金属串配合物[Ni3(L)4(NCS)2](L = dpa-, mpta-, mdpa-, mppa-)结构和磁性的理论研究

应用密度泛函理论BP86方法结合自然键轨道分析方法对具有分子导线潜在应用前景的金属串配合物[Ni₃(L)₄(NCS)₂](L = dpa^- (1), mpta^- (2), mdpa^- (3), mppa^- (4))进行研究,分析了桥联配体L对Ni―Ni相互作用和磁耦合性质的影响.结果得到: (1)配合物的基态均是对应于五重态(HS)的反铁磁(AF)单重态, HS的能量和结构与AF态相近, Ni₃⁶⁺链形成了三中心四电子σ键(σ₂σ_nb¹σ^*1). (2) dpa^-引入甲基成为mdpa^-,对Ni―Ni、Ni―N距离影响不大; 3H-吡咯环和噻唑环取代吡啶环后, N1―N2、Ni―Ni距离增大, Ni2―N2键长缩短,但噻唑环的影响较小;故Ni―Ni相互作用强度为1 ≈ 3 > 2 > 4. (3)预测了3和4的J_ab值为-103和-88 cm^-1,随Ni―Ni相互作用增强磁耦合效应增大. Ni―Ni相互作用越大,通过Ni₃⁶⁺链σ型轨道的直接磁耦合越强; Ni2―N2键越强,通过涉及桥联配体的间接磁耦合越强,直接磁耦合比间接磁耦合更强.     

Syntheses and Structures of New Trinuclear MIILnMII (M = Ni,Co; Ln = Gd,Ce) Complexes with 2, 6‐Bis(acetobenzoyl)pyridine

One‐pot reactions of 2, 6‐bis(acetobenzoyl)pyridine (H₂L) with a mixture of LnCl₃ (Ln = Ce, Gd) and Ni(CH₃COO)₂ (ratio 2:1:2) in CH₂Cl₂/MeOH in the presence of a supporting base like Et₃N give trinuclear complexes with the general composition [Ni₂Ln(L)₂(CH₃COO)₃(MeOH)_2/3] ( 1 ) in high yields. Trinuclear [Ni₂Ln(L)₂(PhCOO)₃(MeOH)₂] ( 2 ) complexes are formed when similar reactions are performed starting from NiCl₂, and benzoic acid (PhCOOH) is added subsequently. Under the same conditions, reactions with the corresponding cobalt(II) salts result in the formation of a neutral [Co₈(μ₃‐O)₂(L)₆] complex, which has a bis(triple‐helical) structure. The cobalt(II) analogues to compounds 1 and 2 , however, can be synthesized by a pre‐treatment of the lanthanide salts with H₂L and subsequent addition of the cobalt salts, and benzoic acid (in the case of 2 ).     

Synthesis and Crystal Structures of the Molybdenum(II) Complexes with the N,N‐dimethylthiocarbamoyl Containing Ligand: Crystal Structures of β [Mo(CO)2{η2‐S2P(OEt)2}(η2‐SCNMe2)(PPh3)] and [Mo(CO)2(η3‐Tp)(η2‐SCNMe2)(PPh3)]

Reactions of the thiocarbamoyl‐molybdenum complex [Mo(CO)₂(η²‐SCNMe₂)(PPh₃)₂Cl] 1 , and ammonium diethyldithiophosphate, NH₄S₂P(OEt)₂, and potassium tris(pyrazoyl‐1‐yl)borate, KTp, in dichloromethane at room temperature yielded the seven coordinated diethyldithiophosphate thiocarbamoyl‐molybdenum complexe [Mo(CO)₂{η²‐S₂P(OEt)₂}(η²‐SCNMe₂)(PPh₃)] β‐3 , and tris(pyrazoyl‐1‐yl)borate thiocabamoyl‐molybdenum complex [Mo(CO)₂(η³‐Tp)(η²‐SCNMe₂)(PPh₃)] 4 , respectively. The geometry around the metal atom of compounds β‐3 and 4 are capped octahedrons. The α‐ and β‐isomers are defined to the dithio‐ligand and one of the carbonyl ligands in the trans position in former and two carbonyl ligands in the trans position in later. The thiocabamoyl and diethyldithiophosphate or tris(pyrazoyl‐1‐yl)borate ligands coordinate to the molybdenum metal center through the carbon and sulfur and two sulfur atoms, or three nitrogen atoms, respectively. Complexes β‐3 and 4 are characterized by X‐ray diffraction analyses.     

DNA Intercalating Near-Infrared Luminescent Lanthanide Complexes Containing Dipyrido[3,2-a:2′,3′-c]phenazine (dppz) Ligands: Synthesis,Crystal Structures,Stability, Luminescence Properties and CT-DNA Interaction

In order to create near-infrared (NIR) luminescent lanthanide complexes suitable for DNA-interaction, novel lanthanide dppz complexes with general formula [Ln(NO₃)₃(dppz)₂] (Ln = Nd³⁺, Er³⁺ and Yb³⁺; dppz = dipyrido[3,2-a:2′,3′-c]phenazine) were synthesized, characterized and their luminescence properties were investigated. In addition, analogous compounds with other lanthanide ions (Ln = Ce³⁺, Pr³⁺, Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Tm³⁺, Lu³⁺) were prepared. All complexes were characterized by IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction analysis of the complexes (Ln = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Eu³⁺, Er³⁺, Yb³⁺, Lu³⁺) showed that the lanthanide’s first coordination sphere can be described as a bicapped dodecahedron, made up of two bidentate dppz ligands and three bidentate-coordinating nitrate anions. Efficient energy transfer was observed from the dppz ligand to the lanthanide ion (Nd³⁺, Er³⁺ and Yb³⁺), while relatively high luminescence lifetimes were detected for these complexes. In their excitation spectra, the maximum of the strong broad band is located at around 385 nm and this wavelength was further used for excitation of the chosen complexes. In their emission spectra, the following characteristic NIR emission peaks were observed: for a) Nd³⁺: ⁴F_3/2 → ⁴I_9/2 (870.8 nm), ⁴F_3/2 → ⁴I_11/2 (1052.7 nm) and ⁴F_3/2 → ⁴I_13/2 (1334.5 nm); b) Er³⁺: ⁴I_13/2 → ⁴I_15/2 (1529.0 nm) c) Yb³⁺: ²F_5/2 → ²F_7/2 (977.6 nm). While its low triplet energy level is ideally suited for efficient sensitization of Nd³⁺ and Er³⁺, the dppz ligand is considered not favorable as a sensitizer for most of the visible emitting lanthanide ions, due to its low-lying triplet level, which is too low for the accepting levels of most visible emitting lanthanides. Furthermore, the DNA intercalation ability of the [Nd(NO₃)₃(dppz)₂] complex with calf thymus DNA (CT-DNA) was confirmed using fluorescence spectroscopy.     

195Pt-NMR-spektroskopischer Nachweis gemischter Hexahalogenodiplatinate(II), [Pt2ClnBr6 − n]2−, n = 0 – 6

¹⁹⁵Pt NMR Spectroscopic Evidence of Mixed Hexahalogenodiplatinates(II), [Pt₂Cl_nBr_{6 ? n}]^2?, n = 0 – 6 The complete system of the mixed complex ions [¹⁹⁵Pt₂Cl_nBr_{6 – n}]^2?, n = 0 – 6, is formed by stirring a suspension of the tetrabutylammonium salt(TBA)₂[¹⁹⁵PtCl₄] in an aqueous solution of KBr at 80°C. The mixture recrystallized from acetone/diethyl ether contains the 24 possible species, 12 with two equivalent ¹⁹⁵Pt atoms resulting in 12 singlets and 12 with inequivalent ¹⁹⁵Pt atoms resulting in 24 dublets. The expected 60 signals are really observed in the high resolution 1D-¹⁹⁵Pt-nmr spectrum. Using characteristic increments of chemical shifts, differentiating ²J(¹⁹⁵Pt ? ¹⁹⁵Pt) coupling constants and a 2D-¹⁹⁵Pt/¹⁹⁵Pt-COSY spectrum the complete and unambiguous assignment of all resonances is achieved. The presence of all components including the geometric isomers and their distribution derived from measured intensities reveal the statistical formation.     

Synthesis,Characterization and Magnetic Studies of μ‐Oxamido Copper (II) ‐ Chromium (III) Heterodinuclear Complexes

Three new μ‐oxamido‐bridged heterodinuclear copper (II)‐chromium (III) complexes formulated [Cu(Me₂oxpn)Cr‐(L)₂](NO₃)₃, where Me₂oxpn denotes N,N'‐bis(3‐amino‐2, 2‐dimethylpropyl)oxamido dianion and L represents 5‐methyl‐1,10‐phenanthroline (Mephen), 4,7‐diphenyl‐1,10‐phenanthroline (Ph₂phen) or 2,2′‐bipyridine (bpy), have been synthesized and characterized by elemental analyses, IR and electronic spectral studies, magnetic moments of room‐temperature and molar conductivity measurements. It is proposed that these complexes have oxamido‐bridged structures consisting of planar copper (II) and octahedral chromium (III) ions. The variable temperature magnetic susceptibilities (4.2–300 K) of complexes [Cu(Me₂oxpn)Cr(Ph₂phen)₂](NO₃)₃ (1) and [Cu(Me₂oxpn)Cr(Mephen)₂] (NO₃)₃ (2) were further measured and studied, demonstrating the ferromagnetic interaction between the adjacent chromium (III) and copper (II) ions through the oxamido‐bridge in both complexes 1 and 2. Based on the spin Hamiltonian, ? = ‐ 2J?₁ · ?₂, the exchange integrals J were evaluated as + 21.5 an^?1 for 1 and + 22.8 cm^?1 for 2.     

Synthesis,Characterization, and Highly Selective Ethylene Dimerization to 1‐Butene of [O−NX]Ni(II) Complexes

A series of nickel(II) complexes have been synthesized and characterized. Molecular structure analysis exhibits that a square planar geometry around nickel is adopted. Upon activation with MAO, these nickel(II) complexes are efficient in catalyzing the ethylene dimerization, providing 1‐butene with an activity of up to 1.4×10⁷ g/(mol·h·atm). The heteroatoms of the sidearm in the complexes were proved to have great impact on the activity and selectivity of 1‐butene.     

Photophysics and Acid‐Base Chemistry of Re(CH3bpyCOOH)(CO)3X (X=Cl−, and Imidazole) Complexes

Rheniumtricarbonyl(4′‐methyl‐2,2′‐bipyridine‐4‐carboxylic acid)X (where X is Cl^? and imidazole) complexes have been prepared. These two complexes exhibit similar spectroscopic properties. The metal‐ to‐ligand charge‐transfer (MLCT) absorption and the corresponding emission are observed. This charge transfer band is highly solvent dependent. Due to the stronger electron‐withdrawing ability of the ‐COOH (in comparison to the ‐COO^? group), the MLCT band has red‐shifted during protonation. Emission quantum yields are dramatically reduced while life time remains similar upon protonation. These behaviors are typical in static quenching mechanism by protons. The ground state pK_a of Re(CO)₃ (CH₃bpyCOOH)Cl obtained from the pH titration curve of the complex absorption at 409 nm was 2.5.     

Revisit of trinickel metal string complexes [Ni3L4X2] (L = dipyridylamido,diazaphenoxazine; X = NCS,CN) for quantum transport

Metal string complexes contain a linear metal‐atom chain in which the metal centers are coordinated by four equatorial and two axial ligands. With a variety of transition‐metal elements and ligands, the structural framework drives the flourishing of molecular design and properties. The one‐dimensional configuration makes the compounds suitable for the studies of quantum transport across molecular junctions. In this study, we report the conductance measurements and transmission spectra of three trinickel metal strings, [Ni₃(dpa)₄(NCS)₂] ( 1 ), [Ni₃(dzp)₄(NCS)₂] ( 2 ), and [Ni₃(dpa)₄(CN)₂] ( 3 ) (Hdpa = dipyridylamine, Hdzp, diazaphenoxazine) in which 1 is a prototypical compound, dzp of 2 represents an equatorial ligand more rigid than dpa of 1 , and ─CN is an axial ligand with a ligand‐field effect stronger than ─NCS of 1 . Measurement results of molecular junctions for 1 , 2 , and 3 are 2.69, 3.24, and 17.4 MΩ, respectively. The highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO) gaps calculated by density functional theory in the gas phase for 1 , 2 , and 3 are about 2.65, 2.34, and 3.85 eV, respectively. Zero‐bias transmission spectra of 1 – 3 show that transmission peaks lie just above E_Fermi (the Fermi energy of the gold electrode), suggesting LUMO‐dominant transport pathways. The transmission peaks at E_Fermi are associated with LUMO+2 found in the gas phase. LUMOs in the free space are located at nearly 1 eV below E_Fermi. The shift of molecular orbitals from their isolated form and the alignment of LUMO+2 with the electrode Fermi level manifest the importance and significant of the electrodes' self‐energy on electron transport.     

Synthesis and Characterization of Mixed-Ligand Nickel(II) Chelates of β-Diones and α-Diimines. Crystal and Molecular Structure of [Ni(ncup)2Etacet]ClO4

A series of new nickel(II) perchlorate complexes containing an α-diimine(enR) and the anion of a β-dione (1,3-ketoenol or 1,3-ketoester, βH) was prepared and characterized. The composition and the overall structure of the new chelates depend on ligand concentration, on steric and electronic effects induced by substituents within the ligands and the ability of the perchlorate group to coordinate. The IR and electronic excitation spectra of [Ni(enR)₂β]ClO₄ and [Ni(enR)β(O₂ClO₂)] indicate, in conjunction with other physicochemical measurements, bidentate coordination of the ligands and replacement of the (O,O′) perchlorato group by basic solvents. The structure of the new chelates was further supported by an X-ray structure analysis of [Ni(ncup)₂Etacet]ClO₄, where ncup denotes neocuproine and Etacet the anion of the ethyl acetoacetate (orthorhombic, space group Pc2₁n, a = 14.087(5), b = 14.713(5) and c = 15.952(5) Å, Z = 4). The coordination sphere of nickel is a distorted octahedron, arised from the chromophore NiN₄O₂, in which the base is favored by three neocuproine nitrogens and one Etacet oxygen. The apical sites are occupied by the remaining oxygen and nitrogen atoms, one from Etacet and one from neocuproine respectively.     

Synthesis and X‐ray Crystal Structures of Zinc Dichloride Complexes Supported by a β‐Diimine Ligand

β‐Diimine zinc dichloride complexes [CH₂{C(Me)NAr}₂]ZnCl₂ [Ar = Mes ( 1 ), Dipp ( 2 )] were obtained from the reactions of ZnCl₂ with the corresponding β‐iminoamines [ArN(H)C(Me)CHC(Me)NAr]. Complexes 1 and 2 were characterized by multinuclear NMR (¹H, ¹³C) and IR spectroscopy, elemental analyses as well as by single‐crystal X‐ray diffraction. The energy differences between the enamine‐imine tautomers of the β‐iminoamines were quantified by quantum chemical calculations.     

Synthesis and Nucleophilic Addition Reactions of Tricarbonyl[η5‐2‐(phenylthio)hexadienyl]iron Hexafluorophosphate

3‐Phenylthio‐3‐sulfolene ( 1 ) was readily converted to a C‐5 substituted product 2 , which upon thermolysis and complexation with Fe₂(CO)₉ gave (η⁴‐diene)iron complexes 3a and 3b . Treatment of 3a and 3b with aq. HPF₆ and Ac₂O provided the title compound 5 , which reacted regio‐ and stereospecifically with some nucleophiles to give the addition products 3b and 7 .     

The Interaction of α‐Hydroxycarboxylic Acids with Metal Ions: Lactic Acid (H2L1) and 2‐Methyllactic Acid (H2L2) with Cobalt(II) Crystal and Molecular Structures of [Co(HL1)2(H2O)2]·H2O and [Co(HL2)2(H2O)2]

The cobalt(II) complexes [Co(HL¹)₂(H₂O)₂]·H₂O) ( 1 ) and [Co(HL²)₂(H₂O)₂]( 2 ) [(HL¹)^‐ = (/plusmn;)‐lactate, (HL²)^‐ = 2‐Methyl‐lactate] were prepared and characterized structurally. The cobalt atom is in a distorted octahedral environment in both compounds. Both α‐hydroxycarboxylato ligands are O, O'‐bidentate chelating monoanions. The presence of a lattice water molecule in 1 makes its supramolecular organization different from that of 2 . The thermal behaviour of both compounds was also investigated.     

金属串配合物[MoMoCo(npo)4(NCS)2]的配位结构及其与电场的关系

应用密度泛函理论B3LYP方法研究了具有分子导线潜在应用的金属串配合物[MoMoCo(npo)4(NCS)2](npo=1,8-萘基-2-酮)的配位结构及其受电场作用的影响。配位方式记为(n,m),其中n、m分别表示4个赤道配体npo^-的O与Co和Mo配位的个数:n=0,1,2,3,4;m=4,3,2,1,0。结果表明:(1)零电场下,基态能量高低为(0,4)>(4,0)>(3,1)≈(1,3)>(2,2),5种配位方式均可稳定存在且互为竞争态。Z方向偶极矩μ(Z)值大小为(0,4)(+)>(1,3)(+)>(2,2)(-)>(3,1)(-)>(4,0)(-)(+、-表示μ(Z)值的正负,与Z方向相同即为正,相反即为负),4个npo^-趋向越一致能量越高极性越大。(2)Mo-Mo具有四重键,键长随μ(Z)值减小而减小,而Mo-Co键长则相反。随μ(Z)值减小前线轨道中πNCS(1)轨道能降低,π'NCS(2)轨道能升高。(3)Z方向电场作用下,除(0,4)外所有配位方式的Mo1-N8键显著增长,结构不稳定。(4)电场作用下前线轨道能级交错,μ(Z)为正值的(0,4)、(1,3)的能隙E_LUMO-HOMO在-Z方向电场中降低更显著,μ(Z)为负值的(2,2)、(3,1)和(4,0)的能隙在Z方向电场中降低更显著。分子极性越大,随电场强度增强能隙降低越显著,分子导电性可能越好。(0,4)、(3,1)和(4,0)可能具有整流效应,但(3,1)和(4,0)的稳定性较低。     

Synthesis of β‐Haloketones by β‐Addition Reactions of α,β‐Unsaturated Ketones with BX3 (X = Br,Cl) as Halide Source

A series of β‐bromoketones and β‐chloroketones were synthesized by the addition reactions of α,β‐unsaturated ketones under BX₃ (X = Br, Cl) and ethylene glycol reaction system. The α,β‐unsaturated ester also was successfully converted to its corresponding β‐bromoester under the reaction condition.     

[Cu2Pt(npa)4X2](X=Cl-,NCS-)金属串配合物电子传输性质的研究

使用密度泛函理论(BP86)结合非平衡态格林函数(NEGF)方法研究金属串配合物[Cu₂Pt(npa)₄X₂] (X=Cl^-(1), NCS^-(2); npa=2-naphthyridylphenylamine)的电子结构和电子传输性质, 研究发现: (1)由于轴向配体NCS^-与Cu的结合比Cl^-的强, 使配合物1的Cu-Cu键比2的强而Cu-Pt键比2的弱, 故1的π^*_{Pt dxz/yz}轨道与π^*_Cu-Cu能级差ΔE比2小. (2) 1和2的传输通道均是β自旋的π^*轨道, 主要由π^*_Cu-Cu 和π^*_{Pt dxz/yz}轨道组合而成. ΔE越小π^*越离域, 传输能力越强. 在负偏压下和正偏压小于0.15 V时, 1的电流大于2; 但正偏压大于0.15 V后2的β电流显著高于1. (3) 2具有较好的整流效应. ΔE越大, Pt→Cu方向的传输越容易, 整流效应越强. 正偏压下2的电流显著大于负偏压下的电流, 0.15 V后2的整流比比1高10～40倍. (4)因ΔE_β< ΔE_α, α自旋通道传输能力小于β自旋的, 1和2具有良好的自旋过滤效应(高达80%～99%).     

Synthesis,Crystal Structures,and Magnetic Properties of Two Copper(II) Radical Heterospin Complexes

Two heterospin complexes [Cu(NIT3Py)(cda)H₂O] · H₂O ( 1 ) and [Cu(NIT2Py)(cda)H₂O] · H₂O · CH₃OH ( 2 ) with Cu^II ions and pyridyl‐substituted nitronyl nitroxide radicals (NITxPy = 2‐(x′‐pyridyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide, x = 3, 2; H₂cda = 4‐hydroxy‐pyridine‐2,6‐dicarboxylic acid) were synthesized and characterized structurally and magnetically. The single crystal structures show that the two complexes are both two‐spin complexes, in which the different radicals make the two complexes have different hydrogen bonding interactions to form 2D and 1D supramolecular network for complexes 1 and 2 , respectively. The magnetic measurements indicate that complexes 1 and 2 both exhibit antiferromagnetic interactions between Cu^II and radicals.     

1,1′-Disubstituierte Titanocen-dithiolen-Chelate des Typs (η5-Me3EC5H4)2Ti(S2C2R2) (E = C,Si, Ge)

1,1′-Disubstituted Titanocene Dithiolene Chelates of Type (η⁵-Me₃EC₅H₄)₂Ti(S₂C₂R₂) (E = C, Si, Ge) Reaction of the titanocene dichlorides (η⁵-Me₃EC₅H₄)₂TiCl₂ (E = C, 1a ; E = Si, 1b ; E = Ge, 1c ) with the 1,2-dithiolates (NaS)₂C₂H₂, (NaS)₂C₂(CN)₂ or (LiS)₂C₆H₃Me-4 gave the new titanocene dithiolene chelates (η⁵-Me₃EC₅H₄)₂Ti(S₂C₂H₂) ( 2a–c ), (η⁵-Me₃EC₅H₄)₂Ti[S₂C₂(CN)₂] ( 3a–c ) and (η⁵-Me₃EC₅H₄)₂Ti(S₂C₆H₃Me-4) ( 4a–c ). These have been characterized by ¹H NMR, IR, and mass spectroscopy, and have been compared with the unsubstituted η⁵-C₅H₅ analogues 2d, 3d and 4d . Activation energies for the chelate ring inversion in solution of 2a–c, 3a–d and 4a–c have been estimated by temperature-dependent ¹H NMR spectroscopy.     

Reaction of Group 15 Trichlorides ECl3 with the Anion [Mo2Cp2(CO)4(μ-PH2)]−; Synthesis and Characterization of the First Complexes Featuring a Hetero μ,η2-PE ligand (E=As,Sb)

An Me ₂ PE tetrahedrane framework is seen in complexes 2 a – c (E=P, As, Sb), which are prepared from the appropriate trichlorides and 1 in THF. The structures of the new antimony- and arsenic-containing compounds 2 b and 2 c have been determined—this is the first structural characterization of complexes with μ,η²-PE heteroligands from elements of Group 15.     

Iridium(I)‐catalyzed C−H Borylation of α,β‐Unsaturated Esters with Bis(pinacolato)diboron

A new process has been developed for the iridium(I)‐catalyzed vinylic C?H borylation of α,β‐unsaturated esters with bis(pinacolato)diboron (B₂pin₂). These reactions proceeded in octane at temperatures in the range of 80–120 °C to afford the corresponding alkenylboronic compounds in high yields with excellent regio‐ and stereoselectivities. The presence of an aryl ester led to significant improvements in the yields of the acyclic alkenylboronates. Crossover experiments involving deuterated substrates as well as a mixture of stereoisomers confirmed that this reaction proceeds via a 1,4‐addition/β‐hydride elimination mechanism. Notably, this reaction was also used to develop a one‐pot borylation/Suzuki–Miyaura cross‐coupling procedure.