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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines a...

Two novel lead ion imprinted adsorbents were prepared based on tridentate functionalized mesoporous silica material. Adsorption sites and behaviors were investigated. The adsorbent BPMA-Pb-IIMS pos...

2-Arylbenzo[d]oxazole is an important structural motif in pharmaceutical chemistry, while its regioselective halogenation still remains challenging due to the many possible reaction sites on the two aromatic systems. Herein, we report a transition metal catalysed chlorination, bromination and iodination of 2-arylbenzo[d]oxazole with N-halosuccinimide, in which ruthenium-catalysed halogenation occurred on the C7-position and rhodium-catalysed halogenation occurred on the ortho-position. The C7 halogenation was only observed for 5-methyl-2-(p-substituted)arylbenzo[d]oxazoles under rhodium catalysis. Preliminary mechanistic experiments and density functional theory (DFT) calculations suggested that the C7-halogenation catalysed by Ru might have a single-electron-transfer (SET) radical process, while the ortho-selective halogenation catalysed by Rh proceeds probably through a redox-neutral SN2-type mechanism. The different selectivity of Rh catalysed halogenation could be due to the charge difference between benzo[d]oxazolyl and aryl rings. The two kinds of halogenated products were proved to be versatile by constructing aryl and alkynyl groups on the C–X site via Suzuki and Sonogashira cross-coupling reactions.

A series of benzoxazolyl and benzothiazolyl phosphine ligands 4a-4g were synthesized and characterized, which prepared from commercially available 2-aminophenol/2-aminobenzenethiol and 2-bromobenzaldehyde via cyclization and phosphination. The representative ligands 4c and 4e were determined by single-crystal X-ray diffraction. The corresponding iridium complexes could be generated in situ when [Cp*IrCl2]2 (Cp* = pentamethylcyclopentadienyl) encountered ligands. The molecular structures of complexes 5c and 5e were crystallographically characterized. The dihedral angles of N (1)-C (1)-C (8)-C (9) showed an increasing twist compared with the corresponding ligand. The iridium (III) catalysts were screened, [Cp*IrCl2]2/4a proved to be the optimal catalyst, which exhibited efficient catalytic activity toward versatile alkylations including ketones, secondary alcohols and amines with primary alcohols. Additionally, the synthesis of quinolines from ketones with 2-aminobenzyl alcohol by intermolecular cyclization and indole from 2-(2-aminophenyl)ethanol by intramolecular cyclization were achieved under the optimized conditions.

Herein, a general and practical route to 2-(2-aminophenyl)- and 2-(2-alkoxyphenyl)-substituted benzazoles by nucleophilic aromatic substitution (SNAr) is described. Upon treatment with Cs2CO3, the formation of C–N, C–O bonds occur between fluorine-substituted 2-aryl benzazoles and a diverse range of nitrogen, oxygen nucleophiles to provide the targets in good to excellent yields. Commercially available nucleophiles and high atom economy are notable features of the protocol. Meanwhile, the construction of C(sp2)–C(sp3) bond was also furnished in the presence of palladium catalyst.

Supported metal nanoparticles (NPs) catalysts in constructing benzene-fused cyclic framework with chirality is very challenging. Dihydrobenzofuran and its derivatives are significant heterocyclic units in biologically molecules. Herein, size-controlled Pd NPs fixed on mesoporous silica (Pd/MS-xT) SBA-15, FDU-12 and mesocellular silica foams (MCFs) were utilized to synthesize racemic and asymmetric iodomethyl dihydrobenzofuran for the first time. The size of Pd NPs was regulated by increasing NaBH4 reduction treatments times (-xT) and enlarging supports pore. Based on large mesopore of MCF-3, supported catalyst 3%Pd/MCF-3-4T possessed larger Pd size gave the excellent performance at 92% racemic yield. Under chiral phosphine modifier N–Me-Xu3, we implemented more deserving asymmetric reaction over 3%Pd/MCF-3-1T with smaller Pd NPs. TGA for organic surface coverage demonstrated that the substrate preferred larger Pd NPs, N–Me-Xu3 capped more easily on smaller ones. Besides, effects of reaction medium and N–Me-Xu3 additive quantity further revealed the coordination of chiral modifier on Pd/MCF-3 was the determinant. For broader visions, the performance dependence based on surface properties of heterogeneous catalyst would play crucial contributions towards construction of complexed organic molecules.

N-Heterocyclic carbene (NHC), generated in situ from easily available N-heterocyclic imidazolium salt with air as terminal oxidant, has successfully been utilized as a cheap and efficient catalyst for one-pot aerobic oxidative synthesis of 2-arylbenzo[d]oxazoles, 2-substituted benzo[d]thiazoles, and 1,2-disubstituted benzo[d]imidazoles.

Mesoporous silica (SBA-15)-supported iridium catalysts are prepared by grafting of the newly developed cyclometalated iridium 2-aryl benzoxazole complexes with 3-(triethoxysilyl)-propyl-isocyanate (TEPIC) as a linker. The supported catalysts are characterized by solid-state NMR spectroscopy, small-angle X-ray scattering (SAXS), nitrogen physisorption, FTIR spectroscopy, and electron microscopy analysis, which indicate that the coordination environment of the iridium center as well as the two-dimensional hexagonal pore structure of SBA-15 is maintained after the immobilization. These supported catalysts have been successfully applied to the selective transfer hydrogenation of quinoline derivatives to 1,2,3,4-tetrahydroquinolines (THQs) with formic acid in pure water. Moreover, by simply adapting the amount of formic acid used, N-formyltetrahydroquinolines (FTHQs) could be selectively synthesized from quinolines in two-step, one-pot transfer hydrogenation/N-formylation reactions with these supported catalysts. Notably, these supported catalysts showed better catalytic reactivity than their homogeneous analogs, and they can be easily reused 12 times in the transformation of quinoline to N-formyltetrahydroquinoline (FTHQ) without significant loss of activity.

Fundamental understanding of the real catalytic species in water oxidation is a major knowledge gap that must be overcome in order to develop artificial water splitting systems and produce chemical fuels from solar energy. In an effort to analyze the transformation and catalytic resting state of [Cp*Ir(pmNHC)Cl]Cl [pmNHC = 1-(2-pyrimidyl)-3- n -butylimidazol-2-ylidene, Cp* = pentamethylcyclopentadienyl] in water oxidation using potassium peroxymonosulfate (Oxone) as primary oxidant, we found the precatalyst evolved into blue solution when a small amount of Oxone was added while further oxidation yield purple solution. These species have been proven to be homogeneous and they remain active in water oxidation. 1 H NMR profiles and MALDI-MS data suggested a rapid oxidation of the Cp* ligand to acetone, formic and acetic acid. 1 H NMR, TEM-EDX as well as MALDI-MS data indicated a continuous degradation of pyrimidyl, butyl and NHC groups. MALDI-MS, XANES and 17 O NMR spectroscopy data of the blue species are most consistent with an iridium(III) compound with two waters, one dioxygen and pmNHC group. The catalytic resting purple species probably consists of an iridium(III) complex with three waters, one chloride and one bicarbonate ligand. Besides, the presence of a small amount of iridium aqua ion oligomers was observed in the purple species. The formation of polymers and nanoparticles is likely to be inhibited by the acid environment.

Three highly efficient adsorbents Pb-IIMS-SBA-15, Pb-IIMS-MCM-41 and Pb-IIMS-FDU-12 for Pb(II) were prepared by grafting the functional monomer 4-(di (1H-pyrazol-1-yl) methyl) phenol (DPP) on corresponding mesoporous silicas with Pb(II) as temple. All these three Pb(II) ion-imprinted mesoporous silica (Pb-IIMS) were characterized by Fourier transform-infrared spectroscopy (FT-IR), solid-state 29 Si and 13 C NMR spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), N 2 adsorption–desorption analysis and small angel X-ray diffraction (XRD). The adsorption experiments revealed three Pb-IIMS all possessed considerable adsorption performance for Pb(II), their adsorption profiles obeyed pseudo-second-order kinetics and Langmuir isotherm model. Compared with their corresponding non-imprinted materials, three Pb-IIMS displayed satisfactory selectivity to Pb(II) over seven competing metal ions. Among them, Pb-IIMS-MCM-41 particularly owned outstanding adsorption performance and selectivity, the maximum adsorption capacity as high as 344.8 mg g −1 , as well as excellent reusability through twelve adsorption-desorption cycles. Additionally, Pb-IIMS-MCM-41 was employed as packing material to construct a solid-phase extraction column for detection of Pb(II), which exhibited detection limit of 0.015 μg L −1 , then method was successfully applied to the removal and determination of trace Pb(II) in practical water samples.

A new method coupling novel solid-phase extraction (SPE) with inductively coupled plasma-atomic emission spectrometry (ICP-AES) was developed, based on the adsorbent prepared by modifying a strong-coordinating bis-pyrazolyl functional monomer onto mesoporous silica SBA-15. The adsorbent DPP@SBA-15 was characterized by a set of analytical techniques, as well as studied the optimized various experimental parameters such as pH, stripping agent, adsorption capacity and equilibrium adsorption time. This newly developed adsorbent material do exhibit good chemical and mechanical stability, satisfactory adsorption capacity (72.5 mg/g) and high selectivity for Cr(III). Consequently, the DPP@SBA-15 was utilized as SPE adsorbent for adsorption of Cr(III) and determination of Cr(VI). An excellent linearity was shown in the range of 1–20 μg/mL− 1 (R2 = 0.9999), and the limit of determination 0.028 μg/mL− 1. Furthermore, Cr(VI) released from artificial ring was successfully detected and considerable recoveries varying from 97.6 to 103.0% were attained.

Seven new chelated cyclometalated Ir complexes of ABON,P, ABON,O, and ABON,C(carbene) based on a rigid and tunable 2-arylbenzo[d]oxazole backbone have been prepared for the N-methylation of amines. Among these three coordinated modes, ABON,C(carbene)-chelated iridium-based catalysts exhibited good performance in the monomethylation of aromatic amines with methanol (MeOH) as the green methylation reagent. The steric-modified synthesis of ABON,C(carbene) complexes was described. The most active ABON,C(carbene) complex with marginal steric hindrance as a catalyst was obtained from the benzoxazole ring without a substituent and methyl group of the benzimidazole ring on the N-heterocyclic carbene (NHC) ligand. A variety of amines including para- and meta-substituted aromatic amines, as well as heterocyclic amines, were formulated as suitable substrates. Importantly, this catalyst considerably promoted the yield of the N-methylation of ortho-substituted aromatic amines. Controlled kinetic experiments and deuterium-labeling reactions of these ortho-substituted amines were conducted under optimized conditions. On the basis of the experimental results, a plausible mechanism was proposed.

The past decades have witnessed the fast growth of ortho-directing group assisted in C H activation and olefination. Herein we addressed these olefination products’ photo-induced E → Z isomerization in term of various ortho-substitution groups. Initially, we discovered ortho benzoxazolyl aryl acrylates effectively undertook E → Z isomerization (up to 88% yields) under 365 nm direct irradiation. Furthermore, scoping other five directing groups in C H activation and olefination revealed that acetylamino group also present to be good ortho-substituted groups that enhancing E → Z isomerization. Controlled experiment shows the substitution position is vital for photo-induced isomerization or [2 + 2] cycloaddition. Lastly, prevalent interesting fluorescent quenching/change phenomenon were always in accompany with the isomerization. X-ray single crystallography disclose the isomerization process undertook significant conjugated distortion of the aryl acrylates fragment, we proposed such change could contribute to fluorescent and absorbent decrease.

Selective synthesis driven by appropriate support properties of heterogeneous catalysts is promising, but long-term process to explore. In this work, we prepared and confirmed series of hydrophobic ethyl bridges modulated periodic mesoporous organosilica fixed with 1-methyl-3-(3-(trimethoxysilyl)propyl)-1H-imidazole-3-iumiodide (MBIm-PMO-x). The contents of hydrophobic ethyl bridges (x) were 0, 5, 15, 25, 35 mol%. These materials were applied for synthesizing heterocyclic compound 2-arylbenzoxazoles with arylaldehydes and 2-aminophenol. Among them, MBIm-PMO-15, hydrophobic ethyl bridge was 15 mol%, dramatically enhanced the yields of synthesizing electron-deficient 2-arylbenzoxazoles. For substrates with different electronic properties, we found MBIm-PMO-15 exhibited the reversed catalytic activity in relation to corresponding homogeneous MBIm. Further research, FT-IR adsorption and UV–vis detection tests demonstrated this kind heterogeneous catalyst surface prefers adsorbing electron-deficient intermediates Schiff base to electron-rich ones. It is the specific adsorption motivate MBIm-PMO-15 highly selectivity towards electron-deficient 2-arylbenzoxazoles. In a broader vision, surface driven selective adsorption of heterogeneous catalyst for substrate could act as an alternative strategy to get special target products.

A method for the determination of 22 phthalate esters in polystyrene food-contact materials has been established using ultraperformance convergence chromatography with tandem mass spectrometry. In this method, 22 phthalate esters were analyzed in

Four mesoporous SBA-15-immobilized N-heterocyclic carbene (NHC) palladium catalysts with different nitrogen ligands were synthesized. The activity and recyclability of the catalysts were investigated in Suzuki–Miyaura cross-coupling reaction of typical aryl chlorides and arylboronic acids. Bulky NHC moiety was essential for efficiency, while tethering of nitrogen ligands on both support and NHC group could dramatically improve recyclability of the catalysts. The strategy offers an alternative strategy for designing highly efficient and recyclable immobilized catalysts. Mesoporous silica-immobilized palladium catalysts with the bulky N-heterocyclic carbene and tethered “throw-away”nitrogen ligands were found to be highly efficient and recyclable for Suzuki–Miyaura coupling reaction of inactive aryl chlorides.

An imino-N-heterocyclic carbene palladium(II) complex with a bulky substituted group on the imino nitrogen was used to catalyze the direct arylation of electron-deficient fluoroarenes with aryl halides. A series of electron-poor substrates and aryl bromides could be coupled in good to excellent yields with satisfactory position selectivity (20 examples, up to 93%). These arylations could proceed at a relatively low temperature (80 °C, 20 examples, up to 95%) with mono-N-protected amino acid assistance. Some of them even gained higher yields than those at high temperature (110 °C). Otherwise, some aryl iodides can forge cross-coupling products in yields of nearly 30% under the optimized conditions. The rate profiles for arylation of electron-poor arenes were measured in the presence of the imino-N-heterocyclic carbene palladium(II) complex or Pd(OAc)2 as the catalyst, which showed that the former could keep catalytic activity for a longer time. Computational studies indicated that the imino nitrogen in the...

Multifunctional yolk–shell microspheres are synthesized through a combined interfacial sol–gel coating and surfactant-templating co-assembly method and are demonstrated as efficient and easily recyclable nanocatalysts for catalytic epoxidation of styrene.

A family of ruthenium complexes with different ligands was utilized in racemization of (R)-1-phenylethanol to investigate the potential influence of the ligands coordinated to the ruthenium center. Kinetic experiments showed that 16-electron cymene ruthenium complex with two chloro-bridge bonds and 18-electron ones with easily dissociative ligands are highly active for catalytic racemization of alcohols. Possible racemization mechanism for cymene ruthenium complexes was then proposed. Computational analysis of dissociation energy barrier, NBO analysis and reaction potential energy surface suggest that ligand-dissociation process is the vital step of the racemization catalyzed by cymene ruthenium complexes. Thereafter, these complexes were applied in the DKR of secondary alcohols to verify their efficiency and applicability.

Dichloro(η6-p-cymene) (1-butyl-3-cyclohexyl-imidazolin-2-ylidene) ruthenium(II) (RuL) was synthesized and confirmed. Five heterogeneous catalysts with similar ruthenium cores were prepared by chemical immobilization method using various silica-based supports, including mesoporous silica SBA-15 of different pore sizes (Ru/Si-9, Ru/Si-8, and Ru/Si-7), nonporous silica particles (Ru/SiO2), and surface trimethylsilylated SBA-15 (Ru/SiMe). The dynamic kinetic resolution (DKR) of 1-phenylethanol, which includes metal–enzyme bicatalytic racemization in tandem with stereoselective acylation, gave product in 99% yield and 0% ee with homogeneous catalyst RuL, whereas the heterogeneous Ru/Si-8 exhibited high catalytic activity and enantioselectivity (up to 96% yield and 99% ee). The racemization and acylation abilities of different catalysts were analyzed. The influences of pore size and surface properties for heterogeneous catalysts were investigated, and the nanocage effect was found to be the key factor in stereo...

New 4-acetylbenzyl-N-heterocyclic carbene ligands (1–4) have been used to synthesize iridium complexes 6–9 and ruthenium complex 10. All complexes were characterized by FT-IR, 1H and 13C NMR spectroscopy, elemental analysis, and in the case of 6, by X-ray diffraction studies. The catalytic performance of these iridium and ruthenium complexes for transfer hydrogenation of ketones and imines and N-alkylation of amines with primary alcohols were tested in a range of substrates, and showed high catalytic activity with 1 mol% catalytic loading. The neutral complex 8 with two acetyl groups also showed good catalytic efficiency under lower catalyst loading (0.01 mol%), with the maximum TON of 8000, while on the other hand, the cationic complex 9 with PF6− as counteranion showed good to excellent catalytic activity toward the N-alkylation of amines in a wide scope of substrates. We also found out that the Ir complex 6′ was formed through the intramolecular C H activition of 6 under the transfer hydrogenation conditions.

Multifunctional microspheres with core–shell structures consisting of a core of nonporous carbon-protected magnetite particles, a transition layer of active Pd (or Pt) nanoparticles, and an outer shell of ordered mesoporous silica with perpendicularly aligned pore channels were synthesized based on colloid and interface chemistry. As a magnetically separable catalyst system, such microspheres hold a good potential in liquid phase catalysis.

A mesoporous silica (SBA-15)-supported pyrimidine-substituted N-heterocyclic carbene iridium complex was prepared and used as a catalyst for both environmentally friendly N-alkylation of amines and β-alkylation of secondary alcohols with primary alcohols. The structure of the supported iridium catalyst was characterized by Fourier transform infrared (FT-IR), 13C and 29Si solid-state nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), iridium K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopic analyses which demonstrated that the coordination environment of the iridium centre and the 3-dimensional-hexagonal pore structure of SBA-15 were retained after the immobilization. The catalyst was found to be highly efficient for both kinds of reaction on a wide range of substrates under mild conditions. Moreover, the supported iridium catalyst was obviously superior to the unsupported one in the N-alkylation of aniline and β-alkylation of 1-phenylethanol with benzyl alcohol as substrate, which indicated that not only the iridium complex moiety but also the support material contributed to the catalytic activity of the supported iridium catalyst in these reactions. The supported iridium catalyst can be easily recycled by simple washing without chemical treatment, and exhibited excellent recycling performance without notable decrease in catalytic efficiency even after twelve test cycles for N-alkylation of aniline with benzyl alcohol, nine cycles for N-alkylation of different amines with different alcohols, and eight cycles for β-alkylation of 1-phenylethanol with benzyl alcohol, respectively.

2-Arylbenzazoles are promising molecules for potential applications in medicine and material areas. Efficient protocols for direct regioselective functionalization of 2-arylbenzoxazoles are in high demand. Herein, we disclose a general method for selective ortho-olefination of 2-arylbenzo[d]oxazoles with alkenes enabled by versatile Cp*Rh(III) in high yields. This protocol features broad functional group tolerance and high regioselectivity. Intermolecular competition studies and kinetic isotope effect experiments imply that the oxidative olefination process occurs via an electrophilic C-H activation pathway. The molecular structure of the m-fluoro-substituted olefination product confirms regioselective C-H activation/olefination at the more hindered site in cases where the meta F atom or heteroatom substituent existed. Apparent torsion angles were observed in the structures of mono- and bis-olefination products, which resulted in distinct different chemical shifts of olefinic protons. Additionally, two gram-scale reactions and further transformation experiments demonstrate that this method is practical for synthesis of ortho-alkenylated 2-arylbenzoxazole derivatives.

Several N-heterocyclic carbene palladium catalyzed oxidation of nonactivated sp3 C–H bonds in linear primary and secondary trifluoroacetic acid esters have been developed. A high selectivity for th...

A salicylaldiminato imidazolium salt that bears both a Schiff base and imidazolium salt moiety was used to synthesize heterometallic compounds that could serve as multifunctional catalysts in certain reactions. The successful preparation of seven mononuclear compounds with a variety of transition metals (Pd, Ir, Ru, Zn, Ni) illustrated the high versatility of this class of ligands, which is crucial for the design of catalysts. Synthesis of homodinuclear compounds and heterotrinuclear compounds provided practical methods to connect multiple metal fragments through these ligands. The heterotrinuclear complex (Ni/Ir) was employed as a catalyst in the reaction of dehalogenation/transfer hydrogenation of halo-acetophenones. The preliminary catalytic study showed that this heterometallic species is more active than a combination of the corresponding monometallic species.

Seven tripodal imidazolium salts were synthesized and used as catalyst precursors in cross-coupling reactions of aryl halides with arylboronic acids. Effect of counterions and central cores of seven tripodal imidazolium salts was investigated. The tripodal imidazolium salt anchored to benzene with anion PF 6 − was found most effective with Pd(OAc) 2 for the cross-coupling of aryl bromides with arylboronic acids.

Core-shell magnetic porous microspheres have wide applications in drug delivery, catalysis and bioseparation, and so on. However, it is great challenge to controllably synthesize magnetic porous microspheres with uniform well-aligned accessible large mesopores (>10 nm) which are highly desired for applications involving immobilization or adsorption of large guest molecules or nanoobjects. In this study, a facile and general amphiphilic block copolymer directed interfacial coassembly strategy is developed to synthesize core-shell magnetic mesoporous microspheres with a monolayer of mesoporous shell of different composition (FDUcs-17D), such as core-shell magnetic mesoporous aluminosilicate (CS-MMAS), silica (CS-MMS), and zirconia-silica (CS-MMZS), open and large pores by employing polystyrene-block-poly (4-vinylpyridine) (PS-b-P4VP) as an interface structure directing agent and aluminum acetylacetonate (Al(acac)3 ), zirconium acetylacetonate, and tetraethyl orthosilicate as shell precursors. The obtained CS-MMAS microspheres possess magnetic core, perpendicular mesopores (20-32 nm) in the shell, high surface area (244.7 m2 g-1 ), and abundant acid sites (0.44 mmol g-1 ), and as a result, they exhibit superior performance in removal of organophosphorus pesticides (fenthion) with a fast adsorption dynamics and high adsorption capacity. CS-MMAS microspheres loaded with Au nanoparticles (≈3.5 nm) behavior as a highly active heterogeneous nanocatalyst for N-alkylation reaction for producing N-phenylbenzylamine with a selectivity and yields of over 90% and good magnetic recyclability.

Three neutral trinuclear palladium(II) complexes [Ph 3 PPdCl(μ-4-PyS)] 3 (1), [Cy 3 PPdCl(μ-4-PyS)] 3 (2) and [(PhO) 3 PPdCl(μ-4-PyS)] 3 (3) (4-PyS = pyridine-4-thiolate) were self-assembled from corresponding metal fragments [R 3 PPdCl 2 ] 2 with lithium pyridine-4-thiolate (PySLi). The crystal structure reveals that complex 1 possesses a triangular macrocyclic structure in which the distances of Pd(1)··· Pd(2), Pd(2)···Pd(3) and Pd(3)···Pd(1) are 7.764, 7.684 and 7.944 A, respectively. An equilibrium between trinuclear complex 1 and mononuclear complex (Ph 3 P) 2 PdCl(4-PyS) (4) in solution through coordination and de-coordination of the PPh 3 ligand is confirmed by 31 P NMR spectroscopy. A comparative study on the Suzuki-Miyaura coupling reaction showed that complexes 1 and 2 are more active precatalysts than [R 3 PPdCl 2 ] 2 complexes without a PyS group.

Neutral trinuclear metallomacrocycles, [Cp∗RhCl(μ-4-PyS)]3 (3) and [Cp∗IrCl(μ-4-PyS)]3 (4) [Cp∗ = pentamethylcyclopentadienyl, 4-PyS = 4-pyridinethiolate], have been synthesized by self-assembly reactions of [Cp∗RhCl2]2 (1) and [Cp∗IrCl2]2 (2) with lithium 4-pyridinethiolate, respectively. In situ reaction of complex 3 with three equivalent of lithium 4-pyridinethiolate resulted in [Cp∗Rh(μ-4-PyS)(4-PyS)]3 (5) containing both skeleton and pendent 4-PyS groups. Chelating coordination of 2-pyridinethiolate broke down the triangular skeleton to give mononuclear metalloligands Cp∗Rh(2-PyS)(4-PyS) (6) and Cp∗Ir(2-PyS)(4-PyS) (7) [2-PyS = 2-pyridinethiolate], which could also be synthesized from Cp∗RhCl(2-PyS) (10) and Cp∗IrCl(2-PyS) (11) with lithium 4-pyridinethiolate. The coordination reactions of 6 with complexes 1 and 2 gave dinuclear complexes [Cp∗Rh(2-PyS)(μ-4-PyS)][Cp∗RhCl2] (8) and [Cp∗Rh(2-PyS)(μ-4-PyS)][Cp∗IrCl2] (9), respectively. Molecular structures of 3, 4, 6 and 11 were determined by X-ray crystallographic analysis. All the complexes have been well characterized by elemental analysis, NMR and IR spectra.

The reactions of Cp ∗ CoI 2 (CO) with heterocyclic thione ligands yields a η 2 -N, S coordination family of cobalt complexes for adjacent N, S donor atoms, and dinuclear disulfide cobalt complexes for opposite N, S donor atoms.

Four half-sandwich cobalt complexes, Cp∗Co(2-PyS)2 (2), Cp∗Co(2-PyS)2 · HI (3), Cp∗Co(2-PyS) (4-PyS) (4), (Cp∗Co)2(μ-PhS)2(μ-2-PyS)I (5) [Cp∗ = pentamethylcyclopentadienyl, 2-PyS = 2-pyridinethiolate, 4-PyS = 4-pyridinethiolate, PhS = benzenethiolate] were successfully synthesized by the reactions of 2-pyridinethione, lithium 4-pyridinethiolate and lithium benzenethiolate with Cp∗Co(2-PyS)I (1), respectively. Complexes 2 and 3 have the structures with two 2-pyridinethiolates ligands coordinated to the cobalt atom. Two different pyridinethiolates ligands can be identified in complex 4. The molecular structure of 5 consists of two Cp∗–Co fragments, which are triply bridged by three sulfur atoms from different ligands. The molecular structures of 3 and 5 were determined by X-ray crystallographic analysis. All the complexes have been well characterized by elemental analysis, NMR and IR spectra.

Five binuclear half-sandwich cobalt complexes, [(η5-C5H4)Co(CO)I2]2SiMe2 (3), [(η5-C5H4)Co(S2C2B10H10)]2SiMe2 (4), [(η5-C5H4)]2Co2(μ2-S2C2B10H10)SiMe2 (5), [(η5-C5H3)CoI2](μ-I)[(η5-C5H3)Co(CO)I](SiMe2)2 (8), [(η5-C5H3)Co(S2C2B10H10)]2(SiMe2)2 (9), were successfully synthesized in moderate yield by the reactions of corresponding ligands, (C5H5)2SiMe2 (1) and (C5H4)2(SiMe2)2 (6), respectively. The molecular structures of 3, 5, 6, 8 and 9 was determined by X-ray crystallographic analysis, which distinctly depict various molecular structures containing the Cp rings and the metal centers with halide or 1,2-dicarba-closo-dodecaborane-1,2-dithiolato ligands. For the (η5-C5H4)2SiMe2 complexes, coordination of the fragments CpCo favors a exo conformation. With the rigid structure of the di-bridged ligand (C5H4)2(SiMe2)2, only cis isomers of the corresponding (η5-C5H3)2(Si2Me2)2 complexes are formed. All the complexes have been well characterized by elemental analysis, NMR and IR spectra.

The half-sandwich cobalt(III) and rhodium(III) complexes with pyridine-2-thiolato ligands Cp*Co(PyS)I (3) and Cp*Rh(PyS)Cl (4) [Cp* = pentamethylcyclopentadienyl, PyS = pyridine-2-thiolate] were obtained by reactions of lithium pyridine-2-thiolate (PySLi) with Cp*Co(CO)I2 (1) and [Cp*RhCl2]2 (2), respectively, in high yield. Complexes 3 and 4 reacted with monodentate LiSC2(H)B10H10 to give Cp*Co(PyS)[SC2(H)B10H10] (5) and Cp*Rh(PyS)[SC2(H)B10H10] (6), respectively. Reactions of 3 and 4 with Li2S2C2B10H10 resulted in C−H activation of a methyl group of the Cp* of the cobalt complex to give [(C5Me4CH2SC5H4N)Co(S2C2B10H10)] (7). No such activation of a methyl group of the Cp* of the rhodium complex occurred, and Cp*Rh[Py(H)S](S2C2B10H10) (8) was the product.

The reaction of bis[(2-methoxyethyl)cyclopentadienyl] titanium dichloride with dilithium dithiolato carborane in THF give a novel hexanuclear organotitanium ion complex [ Cp 6 ′ Ti 6 ( μ 3 -O ) 8 ] [ C 2 B 10 H 10 ( μ - S 2 ) 2 C 2 B 9 H 10 ] 2 (Cp′ = C5H4CH2CH2OCH3) ([1][2]2) as yellow crystal blocks. The cation [1]2+ has an octahedral metallic skeleton of six titanium atoms with the tricoordinated oxygen (μ3-O) and the anion [2]− consists of two S2 bridged 7,8-dicarbaundecaborate cluster and 1,2-dicarba-closo-dodecaborate cluster.

Two half-sandwich rhodium complexes with sulfur or oxygen functionalized cyclopentadienyl ligands [η5-C5H4(CH2)2SCH2CH3]RhI2 3, {[η5-C5H4(CH2)2OCH3]RhI2}2 4 have been synthesized and characterized by IR, 1H-NMR spectra and Elemental analyses. The molecular structures of complexes 3 and 4 have been determined by X-ray crystallographic analysis. Complexes 3, 4 with a pendent arm on cyclopentadienyl ligand have been tested as catalysts for ethylene and norbornene polymerization in the presence of MAO. Complexes 3 and 4 kept high activities of ca. 106 g PE mol−1 Rh h−1 with morderate molecular weight (Mw ≈ 105 g mol−1) of polyethylene in the ethylene polymerization. Catalytic activities, molecular weights of polyethylene have been investigated under the various reaction conditions.

Four new dichalcogenolate carborane bridged binuclear rhodium(I) complexes [Rh2(COD)2(μ2-E2C2(B10H10))] [COD = cycloocta-1,5-diene (C8H12), E = S (2a), Se (2b)] and [Rh2(CO)2(μ2-E2C2(B10H10))] [E = S (3a), Se (3b)] have been prepared by the reactions of the dilithium dichalcogenolate carboranes Li2E2C2B10H10 (E = S, Se) with [Rh(COD)Cl]2 or [Rh(CO)2Cl]2, respectively. The complexes have been fully characterized by 1H, 13C, 11B NMR and IR spectroscopy as well as by element analyses. The molecular structures of 2a, 2b and 3a have been determined by single-crystal X-ray diffraction analyses, which show the strong metal–metal interaction between two rhodium atoms.

The 16-electron half-sandwich iridium complexes [Cp*Ir{E 2 C 2 (B 1 0 H 1 0 )}] [E = S (la), Se (1b)] (Cp* = η 5 -C 5 Me 5 ) [Cp*Ir[E 2 C 2 (B 1 0 H 1 0 )] = η 5 -pentamethylcyclopentadienyl-[1,2-dicarba-closo-dodecaborane(12)-dichalcogenolato]iridium] reacted with Co 2 (CO) 8 in toluene solution to afford the trinuclear clusters [Cp*Ir{E 2 C 2 (B 1 0 H 1 0 )}]{Co 2 (CO) 5 } [E = S (2a), Se (2b)] and mononuclear complexes [Cp*Ir(CO){E 2 C 2 (B 1 0 H 1 0 )}] [E = S (3a), Se (3b)] as byproducts. Compounds 2a and 2b contain closed IrCo 2 triangle geometry with one Co-Co and two Ir-Co bonds. The dinuclear IrFe complexes [Cp*Ir{E 2 C 2 (B 1 0 H 1 0 )}]{Fe(CO) 3 } [E = S (4a), Se (4b)] were obtained from the reactions of la and 1b with Fe(CO) 5 in the presence of Me 3 -NO. The molecular structures of 2a, 2b, and 4b have been determined by X-ray crystallography.

Sulfur and oxygen functionalized cyclopentandienyl half-sandwich cobalt dicarbonyl complexes [η5-C5H4(CH2)2SCH2CH3]Co(CO)2 (3) and [η5-C5H4(CH2)2OCH3]Co(CO)2 (7) were prepared. Oxidation of 3 or 7 with I2 led to formation of 18-electron complexes [η5-C5H4(CH2)2SCH2CH3]CoI2 (4) and [η5-C5H4(CH2)2OCH3]Co(CO)I2 (8). The reactions of diiodide complex (4) with dilithium 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolates [(THF)3LiE2C2B10H10Li(THF)]2 [E=S (1a), Se (1b)] afforded 18-electron mononuclear complexes [η5-C5H4(CH2)2SCH2CH3]Co(E2C2B10H10) [E=S (5a), Se (5b)] in which sulfur atoms of side-chain were attached via an intramolecular coordination. Complex 7 reacted with 1a and 1b to give the binuclear complexes {[η5-C5H4(CH2)2OCH3]Co(E2C2B10H10)}2 [E=S (10a), Se (10b)]. The molecular structures of 5a and 10b were determined by X-ray crystallographic analysis. According to the X-ray structure analyses, 10b contains two o-carborane diselenolate bridges, and each Cp′Co fragment is attached to one terminal and two bridging selenolato ligands. The central Co2Se2 four-membered ring is planar, and the direct metal–metal interaction is absent.

The two title CuII complexes, [Cu2(NCO)4(tmeda)2] (tmeda is tetra­methyl­ethyl­enedi­amine, C6H16N2), (I), and [Cu(NCO)2(pn)]n (pn is 1,3-di­amino­propane, C3H10N2), (II), have been synthesized and their crystal structures determined. In (I), which lies about an inversion centre, each Cu centre possesses a distorted tetragonal–pyramidal geometry with four basal N atoms from two cyanate anions [Cu—N = 1.945 (2) and 1.948 (3) A] and one tmeda mol­ecule [Cu—N = 2.053 (2) and 2.071 (2) A], and one axial O atom [Cu—O = 2.737 (3) A] from another cyanate anion. The two neighbouring Cu atoms in (I) are joined by a pair of cyanates in an end-to-end fashion, forming a dimer. In (II), each Cu centre adopts a distorted square-bipyramidal geometry, with four equatorial N atoms from two cyanates [Cu—N = 1.988 (2) and 2.007 (3) A] and a pn ligand [Cu—N = 1.996 (3) and 2.011 (3) A], and one apical N atom [Cu—N = 2.437 (3) A] and an apical O atom [Cu—O = 2.900 (3) A] from two cyanates. In contrast with (I), the two neighbouring Cu atoms in (II) are bridged by two cyanates in an end-on fashion, to form a centrosymmetric dimeric unit. These units are further crosslinked, forming a two-dimensional network structure, via weak interactions between the bridging cyanate O atom and a neighbouring Cu atom, plus interactions of the amine H atoms with the cyanate O atoms and the terminal cyanate N atom.

Cobaltocene [η 5 -C 5 H 4 COOC(CH 3 )CH 2 ] 2 Co ( 1 ) was synthesized from CoCl 2 ·6H 2 O at −30 °C. 1 showed two reversible redox potentials at −0.335 and −1.418 V, respectively. It was found that the electron-withdrawing substituent on the cyclopentadienyl ligand facilitated the formation of cobaltocene quantitatively. (η 5 -C 5 H 4 COOCH 3 )Co(C 8 H 12 ) ( 2 ) was synthesized from 1 at −50 °C under sodium amalgam and the structure of 2 was determined by single-crystal X-ray diffraction. The change of the electron-withdrawing group from the carboisopropenyloxy to the carbomethoxy group on the cyclopentadienyl ligand is also discussed.

Two new complexes, [Cu(C(2)N(3))(2)(dien)] (dien is diethylenetriamine, C(4)H(13)N(3)), (I), and [Cu(C(2)N(3))(trien)](C(2)N(3)) (trien is triethylenetetramine, C(6)H(18)N(4)), (II), have been characterized by single-crystal X-ray diffraction. Both complexes display a distorted tetragonal-pyramidal geometry. In (I), the Cu atom is coordinated in the basal plane by three diethylenetriamine N atoms [Cu-N = 2.000 (2), 2.004 (2) and 2.025 (2) A] and one terminal N atom [Cu-N = 1.974 (2) A] from one monodentate dicyanamide group, and in the apical position by one terminal N atom [Cu-N = 2.280 (2) A] from the other monodentate dicyanamide group. In (II), the Cu atom is surrounded by four triethylenetetramine N atoms [Cu-N = 2.012 (2), 2.014 (2), 2.019 (2) and 2.031 (2) A in the basal plane] and a terminal N atom [Cu-N = 2.130 (2) A in the apical site] from one monodentate dicyanamide group. The other dicyanamide anion is not directly coordinated to the metal atom. In both (I) and (II), hydrogen-bond interactions between the uncoordinated terminal N atoms of two dicyanamide ions and the amine H atoms lead to the formation of three-dimensional networks.

Organocobalt compounds C5H4RCoLL' (2a),(2b), (2b') and (2c) (L = CO, L' = PR3; a, R = -COOC(CH3)[dbnd]CH2; b, R = -COOCH2C6H5; c, R = -COOCH2CH[dbnd]CH2.) were prepared and characterized. The electronic spectra and the electrochemical properties of compounds (2a), (2b), (2b'), (2c) and their analogues (la), (lb), (lc), (ld) (L = L'[dbnd]CO; d, R = -CH2COOCH2CH[dbnd]CH2) and (3) (L = L' = PR3, R = -COOCH2C6H5) were also studied. It was found that (2a), (2b), (2b'), (2c) exhibited two reversible peaks during electrochemical oxidation which were attributed to the formation of two reaction intermediates. Their dicarbonyl or bis(phosphine) analogues did not show such reversible peaks during electrochemical oxidation. The compounds (2a), (2b), (2b') and (2c) exhibited the best ability of anti-oxidation among the three types of the organocobalt compounds.

Reaction of (C 5 H 4 Me) 3 Ln and TzH (5-phenyl-1H-tetrazole) in THF affords complexes [(C 5 H 4 Me) 2 LnTz] 2 [Ln=Yb ( 1 ), Er ( 2 )]. 1 crystallized in the space group C 2/ c , with unit cell dimensions a =25.596(2), b =8.342(1), c =21.573(2) A, β =129.322(9)°. V =3563.5(8) A 3 and Z =8 for D c =1.776 g cm −3 . Least-squares refinement of the model based on 2700 reflections converged to a final R =0.031. The molecule is centrosymmetric dimer in which each ytterbium atom is coordinated by two methylcyclopentadienyl groups and three nitrogen atoms of the bridging Tz ligands to form a distorted trigonal-bipyramidal geometry. When there is a small amount of (C 5 H 4 Me) 2 Ln(C 5 H 5 ) in (C 5 H 4 Me) 3 Ln, the 1:1 complexes [{(C 5 H 4 Me)(C 5 H 5 )LnTz} 2 ][{(C 5 H 4 Me) 2 LnTz} 2 ] (Ln=Dy ( 3 ), Gd ( 4 )) were obtained in crystalline form. 3 and 4 crystallize as isomorphous crystals of space group P 1 with the following unit cell parameters ( 3 / 4 ): a =9.374(2)/9.420(4), b =13.048(2)/13.215(4), c =16.542(4)/16.677(5) A, a =86.95(2)/87.24(2), β =74.61(1)/74.50(3), γ =77.31(1)/77.08(3)°, Y =1903(1)/1950(1) A 3 , Z =2, D c =1.602/1.545 g cm −3 , R =0.046/0.051. Crystallographic data for 3 and 4 show that there are two disconnected structural units [(C 5 H 4 Me)(C 5 H 5 )Ln( μ - η 1 : η 2 -Tz)] 2 and [(C 5 H 4 Me) 2 Ln( μ - η 1 : η 2 -Tz)] 2 , crystallizing in one asymmetrical unit, each of which is tetrazolate-bridged dimer and has an inversion center. The bridging unit Ln 2 N 6 is planar. All three structures reveal an unusual bonding mode of the tetrazolate ligand, in which the tetrazolate group acts as both a bridging and chelating ligand, with the nitrogen atoms at 1, 2 and 3-position taking part in bonding.

Four half-sandwich cobalt complexes bearing pendant sulfur or oxygen ligands have been reported and tested as catalysts for olefin polymerization in the presence of MAO. The molecular structure of complexes 1 has been determined by X-ray crystallographic analysis. Complexes 1 and 2 exhibited high activities of up to 106 g PE mol−1Co h−1 with moderate molecular weight (Mw ≈ 104 g mol−1) of polyethylene in the ethylene polymerization.

The catalyst can be recovered by simple filtration and reused eight or twelve times (β-alkylation resp.

Optimal reaction conditions are found for the regioselective monoarylation of disubstituted arenes.