二茂铁甲酰丙酮缩水杨酰肼的d-过渡、ⅡB族及主族金属配合物研究

将二茂铁甲酰丙酮与水杨酰肼缩合,得含二茂铁基的多齿配体C₅H₅FeC₅H₄C(OH)=CHC(CH₃)=NNHCOC₆H₄OH(简记作FcacacshH₂),该配体分别与d-过渡、ⅡB族及主族金属乙酸盐反应,合成了几个中性固体配合物。经元素分析、红外光谱、紫外—可见光谱、氢核磁共振谱、穆斯堡尔谱、摩尔电导测定对配合物进行表征并研究其性质。     

希土硼氢化物的研究 Ⅹ.含[B_(10)H_9NH_2COCH=CH_2]~-的双苯甲酰丙酮缩1,3—丙二胺希土(Ⅲ)配合物的研究

将闭式+氢+硼酸阴离子酰胺衍生物[B_(10)H_9NH_2COCH=CH_2]~-、双苯甲酰丙酮缩1,3-丙二胺C_6H_5C(OH)=CHC(CH_3)=N(CH_3)CH=C(OH)C_6H_5(Bapn)及希土氯化物在丙酮-乙醇混合溶剂中进行反应,得到分子式为Ln(Bapn)_3[B_(10)H_9NH_2COCH=CH_2]_3(Ln=La,Nd,Sm,Eu,Gd,Dy)的混式配体希土配合物。通过元素分析、IR、~1H NMR及摩尔电导率的测定对配合物进行了表征,还通过DTA-TG方法研究了它们的热性质。     

苯甲酰丙酮苯甲酰腙锰配合物的合成

以氧、氮为配位原子的锰配合物特别是多核配合物由于可作为多种锰蛋白活性部位的模型配合物研究,因此日益受到人们的关注。以β-二酮和芳酰肼形成的腙类化合物(H_2L)可作为三齿配体(ONO)以HL~-和L~(2-)的形式和过渡金属离子配位,但至今未见有关锰配合物的研究报导。本文利用由苯甲酰丙酮和苯甲酰肼缩合而形成的苯甲酰丙酮苯甲酰腙C_(17)H_(16)O_2N_2(H_2L)合成了锰(Ⅲ)配合物Mn(HL)L、Mn(HL)L·H_2O和Mn_2L_2(OCH_3)_2·2H_2O。     

含N-苯甲酰皮考林酰肼的钒酰、镍及锰配合物的合成和晶体结构

合成了3个含N-苯甲酰皮考林酰肼(简写为HL)的钒、镍和锰配合物[VO_2L](1,C_(13)H_(10)N_3O_4V,M_r=323.18),[NiL_2]·0.5CH_3OH(2,C_(26.5)H_(22)N_6NiO_(4.5),Mr=555.21)和[MnL_2]·0.5CH_3OH(3,C_(26.5)H_(22)MnN_6O_(4.5),Mr=551.44)。配合物1属三斜晶系,空间群为P1,a=0.71241(3)nm,b=0.89625(6)nm,c=1.11706(6)nm,α=94.715(2)°,β=102.053(2)°,γ=112.375(3)°,V=0.63461(7)nm~3,Z=2,F(000)=328,μ(MoKα)=0.802mm~(-1),R=0.0290,wR=0.0816;配合物2属单斜晶系,空间群为C2/c,a=2.5875(1)nm,b=1.4868(1)nm,c=1.8353(1)nm,β=134.470(4)°,V=5.2081(5)nm~3,Z=8,F(000)=2368,μ(MoKα)=0.795mm~(-1),R=0.0459,wR=0.1330;配合物3属单斜晶系,空间群为C2/c,a=2.60113(3)nm,b=1.45231(4)nm,c=1.92903(1)nm,β=132.824(1)°,V=5.3448(2)nm~3,Z=8,F(000)=2344,μ(MoKα)=0.543mm~(-1),R=0.0457,wR=0.1325。在配合物1中,钒(V)原子具有畸变的N_2O_3四角锥配位构型,晶体内每两个分子通过分子间氢键作用形成缔合分子对。在配合物2和配合物3中,镍(Ⅱ)原子和锰(Ⅱ)原子具有扭曲的N_4O_2八面体配位构型,晶体通过分子间氢键作用形成一维的无限链状结构。红外光谱表明,配体在形成配合物后,ν(C=O)和ν(C=N)红移。电     

基于类salen配体的二苯基锡配合物的合成、抗肿瘤活性及其与DNA相互作用

利用类salen配体二苯乙二酮苯甲酰腙或二苯乙二酮水杨酰腙与二苯基二氯化锡反应,合成了2个二苯基锡配合物[(C_6H_5(O)C=N—N=C(Ph)—(Ph)C=N—N=C(O)—C_6H_5)_2SnPh_2(CH_3OH)]·3CH_3OH (1)和 [(o-OH—C_6H_4(O)C=N—N=C(Ph)—(Ph)C=N—N=C(O)—(o-OH—C_6H_4))_2SnPh_2(CH_3OH)]·CH_3OH (2),通过IR、~1H NMR、~(13)C NMR、~(119)Sn NMR、元素分析、HRMS 以及X射线单晶衍射等表征了配合物结构。测试了配合物1、2的热稳定性及其对癌细胞的体外抑制活性,发现配合物2对癌细胞NCIH460、HepG2、MCF7表现出略优的抑制活性。利用紫外可见吸收光谱、荧光猝灭光谱研究了配合物2与ct-DNA之间的相互作用,结果表明配合物以嵌入模式与DNA结合。     

二(1-苯基-3-甲基-4-三氟乙酰基-吡唑啉酮-5)二乙醇合钴(Ⅱ)混合配体配合物的合成、表征及结构测定

以1-苯基-3-甲基-4-三氟乙酰基-吡唑啉酮-5(简称HPMTFP)和乙醇为配体合成了具有Co(PMTFP)_2·2C_2H_5OH分子式的钴配合物。对配合物的溶解性、摩尔电导、磁性、热谱、中红外光谱、远红外光谱进行了研究。用四圆单晶衍射仪测定了该配合物的分子及晶体结构。晶体属三斜晶系。P1空间群,晶体学参数:a=10.301(4),b=12.038(7),c=13.806(5);α=88.37(5),β=69.62(3),γ=81.70(5)~9;V=1587.6(1.3)3,z=2,d_(calc)=1.44g/cm~3,d_(exp)=1.46g/cm~3。     

两个由4-酰基吡唑啉酮衍生物构筑的Mn(Ⅱ)配合物的合成、晶体结构及性质(英文)

以4-酰基吡唑啉酮衍生物为配体合成了2个Mn(Ⅱ)配合物[Mn2L2(μ-CH3OH)2(CH3OH)2](1)和{[Mn L(μ-CH3OH)]·CH3OH·CHCl3}n(2)(H2L=N-(1-苯基-3-苄基-4-丙烯基-5-吡唑啉酮)-异烟酰肼),利用元素分析、红外光谱、紫外光谱、热重和X-射线单晶衍射分析进行了表征。结果表明反应体系的p H值影响配体的配位方式,所得配合物1为双核结构,而2为2D网状结构。热重分析表明,配合物1的稳定性高于配合物2的。     

基于双吡啶脲类Cd(Ⅱ)、Zn(Ⅱ)、Hg(Ⅱ)配合物的合成及晶体结构

间苯二胺和3-吡啶异氰酸酯在甲苯中加热回流得到双吡啶脲类配体L,然后将配体分别与CdSO_4·8H_2O,ZnI_2,HgI_2,HgCl_2进行配位反应,得到4个配合物{[Cd(L)(SO_4)(H_2O)_3]·H_2O}n(1),{[Zn(L)I_2]·2C_2H_5OH}n(2),{[Hg(L)I_2]·C_2H_5OH}n(3),[Hg(L)Cl_2]·H_2O(4),并用元素分析、FT-IR、X射线单晶衍射、粉末衍射对其进行了表征。配合物1形成一维螺旋链结构,配合物2和3形成一维"之"字链结构,配合物4形成32元环状结构。     

吡嗪酰腙配体Cu(Ⅱ)/Ni(Ⅱ)配合物的合成、晶体结构及DNA结合性质（英文）

合成并通过单晶衍射、元素分析及红外光谱表征了配合物[Ni(L)(HL)](SO_4)_(0.5)·3CH_3OH (1)和[Cu_2(L)_2SO_4]·1.5CH_3OH (2)的结构(HL为3-甲基-2-乙酰吡嗪苯甲酰腙)。单晶衍射实验结果表明,在配合物1中,Ni(Ⅱ)中心离子与2个酰肼配体的[ONN]配位原子组配位,形成扭曲的八面体配位构型;2的最小非对称单元中含有1个独立的双核Cu(Ⅱ)配合物分子,它的2个Cu(Ⅱ)中心由2个酰肼配体中的2个O原子桥联。每个Cu(Ⅱ)离子还与L-配体中的2个氮原子和η_2-SO_4~(2-)阴离子中的1个O原子配位,拥有扭曲的四方锥配位构型。此外,荧光光谱表明配合物和DNA的结合能力强于配体。     

双苯甲酰羟胺-钨酰螯合物的分子结构与晶体结构

苯甲酰羟胺(C_6H_5CONHOH)对钨钼配位效率高,速度快,生成的配合物稳定.在一定的酸性条件下,对钨钼萃取具有较好的分离性能.等及 Agrawal 曾报道该类钨钼配合物均易被高级醇定量萃取,可用于分光光度法测定微量钨和钼.但对配位过程的研究,特别是对配合物结构与性能的研究则未见报道.本文在钨配合物组成、红外光谱、多晶 X 光衍射等研究的基础上培养其单晶,并测定了晶体结构,试图对其性能研究提供一些信息.实验与结构分析配合物(C_7H_6O_2N)_2WO_2由钨酸钠与苯甲酰羟胺混合的水溶液,在 pH-1～6时,用己醇     

Synthesis and structure investigation of the antibiotic amoxicillin complexes of d-block elements

The study of some transition metals (M) and amoxicillin trihydrate (ACT) ligand complexes (M-ACT) that formed in solution involved the spectrophotometric determination of stoichiometric ratios and their stability constants and these ratios were found to be M:ACT = 1:1, 1:2 and 2:1 in some instances. The calculated stability constants of these chelates, under selected optimum conditions, using molar ratio method have values ranging from K(f) = 10(7) to 10(14). These data were confirmed by calculations of their free energy of formation deltaG, which corresponded to their high stabilities. The separated solid complexes were studied using elemental analyses, IR, reflectance spectra, magnetic measurements, mass spectra and thermal analyses (TGA and DTA). The proposed general formulae of these complexes were found to be ML(H2O)w(H2O)x(OH)y(Cl)2, where M = Fe(II), Co(III), w = 0, x = 2, y = 1, z = 0; M = Co(II), w = 0, x = 1, y = 0, z = 1; M = Fe(III), w = 0, x = 1, y = 2, z = 0; M = Ni(II), Cu(II) and Zn(II), w = 2, x = 0, y = 1, z = 0, where w = water of crystallization, x = coordinated water, y = coordinated OH(-) and z = Cl- in the outer sphere of the complex. The IR spectra show a shift of nu(NH) (2968 cm(-1)) to 2984-2999 cm(-1) of imino group of the ligand ACT and the absence of nu(CO) (beta-lactame) band at 1774 cm(-1) and the appearance of the band at 1605-1523 cm(-1) in all complexes suggest that 6,7-enolization takes place before coordination of the ligand to the metal ions. The bands of M-N (at 625-520 cm(-1)) and of M-O (at 889-7550 cm(-1)) proved the bond of N (of amino and imino groups) and O of C-O group of the ligand to the metal ions. The reflectance spectra and room temperature magnetic measurements refer to octahedral complexes of Fe(II) and Fe(III); square planner form of Co(II), reduced Co(III), Ni(II) and Cu(II)-ACT complexes but tetrahedral form of Zn-ACT complex. The thermal degradation of these complexes is confirmed by their mass spectral fragmentation. These data confirmed the proposed structural and general formulae of these complexes.     

The use of IR, magnetism, reflectance, and mass spectra together with thermal analyses in structure investigation of codeine phosphate complexes of d-block elements

Codeine is an analgesic with uses similar to morphines, but it is of much less effect, i.e., it had a mild sedative effect; codeine is usually used as the phosphate form (Cod.P) and is often administrated by mouth with aspirin of paracetamol. Due to its serious use, if it is in large dose, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug in both solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1:1 ratio of metal (M) to ligand (L). The steriochemical structures of the solid complexes were studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of MO bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structures. The prepared complexes were found to have the general formulae [ML(OH)(x)(H2O)(y)](H2O)(z)H3PO4, M: Co(II), Ni(II), and Cu(II), x = 1, y = 0, z = 0; M: Fe(II), x = 1, y = 2, z = 1; Fe(III), x = 2, y = 1, z = 0; Co(III), x = 0, y = 2, z = 1; Zn(II), x = 1, y = 0, z = 3; and L: (Cod.P) of the general formula C18H24NO7P (anhydrate). Octahedral, tetrahedral, and square planer structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies.     

Synthesis, molecular modeling, thermal and spectral studies of metal complexes of hydrazone derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione and thiosemicarbazide

Metal complexes with the general formula [ML(H2O)(CH3OH)x]·nH2O·(CH3OH)y(NO3)z [M=Cu(II), Ni(II), Co(II), VO(IV), Cr(III), Cd(II), Zn(II) or UO2(VI); x=0-2; y=0,1; z=0,1; n=0-2, 6 and L=hydrazone (H2L) derived from condensation of thiosemicarbazide with 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione. The synthesized ligand and its metal complexes have been characterized on the basis of elemental analyses, spectral and magnetic studies as well as thermal gravimetric analysis (TGA). The deprotonated ligand acts as a dibasic tridentate (ONS) via phenolate oxygen, azomethine (CN), and thiolate (C-S) groups. Copper(II) complex exhibits square planar geometry. Nickel(II), chromium(III) and dioxouranium(VI) complexes exhibit octahedral geometry. Cobalt(II), cadmium(II) and zinc(II) complexes showed tetrahedral geometry, whereas oxovanadium(IV) reveals square pyramidal geometry. Thermal analysis are investigated and showed either three or four thermal decomposition steps. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages have been evaluated using Coats-Redfern equations. The molecular parameters of the ligand and its metal complexes have been calculated and correlated with the experimental data such as IR and TGA results.     

Synthesis, characterization and electronic spectra of cefadroxil complexes of d-block elements

Cefadroxil (CD) is an essential pharmaceutical drug used in curing many diseases. Due to its popular use in many pharmaceutical forms, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug both in solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1:1 and 1:2 ratios of metal (M) to ligand (L). The calculated stability constants (Kf) of these complexes (1.5x10(7) to 5x10(13)) and the change in free energy of formation (deltaGf=2.5-12.5 kcal mol(-1) degree(-1)) are indicative of their high stability. The stereo chemical structure of the solid complexes was studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of M-N and M-O bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structure. The prepared complexes were found to have the general formulae [ML(OH)x(H2O)y](H2O)z-M: Fe(II), x=0, y=2, z=1; M: Fe(III) and Co(III), x=1, y=2, z=1; M: Co(II) and Zn(II), x=0, y=1, z=0; M: Ni(II) and Cu(II), x=1, y=0, z=1; L: CD. Octahedral and tetrahedral structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies.     

Small Heteroborane Cluster Systems. 6. Mössbauer Effect Study of Iron Substituted Small Metallaborane Clusters

The M?ssbauer effect spectra for a series of small [Fe(eta(5)-C(5)H(5))(CO)(x)()] substituted metallaborane complexes are reported, where x = 1 or 2. The pentaborane cage in compounds [Fe(eta(5)-C(5)H(5))(CO)(2)B(5)H(7)P(C(6)H(5))(2)] (1), [Fe(eta(5)-C(5)H(5))(CO)(2)B(5)H(8)] (2), and [(Fe(eta(5)-C(5)H(5))(CO)(2))(2)B(5)H(7)] (3) was found to act as a significantly better donor ligand than the ligands in a comparison group of previously reported [Fe(eta(5)-C(5)H(5))(CO)LX] complexes, where L = CO or PPh(3) and X = halide, pseudohalide, or alkyl ligands. These metallaborane complexes were found to most resemble their silyl analogues in M?ssbauer spectral parameters and the electronic distribution around the iron centers. In addition, the M?ssbauer data showed that the [&mgr;-2,3-(P(C(6)H(5))(2)B(5)H(7)](-) ligand was a superior donor to the corresponding unsubstituted [B(5)H(8)](-) ligand. The M?ssbauer spectral results for the metallaborane complexes studied were found to be in general agreement with the anticipated donor and accepting bonding considerations for the cage ligands based upon their infrared and (11)B NMR spectra and X-ray structural features. The M?ssbauer data for the [Fe(eta(5)-C(5)H(5))(CO)B(4)H(6)(P(C(6)H(5))(2))] (4) and [Fe(eta(5)-C(5)H(5))(CO)B(3)H(7)(P(C(6)H(5))(2))] (5) complexes, in comparison with compound 1, showed that as the borane cage becomes progressively smaller, it becomes a poorer donor ligand. A qualitative relationship was found between the observed M?ssbauer isomer shift data and the number of boron cage vertices for the structurally related [Fe(eta(5)-C(5)H(5))(CO)(x)B(y)H(z)P(C(6)H(5))(2)] complexes, where x = 1 or 2, y = 3-5, and z = 6 or 7. The X-ray crystallographic data for compounds 1, 2, 5, and [Fe(eta(5)-C(5)H(5))(CO)B(5)H(8)] (6) were also found to agree with the trends observed in the M?ssbauer spectra which showed that the s-electron density on the iron nucleus increases in the order 5 < 6 < 2 < 1. The X-ray crystal structure of complex 2 is also reported. Crystallographic data for 2: space group P2(1)/c (No. 14, monoclinic), a = 6.084(3) ?, b = 15.045(8) ?, c = 13.449(7) ?, beta = 99.69(5) degrees, V = 1213(1) ?(3), Z = 4 molecules/cell.     

Influence of the metal size in the structure of the complexes derived from a pentadentate [N(3)O(2)] hydrazone

The influence of the metal size in the nuclearity of the complexes derived from the hydrazone ligand 2,6-bis(1-salicyloylhydrazonoethyl)pyridine [H(4)daps] has been investigated. We have synthesised a series of new complexes [M(H(x)daps)] x yH(2)O, (x = 2,3; y = 0-3) with M = Ag (1), Cd (2), Al (3), Sn (4) and Pb (6), using an electrochemical procedure. The crystal and molecular structures have been determined for the mononuclear complexes [Sn(H(2)daps)(H(2)O)(2)] x 4H(2)O (5) and [Pb(H(2)daps)(CN)][Et(4)N] (7). Complex is the first neutral Sn(II) complex derived from a pentadentate hydrazone Schiff base ligand. Complex shows the lead coordinated to the hydrazone donor set and a cyanide ligand, being the first reported complex with the lead atom coordinated to a monodentate cyanide group. Additionally, we have synthesised the lead complex using chemical conditions, in the presence of sodium cyanide which allowed us to isolate the neutral complex [Pb(H(2)daps)] (8). Evaporation of these mother liquors led the novel compound [Pb(Hdaphs)(CH(3)COO)] (9). Complex 9 shows the initial ligand hydrolysed in one of the imine bonds giving rise to a new tetradentate ligand [H(2)daphs] coordinated to the lead atom and a bidentate acetate group. Moreover, the solution behaviour of the complexes has been investigated by (1)H, (113)Cd, (117)Sn and (207)Pb NMR techniques. In particular multinuclear NMR has provided new useful data to correlate factors such as oxidation state, coordination number and nature of the kernel donor atoms due to the new coordination found in complexes 5 and 7. The comparative study of the structures of the complexes derived from this pentadentate [N(3)O(2)] hydrazone ligand let us to conclude that the metal size is a key factor to control the nuclearity of the complexes derived from the ligand [H(4)daps].     

In situ synthesis of trisubstituted methanol ligands and their potential as one-pot generators of cubane-like metal complexes

Two different one pot routes to a variety of metal cubane compounds are reported; one route is based on an in situ benzilic acid type rearrangement and the other involves in situ nucleophilic attack at a ketone. Diketosuccinic acid in basic solution in the presence of certain divalent metal ions undergoes a benzilic acid type rearrangement to generate the carbon oxyanion, C(CO(2) (-))(3)O(-), which serves as a cubane-forming bridging ligand in a series of octanuclear complexes of composition [M(8){C(CO(2))(3)O}(4)](H(2)O)(12) (M=Mg, Mn, Fe, Co, Ni, Zn). At the heart of each of these highly symmetrical aggregates is an M(4)O(4) cubane core, each oxygen component of which is provided by the alkoxo centre of a C(CO(2) (-))(3)O(-) ligand. Reaction of 2,2'-pyridil, (2-C(5)H(4)N)COCO(2-C(5)H(4)N), and calcium nitrate in basic alcoholic solution, which proceeds by a similar benzilic acid type rearrangement, gives the cubane compounds, [Ca(4)L(4)(NO(3))(4)] in which L=(2-C(5)H(4)N)(2)C(COOR)O(-) (R=Me or Et). Nucleophilic attack by bisulfite ion at the carbonyl carbon atom of 2,2'-dipyridyl ketone in the presence of certain divalent metals generates the electrically neutral complexes, [{(C(5)H(4)N)(2)SO(3)C(OH)}(2)M] (M=Mn, Fe, Co, Ni, Zn and Cd). Cubane-like complexes [M(4){(C(5)H(4)N)(2)SO(3)C(O)}(4)] (M=Zn, Mn) can be obtained directly from 2,2'-dipyridyl ketone in one-pot reaction systems (sealed tube, 120 degrees C) if a base as weak as acetate ion is present to deprotonate the OH group of the initial [(C(5)H(4)N)(2)SO(3)C(OH)](-) bisulfite addition compound; the [(C(5)H(4)N)(2)SO(3)C(O)](2-) ligand in this case plays the same cubane-forming role as the ligands C(COO(-))(3)O(-) and (2-C(5)H(4)N)(2)C(COOR)O(-) above. When excess sodium sulfite is used in similar one-pot reaction mixtures, the monoanionic complexes, [M(3)Na{(C(5)H(4)N)(2)SO(3)C(O)}(4)](-) (M=Zn, Mn, Co) with an M(3)NaO(4) cubane core, are formed directly from 2,2'-dipyridyl ketone.     

Interaction of methyl beta-D-xylopyranoside with metal ions: density functional theory study of cationic and neutral bridging and pendant complexes

Density functional theory calculations on complexes of 4C1, 1C4 and 2SO ring conformations of methyl beta-D-xylopyranoside 1 with divalent metal cations, M = Mg2+, Ca2+, Zn2+, and Cd2+, are presented. Bridging and pendant cationic, [M(H2O)41]2+ and [M(H2O)(5)1]2+, as well as neutral complexes, [M(OH)2(H2O)(2)1] and [M(OH)2(H2O)(3)1], and neutral complexes involving a doubly deprotonated sugar, [M(H2O)(4)1(2-)], are considered. In aqueous and chloroform solution the stability of cationic and pendant neutral complexes is greatly diminished compared with gas-phase results. In contrast, bridging neutral complexes [M(OH)2(H2O)(2)1] and those of type [M(H2O)(4)1(2-)], are stabilized with increasing solvent polarity. Solvation also profoundly influences the preferred binding position and ring conformation. Compared with complexes of bare metal cations, additional ligands, e.g., H2O or OH-, significantly reduce the stability of 1C4 ring complexes. Irrespective of the cation, the most stable structure of bridging complexes [M(H2O)(4)1]2+ results from coordination of the metal to O3 and O4 of methyl beta-D-xylopyranoside in its 4C1 ring conformation.     

New rare earth metal complexes with nitrogen-rich ligands: 5,5'-bitetrazolate and 1,3-bis(tetrazol-5-yl)triazenate-on the borderline between coordination and the formation of salt-like compounds

From the two nitrogen-rich ligands BT(2-) (BT=5,5'-bitetrazole) and BTT(3-) (BTT=1,3-bis(1H-tetrazol-5-yl)triazene), a series of novel rare earth metal complexes were synthesised. For the BT ligand, a vast number of these complexes could be structurally characterised by single-crystal XRD, revealing structures ranging from discrete molecular aggregates to salt-like compounds. The isomorphous complexes [La2(BT)3]14 H2O (1) and [Ce2(BT)3]14 H2O (2) reveal discrete molecules in which one BT(2-) acts as a bridging ligand and two BT groups as chelating ligands. The complexes, [M(BT)(H2O)7]2[BT] x (x) H2O (3-5), (M=Nd (3), Sm (4), and Eu (5)), are also isomorphous and consist of [M(BT)(H2O)7]+ ions in which only one BT(2-) acts as a chelate ligand for each metal centre. [Tb(H2O)8]2[BT]3 x H2O (6) and [Er(H2O)8](2)[BT](3)x H2O (7) are salt-like compounds that do not exhibit any significant metal-nitrogen contacts. In the BTT-samarium compound 9, discrete molecules were found in which BTT(3-) acts as a tridentate ligand with three Sm--N bonds.