Pseudo-octahedral Coordination Environment Research Articles

A novel broadband Ba3Ca4(BO3)3(SiO4)Cl:Mn4+ near-infrared phosphor with a special pseudo-octahedral Mn4+ coordination structure.

A pseudo-octahedral coordination structure of Mn4+ has been innovatively designed, which has realized the maximum red shift and the widest full width at half-maximum (FWHM) of Mn4+ emission so far, not only extending the emission wavelength of Mn4+ to the near-infrared (NIR) region, but also effectively broadening its bandwidth. In the Ba3Ca4(BO3)3(SiO4)Cl:Mn4+ (BCBSC:Mn4+) phosphor, the [Mn/Ca1O9] polyhedron contains one [Mn/Ca1O6] octahedron, which constitutes the pseudo-octahedral coordination structure of Mn4+. The BCBSC:Mn4+ phosphor can be excited at 362 nm and 470 nm and exhibits a broadband NIR emission centered at ∼756 nm with a super-wide range from 650 nm to 1100 nm. The FWHM can reach ∼90 nm. In addition, the internal quantum efficiency (IQE) of the BCBSC:0.01Mn4+ phosphor is 69.7%. The unique luminescence characteristics of BCBSC:Mn4+ phosphors are explored using experimental data and first principles calculation. The significant redshift, the abnormal broadband emission, and the high luminous efficiency are closely related to the special highly distorted [Mn/Ca1O6] pseudo-octahedral coordination environment. The results contribute to comprehending the mechanism of the broadband NIR emission of Mn4+ activated phosphors and broaden the research ideas of developing high-performance Mn4+ doped phosphors for NIR phosphor-converted light-emission diode applications.

Synthesis, characterization and third-order nonlinear optical properties studies of Co(II), Zn(II) and Cu(I) complexes incorporating 1-(2-(3-chloropyridine)azo)-2-acenaphthequinol ligand

A new ligand 1-(2-(3-chloropyridine)azo)-2-acenaphthequinol (3-CPAAL) and its corresponding transition metal complexes Co(3-CPAAL-H)2·3-CPAAL·0.5CH3OH·0.5CH2Cl2 (1), Zn(3-CPAAL-H)2·3-CPAAL·0.5CH3OH·0.5CH2Cl2 (2), Cu(3-CPAAL)2NO3·2CH3OH (3) were designed and synthesized. The complexes 1, 2 and 3 were structurally characterized by means of IR, UV–Vis spectra and X-ray single crystal diffraction. The X-ray crystal structures of 1 and 2 exhibit that the central ion (M = Co or Zn) have a pseudo-octahedral coordination environment by two oxygen atoms from acenaphthequinol units and four nitrogen atoms of azo and pyridine units. However, the structure of the complex 3 cationic reveals a seesaw coordination geometry and the copper is four-coordinate bonding to two nitrogen atoms come from azo units and two nitrogen atoms from the chloropyridine rings. The third-order nonlinear optical (NLO) properties of both ligand and complexes 1, 2 and 3 were determined by Z-scan technique with 42 fs laser pulses at 2 kHz repetition rate.

Unusually Distorted Pseudo-Octahedral Coordination Environment Around CoII from Thioether Schiff Base Ligands in Dinuclear [CoLn] (Ln = La, Gd, Tb, Dy, Ho) Complexes: Synthesis, Structure, and Understanding of Magnetic Behavior.

The synthesis, structural characterization, and magnetic behavior of a new family of binuclear CoII-LnIII complexes of formula [LnIIICoIIL2(NO3)3]·H2O (Ln = La, 1; Gd, 2; Tb, 3; Dy, 4; Ho, 5; HL = 3-methoxy-N-(2-(methylsulfanyl)phenyl)salicylaldimine) have been reported. The chosen ligand system HL has adjacent soft ONS and hard OO binding pockets ideal for selective coordination of CoII and 4f metal ions. All the complexes 1-5 exhibit a CoII center in a highly distorted octahedral geometry with the LnIII centers in bicapped square-antiprism geometry. The unique distortion about the CoII center is introduced by the coordination of 4f metal ions in the hard OO coordination site. The distortion is further supported by the presence of -SMe groups giving an S donor atom which owing to its larger size can support large bond distances and angles. The geometry around the CoII centers is intermediate between meridional and facial geometric isomers. The magnetic properties of these complexes have been investigated by a "full model" approach using CONDON with the experimental magnetochemical analysis revealing ferromagnetic Co-Ln coupling in compounds 2-5. Ab initio calculations on the X-ray crystal structures of 1-5 paint a semiquatitative picture about the contribution of the individual anisotropic centers toward the overall magnetic properties of the compounds. Theoretical analysis predicts 1 and 2 as weak single-ion magnet (SIM) and single-molecule magnet (SMM) respectively with CoII being solely responsible for the complex anisotropy. In 2, JCoGd plays a crucial role in preserving the anisotropy contribution of Co by channelizing relaxation via a higher excited exchange doublet. Because of the inefficiency of JCoTb, JCoDy, and JCoHo in quenching single-ion Ln fragment transverse anisotropy and preserving CoII high axial anisotropy (favoring rhombicity), 3-5 lack SMM behavior.

Decacarbonyl(μ-ethylidenimino-1κN:2κC)-μ-hydrido-triangulo-triosmium(3 Os–Os)

The title complex, [Os3(C2H4N)H(CO)10] or [Os3(CO)10(μ-H)(μ-HN=C—CH3-1κN:2κC)], was synthesized in 41.6% yield by reactions between Os3(CO)11(CH3CN) and 2,4,6-trimethylhexahydro-1,3,5-triazine. The central osmium triangle has two OsI atoms bridged by a hydride ligand and a μ-HN= C—CH3-1κN:2κC triazine fragment. Three CO ligands complete the coordination sphere around each OsI atom, while the remaining Os0 atom has four CO ligands. Each Os atom exhibits a pseudo-octahedral coordination environment, discounting the bridging Os—Os bond.

Magnetostructural correlations in S = 1 trans-[Ni{(OPPh2)(EPPh2)N}2(dmso)2], E = S, Se, and related complexes

In this work, the structural and spectroscopic characterization of trans-[Ni{(OPPh2)(EPPh2)N)}2(dmso)2], E = S, Se, complexes is described. These Ni(II) complexes contain two chelating (O,E) = [(OPPh2)(EPPh2)N)]− ligands, as well as two dimethyl sulfoxide (dmso) molecules coordinated via their O atoms. X-ray crystallography studies revealed a highly anisotropic pseudo-octahedral trans-NiO4E2 coordination environment, extending the literature dataset of their trans-[Ni(O,E)2(sol)2], sol = dmf, thf, counterparts. Collectively considered, these six complexes contain similar coordination spheres, exhibiting, however, subtle structural differences due to the nature of the donor atom (E) and solvent molecule (sol) coordinated to Ni(II). The spin Hamiltonian parameters of S = 1 trans-[Ni(O,Se)2(dmso)2], E = S, Se, were accurately determined by high-frequency and -field EPR spectroscopy, applying a methodology already used for trans-[Ni(O,E)2(sol)2], sol = dmf, thf. Magnetostructural correlations are explored between all members of this sub-family of Ni(II) complexes.

Spin Crossover in Fe(II)-M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2-Substituted Pyrazines.

Discovery of spin-crossover (SCO) behavior in the family of Fe(II)-based Hofmann clathrates has led to a "new rush" in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe(2+), square planar tetracyanometalates M(II)(CN)4(2-) (M(II) = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe(II) ion has a pseudo-octahedral coordination environment supported by four μ4-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M(II) = Ni (1), Pd (2), Pt (3); X = Me and M(II) = Ni (4), Pd (5)) or one 2X-pyrazine and one water molecule (X = I and M(II) = Ni (7), Pd (8), Pt (9)), or, alternatively, two distinct Fe(II) positions with either two pyrazines or two water molecules (X = Me and M(II) = Pt (6)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN6 units (1-6) display cooperative spin transition, while Fe(II) ions in N5O or N4O2 surrounding are high spin (HS). Structural changes in the nearest Fe(II) environment upon low-spin (LS) to HS transition, which include ca. 10% Fe-N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of 1-9 (see abstract figure). Effects of a pyrazine substituent and M(II) nature on the hyperfine parameters in both spin states are established.

Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid–Liquid Extraction Systems

The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO(-) anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.

Ligand steric hindrance and electronic effects on β-enaminoketonato half-sandwich chromium(III) olefin polymerization catalysts

A series of new half-sandwich chromium(III) complexes with asymmetric bidentate β-enaminoketonato ligands (3a-f), Cp[PhNC(CF3)CHC(C6H4R(o))O]CrCl (3a, R = H；3b R = CH3; 3c, R = F; 3d, R = CF3; 3e, R = phenyl; 3f, R = naphthyl), have been synthesized by treating CpCrCl2(THF) with 1.0 equiv. of the deprotonated ligands in THF, and the complexes were identified by IR spectra and mass spectra as well as elemental analyses. X-ray structural analysis for 3b and 3e–f revealed that these complexes adopt three-legged piano stool geometry with a pseudo-octahedral coordination environment. Upon treatment with methylaluminoxane, they exhibited moderate to high catalytic activities for ethylene polymerizations. Both the electronic effect and the steric hindrance of the substituents have profound effect on polymerization behaviors. Additionally, these complexes also displayed notable ability to copolymerize ethylene with norbornene, affording the copolymers with high NBE incorporations.

Synthesis and characterization of novel chromium complexes based on β-enaminoketonato ligands and their application to ethylene polymerization

A series of novel non-Cp-based chromium(III) complexes bearing tridentate β-enaminoketonato chelating ligands of type, [R2NC(CF3)C(H)CR1O]CrCl2(thf) (2a: R1=tBu, R2=C6H4OMe(o); 2b: R1=tBu, R2=C9H6N; 2c: R1=tBu, R2=C6H4SMe(o); 2d: R1=Ph, R2=C9H6N; 2e: R1=Ph, R2=C6H4SMe(o)) have been prepared in high yields (e.g. 63–79%) from CrCl3(thf)3 by treating with 1.0equiv. of the deprotonated ligands in tetrahydrofuran. These complexes were identified by IR, and mass spectra as well as elemental analysis. Structures for 2b, 2c and 2e were further confirmed by X-ray crystallography. Non-Cp-based chromium(III) complexes have six-coordinate distorted octahedral geometry, and the heteroatom in the sidearm is coordinated to chromium. When activated by modified methylaluminoxane, complexes 2b and 2c exhibited high activities towards ethylene polymerization. These results indicated that both the donor atoms in side arm and the substituents in backbone significantly affected polymerization behaviors. In order to further explore the structure–reactivity relationship of the catalysts, we synthesized some novel half-sandwich chromium(III) complexes, Cp[R2NC(CF3)C(H)CR1O]CrCl (3a: R1=tBu, R2=C6H4OMe(o); 3c: R1=tBu, R2=C6H4SMe(o); 3e: R1=Ph, R2=C6H4SMe(o)) and investigated their potential application in ethylene polymerization under the similar conditions. Complex 3c adopts a three-legged piano stool geometry with a pseudo-octahedral coordination environment, and the heteroatom in the sidearm is not coordinated to chromium. These half-sandwich chromium complexes all displayed high activities for ethylene polymerization under the same conditions. Neither the donor atom in side arm nor the substituent in backbone significantly affected polymerization behaviors, in complete contrast to the results by non-Cp-based chromium catalysts.

Trans-1,4 selective polymerization of 1,3-butadiene with symmetry pincer chromium complexes activated by MMAO

Tridentate chromium complexes (Cr1–Cr7) incorporated with symmetrical pincer ligand bis(arylimino)pyridine and bis(pyrzaolyl)pyridine have been synthesized and characterized by elemental analyis, FT-IR as well as ESI-MS. X-ray diffraction reveals solids-state structures of Cr2, Cr4 and Cr6 all adopt pseudo-octahedral coordination environment with respect to metal center. All complexes have been tested in stereoregulated polymerization of butadiene under various polymerization conditions. The trans-1,4 and cis-1,4 enchainment of resultant polymer are found to be dependent on the structure of ligand and amount of activator used. Under the optimized condition, free ortho-substitutes Cr catalysts Cr1, Cr3, Cr4 and Cr6 are capable of initiating high trans-1,4 selectivity (trans-1,4: 89.2%–92.0%) with good polymer yields (71.5%–78.0%), while counterparts with ortho-positioned alkyl groups Cr2, Cr5 and Cr7 display mixed selectivities with moderate polymer yields. The sterical effect of ligand and amount of MMAO on the catalytic performance, in particular, the stereoselectivity and polymer yield, has been also elucidated by conjugated diene polymerization mechanism.

A comparative synthetic, magnetic and theoretical study of functional M4Cl4 cubane-type Co(ii) and Ni(ii) complexes

We describe the synthesis, structures, and magnetochemistry of new M4Cl4 cubane-type cobalt(II) and nickel(II) complexes with the formula [M(μ3-Cl)Cl(HL·S)]4 (1: M = Co; 2: M = Ni), where HL·S represents a pyridyl-alcohol-type ligand with a thioether functional group, introduced to allow subsequent binding to Au surfaces. Dc and ac magnetic susceptibility data of 1 and 2 were modeled with a full spin Hamiltonian implemented in the computational framework CONDON 2.0. Although both coordination clusters 1 and 2 are isostructural, with each of their transition metal ions in a pseudo-octahedral coordination environment of four Cl atoms and N,O-donor atoms of one chelating HL·S ligand, the substantially different ligand field effects of Co(II) and Ni(II) results in stark differences in their magnetism. In contrast to compound 1 which exhibits a dominant antiferromagnetic intramolecular coupling (J = -0.14 cm(-1)), 2 is characterised by a ferromagnetic coupling (J = +10.6 cm(-1)) and is considered to be a single-molecule magnet (SMM), a feature of special interest for future surface deposition studies. An analysis based on density functional theory (DFT) was performed to explore possible magnetostructural correlations in these compounds. Using a two-J model Hamiltonian, it revealed that compound 1 has four positive and two (small) negative J(Co···Co) isotropic interactions leading to a S(HS) = 6 ground state. Taking into account the magnetic anisotropy, one would recover a M(S) = 0 ground state since D > 0 from computations. In 2, all the J constants are positive and, in this framework, the zero-field splitting energy characterising the axial anisotropy was estimated to be negative (D = -0.44 cm(-1)). The computational results are consistent with compound 2 being an SMM.

Synthesis, structure, and luminescence properties of arylpyridine-substituted terpyridine Zn(II) and Cd(II) complexes

Two terpyridine derivatives, 4′-(4-(pyridin-4-yl)phenyl)-[2,2′:6′,2″]terpyridine (L1) and 4′-(4′-(pyridin-4-yl)-[1,1′-biphenyl]-4-yl)-[2,2′:6′,2″]terpyridine (L2) have been synthesized by palladium-catalyzed cross-coupling reactions, and their metal complexes [Zn(L1)2](ClO4)2·2MeOH·CHCl3 (1) and [Cd(L2)2](ClO4)2·DMF·2.8H2O (2) characterized by single crystal X-ray crystallography and spectroscopic methods including electronic absorption and emission measurements. In the crystalline materials, both metal ions have the expected pseudo-octahedral N6 coordination environment and the lattice structures appear to be influenced by aromatic–aromatic interactions involving the heteroaryl tails and the pyridyl rings of the terpyridine units. In solution and in the solid state, the complexes display blue emission attributed to an intramolecular charge transfer transition.

Synthesis and structures of (R)-cyclopentadienyl-binaphthoxy titanium(iv) complexes and catalytic properties for olefin polymerization

Two new chiral pre-ligands, (R)-3,3'-bis(tetramethylcyclopentadienyl)-2,2'-bismethoxy-1,1'-bisnaphthalene (1) and (R)-3-tetramethylcyclopentadienyl-2,2'-bismethoxy-1,1'-bisnaphthalene (2), were synthesized by reaction of (R)-3,3'-dilithium-2,2'-bismethoxy-1,1'-bisnaphthalene with 2,3,4,5-tetramethyl-2-cyclopentenone at room temperature. Treatment of the pre-ligands 1 and 2 with butyllithium and Me(3)SiCl first, and subsequently with TiCl(4) (2 and 1 equiv for 1 and 2, respectively) afforded a binuclear complex (R)-3,3'-bis[(tetramethylcyclopentadienyl)trichlorotitanium]-2,2'-bismethoxy-1,1'-bisnaphthalene (3) and a mononuclear complex (R)-3-(tetramethylcyclopentadienyl)trichlorotitanium-2,2'-bismethoxy-1,1'-bisnaphthalene (4) in moderate yields. Complexes 3 and 4 were further converted into constrained geometry complexes (R)-1,1'-bis{2,2'-naphthoxy-3,3'-bis[(tetramethylcyclopentadienyl)dibromotitanium]} (5) and (R)-1-(2-naphthoxy)-1'-(2'-naphthol)-3-(tetramethylcyclopentadienyl)dibromotitanium (6) by treatment with BBr(3). The pre-ligands 1 and 2 were characterized by (1)H and (13)C NMR and high resolution mass spectroscopy (HRMS), and the new titanium complexes 3-6 were characterized by (1)H and (13)C NMR and elemental analyses. Molecular structures of 4, 5, and 6 were determined by single-crystal X-ray diffraction analysis. Complexes 4, 5, and 6 all have a pseudo-octahedral coordination environment and adopt a three-legged piano stool geometry around the titanium atom in their solid state structures. When activated with Al(i)Bu(3) and Ph(3)CB(C(6)F(5))(4), the chiral complexes 5 and 6 show moderate catalytic activities for propylene, 1-hexene, and 5-ethylidene-2-norbornene (ENB) polymerization and ethylene/1-hexene copolymerization. The polymers produced by the chiral 5/(i)Bu(3)Al/Ph(3)CB(C(6)F(5))(4) catalyst system from the 1-hexene, and ENB polymerization and ethylene/1-hexene copolymerization with high comonomer contents exhibit optical activity.

Structural characterization of a cadmium(II)-sulfato complex, [Cd(N,N′-diethyl thiourea)4(SO4)

A cadmium(II) complex, tetrakis(N,N′-diethylthiourea)sulfatocadmium(II), [Cd(Detu)4SO4] (1) is prepared and its crystal structure is determined by X-ray crystallography. The crystal structure of the complex consists of an independent molecule with the central cadmium atom coordinated to four thione sulfur atoms of Detu and two oxygen atoms of the sulfate ligand. The Cd atom has a pseudo-octahedral coordination environment with the cis angles varying from 57.68° to 126.57°, while the trans angles fall in the range of 142° to 169°. The new complex was also characterized by IR and NMR spectroscopy and the spectroscopic data are discussed in terms of the nature of bonding.

Large ultra-high molecular weight polyethylene spherical particles produced by AlR3 activated half-sandwich chromium(iii) catalysts

A series of half-sandwich pentamethylcyclopentadienyl chromium(III) complexes bearing a salicylaldiminato ligand, Cp*[2-R(1)-4-R(2)-6-(CH==NR(3))C(6)H(2)O]CrCl [R(1) = (i)Pr (1, 4), (t)Bu (2, 3, 5), Ad (6); R(2) = H (1, 2, 3), (t)Bu (4, 5, 6); R(3) = (i)Pr (1, 2, 5, 6), (t)Bu (3, 4)], were synthesized. All complexes were characterized by elemental analyses and the structures of complexes 1-4 and 6 were determined by X-ray diffraction analysis. These complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlR(3), complexes 1-6 all catalyze the polymerization of ethylene in a quasi living fashion with good to high catalytic activity under mild conditions and produce ultra-high molecular weight polyethylene as spherical particles with a diameter of 1-6 mm. The catalytic activity of these complexes and the molecular weight of the produced polyethylene can be tuned in a broad range by changing the R(1), R(2), and R(3) groups as well as the AlR(3) cocatalyst. It was found that complex 6 with R(1) = Ad, R(2) = (t)Bu, and R(3) = (i)Pr shows the highest catalytic activity and produces polyethylene with the highest molecular weight.

Dimetallic complexes of macrocycles with two rigid dibenzofuran units as receptors for detection of anionic substrates

The hexaazamacrocycles [28](DBF)(2)N(6) {cyclo[bis(4,6-dimethyldibenzo[b,d]furaniminoethyleneiminoethylene]} and [32](DBF)(2)N(6) {cyclo[bis(4,6-dimethyldibenzo[b,d]furaniminopropyleneiminopropylene]} form stable dinuclear copper(ii) complexes suitable to behave as receptors for several anionic substrates. These two receptors were used to study the binding interactions with several substrates, such as imidazole (Him) and some carboxylates [benzoate (bz(-)), oxalate (ox(2-)), malonate (mal(2-)), phthalate (ph(2-)), isophthalate (iph(2-)), and terephthalate (tph(2-))] by spectrophotometric titrations and EPR spectroscopy in MeOH (or H(2)O):DMSO (1 : 1 v/v) solution. The largest association constant was found for ox(2-) with Cu(2)[32](DBF)(2)N(6)(4+), whereas for the aromatic dicarboxylate anions the binding constants follow the trend ph(2-) > iph(2-) > tph(2-), i.e. decrease with the increase of the distance of the two binding sites of the substrate. On the other hand, the large blue shift of 68 nm observed by addition of Him to Cu(2)[32](DBF)(2)N(6)(4+) points out for the formation of the bridged CuimCu cascade complex, indicating this receptor as a potential sensor for the detection and determination of imidazole in solution. The X-band EPR spectra of the Cu(2)[28](DBF)(2)N(6)(4+) and Cu(2)[32](DBF)(2)N(6)](4+) complexes and the cascade complexes with the substrates, performed in H(2)O:DMSO (1 : 1 v/v) at 5 to 15 K, showed that the CuCu distance is slightly larger than the one found in crystal state and that this distance increases when the substrate is accommodated between the two copper centres. The crystal structure of [Cu(2)[28](DBF)(2)N(6)(ph)(2)]·CH(3)OH was determined by X-ray diffraction and revealed the two copper centres bridged by two ph(2-) anions at a CuCu distance of 5.419(1) Å. Each copper centre is surrounded by three carboxylate oxygen atoms from two phthalate anions and three contiguous nitrogen atoms of the macrocycle in a pseudo octahedral coordination environment.

Synthesis, structures and ethylene polymerization behavior of half-metallocene chromium(iii) catalysts bearing salicylaldiminato ligands

A series of half-metallocene chromium(III) complexes bearing a salicylaldiminato ligand, Cp′[2-R1-4-R2-6-(CH = NR3)C6H2O]CrCl [Cp′ = Cp (1, 5), Cp* (2, 3, 4, 6, 7, 8); R1 = Ph (1, 2, 3, 5, 6, 8), iPr (4), tBu (7); R2 = H (1, 2, 3), Br (4), NO2 (5, 6, 7, 8); R3 = iPr (1, 2, 5, 6, 7), tBu (3, 4, 8)], were synthesized. The structures of complexes 1, 3–5, 7–8 were determined by single crystal X-ray diffraction analysis. The X-ray crystallographic analysis indicates that these complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlEt3, complexes 1–8 exhibit good to high catalytic activity for ethylene polymerization and produce ultra-high molecular weight polyethylene (PE) under mild conditions. The productivity of these complexes is relatively low when activated with AlMe3 and AliBu3. Both the productivity of these catalyst systems and the molecular weight of the produced PE can be tuned in a broad range by changing the ligands and the AlR3 co-catalyst.

Half-Sandwich Chromium(III) Catalysts Bearing Hydroxyindanimine Ligands for Ethylene Polymerization

A series of novel half-sandwich chromium(III) complexes bearing hydroxyindanimine ligands, [Cp*Cr[ArN═CC2H3(CH3)C6HR1R2O]Cl (Ar = Ph, R1 = H, R2 = Me (2a), R2 = Cl (2c); Ar = 2,6-iPr2C6H3, R1 = H, R2 = Me (2b), R2 = Cl (2d); Ar = Ph, R1 = tBu, R2 = Me (2e))], were synthesized by the reaction of Cp*CrCl2(THF) and the sodium salts of the hydroxylindanone-imine ligands in THF at −78 °C. Complex 2c has been confirmed by single-crystal X-ray analysis. The complex adopts a three-legged piano stool geometry with a pseudo-octahedral coordination environment. After activation with only a small amount of AlEt3, these catalytic precursors exhibit high activities (up to 1.68 × 105 g PE (mol Cr)−1 h−1) for ethylene polymerization to afford high molecular weight PE ((5.45−9.23) × 105 g mol−1). The catalytic activities of the chromium complexes increase with decreasing steric hindrance on the nitrogen atom of the hydroxyl-indanone-imine ligand. The introduction of the bulky ortho-tBu group and the para-chlorine atom on ...

Unique Anionic Eight-Connected Net with 36418536 Topology Derived from a Rare Co6(μ3-OH)2(μ-H2O)(CO2)12 Building Block

[(CH3)2NH2]2[Co6(μ3-OH)2(μ-H2O)(ip)6]·2.5H2O (1), where ip2− is the 1,3-benzenedicarboxylate dianion, has been prepared by the solvothermal self-assembly of CoCl2 and H2ip in N,N′-dimethylformamide. Complex 1 contains a rare Co6(μ3-OH)2(μ-H2O)(CO2)12 building block with six crystallographically distinct cobalt(II) ions, one with a trigonal bipyramidal, two with a pseudotetrahedral, and three with a pseudooctahedral coordination environment; the bridging ip2− dianions serve as spacers to yield a unique anionic eight-connected net with 36418536 topology. The magnetic properties of 1 indicate that the six cobalt(II) ions are paramagnetic with, at most, very weak intramolecular antiferromagnetic exchange coupling.

Trans-(2,2′-Bipyridine)dichlorido[methyl 1-(phenylhydrazono)-1-(phenylimino)acetato]ruthenium(II) dichloromethane solvate

The title compound, [RuCl2(C15H13N3O2)(C10H8N2)]·CH2Cl2, has a pseudo-octahedral coordination environment made up of two trans chloride ligands and four N-donor atoms, two of which belong to the azoimine bidentate ligand and two to the bipyridyl molecule. The ester group is disordered over two positions; the site occupancy factors are ca 0.6 and 0.4.