Alkylation of naphthalene with n-butene catalyzed by liquid coordination complexes and its lubricating properties

With the development of coal chemical industry,large amounts of naphthalene and n-butene are produced,and converting them into high value-added products through alkylation has gained particular importance and interest.In this work,liquid coordination complexes(LCCs)were used as acid catalysts for the first time in the naphthalene alkylation reaction under mild conditions to obtain multibutylnaphthalenes with high yield.Various reaction conditions were thoroughly investigated.The LCC consisting of urea and AlCl_(3) showed excellent catalytic performance under optimal reaction conditions,giving 100%conversion of naphthalene and 99.66%selectivity towards multi-butylnaphthalenes.Combining the catalyst properties and catalytic results,a plausible reaction mechanism was proposed.The lubricating properties of the synthesized products were investigated for their potential application as lubricating base oils.The synthesized multi-butylnaphthalenes showed comparable physicochemical properties and tribological performances as the commercial cycloalkyl base oil.

Syntheses,Structures,and Properties of Two Cobalt(Ⅱ)Coordination Complexes Based on(Fluorene-9,9-diyl)dipropanoic Acid and 1,3-Bis(imidazol-1-yl)butane Ligands

Two new cobalt（II） coordination complexes, namely [Co（HL）2（biim）（H2O）2]n·n H2O（1） and [Co（Et L）2（biim）]n·3 n（H2O）·2 n（Et HL）（2）（H2L =（fluorene-9,9-diyl）dipropanoic acid, biim = 1,3-bis（imidazol-1-yl）butane）, have been synthesized using the same starting reactants but different solvent medium. The two complexes exhibit distinctly different structures. Compound 1 exhibits a one-dimensional linear chain structure. However, complex 2 reveals a one-dimensional zigzag chain structure. Thermogravimetric analyses（TGA） and luminescent properties of these two complexes have been discussed.

Synthesis and Crystal Structure of Two Coordination Complexes Based on H_(2)dpa and Tmd Ligands

Two new transition metal compounds, [Mn（dpa）2（tmd）2]n （1, H2dpa = 4-hydroxy-phenyl-acetic acid, tmd = 4,4-trimethylenedipyridine） and [Co4（dpa）6（tmd）4（H2O）4]n·nH2O·nCl2 （2）, have been synthesized by hydrothermal synthesis. Compound 1 crystallizes in the monoclinic system, space group P21/n with a = 9.828（3）, b = 17.493（5）, c = 11.616（4）, β = 110.146（6）o, V = 1874.9（10）3, C42H42MnN4O6, Mr = 753.74, Z = 2, Dc = 1.335 g/cm3, μ = 0.406 mm-1, F（000） = 790, the final R = 0.1047 and wR = 0.2021 for 2698 observed reflections （I 〉 2σ（I））. Compound 2 crystallizes in the monoclinic system, space group P21/c with a = 11.7214（13）, b = 17.1582（19）, c = 24.625（3）, β = 103.055（3）o, V = 4824.4（9）3, C100H104Cl2Co4N8O23, Mr = 2094.55, Z = 2, Dc = 1.443 g/cm3, μ = 0.809 mm-1, F（000） = 2180, the final R = 0.0550 and wR = 0.0673 for 4104 observed reflections （I 〉 2σ（I））. These complexes were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. The structural analyses show that the two compounds are both one-dimensional chain structures. However, compounds 1 and 2 form threedimensional supramolecular structures by hydrogen bonds, respectively.

Syntheses and Crystal Structures of Three Coordination Complexes Based on Ln(Ⅲ) and mpca-Ligand

Three complexes obtained by the reaction of Pr（Ⅲ） or Nd（Ⅲ） salts with 5-methyl-2-pyrazinecarboxylic acid（Hmpca） are structurally determined by single-crystal X-ray diffraction.Complex [Pr（mpca-）3（H2O）2]2·6H2O（1） is composed of dinuclear Pr（Ⅲ） units with two metal centers bridged by two anionic mpca-ligands in a κ^3O,O＇：O＇ bridging mode.Complexes [Pr（mpca-）3]n（2） and [Nd（mpca-）3]n（3） are isostructures,and they consist of polymeric chains based on Ln（Ⅲ） and mpca-ligands.Each pair of adjacent metal centers is linked by three mpca-molecules in a κ^3N,O：O bridging mode.

Hydrothermal syntheses and characterization of three lanthanide coordination complexes constructed by 2,2':6',2''-terpyridine and 2,2'-biphenyldicarboxylic acid

Two 1D coordination polymers [Ln2（dpdc）3（tpy）2·H2O]n [Ln=Nd 1, Yb 2, H2dpdc=2,2＇-biphenyldicarboxylic acid and tpy= 2,2＇：6＇,2＇＇-terpyridine] and one dinuclear complex Er2（dpdc）2（Hdpdc）2（tpy）2 3 were obtained via hydrothermal reactions and determined by X-ray diffraction analysis. The crystal structure data of 1 and 2 revealed that two coordination polymers were isostructural and possessed a 1D chain framework consisting of eight-coordinated Ln（III） centers. In the asymmetric unit, the two Er（III） ions in 3 were both nine-coordinated and had similar coordination environments. The Er（III） ions were bridged by dpdc2-ligands into dinuclear structures. The complexes were also characterized by IR spectra and thermogravimetric analysis. The solid fluorescence of 1 and 3 was also investigated at room temperature.

Two 2D uranyl coordination complexes showing effective photocatalytic degradation of Rhodamine B and mechanism study

Two new hydrostable two-dimensional(2 D) uranyl coordination complexes [(UO_(2))_(5)(μ_(3)-O)_(2)(nbca)_(2)].7 H_(2)O(1) and [(UO_(2))_(3)(nbca)_(2)(H_(2)O)_(3)]·2 H_(2)O(2)(H_(3) nbca=5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized.Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds.The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets.There are UO8 hexagonal bipyramids and UO7 pentagonal bipyramids in 1 while only U07 pentagonal bipyramids in 2.Photocatalytic degradation of rhodamine B(RhB) in aqueous solution was studied.Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min.Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation.The photocurrent density of 2 is more stable than that of 1,which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.

A Theoretical Study of Tris-(o-benzoquinonediimine)-First-Row Divalent Transition Metal Complexes

The ligand o-phenylenediamine (opda) and its oxidized form, o-benzoquinonediimine (bqdi), act as a fascinating candidate coordinating toward transition metal ions leading to the photochemical hydrogen production in absence of photosensitizers. Herein, we report the systematic study of the interaction between the oxidized form bqdi ligand, tris-(o-benzoquinonediimine) with divalent first-row transition metal series using DFT calculations. The lowest energy structures, bond length, binding energies, frontier molecular orbital analysis, natural bond orbitals, and global reactivity descriptor were calculated using B3LYP/6-311G(d,P) level of theory. The time dependent-DFT at the CAM-B3LYP/6-311+G(d,p) level of theory was applied to determine the electronic structures and the optical spectra. The theoretical binding trend of the divalent first-row transition metal series is decreasing as follows: Cu >Ti > V > Co > Ni > Fe > Cr > Zn >Mn. Among them, the binding potency of iron (II) by the bqdi ligand was not predominantly sturdy as compared to other first-row divalent transition metal ions. The origin of strong coordination with Fe(II) is attributed to its extra capability to induce covalent coordination of bqdi ligands. The complex exhibited two strong peaks at 370 nm and 452 nm, due to the HOMO-3 to LUMO+1 and HOMO-1 to LUMO transitions, respectively. Natural bond orbital analysis showed that the major interaction happens between the N lone pair electrons of the ligand with an anti-bonding orbital of metal ions, in which Ti showed the highest interaction energy than other metal ions. The present systemic DFT study of bqdi ligands with the first-row transition metals strongly encourages the future establishment of photochemical hydrogen production in absence of photosensitizers.

Syntheses,Crystal Structures and Properties of Mn(Ⅱ) and Co(Ⅱ) Coordination Complexes Based on 1,10-Phenanthroline Derivative

Two new coordination complexes[Mn(L)_(2)(DNSA)](1) and[Co(L)(1,4-bdc)]_n (2) have been achieved under hydrothermal conditions (H_(2)DNSA=3,5-dinitro-salicylic acid,1,4-bdc=1,4-benzenedicarboxylic acid and L=2-(2-fluoro-6-fluorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline).1 crystallizes in monoclinic,space group P2_1/c with a=15.871(3),b=17.274(4),c=16.078(3)A,β=113.03(3)^(o),V=4056.6(16)A^(3),Z=4,C_(45)H_(22)Cl_(2)F_(2)Mn N_(10)O_(7),M_(r)=978.57,D_(c)=1.602 g/cm^(3),F(000)=1980,μ(Mo Ka)=0.536 mm^(–1),R=0.0437 and w R=0.1065.2 belongs to the monoclinic system,space group C2/c with a=14.665(2),b=30.856(4),c=11.237(2)A,β=111.166(2)^(o),V=4742.0(12)A^(3),Z=8,C_(27)H_(14)Cl Co FN_(4)O_(4),M_r=517.80,D_(c)=1.602 g/cm^(3),F(000)=2312,μ(Mo Ka)=0.889 mm^(–1),R=0.0364 and w R=0.0862.The central Mn(II) ion in 1 is six-coordinated by four nitrogen atoms from two L ligands and two oxygen atoms from one DNSA anion.In 2,the two kinds of 1,4-bdc ligands link neighboring Co(II) atoms to yield a two-dimensional layer structure.The luminescence of 1 has been studied in detail.Moreover,thermal behaviors of 1 and 2 are also investigated.

Two New Coordination Complexes Based on 2,2'-H2biimidazole: Synthesis, Structure, Luminescent Property and Theoretical Calculation

Two new coordination complexes[Cd(L)2(1,2,3-HBTC)]·3H2O(1)and{[Zn(L)(1,2-BDC)]-H2O}n(2)were synthesized under hydrothermal conditions(1,2,3-H3 BTC=1,2,3-tricarboxybenzene,1,2-H2 BDC=1,2-dicarboxybenzene and L=2,2’-H2 biimidazole).1 crystallizes in monoclinic,space group P21/c with a=12.256(5),b=11.620(5),c=17.479(5)A,β=95.548(5)°,V=2477.6(16)A^3,Z=4,C21H22N8 O9 Cd,Mr=642.86,Dc=1.724 g/cm^3,F(000)=1296,μ(MoKa)=0.950 mm^-1,R=0.0546 and wR=0.1724.2 belongs to the monoclinic system,space group P21/c with a=7.408(4),b=20.743(10),c=10.194(5)A,β=95.648(6)°,V=1477.3(12)A^3,Z=4,C14H12N4 O5 Zn,Mr=381.65,Dc=1.716 g/cm3,F(000)=776,μ(MoKa)=1.698 mm^-1,R=0.0574 and wR=0.1632.The central Cd(Ⅱ)ion in 1 is coordinated with five atoms,forming a slightly distorted square-pyramidal geometry.The central Zn(Ⅱ)ion in 2 is four-coordinated by two nitrogen atoms from one L ligand and two oxygen atoms from two different 1,2-BDC anions.In addition,luminescent property of 1 has been investigated,and natural bond orbital(NBO)analysis of 2 has been calculated by the B3LYP/LANL2DZ method.

Synthesis,Crystal Structure and Luminescent Property of a New Indium(Ⅲ)Coordination Polymer

A new coordination complex [In（pda）1.5（bpy）]n （1, H2pda = 1,4-phenylenediacetic acid, bpy = 2,2＇-bipyridine） has been synthesized under hydrothermal conditions and characterized by IR spectrum, elemental analysis, PXRD and single-crystal X-ray diffraction analysis. Crystal data for the title complex are as follows： monoclinic system, space group P21/n with a = 11.8015（7）, b = 15.9551（10）, c = 11.8858（8）A^°, β = 94.844（6）°, V = 2230.0（2） A^°3, Mr = 559.25, Z = 4, F（000） = 1124, Dc = 1.666 g/cm^3, μ（MoKα） = 1.106 mm^-1, R = 0.0269 and wR = 0.0569 for 4534 observed reflections with I 〉 2σ（I）. Complex 1 displays a 3D supermolecular structure based on the 1D zizag chains. Fluorescence spectrum measurement indicates that complex 1 shows strong fluorescence emission with a maximum peak at 447 nm in the solid state at room temperature.

Crystal Structure and Luminescent Property of a Coordination Complex Constructed with Pyrazine and 1,4-Phenylenediacetic Acid

A new coordination complex [Cd(pda)(pyz)(H2O)2]n(1, H2 pda = 1,4-phenylenediacetic acid, pyz = pyrazine) have been synthesized and structurally characterized. Crystal data for the title complex are as follows: orthorhombic system, space group Ccmb with a = 11.5245(3) b = 19.5069(5) c = 11.4231(3) A, V = 2568.00(12) A3, Mr = 188.31, Z = 16, F(000) = 1480, Dc = 1.948 g/cm3, μ(Mo Kα) = 1.725 mm-1, R = 0.0195 and w R = 0.0462 for 1357 observed reflections with I 】 2σ(I). In the title complex, the central Cd(II) ion is located in a distorted octahedral coordination environment. Two Cd(II) ions are bridged by two pda2- ligands and one pyz ligand to form a bi-loop structure. Luminescent property of the complex has also been studied.

Two Cobalt(II) Complexes Derived from the Hydrolysis Product of Di-Schiff Base Ligand N,N'-Bis-(1-benzimidazo-2-yl-ethylidene)-ethane-1,2-diamine:Preparation,Characterization and Crystal Structure of the 6-Coordinate Species [CoL_2]X·H_2O (X = ClO_4^-, N

The reactions of Co（C1O4）2·6H2O and Co（NO3）2.6H2O with the di-Schiff base ligand N,N＇-bis-（1-benzimidazo-2-yl-ethylidene）-ethane-1,2-diamine （LA） in ethanol have been investigated. The reactions of LA with excess amount of cobalt salts yield the six-coordinate complexes [CoL2]（ClO4）E·H2O 1 and [CoL2]（NO3）E·H2O 2 as isolatable products （L= N-（1- benzimidazo-2-yl-ethylidene）-ethane-1,2-diamine）, where L is a tri-dentate mono-Schiff base ligand, resulting from the hydrolysis of the precursor di-Schiff base LA. Both complexes were characterized by X-ray crystallography. Crystal data for complex 1： monoclinic, space group P21/c, a = 11.9214（10）, b = 23.5828（17）, c = 14.0387（12）A, β = 135.219（4）°, C22H30Cl2CoN8O9, Mr = 680.37, V = 2780.1（4） A^3 ,Z = 4, Dc = 1.625 g/cm^3,μ（MoKa） = 0.876 mm^-1, F（000） = 1404, the final R = 0.0725 and wR = 0.1530 for 5726 observed reflections （I 〉 2σ（I））. Crystal data for complex 2： monoclinic, space group P21/c, a = 18.2162（16）, b = 10.0610（6）, c = 18.593（2）A, β = 130.099（3）°, C22H30CoN10O7, Mr = 605.49, V = 2606.5（4） A3 Z = 4, Dc = 1.543 g/cm^3,μ（MoKa） = 0.722 mm^-1, F（000） = 1260, the final R = 0.0619 and wR = 0.1429 for 5194 observed reflections （I 〉 2σ（I））. X-ray diffraction analysis reveals that each cobalt atom in the two complexes is chelated by six nitrogen atoms from two tridentate iigands L, exhibiting a slightly distorted octahedral coordination sphere. In both complexes, the strong hydrogen-bonding interactions between the lattice waters and N-H groups of the ligands result in 1D chains which are further connected by ClO4^- （or NO3^-） groups to form a 3D framework. In complex 2, the strong π-π interactions increase the stability of the structure.

Two Cobalt(Ⅱ)Coordination Polymers Based on Tetrazylphosphonate and Tetrazylphosphonic Acid Ligands

Two cobalt coordination polymers with the same 2D structure have been hydrothermally synthesized based on two bifunctional ligands with tetrazole and phosphonate（phosphonic acid） groups,namely,diethyl 4-（2H-1,2,3,4-tetrazol-5-yl） benzylphosphonate（C_2H_5-L1） and 4-（2H-1,2,3,4-tetrazol-5-yl）benzylphosphonic acid（H_2L2）. The structures of the two complexes are characterized by elemental analysis,IR,TGA and X-ray single-crystal/powder diffraction. The pink block crystals of complex [Co（L1）（H_2O）]·H_2O（1） belong to the monoclinic system,space group C2/m with a = 20.8390（11）,b = 7.2695（3）,c = 10.0156（6） A,β = 109.773（7）°,V = 1427.80（13） A^3,Z = 4,D_c = 1.680 mg/cm^-3,M_r = 361.16,F（000） = 740,R = 0.0316 and wR = 0.0826 for 1702 observed reflections（I 〉 2σ（I））. The purple block crystals of complex [Co（L2）（H_2O）]·2H_2O（2） also belong to the monoclinic system,space group C2/c with a = 25.5382（16）,b = 7.3844（3）,c = 15.1925（11） A,β = 124.238（9）°,V = 2368.6（2） A^3,Z = 8,D_c = 1.969 mg/cm^-3,M_r = 351.12,F（000） = 1432,R = 0.0475,wR = 0.1617 for 2088 observed reflections（I 〉 2σ（I））. Both the nitrogen atoms of tetrazole group and oxygen atoms of phosphonate（phosphonic acid） groups in the ligands coordinated with the metal cobalt. The magnetic property of complex 1 is also investigated.

Synthesis, Structure and Magnetic Property of One Ni~Ⅱ Based Coordination Polymer

One new coordination polymer, [Ni（m-bix）（m-BDC）]（1, m-bix = 1,3-bis（imidazol-1-ylmethyl）benzene, m-BDC = 1,3-benzenedicarboxylic acids）, has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TGA and X-ray single-crystal diffraction. The green block crystal of complex 1（C22H18N4Ni O4） belongs to monoclinic system, space group P21/c with a = 10.0418（3）, b = 23.8651（6）, c = 8.7872（2） A, β = 112.333（3）°, V = 1947.88（9）A3, Z = 4, Dc = 1.572 g/cm^3, Mr = 461.11, F（000） = 952, R = 0.0335 and w R = 0.0683 for 2827 observed reflections（I 〉 2σ（I））. Complex 1 exhibits a novel 6-connected 3D sxd type topological framework. The magnetic characterization of complex 1 shows antiferromagnetic coupling exchange.

Structure and Magnetic Properties of a Bipyridine-bridged One-dimensional Ni(Ⅱ) Coordination Polymer

A polymer, [NiL（bipy）·2H2O]n（1, bipy = 4,4ˊ-bipyridine）, has been acquired by the reaction of Ni（OAc）2·4H2O with N,Nˊ-bis（2-hydroxyl-5-fluorobenzyl）-2-hydrxylpropane dii- mine in the presence of 4,4ˊ-bipyridine. X-ray crystallographic analysis shows that it is comprised of a mononuclear Ni（Ⅱ） complex [NiL] linked by 4,4ˊ-bipyridine. Its crystal crystallizes in the orthorhombic system, space group C2/c with a = 22.595（3）, b = 18.395（2）, c = 15.434（2） , V = 6155（1）3, Dc = 1.259 g/cm-3, Z = 8, Mr = 583.23, F（000） = 2416.0, μ（MoKa） = 0.681 mm-1, S = 1.049, R = 0.0512 and wR = 0.1108 for 6032 observed reflections（I 〉 2σ（I））. There are water hexamers in the complex. A weak overall ferromagnetic behavior has been evaluated by Curie-Weiss rule and by the formula of alternating ferro-ferromagnetic coupling in one-dimensional Ni（Ⅱ） chain, which gives g = 2.005（1） and J1 = 0.31（3） cm-1.

Thermochemical Study on Coordination Complex of Neodymium Trichloroacetic Acid with 8-Hydroxyquinoline

Two coordinate reactions, NdCl 3·6H 2O(s) +3CCl 3COOH(s)( or TCA) =Nd(TCA) 3·3H 2O(s) +3HCl(g) +3H 2O(l) and Nd(TCA) 3·3H 2O(s) +2C 9H 7NO(s)= Nd(TCA)(C 9H 6NO) 2 (s) +2CCl 3COOH(s) +3H 2O(l), were studied by the classical solution calorimetry at 298.15K. The molar dissolution enthalpies of the reactants and the products in certain solvent (the first reaction in 1 mol·L -1 HCl, the second in a mixed solution consisting of absolute ethyl alcohol, dimethyl sulfoxide and 4 mol·L -1 HCl ) were measured by using an isoperibol calorimeter at 298.15K . From the results and other auxiliary quantities, the standard molar formation enthalpies of [Nd(TCA) 3·3H 2O,s,298.15K] and [Nd(TCA) (C 9H 6NO) 2 ,s, 298.15K] are determined as Δ fH m °[Nd(TCA) 3·3H 2O,s,298.15K]= -3053.3 kJ·mol -1 and Δ fH m° [Nd(TCA) (C 9H 6NO) 2 ,s, 298.15K] = -1355.6 kJ·mol -1 .

Investigations of the electron paramagnetic resonance parameters and the tetragonal local structure for (VCl_6)^(4-) coordination complex in MCl:V^(2+) (M=Na,K,Rb) systems

By simulating the electron paramagnetic resonance （EPR） and optical spectra on the basis of the 120 × 120 complete energy matrix, this paper determines the local lattice structure parameters R1 and R2 for MCl：V2＋ （M=Na, K, Rb） systems at 77K, 195 K and RT （room temperature 295 K or 302 K）, respectively. The theoretical results indicate that there exists a compressed distortion in MCl：V2＋ systems. Meanwhile, it finds that the structure parameters R1, R2 and ｜△R｜（ = R1 - R2） increase with the rising temperature. Subsequently, from the analysis it concludes that the relation of EPR parameter D vs. △R is approximately linear. Finally, the effects of orbital reduction factor k on the g factors for the three systems have been discussed.

Synthesis and Crystal Structure of a 1-D Chain Coordination Complex {[Mn_2(HCAM)_3(H_2bipy)]·5H_2O}_n

The 1-D chain coordination complex of {[Mn2（HCAM）3（H2bipy）]·5H2O}n （H3CAM = 4-hydroxypyridine-2,6-dicarboxylic acid, bipy = 4,4＇-bipyridine） has been synthesized by the reaction of 4-hydroxypyridine-2,6-dicarboxylic acid, 4,4＇-bipyridine and manganese carbonate under hydrothermal conditions, and its crystal structure was determined by X-ray diffraction method The crystal belongs to the monoclinic system, space group P21/n with a = 10.110（2）, b = 20.159（4）, c = 17.861（4）A,β = 99.67（3）°, V = 3.5884（12） nm3, Mr= 901.47, Z = 4, Dc= 1.669 g.cm^-3, μ= 0.798 mm^-1, F（000） = 1840, the final R = 0.0713 and ωR = 0.1853. The complex forms a 1-D chain bridged by HCAM, protonated 4,4-bipyridines link the 1-D chains to construct 2-D networks via N-H...O hydrogen bonds, and networks are further extended via π-π stacking and hydrogen bonds into 3-D supramolecular framework.

Synthesis and Characterization of a Novel Coordination Complex Based on Fluorescein

A novel coordination complex,{[Cd）2（C（20）H（10）O5）2（H2O）4]·10H2O}n,has been synthesized based on fluorescein（2-（6-hydroxy-3-oxo-3 H-xanthen-9-yl） benzoic acid） and systematically characterized by elemental analysis,infrared（IR） spectrum,thermo gravimetric analysis（TGA）,powder X-ray diffraction（PXRD） and single-crystal X-ray diffraction.Compound 1 crystallizes in monoclinic,space group P2/n with a = 20.428（5）,b = 8.084（2）,c = 21.689（5）A,β = 96.360（5）°,Mr = 993.46,V = 3559.7（15）A^3,Z = 4,Dx = 1.845 g/cm^3,μ = 1.276 mm^-1,F（000） = 1974,GOOF = 1.044,λ（Mo Kα） = 0.71073 ？,the final R = 0.0553 and wR = 0.1720 for 7245 observed reflections with I 〉 2σ（I）.

Studies on the Stability of Four－membered Ring Chelates（Ⅳ）──Sulphur Coordinated Xanthate Complexes

Fifteen M(S2COR)n complexes were prepared.According to the data provided by IR,UV-Vis absorption spectrometry and X-ray diffraction,this paper covers the relationship between molecular structures of xanthate complexes and their absorption spectra and a criterion of chelate stability is also proposed.The stability mechanism of xanthate chelates and related rules were investigated.