Complexation of (1Z, 2Z)- N ′-1-, N ′-2-dihydroxy- N -1-, N -2-dipyridin-2-ylethanedimidamide in mono and dinuclear Zn(II), Cd(II), Hg(II) and Sn(IV) complexes

Mononuclear O,O-coordinated complexes K₂(MLCl₂) M = Zn(II), Cd(II) and dinuclear complexes (MZnLCl₂R₂)^x along with dinuclear N,N-coordinated complexes (M′ZnH₂LCl₂R₂)^y (where M = Zn(II), Cd(II), Hg(II) and M′ = M and Sn(IV); R = Cl, CH₃; x = 0, ?2; y = 0, +2) of N′-1-,N′-2-dihydroxy-N-1-,N-2-dipyridin-2-ylethanedimidamide (H₂L) have been prepared. All complexes have been characterized by ¹H NMR, IR, EI-mass spectroscopy and elemental microanalysis. These results are in agreement with our prediction for structures of mono and dinuclear complexes of H₂L and L^?2 with Zn(II) in the gas phase by theoretical studies.     

Synthesis,crystal and molecular structure of the 3:2 complex between europium nitrate and the A-isomer of dicyclohexyln-18-crown-6: Conformational study of the ligand

The crystal and molecular Structure of bis[dinitrato-(2,5,8,15,18,21-hexaoxatricyclo[20.4.0.0^9,14]hexa-consane)europium(III)]pentakis(nitrato) europiate(III) ([Eu(NO₃)₂·L_A]₂[Eu(NO₃)₅]) has been determined from single-crystal X-ray diffraction. The complex crystallizes in the monoclinic space group P2₁/c (ITC No. 14): a = 13.614(3)Å, b = 21.697(4)Å, c = 22.591(5)Å, β = 107.15(2)°, Z = 4. The structure was refined to a final R value of 0.055 (R_w = 0.055). The asymmetric unit contains three independent ions with approximate C₂ symmetry: [Eu(NO₃)₅]^2? and two distinct [Eu(NO₃)₂.L_a]⁺ cations with the macrocyclic ligand in the cis-syn-cis-conformation (A-isomer). The Eu(III) ions are 10-coordinated with the following mean bond lengths: Eu? O(nitrate) = 2.46(3)Å in the anion and the two cations, Eu? O(ether) = 2.55(9)Å in both cations. For the uncomplexed A-and B-isomers, as well as for their complexes with various metal ions, a conformational analysis has been made on the six O-atoms of the ligand which can be considererd as a fluxional ring. In the presently reported europium complex cations, the oxygen-ring conformation is almost a perfect boat with the metal ions lying in the least-sqiares plane of the O-atoms (deviation: 0.02–0.05Å). The same conformation prevails in all the complexes containing the A-isomer(exception: dimethylthallium complex) and in most of the complexes with the B-isomer. For this isomer, a chair conformation is found in the uncomplexed ligand, in the sodium complex, and in the complex with dimethylthallium. The occurrence of these conformations is discussed with respect to the crystallographic symmetry of the complexes and the relative mean M? O and O? O distances.     

Metal‐Ion Sensing Europium(III) Complexes with Bidentate Phosphine Oxide Ligands Containing a 2,2′‐Bipyridine Framework

Novel Eu^III complexes with bidentate phosphine oxide ligands containing a bipyridine framework, i.e., [3,3′‐bis(diphenylphosphoryl)‐2,2′‐bipyridine]tris(hexafluoroacetylacetonato)europium(III) ([Eu(hfa)₃(BIPYPO)]) and [3,3′‐bis(diphenylphosphoryl)‐6,6′‐dimethyl‐2,2′‐bipyridine]tris(hexafluoroacetylacetonato)europium(III) ([Eu(hfa)₃(Me‐BIPYPO)]), were synthesized for lanthanide‐based sensor materials having high emission quantum yields and effective chemosensing properties. The emission quantum yields of [Eu(hfa)₃(BIPYPO)] and [Eu(hfa)₃(Me‐BIPYPO)] were 71 and 73%, respectively. Metal‐ion sensing properties of the Eu^III complexes were also studied by measuring the emission spectra of Eu^III complexes in the presence of Zn^II or Cu^II ions. The metal‐ion sensing and the photophysical properties of luminescent Eu^III complexes with a bidentate phosphine oxide containing 2,2′‐bipyridine framework are demonstrated for the first time.     

Stability of isomerous chelates in M(II)-thiocarbamoylmethanamide-ethandial systems according to the DFT B3LYP method (M = Mn, Fe, Co, Ni, Cu, Zn)

Calculations of the optimal geometry and standard thermodynamic parameters of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) isomerous macrotricyclic complexes with MN₂O₂, MN₂S₂, and MN₄ chelate bonds, which can in principle appear as a result of template processes between gelatine-immobilized hexacyanoferrates (II) of corresponding M(II) metal ions, thiocarbamoylmethaneamide (thiooxamide) H₂N-C(=S)-C(=O)-NH₂, and ethanedial HC(=O)-CH(=O), were performed according to the B3LYP hybrid density functional method using a 6-31G(d) basis set with the Gaussian 98 program. It was found that of all of the considered M(II), the most stable are complexes with MN₄ chelate bonds, where the values of a standard enthalpy Δ_f H ₂₉₈^o and a standard Gibbs energy, Δ_f G ^o for all complexes studied are positive.     

On Mixed-Valence Dinuclear PtII,PtIII Nucleobase Complexes Derived from cis-Diamineplatinum(II): Effect of steric bulk of amine ligands on the Pt-oxidation state

A series of closely related dinuclear (head-head) Pt^II complexes of general composition cis-[a₂PtL₂Pta′₂]²⁺ with a,a′ = NH₃ or CH₃NH₂ and L = 1-methyluracilate-N3,O4 (1-MeU) or 1-methylthyminate-N3,O4 (1-MeT) has been prepared and the solution behavior toward Ce^IV oxidation studied. The X-ray crystal structure of a representative example cis-[(CH₃NH₂)₂Pt(1-MeU)₂Pt(CH₃NH₂)₂](ClO₄)₂ · 0.5 H₂O ( 1b ), has been determined: Monoclinic, space group P2₁/c, a = 11.907(7) Å, b = 19.087(14) Å, c = 12.525(7) Å, β = 90.49(4)°, Z = 4. Oxidation of these diplatinum(II) complexes ([Pt^2.0]₂) with Ce^IV in aqueous solution to the corresponding diplatinum(III) species ([Pt^3.0]₂) proceeds via tetranuclear [Pt^2.25]₄ or dinuclear [Pt^2.5]₂ mixed-valence state compounds, depending on the nature of the a′ ligands: with a′ = NH₃, blue green [Pt^2.25]₄ forms, whereas with a′ = CH₃NH₂, purple [Pt^2.5]₂ represents the intermediate. This difference is interpreted in terms of differences in bulk between NH₃ and CH₃NH₂ ligands trans to the O(4) positions of the bridging nucleobases which influence the ability of dinuclear species to associate via the O(4)₂ Pt a₂′ faces.     

Crystal structures of <Emphasis Type="Italic">tris</Emphasis>-hexafluoro-acetylacetonates of aluminum and scandium

The structures of tris-hexafluoroacetylacetonates Al(hfa)₃ and Sc(hfa)₃·H₂O are determined by single crystal X-ray crystallography (Bruker-Nonius X8 Apex diffractometer, MoK _α radiation, T = 150(2) K). The Al(hfa)₃ complex is trigonal, a = 17.8944(11) Å, c = 12.4061(11) Å, P-3c1 space group, V = 3440.3(4) ų, Z = 6, R = 0.076. The Sc(hfa)₃·H₂O complex is monoclinic, a = 16.0926(4) Å, b = 14.7980(3) Å, c = 24.4020(5) Å, β = 125.641(1)°, P2₁/c space group, V = 4722.54(18) ų, Z = 8, R = 0.060. The structures of the complexes are formed by neutral molecules; the coordination environment of the metal atom involves six oxygen atoms of three β-diketone ligands (Al(hfa)₃) and, additionally, a water oxygen atom (Sc(hfa)₃·H₂O). The shortest Al...Al distance is 6.203(6) Å. The Sc(hfa)₃·H₂O molecules are joined in dimers by hydrogen bonds with Sc...Sc separations of 5.6992(8) Å and 5.6853(8) Å. In the crystals, the molecules are joined by van der Waals interactions, moreover, there are intermolecular contacts F...H ～ 2.5 Å in the structure of Sc(hfa)₃·H₂O.     

A water-soluble multisite ionophore ligand bearing pyridine and aminothiophenol functionality. Synthesis, spectroscopy and electrochemistry of its complexes, and peripheral reactivity of the (E,E)M (M = Ni) complex with Pd2+ and Ag+

The design, synthesis and coordination of a novel multisite vic-dioxime compound, LH₂, containing flexible pyridine substituents and aminophenylsulfanyl moieties on the periphery, facilitating solubility in water as pyridinium hydrochloride salt are described. LH₂ was prepared by the reaction between 2-(2-pyridylethylamino)-benzenethiol and (E,E)-dichloroglydioxime. Mononuclear [(E,E)M] (M=Ni^II, Cu^II, Co^II, Fe^II and Mn^II) and dinuclear uranyl (UO₂ ^II) complexes of LH₂ were isolated and characterized with metal:ligand ratios of 1:2 and 2:2, respectively. The reaction of Na₂PdCl₄·3H₂O and AgNO₃ in DMF with the mononuclear complex, (LH)₂Ni, resulted in the formation of the heterotrinuclear complexes [Pd₂Ni(LH)₂]Cl₄ and [Ag₂Ni(LH)₂](NO₃)₂. The complexes were characterized by elemental analysis, ¹H-n.m.r., u.v.--vis. spectroscopy, i.r., and MS (LSIMS). The redox properties of the complexes were studied by cyclic voltammetry.     

Effects of Chain Ends on Thermal and Mechanical Properties and Recyclability of Poly(γ-butyrolactone)

This work investigates effects of poly(γ-butyrolactone) (PγBL) with different initiation and termination chain ends on five types of materials properties, including thermal stability, thermal transitions, thermal recyclability, hydrolytic degradation, and dynamic mechanical behavior. Four different chain-end-capped polymers with similar molecular weights, BnO-[C(=O)(CH₂)₃O]_n-R, R = C(=O)Me, C(=O)CH=CH₂, C(=O)Ph, and SiMe₂CMe₃, along with a series of uncapped polymers R′O-[C(=O)(CH₂)₃O]_n-H (R′ = Bn, Ph₂CHCH₂) with M_n ranging from low (4.95 kg mol⁻¹) to high (83.2 kg mol⁻¹), have been synthesized. The termination chain end R showed a large effect on polymer decomposition temperature and hydrolytic degradation, relative to H. Overall, for those properties sensitive to the chain ends, chain-end capping renders R-protected linear PγBL behaving much like cyclic PγBL. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2271–2279     

Complexes of Crown Ether‐Containing N‐Phosphorylated Thioamides and Thioureas with CoII,ZnII and PdII Cations

The reaction of the potassium salts of N‐phosphorylated thioureas [4′‐benzo‐15‐crown‐5]NHC(S)NHP(Y)(OiPr)₂ (Y = S, HL^I ; Y = O, HL^II ) with Zn^II and Co^II cations in aqueous EtOH leads to complexes of formulae Zn(L^I,II‐S,Y)₂ (Y = S, 1 ; Y = O, 2 ) and Co(L^I‐S,S′)₂ ( 3 ), while interaction of the potassium salt of N‐phosphorylated thioamide [4′‐benzo‐15‐crown‐5]C(S)NHP(O)(OiPr)₂ ( HL^III ) with Zn^II in the same conditions leads to the complex Zn(HL^III)(L^III‐S,O)₂ ( 4 ). The reaction of the potassium salt of crown ether‐containing N‐phosphorylated bis‐thiourea N,N′‐[C(S)NHP(O)(OiPr)₂]₂‐1,10‐diaza‐18‐crown‐6 ( H₂L ) with Co^II, Zn^II and Pd^II cations in anhydrous CH₃OH leads to complexes M₂(L‐O,S)₂ (M = Co, 5 ; Zn, 6 ; M = Pd, 7 ). Thioamide HL^III was investigated by single‐crystal X‐ray diffraction.     

Two 1-D europium coordination polymers: synthesis,crystal structure and fluorescence

Two new complexes {[Eu(2, 4-DFBA)₃ · (H₂O)₂] · H₂O} _n (1) and [Eu(2-BrBA)₃ · H₂O] _n (2) (2, 4-DFBA = 2, 4-difluorobenzoate, 2-BrBA = 2-bromobenzoate) have been synthesized and characterized by single crystal X-ray diffraction. 1 has a 1-D chain structure, in which Eu(III) ions are bridged by single COO^? groups and a 2-D supramolecular network is formed by hydrogen bond interactions. In 1, each Eu(III) is eight-coordinate with six oxygens from four 2,4-DFBA ligands and two waters. 2 has a 1-D chain structure, in which Eu(III) ions are bridged by bridging-chelating-bridging COO^? groups. In 2, each Eu(III) ion is nine-coordinate with eight oxygens from five 2-BrBA ligands and one water. The two complexes exhibit intense luminescence at room temperature. The ⁵D₀ → ⁷F _j (j = 0–4) transition emissions of Eu(III) have been observed.     

Complexation Properties of N,N′,N″,N′′′‐[1,4,7,10‐Tetraazacyclododecane‐1,4,7,10‐tetrayltetrakis(1‐oxoethane‐2,1‐diyl)]tetrakis[glycine] (H4dotagl). Equilibrium,Kinetic, and Relaxation Behavior of the Lanthanide(III) Complexes

Eu³⁺, Dy³⁺, and Yb³⁺ complexes of the dota‐derived tetramide N,N′,N″,N′′′‐[1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetrayltetrakis(1‐oxoethane‐2,1‐diyl)]tetrakis[glycine] (H₄dotagl) are potential CEST contrast agents in MRI. In the [Ln(dotagl)] complexes, the Ln³⁺ ion is in the cage formed by the four ring N‐atoms and the amide O‐atom donor atoms, and a H₂O molecule occupies the ninth coordination site. The stability constants of the [Ln(dotagl)] complexes are ca. 10 orders of magnitude lower than those of the [Ln(dota)] analogues (H₄dota=1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid). The free carboxylate groups in [Ln(dotagl)] are protonated in the pH range 1–5, resulting in mono‐, di‐, tri‐, and tetraprotonated species. Complexes with divalent metals (Mg²⁺, Ca²⁺, and Cu²⁺) are also of relatively low stability. At pH>8, Cu²⁺ forms a hydroxo complex; however, the amide H‐atom(s) does not dissociate due to the absence of anchor N‐atom(s), which is the result of the rigid structure of the ring. The relaxivities of [Gd(dotagl)] decrease from 10 to 25°, then increase between 30–50°. This unusual trend is interpreted with the low H₂O‐exchange rate. The [Ln(dotagl)] complexes form slowly, via the equilibrium formation of a monoprotonated intermediate, which deprotonates and rearranges to the product in a slow, OH^?‐catalyzed reaction. The formation rates are lower than those for the corresponding Ln(dota) complexes. The dissociation rate of [Eu(dotagl)] is directly proportional to [H⁺] (0.1–1.0M HClO₄); the proton‐assisted dissociation rate is lower for [Eu(H₄dotagl)] (k₁=8.1?10^?6 M ^?1 s^?1) than for [Eu(dota)] (k₁=1.4?10^?5 M ^?1 s^?1).     

Dinuclear rare-earth picrate complexes based on a multidentate amide ligand: syntheses,crystal structures,and luminescence properties

A new amide-based multidentate ligand, N,N′-1,2-ethanediyl-bis{2-[(N,N-diethylcarbamoyl)methoxy]benzamide} (L) reacts with M(Pic)₃?·?6H₂O to give rare-earth picrate complexes [M₂L₂(Pic)₄(H₂O)₂](Pic)₂ (M = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Yb (7), Y (8)). X-ray single-crystal diffraction analyses indicate that dinuclear complexes 3?·?2C₄H₈O₂, 6?·?2C₄H₈O₂, and 8?·?2CH₃CN are isomorphous. Each metal is nine-coordinate by four oxygen atoms of two ligands, four oxygen atoms of two bidentate picrates, and one water molecule with a distorted monocapped square antiprism. With hydrogen bonds between the free picrate anions and the coordination cations the complexes exhibit 2-D layers. The luminescent properties of 3 [Eu₂L₂(Pic)₄(H₂O)₂](Pic)₂ are described and factors that influence luminescent intensities are also discussed.     

Group 3 and lanthanide triflate-complexes with [N,N,O]-donor ligands: synthesis,characterization, and cytotoxic activity

Group 3 and rare-earth triflate-complexes M(OTf)₂(bdmpza) {M?=?Sc (1^Sc ), Y (1^Y ), La (1^La ), Sm (1^Sm ), Eu (1^Eu ) OTf?=?SO₃CF₃} bearing the heteroscorpionate ligand bdmpza {bdmpza?=?bis(3,5-dimethyl-pyrazol-1-yl)acetate} have been synthesized and characterized, together with the yttrium and europium complexes M(OTf)(bdmpza)₂ {M?=?Y (2^Y ), Eu (2^Eu )}. The photoluminescent behavior of 2^Eu has been investigated. The coordination mode of the [N,N,O]-donor in these complexes has been elucidated by DFT calculations. The cytotoxic effect of selected complexes and of the free ligand toward HeLa cells has been evaluated.     

Further Evidence for ‘Extended’ Cumulene Complexes: Derivatives from Reactions with Halide Anions and Water

Reactions of [Ru{C=C(H)-1,4-C₆H₄C≡CH}(PPh₃)₂Cp]BF₄ ([ 1 a ]BF₄) with hydrohalic acids, HX, results in the formation of [Ru{C≡C-1,4-C₆H₄-C(X)=CH₂}(PPh₃)₂Cp] [X=Cl ( 2 a-Cl ), Br ( 2 a-Br )], arising from facile Markovnikov addition of halide anions to the putative quinoidal cumulene cation [Ru(=C=C=C₆H₄=C=CH₂)(PPh₃)₂Cp]⁺. Similarly, [M{C=C(H)-1,4-C₆H₄-C≡CH}(LL)Cp ]BF₄ [M(LL)Cp’=Ru(PPh₃)₂Cp ([ 1 a ]BF₄); Ru(dppe)Cp* ([ 1 b ]BF₄); Fe(dppe)Cp ([ 1 c ]BF₄); Fe(dppe)Cp* ([ 1 d ]BF₄)] react with H⁺/H₂O to give the acyl-functionalised phenylacetylide complexes [M{C≡C-1,4-C₆H₄-C(=O)CH₃}(LL)Cp’] ( 3 a – d ) after workup. The Markovnikov addition of the nucleophile to the remote alkyne in the cations [ 1 a–d ]⁺ is difficult to rationalise from the vinylidene form of the precursor and is much more satisfactorily explained from initial isomerisation to the quinoidal cumulene complexes [M(=C=C=C₆H₄=C=CH₂)(LL)Cp’]⁺ prior to attack at the more exposed, remote quaternary carbon. Thus, whilst representative acetylide complexes [Ru(C≡C-1,4-C₆H₄-C≡CH)(PPh₃)₂Cp] ( 4 a ) and [Ru(C≡C-1,4-C₆H₄-C≡CH)(dppe)Cp*] ( 4 b ) reacted with the relatively small electrophiles [CN]⁺ and [C₇H₇]⁺ at the β-carbon to give the expected vinylidene complexes, the bulky trityl ([CPh₃]⁺) electrophile reacted with [M(C≡C-1,4-C₆H₄-C≡CH)(LL)Cp’] [M(LL)Cp’=Ru(PPh₃)₂Cp ( 4 a ); Ru(dppe)Cp* ( 4 b ); Fe(dppe)Cp ( 4 c ); Fe(dppe)Cp* ( 4 d )] at the more exposed remote end of the carbon-rich ligand to give the putative quinoidal cumulene complexes [M{C=C=C₆H₄=C=C(H)CPh₃}(LL)Cp’]⁺, which were isolated as the water adducts [M{C≡C-1,4-C₆H₄-C(=O)CH₂CPh₃}(LL)Cp’] ( 6 a–d ). Evincing the scope of the formation of such extended cumulenes from ethynyl-substituted arylvinylene precursors, the rather reactive half-sandwich (5-ethynyl-2-thienyl)vinylidene complexes [M{C=C(H)-2,5-^cC₄H₂S-C≡CH}(LL)Cp’]BF₄ ([ 7 a – d ]BF₄ add water readily to give [M{C≡C-2,5-^cC₄H₂S-C(=O)CH₃}(LL)Cp’] ( 8 a – d )].     

Syntheses,crystal structures,and properties of two dinuclear iron(III) complexes constructed with 1,2,3,5-benzenetetracarboxylic acid and chelating N-donor auxiliary coligands

Two dinuclear Fe(III) metal–organic complexes with tetracarboxylate and chelating N-donor ligands, [Fe(Hbtec)(phen)(H₂O)]₂·2H₂O (1) and [Fe(Hbtec)(bpy)(H₂O)]₂·2H₂O (2) (H₄btec = 1,2,3,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) have been prepared and characterized by elemental analysis, IR spectroscopic, and X-ray diffraction methods. Both complexes crystallize in the monoclinic space group P2₁/c with two Fe(III) ions bridged by two Hbtec^3? ligands into a dinuclear unit. Hydrogen bonding connects the dinuclear units into a 3-D framework. The dinuclear units are 10-connected nodes that produce a 3-D framework with topology Schläfli symbol as (3¹²·4²⁸·5⁵). Thermal stabilities and luminescent properties of the two complexes have also been investigated.     

Di‐ and triphenylacetate complexes of yttrium and europium

The significant variety in the crystal structures of rare‐earth carboxylate complexes is due to both the large coordination numbers of the rare‐earth cations and the ability of the carboxylate anions to form several types of bridges between rare‐earth metal atoms. Therefore, these complexes are represented by mono‐, di‐ and polynuclear complexes, and by coordination polymers. The interaction of LnCl₃(thf)_x (Ln = Eu or Y; thf is tetrahydrofuran) with sodium or diethylammonium diphenylacetate in methanol followed by recrystallization from a DME/THF/hexane solvent mixture (DME is 1,2‐dimethoxyethane) leads to crystals of the non‐isomorphic dinuclear complexes tetrakis(μ‐2,2‐diphenylacetato)‐κ⁴O:O′;κ³O,O′:O′;κ³O:O,O′‐bis[(1,2‐dimethoxyethane‐κ²O,O′)(2,2‐diphenylacetato‐κ²O,O′)europium(III)], [Eu(C₁₄H₁₁O₂)₆(C₄H₁₀O₂)₂], (I), and tetrakis(μ‐2,2‐diphenylacetato)‐κ⁴O:O′;κ³O,O′:O′;κ³O:O,O′‐bis[(1,2‐dimethoxyethane‐κ²O,O′)(2,2‐diphenylacetato‐κ²O,O′)yttrium(III)], [Y(C₁₄H₁₁O₂)₆(C₄H₁₀O₂)₂], (II), possessing monoclinic (P2₁/c) symmetry. The [Ln(Ph₂CHCOO)₃(dme)]₂ molecule (Ln = Eu or Y) lies on an inversion centre and exhibits three different coordination modes of the diphenylacetate ligands, namely bidentate κ²O,O′‐terminal, bidentate μ₂‐κ¹O:κ¹O′‐bridging and tridentate μ₂‐κ¹O:κ²O,O′‐semibridging. The terminal and bridging ligands in (I) are disordered over two positions, with an occupancy ratio of 0.806 (2):0.194 (2). The interaction of EuCl₃(thf)₂ with Na[Ph₃CCOO] in methanol followed by crystallization from hot methanol produces crystals of tetrakis(methanol‐κO)tris(2,2,2‐triphenylacetato)‐κ⁴O:O′;κO‐europium(III) methanol disolvate, [Eu(C₁₉H₁₅O₂)₃(CH₃OH)₄]·2CH₃OH, (III)·2MeOH, with triclinic (P) symmetry. The molecule of (III) contains two O,O′‐bidentate and one O‐monodentate terminal triphenylacetate ligand. (III)·2MeOH possesses one intramolecular and four intermolecular hydrogen bonds, forming a [(III)·2MeOH]₂ dimer with two bridging methanol molecules.     

Structures and fluorescence of two new hetero-dinuclear lanthanide(III) complexes derived from a Schiff-base ligand

Two isostructural dinuclear lanthanide(III)/Schiff-base complexes [{Ce_1.5Eu_0.5(clapi)}₂]·2CH₃CN (1) and [{La_1.5Eu_0.5(clapi)}₂]·2CH₃CN (2) {H₃clapi = 2-(5-chloride-2-hydroxyphenyl)-1,3-bis[4-(5-chloride-2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine} have been prepared by template procedure and characterized by elemental analyses, ICP, IR, and single-crystal X-ray diffraction analyses. Lanthanide ions Ce(III) and Eu(III) in 1, and La(III) and Eu(III) in 2 are disordered with occupancies 0.75 for Ce and 0.25 for Eu in 1; 0.75 for La and 0.25 for Eu in 2. In the compounds, each lanthanide is coordinated to four N and four O atoms from two clapi^3? ligands, forming a distorted square antiprism. Two phenol oxygen atoms from the middle arms of the two heptadentate μ₂-bridging ligands connect the two Ce(Eu) atoms in 1, and La(Eu) in 2. The solution of the two complexes in CH₂Cl₂ exhibits red fluorescence from Eu³⁺ ions at 77 K, very weak at room temperature.     

Structure and properties of heterocomplex compounds based on lead(II) hexafluoroacetylacetonate and copper(II) β-diketonates

Single crystal X-ray diffraction study has been performed for heterometallic complexes based on lead(II) hexafluoroacetylacetonate and copper(II) β-diketonates. Crystal data for Cu(aa)₂·Pb(hfa)₂: a = 8.741(2) Å, b = 12.124(2) Å, c = 13.741(3) Å, α = 89.70(3)°, β = 89.50(3)°, γ = 75.06(3)°, space group P-1, Z = 2, d _calc = 2.084 g/cm³; for Cu(hfa)₂ Pb(hfa)₂: a = 9.334(2) Å, b = 14.584(3) Å, c = 23.102(5) Å, β = 96.82(3)°, space group P2₁/c, Z = 4, d _calc = 2.338 g/cm³. It is demonstrated that the principal structural motif for these compounds is a chain coordination polymer, which consists of alternating molecules of the complexes. The results of a thermogravimetric study for the compounds are reported.     

Mono‐ and dinuclear CuII complexes of the benzyldipicolylamine (BDPA) ligand: crystal structure,synthesis and characterization

The crystal structures of mono‐ and dinuclear Cu^II trifluoromethanesulfonate (triflate) complexes with benzyldipicolylamine (BDPA) are described. From equimolar amounts of Cu(triflate)₂ and BDPA, a water‐bound Cu^II mononuclear complex, aqua(benzyldipicolylamine‐κ³N ,N′ ,N ′′)bis(trifluoromethanesulfonato‐κO )copper(II) tetrahydrofuran monosolvate, [Cu(CF₃SO₃)₂(C₁₉H₁₉N₃)(H₂O)]·C₄H₈O, (I), and a triflate‐bridged Cu^II dinuclear complex, bis(μ‐trifluoromethanesulfonato‐κ²O :O ′)bis[(benzyldipicolylamine‐κ³N ,N′ ,N ′′)(trifluoromethanesulfonato‐κO )copper(II)], [Cu₂(CF₃SO₃)₄(C₁₉H₁₉N₃)₂], were synthesized. The presence of residual moisture in the reaction medium afforded water‐bound complex (I), whereas dinuclear complex (II) was synthesized from an anhydrous reaction medium. Single‐crystal X‐ray structure analysis reveals that the Cu^II centres adopt slightly distorted octahedral geometries in both complexes. The metal‐bound water molecule in (I) is involved in intermolecular O—H…O hydrogen bonds with triflate ligands and tetrahydrofuran solvent molecules. In (II), weak intermolecular C—H…F(triflate) and C—H…O(triflate) hydrogen bonds stabilize the crystal lattice. Complexes (I) and (II) were also characterized fully using FT–IR and UV–Vis spectroscopy, cyclic voltammetry and elemental analysis.     

N,N-Dialkylcarbamato Complexes of the d10 cations of copper,silver, and gold

The reaction of CuO'Bu with CO₂, and ⁱPr₂NH in the presence of PPh₃, gives the dialkylcarbamato complex [Cu(O₂CNⁱPr₂)(PPh₃)₂] ( 1 ). The CO₂/R₂NH system (R = Me, Et) in an appropriate organic medium reacts with Ag₂O giving the corresponding N,N-dialkylcarbamato complexes of analytical formula [Ag(C₂CNR₂)] (R = Me, 2 ; R = Et, 3 ). The methyl derivative 2 was characterized by X-ray diffraction methods. Crystal data of 2 : for [Ag₂(O₂CNMe₂)₂], C₆H₁₂Ag₂N₂O₄, mol. wt. 391.9; monoclinic, space group P2₁/c, a = 12.08(1), b = 3.797(2), c = 11.316(7) Å, β = 113.37(6)°, V = 476.3 ų, Z = 2, D_c = 2.732 g cm^?3; μ(MoK_α) = 40.64 cm^?1, F(000) = 376.0; R = 0.059, R_w = 0.067; g.o.f. 1.27. The structure consists of dinuclear [(Ag₂OCNMe₂)₂] units with slightly distorted linearly two-coordinated Ag-atoms containing bridging carbamato groups to form a substantially planar eight-membered ring with an intra-annular Ag? Ag distance of 2.837(2) Å; the dinuclear units are further joined by Ag? O bonds to form an infinite array. Compound 3 , which is presumably dinuclear, as suggested by cryoscopic measurements in benzene, undergoes a structural fission with PPh₃, giving the mononuclear triphenylphosphine derivative [Ag(O₂CNEt₂)(PPh₃)₂] ( 4 ). The amine-catalyzed conversion of Ag₂O into Ag₂CO₃, in the presence of the ⁱPr₂NH/CO₂ system, is also reported. Cl-Exchange from [AuCl(PPh₃)] with [Ag(O₂CNEt₂)] ( 3 ) gives the first N,N-dialkylcarbamato complex of gold, namely [Au(O₂CNEt₂)(PPh₃)] ( 5 ), which crystallizes in the monoclinic system: C₂₃H₂₅AuNO₂P · 0.5 C₇H₁₆, mol. wt. 625.5, space group P2₁/c; a = 13.212(5), b = 12.25(1), c = 16.795(6) Å, β = 109.09(2)°, V = 2568(2) Å₃, Z = 4, D_c, = 1.618 g cm^?3; μ(AgK_α) = 31.40 cm^?1, F(000) = 1236.0; R = 0.058; R_w = 0.064; g.o.f. 2.121. The compound contains two-coordinated Au-atom, namely to the P-atom and to the O-atom of the monodentate carbamato group, the P? Au? O bond angle being 174.7(3)°. The reaction with MeI showed these compounds to react predominantly at the carbamato O-atom giving the corresponding urethanes R₂NCO₂Me. Evidence was gathered for the transient coordination of CO to Ag in 3 .