3e). The cyclopentadienyl phenoxy-imine and -amine complexes Cp{2-But-6-(RNCH)C6H3O}MCl2 and Cp{2,4-But2-6-(R′NCH2)C6H2O}MCl2 (M=Ti: 4a–4e, Zr: 5a–5e) were prepared similarly through reaction with CpMCl3. The crystal and molecular structures of 2a, 3a, 4a and 4e have been determined. 2a and 3a are isostructural and exhibit a distorted octahedral geometry. 4a has a distorted square-pyramidal structure whereas 4e is essentially tetrahedral and the nitrogen does not coordinate. All new complexes are active for the polymerisation of ethene when activated with methyaluminoxane. 4b, 5a, 5d and 5e are active for the copolymerisation of ethene and 1-hexene and the oligomerisation of 1-hexene. [Copyright &y& Elsevier]

Fully-solvated, divalent lanthanide dication complexes free of coordinating anions, [LnLx]2+, in which L=MeCN, THF, have been synthesized by protonation of amide, indenyl, and pentamethylcyclopentadienyl precursors. The Sm(II) dication [Sm(THF)7]2+ was initially isolated as [Sm(THF)7][BPh4]2, (1), by protonolysis of the indenyl complex (C9H7)2Sm(THF)3 with [Et3NH][BPh4]. Compound 1 can also be obtained from (C5Me5)Sm[N(SiMe3)2](THF)2 and [Et3NH][BPh4]. The Yb analog, [Yb(THF)6][BPh4]2, (2), was obtained from the reaction of the bimetallic [(C5Me5)Yb(THF)]2(C8H8) with AgBPh4 and the reaction of (C5Me5)Yb[N(SiMe3)2](THF)2 with [Et3NH][BPh4], but [YbLx]2+ is best obtained from the reaction of Yb[N(SiMe3)2]2(THF)2 with [Et3NH][BPh4]. Reaction of Yb[N(SiMe3)2]2(THF)2 with [Et3NH][BPh4] in THF followed by recrystallization from acetonitrile affords [Yb(MeCN)8][BPh4]2, (3). The seven THF molecules in 1 form a pentagonal bipyramidal ligand environment around Sm2+. Complex 2 has an octahedral Yb2+ coordination environment and 3 has a distorted square antiprismatic arrangement of MeCN ligands around Yb2+. [Copyright &y& Elsevier]

Reactions of nickelocene with metallic sodium in the presence of internal alkenes: trans-3-hexene, cis-2-heptene and 2,3-dimethyl-2-butene have been studied. It was found that {NiCp} species generated in the reaction of nickelocene with sodium dehydrogenate internal alkenes to alkynes. The latter form then complexes with tri(cyclopentadienylnickel) (NiCp)3RC&z.tbnd6;CR and with di(cyclopentadienylnickel) (NiCp)2RC&z.tbnd6;CR. If the methyl group is adjacent to the alkene double bond, the activation of the C&z.sbnd;H bonds of this group leads to the formation of alkylidyne tri(cyclopentadienylnickel) clusters. In the reaction of nickelocene with lithium in the presence of 1,5-hexadiene, alkylidyne tri(cyclopentadienylnickel) cluster (NiCp)3CCH2CH2CH2CH&z.dbnd6;CH2 and intramolecularly stabilised complex CpNiCH(CH3)CH2CH2CH&z.dbnd6;CH2 were formed. In all the reactions studied di-, (NiCp)2CpH, and tetra(cyclopentadienylnickel), (NiCp)4Hx, compounds were formed besides the other products. [Copyright &y& Elsevier]

The reaction of CpMoCl2 with diazadiene ligands RN&z.dbnd6;CH&z.sbnd;CH&z.dbnd6;NR (R2&z.sbnd;dad) affords the corresponding paramagnetic complexes CpMoCl2(R2&z.sbnd;dad) (R=Ph, 1; p-Tol, 2; C6H3Pr2i-2,6, 3; and Pri, 4). All compounds have been characterized by EPR spectroscopy and have been investigated by cyclic voltammetry. They display one-electron oxidation and reduction processes, these being reversible or irreversible depending on the nature of R. The irreversibility of the reduction wave is due to a chemical follow-up process which consists of chloride loss from the reduced product. This phenomenon is suppressed in the presence of excess chloride in solution. An X-ray structure of 3 verifies the mononuclear nature of the compound and the chelating mode of the dad ligand, the MoN2C2 ring being essentially planar. The N&z.sbnd;C and C&z.sbnd;C bond distance pattern suggests the important contribution of an enediamido Mo(V) limiting form. In the presence of 1-bromoethylbenzene, complexes 1–4 catalyze the controlled/‘living’ radical polymerization of styrene. Complex 3 also leads to a controlled/‘living’ radical polymerization of styrene in the presence of AIBN (α,α-azoisobutyronitrile) as a radical generator. Therefore, this is the second example of a compound which is capable of controlling the styrene radical polymerization under both ATRP and SFRP conditions. [Copyright &y& Elsevier]

Reactions of (ring)MoCl3 [ring=cyclopentadienyl, η5-C5H5 (Cp) and indenyl η5-C9H7 (Ind)] with salts of the N,N-diethyldithiocarbamate (S2CNEt2)−, O,O′-diethyldithiophosphate [S2P(OEt)2]−, N,N′-diphenylformamidinate [CH(NPh)2]−, acetate (O2CCH3)− and acetylacetonate [CH3COCH(O)CH3]− (acac)− anions yield the molybdenum(IV) complexes of the type (ring)MoCl2X. Characterisation of new compounds by elemental analysis, IR and 1H-NMR spectroscopy and magnetic susceptibility measurements is discussed. [Copyright &y& Elsevier]

In this work the synthesis of mono(cyclopentadienyl)lanthanide compounds containing methanesulfonate anion and pyrazinamide ligand is presented. The compounds were characterized by elemental analyses, complexometric titration with EDTA, thermal analyses, and vibrational spectra in the infrared region. In a preliminary catalytic study these compounds were active in ethylene polymerization when MAO was used as cocatalyst producing low crystalline polyethylene. [Copyright &y& Elsevier]

The ligand C[sub 5] H[sub 4] (CH[sub 2] CH[sub 2] CAr[sup F] [sub 2] OH) (3) (Ar[sup F] = 3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] ) was prepared in two steps, from the iodo ester ICH[sub 2] CH[sub 2] CO[sub 2] Me by way of the cyclopentadienyl ester C[sub 5] H[sub 5] CH[sub 2] CH[sub 2] CO[sub 2] Me (2), in 55% overall yield. Thermal reaction of 3 with {Y[N(SiMe[sub 3] )[sub 2] ][sub 2] (THF)[sub 2] (µ-Cl)}[sub 2] afforded the neutral chloride complex {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )[sub 2] ]}YCl{THF}[sub n] (5a: n = 2, 5b: n = 1). Metathesis reactions of 5 with 1 equiv of NaN(SiMe[sub 3] )[sub 2] , LiO-2,6-t-Bu[sub 2] C[sub 6] H[sub 3] , and LiCH(SiMe[sub 3] )[sub 2] afforded {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )[sub 2] ]}Y{N(SiMe[sub 3] )[sub 2] }{THF}[sub n] (6), {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )[sub 2] ]}Y{O-2,6-t-Bu[sub 2] C[sub 6] H[sub 3] }{THF}[sub n] (7), and {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )[sub 2] ]}Y{CH(SiMe[sub 3] )[sub 2] }{THF}[sub n] (8), respectively, (a: n = 2, b: n = 1). Exposure of the bis(THF) solvates to reduced pressure resulted in desolvation to the mono(THF) adducts for 5–8. The solid state structure of 6b was established by X-ray crystallography. In addition, formation of a spirocyclic ether (C[sub 4] H[sub 6] CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )[sub 2] 4), obtained by the intramolecular cyclization of ligand 3, was confirmed by X-ray crystallography. Key words: yttrium, organometallic, cyclopentadienyl, X-ray, alkoxide, chelate, alkyl, hybrid ligand, NMR, cyclization.On a préparé le ligand C[sub 5] H[sub 4] (CH[sub 2] CH[sub 2] CAr[sup F] [sub 2] OH) (3) (Ar[sup F] = 3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] ) en deux étapes à partir de l'ester iodé ICH[sub 2] CH[sub 2] CO[sub 2] Me, par le biais de l'ester cyclopentadiényle, C[sub 5] H[sub 5] CH[sub 2] CH[sub 2] CO[sub 2] Me (2), avec un rendement global de 55%. La réaction thermique du composé 3 avec {Y[N(SiMe[sub 3] )[sub 2] ][sub 2] (THF)[sub 2] (µ-Cl)}[sub 2] conduit à la formation du complexe chloré neutre {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )]}YCl{THF}[sub n] (5a: n = 2, 5b: n = 1). Les réactions de métathèse des composés 5 avec un équivalent de NaN(SiMe[sub 3] )[sub 2] , LiO-2,6-t-Bu[sub 2] C[sub 6] H[sub 3] et LiCH(SiMe[sub 3] )[sub 2] conduisent respectivement au {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )]}Y{N(SiMe[sub 3] )[sub 2] }{THF}[sub n] (6), {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )]}Y{O-2,6-t-Bu[sub 2] C[sub 6] H[sub 3] }{THF}[sub n] (7) et {η[sup 5] :η[sup 1] -C[sub 5] H[sub 4] [CH[sub 2] CH[sub 2] C(O)(3,5-C[sub 6] H[sub 3] (CF[sub 3] )[sub 2] )]}Y{CH(SiMe[sub 3] )[sub 2] }{THF}[sub n] (8) (a: n = 2, b: n = 1). Si l'on soumet les produits bis(THF) solvatés 5–8 à une pression réduite, il en résulte une désolvatation conduisant aux adduits mono(THF). On a déterminé la structure du composé 6b par diffraction des rayons X. De plus on a confirmé par diffraction des rayons X que la cyclisation intramoléculaire du ligand 3 conduit à la formation d'un éther spirocyclique, C[sub 4] H[sub 6] CH[sub 2] CH[sub 2] (CO)(3,5-C[sub 6] H[sub 5] (CF[sub 3] )[sub 2] )[sub 2] (4). Mots clés : yttrium, organométallique, cyclopentadiényle, rayons X, alcoolate, chélate, alkyle, ligand hybride, RMN, cyclisation. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Substituent effects in several titanium(IV)–trichloride half-sandwich complexes with η5-coordinated cyclopentadienyl or indenyl ligands including (η5-C5H5)TiCl3 (1), (η5-C9H7)TiCl3 (2), (η5-1-SiMe3&z.sbnd;C9H6)TiCl3 (3), (η5-1-Me&z.sbnd;C9H6)]TiCl3 (4), (η5-4-Me&z.sbnd;C9H6)]TiCl3 (5), [η5-5,6-(CH2)3&z.sbnd;C9H5]TiCl3 (6), (η5-2-SiMe3&z.sbnd;C9H6)TiCl3 (7), (η5-1,3-Me2-C9H5)TiCl3 (8), (η5-4,7-Me2&z.sbnd;C9H6)TiCl3 (9), [η5-3,4-(CH2)3&z.sbnd;C9H5]TiCl3 (10), (η5-1-SiMe3&z.sbnd;4,7&z.sbnd;Me2&z.sbnd;C9H4)TiCl3 (11) and (η5-1,3,4,7-Me4&z.sbnd;C9H3)TiCl3 (12) were studied with cyclic voltammetry (CV) and UV–vis spectroscopy. Cyclic voltammograms of 1–12 showed current waves caused by the reversible redox process of the Ti(IV)/(III) redox couple at electrode potentials typical for d0-titanium centers. In UV–vis spectra, two major absorption bands between 400–430 and 530–590 nm were observed. The latter is assigned to a ligand to metal charge transfer (LMCT). A comparison shows that the alkylation or Me3Si-substitution (complexes 3–12) induces a shift of the corresponding absorption to longer wavelengths indicating a smaller energy gap between the frontier orbitals. Based on the experimental data an additive increment system for Me3Si and alkyl-substituted η5-indenyl derivatives of titanium(IV)–trichloride species is proposed. [Copyright &y& Elsevier]

Nickelocene reacts with organolithium or -magnesium compounds forming unstable 16 VE species {CpNiR}. These species reacts further yielding many new organonickel compounds. The type of R group has a decisive influence on the course of {CpNiR} transformations. If R possesses easily accessible α- or β-hydrogen atoms, then hydrogen elimination is the main reaction course and many cyclopentadienylnickel clusters are formed. The absence of α- and β-hydrogen favours a coupling reaction with R&z.sbnd;R formation. Facile stabilisation of free radicals causes homolytic cleavage of the Ni&z.sbnd;C bond with alkylation of cyclopentadienyl ring. Some kinds of R groups e.g. R=CHPh2 facilitate formation of a carbene :CPh2 which can react with nickelocene yielding alkylated nickelocene derivatives. {CpNiR} can also undergo intramolecular stabilisation as it occurs for R=CPh3. In most cases the above reactions proceed simultaneously yielding a complex mixture of several compounds. On the other hand some reactions proceed quite selectively forming products in high yield so they can be applied in syntheses. [Copyright &y& Elsevier]

This review describes recent advances in the synthesis and polymerization chemistry of organolanthanide complexes (including those of scandium and yttrium), with emphasis being placed on the complexes that show novel activity and selectivity in polymerization reactions. [Copyright &y& Elsevier]

The photolytic CO-substitution reaction of the organoiron thiocarboxylate complexes CpFe(CO)2SCOR (R=CH3, 2-CH3C6H4, 2-NO2C6H4, 4-NO2C6H4, 3,5-(NO2)2C6H3) with diphosphines (Ph2P(CH2)nPPh2) [n=1 (dppm), n=2 (dppe), n=3 (dpppr), n=4 (dppb), n=5 (dppp), n=6 (dpph)] at room temperature using 1:2 (metal–ligand) molar ratio afforded exclusively the disubstituted complexes CpFe(Ph2P(CH2)nPPh2)SCOR when n=1, 2 and 3 and the monosubstituted analogs CpFe(CO)(Ph2P(CH2)nPPh2)SCOR when n=4, 5 and 6. This reaction was found to be strongly influenced by the backbone length of the diphosphine ligand, the nature of the R group of the thiocarboxylate moiety and the metal–ligand molar ratios. The crystal structure of CpFe(dppm)SCO(3,5-(NO2)2C6H3) was determined. [Copyright &y& Elsevier]

The 60-electron tetrahedral clusters W2Ir2(μ-L)(CO)8(η5-C5H4Me)2 [L=dppe (2), dppf (3)] have been prepared from reaction between W2Ir2(CO)10(η5-C5H4Me)2 (1) and the corresponding diphosphine in 52 and 66% yields, respectively. A structural study of 2 reveals that three edges of a WIr2 face are spanned by bridging carbonyls, that the iridium-ligated diphosphine coordinates diaxially and that the tungsten-bound methylcyclopentadienyls coordinate axially and apically with respect to the plane of bridging carbonyls. A structural study of 3 reveals that the dppf ligand bridges an Ir&z.sbnd;Ir bond which is also spanned by a bridging carbonyl; tungsten-ligated methylcyclopentadienyl ligands and terminal carbonyls result in electronic asymmetry (17e and 19e iridium atoms) in the electron-precise cluster. Both clusters show two reversible one-electron oxidation processes and an irreversible two-electron reduction; the dppf-containing cluster 3 has a further, irreversible, one-electron oxidation process. UV–vis-NIR spectroelectrochemical studies of the 2→2+→22+ progression reveal the appearance of a low-energy transition on oxidation to 2+ which persists on further oxidation to 22+. [Copyright &y& Elsevier]

The sodium complexes [NaC5H5(15-crown-5)] (1a), [NaC9H7(15-crown-5)] (1b), and [NaC13H9(15-crown-5)] (1c, C5H5=cyclopentadienyl, C9H7=indenyl, C13H9=fluorenyl) were synthesized from NaC5H5, NaC9H7, NaC13H9, and 15-crown-5. Single crystal X-ray diffraction analyses were carried out for all three compounds 1a, 1b, 1c, and show that monomeric units were present in the solid state with the organic aromatic anion coordinated to the sodium cation via the five-membered ring. [Copyright &y& Elsevier]

Metallocenes of yttrium and the lanthanides with bis(phosphinimino)methanides in the coordination sphere are reported. Reaction of [{CH(PPh2NSiMe3)2-κ2N,N′,κC}LnCl2]2 (Ln=Y, Sm, Er) with Na(C5H5) in a 1:4 molar ratio in THF afforded the corresponding metallocenes [(η5-C5H5)2Ln{CH(PPh2NSiMe3)2-κ2N,N′,κC}]. The structures of these new compounds were investigated in solution and in the solid state. Single crystal X-ray structures show that both imine groups and the methine carbon are bound to the lanthanide atom. [Copyright &y& Elsevier]

Diarylmercury(II) compounds, HgR2 (particularly bis(pentafluorophenyl)mercury), which are easily prepared and are stable to air and moisture, are attractive reagents for the synthesis of highly reactive lanthanoid organometallics and complexes. Thus, reactions of HgR2 (R=C6F5) with elemental lanthanoids in donor solvents generate organolanthanoid species that when subsequently treated with a protic reagent LH (e.g. C5R5H, ArOH, R2NH) eliminate volatile RH giving cyclopentadienyl-, aryloxo- and organoamido-lanthanoids, respectively. Combining these two steps in a convenient ‘one-pot’ reaction between Ln metal, HgR2 and LH provides a versatile synthetic method (redox transmetallation–ligand exchange) for a wide variety of lanthanoid complexes and exploits the high reactivity of the initially generated lanthanoid&z.sbnd;carbon bond. The syntheses are possible even in instances where the intermediate organolanthanoid complex cannot be isolated or detected. The increasing scope of redox transmetallation–ligand exchange often makes it competitive with metathesis and its simplicity can make it superior. Previously unreported applications viz. to [Ln(C5H5)3(THF)] complexes, [Yb(C5H5)2(THF)2] and [Yb(C5Me5)2(THF)2] are included. [Copyright &y& Elsevier]

Hypoxia imaging agents can play an important role in the tumor treatment by avoiding the worse effect of radiotherapy and chemotherapy due to the tumor hypoxia. Due to the small size and easy coordination, tricarbonyl technetium-99m can be used to label a wide range of imaging agents. In this work, the tricarbonyl 99m Tc labeled small-sized hypoxia imaging agents containing 2-nitroimidazoles were prepared, which have different carbon chain lengths between cyclopentadienyl and 2-nitroimidazole, and which have one or two 2-nitroimidazole groups. The results of S180 cell experiment and biodistribution indicated that these molecules have different hypoxic selectivity. When contains one 2-nitroimidazole, as the carbon chain lengthens, which means the molecular volume becomes larger, hypoxia cellular uptake and selectivity decrease in S180 cell uptake experiment. In biodistribution study in mice bearing S180 tumor, Tc-2 (1-cyclopentadienyl-5-(2-nitro-1H-imidazol-1-yl)-pentan-1-one tricarbonyl 99m Tc complex), which has intermediate carbon chain, is better due to the more complex factors. Its tumor/blood (T/B) ratio is 3.56 ± 0.25, tumor/muscle(T/M) ratio is 1.73 ± 0.29 and tumor uptake is 2.23 ± 0.24%ID/g at 2 h. Comparing to other tricarbonyl technetium complexes containing one 2-nitroimidazole, the complexes in this work have an advantage in tumor/blood ratio and tumor uptake. This suggests that the small-volume cyclopentadienyl may have an advantage when used as a ligand. When contains two 2-nitroimidazole groups, the complex, 1-cyclopentadienyl-5-di(2-(2-nitro-1H-imidazol-1-yl)ethyl)amino-pentan-1-one tricarbonyl 99m Tc complex (Tc-4), has the better results in the cell experiment than those which contain one 2-nitroimidazole group. Thus the hypoxia imaging agent contains two 2-nitroimidazole groups is more advantageous, but further modifications of Tc-4 are needed to improve its clearance rate in the blood, because the increased lipophilicity leads to a decrease in the T/B ratio of Tc-4. In conclusion, small volume hypoxia imaging agents with two 2-nitroimidazole groups may be the trend of development., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The electron-rich cyclopentadienyl and the analogous indenyl and fluorenyl ligands (collectively denoted here as Cp') have been impactful in stabilizing electron-deficient metal centers including the highly electropositive alkaline earths. Being in the s-block, the group 2 metals follow a major periodic variation in their atomic and ionic properties which is reflected in those Cp' compounds. This article presents an overview of this class of compounds for all the five metals from beryllium to barium (radium is excluded for its radioactivity), highlighting their systematic variation., (© 2021 Wiley-VCH GmbH.)

The molecular structure of [CpFe(CO)2]3In (Cp=η5-C5H5) has been determined and contains a planar, three-coordinate indium center bound to three CpFe(CO)2 moieties by unsupported In–Fe bonds. The orientation of the CpFe(CO)2 units relative to the Fe3In plane precludes π-type interaction between iron and indium, while comparison with the isostructural gallium analog suggests the orientation of the CpFe(CO)2 units is controlled by the size of the central atom and the inter-ligand steric repulsion. Crystal data: monoclinic, monoclinic, C2/ c, a = 26.911(5), b = 10.838(2), c = 16.474(3)Å, β = 111.63(3)°, V = 4465(2)Å3 and, Z = 8. [ABSTRACT FROM AUTHOR]

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Copyright of Chemical Monthly / Monatshefte für Chemie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)