STRUCTURAL STUDIES ON PYRAZOLYLPYRIDINE LIGANDS AND COMPLEXES. 2. COMPARISONS BETWEEN BISPYRAZOLYLPYRIDINE LINKAGE ISOMERS AND WITH 2,2′,6′,2″-TERPYRIDINE JERZY ZADYKOWICZ

Abstract

Crystal structures were obtained for the 3(C),2′;6′,3″(C)-linked bispyrazolylpyridines 2,6-di(2H-4,5,6,7-tetrahydroindazol-3-yl)pyridine (1), 2,6-di(l-methyl-4,5,6,7-tetrahydroindazol-3-yl)pyridine (2), 2,6-di(1 -(4-ethoxycarbonylphenyl)-4,5,6,7-tetrahydroindazol-3-yl)pyridine (3) and for the homoleptic Ru^II complex of 2, [Ru(2)₂]Cl₂, which crystallized with 7 molecules of CHCl₃. Ligand 1 adopts the inter-and intramolecularly hydrogen-bonded syn,syn rotameric conformation, while 2 and 3 were in the anti,anti forms. Relative to the latter, iigand distortions were assessed in 1 (considered as a H⁺ complex) and [Ru(2)₂]Cl₂. Comparisons were drawn with other tridentate ligands containing a pyridine nucleus, specifically the 1(N),2′;6′,1″(N″) linkage isomers and 2,2′;6′,2″-terpyridine, in both free and Ru^II complexed forms, as well as with their bidentate analogues. Unlike with bidentate ligands, the bonds to the pyridine moiety are shortest, the outer heterocyclic rings are drawn inward and, overall, the ligands remain fairly planar. Flanking substituents remain well splayed out in the 1,2′;6′,1″-linked bispyrazolylpyridines, are more parallel in the 3,2′;6′,3″ linkage isomers and are unfavorably compressed in terpyridines.     

Crystal structures of [Ru(terpy)(HPB)(H2O)](PF6)2 and [Ru(terpy)(HPB)(2-picoline)](PF6) and the kinetics studies of the aqua ligand substitution by pyridine and substituted pyridines

The crystal structures of [Ru(terpy)(HPB)(H₂O)](PF₆)₂, 1, and [Ru(terpy)(HPB)(2-picoline)](PF₆), 2, (where terpy = 2,2′:6′,2′′-terpyridine and HPB = 2-(2′-hydroxyphenyl)-benzoxazole) have been determined. Both structures show slightly distorted octahedral coordination around the ruthenium center. In complex 1, the imine nitrogen of the HPB ligand occupies an axial position and is trans to the aqua ligand whereas in complex 2, the imine nitrogen is trans to the nitrogen of the 2-picoline ligand. The Ru-N(2-picoline) bond distance is much longer than the other Ru-N bonds in the complex due to steric effects from the methyl group of 2-picoline. In both complexes, the phenolate oxygen of the HPB ligand is in the equatorial position and trans to the center nitrogen of the terpyridine. The reaction of [Ru(terpy)(HPB)(H₂O)](PF₆)2 with pyridine and its analogs, 2-picoline and 4-picoline in dichloromethane was monitored spectrophotometrically. There is an initial reduction of the [Ru(III)-H₂O] complex to [Ru(II)-H₂O] complex prior to the substitution of the aqua ligand. The values of the activation parameters indicate that the substitution of the aqua ligand by pyridine, 2-picoline and 4-picoline follow an associative mechanism.     

基于过渡金属离子与三联吡啶的配位作用构筑全共轭层-层 自组装超薄功能膜

本文利用所合成的4'-（4''-重氮基）苯基-（2,2':6',2'）-三联吡啶氟硼酸盐（Diazo-tpy）在紫外光照射下的光分解反应特性,实现三联吡啶基团与基片之间形成共轭价键连接,这不仅提高了自组装膜的稳定性,而且降低了载流子在两者之间传输时的阻抗;在此基础上,通过两端含三联吡啶的直线型配体1,4-二-(2,2':6',2'-三联吡啶)基苯（Bi-tpy）与四种过渡金属离子（Mtn+：Pt4+、Ru3+、Rh3+、Pd2+）之间的配位作用,通过层－层自组装制备了全共轭金属－有机自组装超薄功能膜。由紫外-可见光谱跟踪自组装过程证明了自组装过程的成功实现,还分析了金属离子的种类对自组装的影响规律。光电转换测试表明Bi-tpy/Ru3+自组装膜要比Bi-tpy/ Pt4+具有更明显的光电转换性能;同时,由于缺陷与阻抗随层数的增加而增大的原因,在自组装6层时光电流达到最大值。这为我们设计新型光电转换器件提供参考依据。     

Syntheses,structures and catalytic properties of new mononuclear terpyridine-manganese(II) complexes with tetraphenylimido-diphosphinate and diphenylphosphinate ligands

Treatment of manganese(II) acetate tetrahydrate [Mn(CH3COO)₂·4H₂O] with one equivalent of 2,2′:6′,2′′-terpyridine (terpy) and two equivalents of potassium tetraphenylimido-diphosphinate K[N(Ph₂PO)₂] in methanol afforded a mononuclear manganese(II) complex, [(terpy)Mn{η¹-O-N(Ph₂PO)₂}₂(H₂O)] (1), with two terminal [N(Ph₂PO)₂]– ligands. Interaction of [Mn(CH₃COO)₂·4H₂O] with one equivalent of terpy in the presence of both K[N(Ph₂PO)₂] and Ph₂PO₂K in methanol gave a mononuclear manganese(II) complex [(terpy)Mn(η¹-O-O₂PPh₂){N(Ph₂PO)₂}] (2) with a chelated [N(Ph₂PO)₂]– ligand. Treatment of manganese(II) dichloride tetrahydrate [MnCl₂·4H₂O] with three equivalents of K[N(Ph₂PO)₂] in methanol resulted in isolation of a mononuclear manganese(III) complex [Mn{η¹-O-N(Ph₂PO)₂}-{N(Ph₂PO)₂}₂] (3) with one terminal and two chelated [N(Ph₂PO)₂]– ligands. Reaction of [Mn(CH₃COO)₂·4H₂O] with one equivalent of 4′-phenyl-[2,2′:6′,2′′]-terpyridine (4-Ph-terpy) and two equivalents of Ph₂PO₂K in methanol gave [(4-Ph-terpy)Mn(η¹-O-O₂PPh₂)₂(H₂O)] (4) with a labile water molecule. Complexes 1–4 have been spectroscopically characterized and their structures have been established by single-crystal X-ray diffraction. Catalytic behavior of 1 and 4 for sulfide oxidation was also investigated.     

Two Bulky Conjugated 4′‐(4‐Hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine‐based Layered Complexes: Synthesis,Structure, and Photocatalytic Hydrogen Evolution Activity

Two new layered complexes with the formulas of {[Cu(H₂O)(HL)₂Cl](NO₃)}_n ( 1 ) and {[Cu(H₂O)₂(HL)₂](NO₃)₂}_n ( 2 ) were solvothermally synthesized by the reactions of the bulky conjugated 4′‐(4‐hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine ligand (HL) with different Cu^II salts, which were further used as photocatalysts to achieve hydrogen production from water splitting. Single‐crystal structural analyses reveal that both complexes feature coplanar (4 4) layers with different connection manners between the HL extended Z‐shaped chains. More interestingly, 1 possessing more negative conduction band potential and higher structural stability exhibits a large hydrogen production rate of 2.43 mmol · g^–1 · h^–1, which is four times higher than that of 2 . Thus, the Cu^II‐based coordination polymers modified by the bulky conjugated organic ligand can become potentially promising non‐Pt photocatalysts for hydrogen production from water splitting.     

Structural characterization of a hybrid terpyridine–pyrazine ligand and its one‐dimensional ZnII coordination polymer: a computational approach to conventional and nonconventional intermolecular interactions

The structures of a new hybrid terpyridine–pyrazine ligand, namely 4′‐[4‐(pyrazin‐2‐yl)phenyl]‐4,2′:6′,4′′‐terpyridine (L2), C₂₅H₁₇N₅, and its one‐dimensional coordination polymer catena‐poly[[bis(acetylacetonato‐κ²O,O′)zinc]‐μ‐4′‐[4‐(pyrazin‐2‐yl‐κN⁴)phenyl]‐4,2′:6′,4′′‐terpyridine‐κN¹], [Zn(C₅H₇O₂)₂(C₂₅H₁₇N₅)]_n or [Zn(acac)₂(L2)]_n (Hacac is acetylacetone), are reported. Packing interactions in both crystal structures are analyzed using Hirshfeld surface and enrichment ratio techniques. For the simpler structure of the monomeric ligand, further studies on the interaction hierarchy using the energy framework approach were made. The result was a complete picture of the intermolecular interaction landscape, which revealed some subtle details, for example, that some weak (at first sight negligible) C—H…N interactions in the structure of free L2 play a relevant role in the crystal stabilization.     

基于配位自组装的全共轭三联吡啶-过渡金属环状超分子的构筑及其光、电化学性能*

2,2':6,2"-三联吡啶全共轭衍生物在与过渡金属离子配位络合后形成的全共轭配合物,因具有特殊的大π-π电子结构和金属-配体相互作用,成为构筑新型功能材料的重要基元,被广泛应用于光电转换、化学/生物检测、催化有机合成等领域。本文主要介绍近年来全共轭“三联吡啶-过渡金属离子（tpy-Mt）”环状超分子配合物的合成及其在光、电化学性能方面的研究进展,并探讨了该领域存在的问题及今后的发展方向。     

Electrochemical properties of 2,2":6",2″-terpyridine complexes of platinum(ii) with arenethiolate ligands. Alkylation of reduced forms of the complexes

Three mixed-ligand terpyridine-thiolate Pt^II complexes containing 2,2":6",2-terpyridine (tpy) and para-substituted thiophenolate ions, [(tpy)Pt(SC₆H₄-4-X)]BF₄ (X = NMe₂, H, NO₂) were synthesized. The complexes were isolated as chlorides or tetrafluoroborates and characterized by electrochemistry, visible electronic spectroscopy and ¹H NMR spectroscopy, and elemental analysis. Remarkable influence of the electron-donating/withdrawing properties of the substituent in the thiolate ligand on the physicochemical properties of the complexes, in particular, on the electrochemical reduction potentials, was found. The reduced forms of the complexes undergo electrochemically initiated alkylation with alkyl halides, resulting in the formation of Pt alkyl compounds.     

Synthesis of Terpyridine Derivatives Containing β—Cyclodextrin

A novel β-cyclodextrin-based terpyridine derivatives has been prepared by the coupling of 4‘‘‘‘‘‘‘‘-(4“-bromomethyl phenyl)-2,2‘‘‘‘‘‘‘‘:6‘‘‘‘‘‘‘‘,2“-terpyridine with mono-6-hydroxy permethylated β-cyclodextrin.The cyclodextrin dimmer appending a 4‘‘‘‘‘‘‘‘-phenyl-2,2‘‘‘‘‘‘‘‘:6‘‘‘‘‘‘‘‘,2“-terpyridine spacer on the primary faces was synthesized by reaction of 4‘‘‘‘‘‘‘‘-phenyl-2,2‘‘‘‘‘‘‘‘:6‘‘‘‘‘‘‘‘,2“-terpyridine-6,6‘‘‘‘‘‘‘‘-dicarbonitrile with an excess of 6-deoxy-6-O-tosyl-β-cyclodextrin.