Structural development of free or coordinated 4'-(4-pyridyl)-2,2':6',2'-terpyridine ligands through N-alkylation: new strategies for metallamacrocycle formation

A series of N-alkylated derivatives of [Ru(pytpy)(2)]2+ (pytpy=4'-(4-pyridyl)-2,2':6',2'-terpyridine) has been synthesised and characterised. These include both model and functionalised complexes that complement previously reported iron(II) analogues. Reaction of [Ru(pytpy)(2)]2+ with bis[4-(bromomethyl)phenyl]methane leads to the formation of a [2+2] ruthenamacrocycle. Related ferramacrocycles could not be accessed by this route, and instead were prepared in two steps by first reacting bis[4-(bromomethyl)phenyl]methane or 4,4'-bis(bromomethyl)biphenyl with two equivalents of pytpy, and then treating the resulting bis(N-alkylated) product with iron(II) salts.     

Routes to metallodendrimers: synthesis of isomeric neutral metallomacromolecules based on bis(2,2':6',2"-terpyridine)ruthenium(II) connectivity

Routes for the syntheses of isomeric, zwitterionic, bisterpyridine-Ru(II)-based macromolecules are described. Access to these novel architectures is facilitated by the construction of terpyridine-modified, 1-->3 C-branched, ester-terminated building blocks. Constitutional isomers result from the interchangable placement of methyl and tert-butyl ester groups on both the branched framework near the Ru(II) centers and the termini of the branched construct. Water solubility is imparted to each isomer through selective transformation of the tert-butyl esters to their corresponding carboxylates. Along with the standard characterization techniques, electrochemical and spectroscopic data also support the structural formation.     

Ruthenium(II) complexes with improved photophysical properties based on planar 4'-(2-pyrimidinyl)-2,2':6',2' '-terpyridine ligands

A series of new tridentate polypyridine ligands, made of terpyridine chelating subunits connected to various substituted 2-pyrimidinyl groups, and their homoleptic and heteroleptic Ru(II) complexes have been prepared and characterized. The new metal complexes have general formulas [(R-pm-tpy)Ru(tpy)]2+ and [Ru(tpy-pm-R)2]2+ (tpy = 2,2':6',2' '-terpyridine; R-pm-tpy = 4'-(2-pyrimidinyl)-2,2':6',2' '-terpyridine with R = H, methyl, phenyl, perfluorophenyl, chloride, and cyanide). Two of the new metal complexes have also been characterized by X-ray analysis. In all the R-pm-tpy ligands, the pyrimidinyl and terpyridyl groups are coplanar, allowing an extended delocalization of acceptor orbital of the metal-to-ligand charge-transfer (MLCT) excited state. The absorption spectra, redox behavior, and luminescence properties of the new Ru(II) complexes have been investigated. In particular, the photophysical properties of these species are significantly better compared to those of [Ru(tpy)2]2+ and well comparable with those of the best emitters of Ru(II) polypyridine family containing tridentate ligands. Reasons for the improved photophysical properties lie at the same time in an enhanced MLCT-MC (MC = metal centered) energy gap and in a reduced difference between the minima of the excited and ground states potential energy surfaces. The enhanced MLCT-MC energy gap leads to diminished efficiency of the thermally activated pathway for the radiationless process, whereas the similarity in ground and excited-state geometries causes reduced Franck Condon factors for the direct radiationless decay from the MLCT state to the ground state of the new complexes in comparison with [Ru(tpy)2]2+ and similar species.     

Alkylimido osmium(VI) and ruthenium(VI) porphyrins. Crystal and molecular structures of Os(TTP)(O)(NBut)- EtOH and OS(4-C1-TPP)(NBut)2

Oxo(tert-butylimido) or bis(tert-butylimido)osmium(VI) porphyrins Os(Por)(O)( NBu^t) and Os(Por)(NBu^t)2, [Por=meso-tetrakis(p-tolyl)porphyrinato (TTP) and meso-tetrakis(4-chlorophenyl)porphyrinato (4-CI-TPP)] were synthesized by air oxidation of bis(tert-butylamine)osmium(II) porphyrins [Os(Por)(H₂NBu^t)n (Por=TPP, 4-C1-TPP], depending on whether text-butylamine is present. The bis(tert-butylamine)ruthenium(II) porphyrins [Ru(Por)(H₂NBu^t)z, Por=TTP, 4-CI-TPP] can undergo bromine oxidation to give oxo(tert-butylimido)ruthenium(VI) complexes in quantitative yields. All these nem complexes were characterized by ¹H NMR, UV-Visible and IR spectroscopy. The X-ray crystal structures of Os(TTP)(O)(NBu^t).EtOH and Os(4-Cl-TPP)(NBu^t)₂ have been determined. Crystal data: for Os(TTP)(O)(NBu').EtOH: monoclinic, space group P2₁/c, a=1.3546(6) nm, b=2.3180(3) am, c=1.6817(3) nm, β=90.84(2)°, V=527.97(1) nm³, Z=4. The Os=O and Os=NBu^t distances in Os(TTP)(O)(NBu^t).EtOH are 0.1772(7) nm and 0.1759(9) nm, respectively. The average Os=NBu^t distance of Os(4-C1-TPP)(NBu^t)₂ is 0.1775 nm.     

Synthesis, luminescence, and electrochemical studies of tris(homoleptic) ruthenium(II) and osmium(II) complexes of 6'-tolyl-2,2':4',2'-terpyridine

The synthesis and photophysical and electrochemical properties of tris(homoleptic) complexes [Ru(tpbpy)3](PF6)2 (1) and [Os(tpbpy)3](PF6)2 (2) (tpbpy = 6'-tolyl-2,2':4',2' '-terpyridine) are reported. The ligand tpbpy is formed as the side product during the synthesis of 4'-tolyl-2,2':6',2' '-terpyridine (ttpy) and characterized by single-crystal X-ray diffraction: monoclinic, P21/c. The tridentate tpbpy coordinates as a bidentate ligand. The complexes 1 and 2 exhibit two intense absorption bands in the UV region (200-350 nm) assignable to the ligand-centered (1LC) pi-pi* transitions. The ruthenium(II) complex exhibits a broad absorption band at 470 nm while the osmium(II) complex exhibits an intense absorption band at 485 nm and a weak band at 659 nm assignable to the MLCT (dpi-pi*) transitions. A red shifting of the dpi-pi* MLCT transition is observed on going from the Ru(II) to the Os(II) complex as expected from the high-lying dpi Os orbitals. These complexes exhibit ligand-sensitized emission at 732 and 736 nm, respectively, upon light excitation onto their MLCT band through excitation of higher energy LC bands at room temperature. The MLCT transitions and the emission maxima of 1 and 2 are substantially red-shifted compared to that of [Ru(bpy)3](PF6)2 and [Os(bpy)3](PF6)2. The emission of both the complexes in the presence of acid is completely quenched indicating that the emission is not due to the protonation of the coordinated ligands. Our results indicate the occurrence of intramolecular energy transfer from the ligand to the metal center. Both the complexes undergo quasi-reversible metal-centered oxidation, and the E1/2 values for the M(II)/M(III) redox couples (0.94 and 0.50 V versus Ag/Ag+ for 1 and 2, respectively) are cathodically shifted with respect to that of [Ru(bpy)3](PF6)2 and [Os(bpy)3](PF6)2 (E1/2 = 1.28 and 1.09 V versus Ag/Ag+, respectively). The tris(homoleptic) Ru(II) and Os(II) complexes 1 and 2 could be used to construct polynuclear complexes by using the modular synthetic approach in coordination compounds by exploiting the coordinating ability of the pyridine substituent. Furthermore, these complexes offer the possibility of studying the influence of electron-withdrawing and electron-donating substituents on the photophysical properties of Ru(II) and Os(II) polypyridine complexes.     

Structural, redox, and photophysical studies of the tetra(pyridyl)porphyrin complex containing four (2,2'-bipyridine)(2,2':6',2"-terpyridine)ruthenium(II) groups

New hybrid complexes of polypyridyl ruthenium and pyridylporphyrins have been prepared by the coordination of pyridyl nitrogens to the ruthenium centers. A 1:4 hybrid complex, [{Ru(bpy)(trpy)}4(mu4-H2Py4P)]8+ ([1]8+) (bpy = 2,2'-bipyridine; trpy = 2,2':6',2"-terpyridine; H2Py4P = 5,10,15,20-tetra(4-pyridyl)porphyrin), has been characterized by the single-crystal X-ray diffraction method. A 1:1 complex, [{Ru(bpy)(trpy)}(H2PyT3P)]2+ ([2]2+) (H2PyT3P = 5-(4-pyridyl)tritolylporphyrin) has also been prepared. The Soret band of the porphyrin ring shifts to longer wavelength with some broadening, the extent of the shift being larger for [1]8+. Cyclic voltammograms of the two complexes show simple overlap of the component redox waves. The complexes are weakly emissive at room temperature, which becomes stronger at lower temperatures. While [1]8+ at >140 K and [2]2+ at 77-280 K show only porphyrin fluorescence, [1]8+ at <140 K shows ruthenium and porphyrin phosphorescence, in addition to the porphyrin fluorescence.     

Synthesis and Structure of Trimethylplatinum(IV) Iodide Complex of 4'-(4-Methoxyphenyl)-2,2':6',2'-terpyridine Ligand and its Halogen Bonding Property

The synthesis and structural characterization of a new trimethylplatinum(IV) iodide complex of 4'-(4-methoxyphenyl)-2,2':6',2''-terpyridine ligand L, {PtMe₃IL} ( 1 ) is reported. The X-ray crystal structure shows that the terpyridine ligand L binds the platinum(IV) metal center in bidentate fashion, which is well supported by the ¹H NMR spectrum of 1 . The complex 1 upon crystallization with 1,4-diiodotetrafluorobenzene (DITFB) forms the halogen bonded complex 1a ( 1· DITFB). The structural investigation shows that 1a exhibits the halogen bonding interaction in which the non-coordinated pyridyl nitrogen acts as halogen bond acceptors by forming I ··· N interaction with iodine atom of DITFB. In addition iodine atom of complex 1 also acts as weak halogen bond acceptor.     

基于3,5-二((4'-羧基苄基)氧)苯甲酸和4'-(4-吡啶基)-2,2':6',2"-三联吡啶为混合配体的两个配合物的水热合成与晶体结构

在水热条件下,以3,5-二((4''-羧基苄基)氧)苯甲酸(H₃bcb)和4''-(4-吡啶基)-2,2'':6'',2"-三联吡啶(PYTPY)为混合配体构筑了2个过渡金属配合物[Co(H₂bcb)₂(PYTPY)]_n(1)和[Mn(H₂bcb)₂(PYTPY)]_n(2),利用元素分析、红外光谱以及单晶X射线衍射表征其结构。分析表明配合物1和2为一维链状结构。此外,2个配合物展示了优良的热稳定性。磁化率的测试结果表明,配合物1和2在2 K和8 K以下时展示了反铁磁相互作用。     

Vectorial property dependence in bis {4'-(n-pyridyl)-2,2':6',2"-terpyridine}iron(II) and ruthenium(II) complexes with n = 2, 3 and 4

A comparative structural and spectroscopic investigation of the complexes [M(1)2]2+, [M(2)2]2+ and [M(3)2]2+ in which M = Fe or Ru, and ligands 1, 2 and 3 are 4'-(2-pyridyl)-, 4'-(3-pyridyl)- and 4'-(4-pyridyl)-2,2':6',2"-terpyridine, respectively, is reported. The complexes [Ru(1)2]2+, [Ru(2)2]2+ and [Ru(3)2]2+ undergo mono- and bis-N-methylation. The consequences of methylation on the absorption spectra and electrochemical properties are discussed; the solid-state structure of the bis(N-methylated) derivative of [Ru(2)2][PF6]2 is presented.     

4'-(3-甲氧基-4-羟基苯基)-2,2':6', 2"-三联吡啶及其铜、锌配合物的合成、结构和性质

通过一锅反应制备了4′-(3-甲氧基-4-羟基苯基)-2,2′∶6′,2″-三联吡啶(L),通过重结晶的方法得到了其醋酸盐单晶体(HL)(CH3COO)(1),并以L为配体组装了过渡金属配合物[Cu(NO3)(CH3OH)L](NO3)(2)和[Zn(NO3)2L](C2H5OH)(3),通过元素分析、IR光谱和单晶X-射线衍射等表征了3个化合物的结构。结果表明,化合物1中,三联吡啶环呈反-反构型,而在2和3中,三联吡啶环呈现出顺-顺构型,然后采取三齿螯合模式连接金属离子形成单核单元。3个化合物中,三联吡啶分子之间以及它们与溶剂分子之间形成的氢键、π-π堆积和范德华力等相互作用将化合物1~3的单核单元连接形成三维网状结构。     

4'-(5'-R-pyrimidyl)-2,2':6',2'-terpyridyl (R = H, OEt, Ph, Cl, CN) platinum(II) phenylacetylide complexes: synthesis and photophysics

A series of new square-planar 4'-(5'-R-pyrimidyl)-2,2':6',2'-terpyridyl platinum(II) phenylacetylide complexes ( 1a- 5a) bearing different substituents (R = H, OEt, Ph, Cl, CN) on the pyrimidyl ring have been synthesized and characterized. The electronic absorption, photoluminescence, and triplet transient difference absorption spectra were investigated. All of the complexes exhibit broad, moderately strong absorption between 400 and 500 nm that can be tentatively assigned to the metal-to-ligand charge transfer ( (1)MLCT) transition, possibly mixed with some ligand-to-ligand charge transfer ( (1)LLCT) character. Photoluminescence arising from the (3)MLCT state was observed both in fluid solutions at room temperature and in a rigid matrix at 77 K. The (1)MLCT/ (1)LLCT absorption bands and the (3)MLCT emission bands for 1a- 5a red-shift in comparison to those of the corresponding 4'-toly-2,2':6',2'-terpyridyl platinum(II) phenylacetylide complex. In addition, the energies of the (1)MLCT/ (1)LLCT absorption and the (3)MLCT emission bands exhibit a linear correlation with the Hammett constant (sigma p) of the 5'-substituent on the pyrimidyl ring. The lifetime of the (3)MLCT emission at room temperature is governed by the energy gap law. The triplet transient difference absorption spectra of 1a- 5a exhibit a broad absorption band from 500 to 800 nm, and a bleaching band between 420 and 500 nm. Complex 5a, which contains the -CN substituent, exhibits a lower-energy triplet absorption band at 785 nm and a shorter lifetime (130 ns) in CH 3CN than 2a, which has the -OEt substituent, does (lambda T1-Tn (max) = 720 nm, tau T = 660 ns). The triplet excited-state absorption coefficients at the band maxima for 1a- 5a vary from 36 600 L.mol (-1).cm (-1) to 115 090 L.mol (-1).cm (-1), and the quantum yields of the triplet excited-state formation range from 0.19 to 0.66. All complexes exhibit a moderate nonlinear transmission for nanosecond laser pulses at 532 nm. Moreover, these complexes can generate singlet oxygen efficiently in air-saturated CH 3CN solutions, with the singlet oxygen generation quantum yield (Phi Delta) varying from 0.24 to 0.46.     

Water-soluble alkylated bis{4'-(4-pyridyl)-2,2':6',2'-terpyridine}ruthenium(II) complexes for use as photosensitizers in water oxidation: a complementary experimental and TD-DFT investigation

A series of N-alkylated derivatives [RuL(2)][PF(6)](4) has been prepared from [Ru(pytpy)(2)][PF(6)](2) (N-alkyl substituent = 4-cyanobenzyl, 4-nitrobenzyl, ethyl, cyanomethyl, allyl, octyl). Solution NMR spectroscopic, electrochemical and photophysical properties are reported, along with the single crystal structure of [Ru(4)(2)][PF(6)](4)·H(2)O (4 = 4'-(4-(1-ethylpyridinio))-2,2':6',2'-terpyridine). Anion exchange leads to the water-soluble [RuL(2)][HSO(4)](4) salts (N-alkyl substituent = benzyl, 4-cyanobenzyl, 4-nitrobenzyl, ethyl, cyanomethyl, allyl, octyl) and the NMR spectroscopic signatures of pairs of hexafluoridophosphate and hydrogensulfate salts are compared. The change in anion has little effect on the energies of absorptions in the electronic spectra, although for all complexes, decreases in extinction coefficients are observed. The emission spectra and lifetimes for the hexafluoridophosphate and hydrogensulfate salts show similar trends; all exhibit an emission close to 720-730 nm (λ(ex) = 510 nm). For a given ligand, L, the emission lifetime decreases on going from [RuL(2)][PF(6)](4) to [RuL(2)][HSO(4)](4). However, trends are the same for both salts, i.e. the longest lived emitters are observed for N-ethyl, N-octyl and N-benzyl derivatives, and the shortest lived emitters are those containing cyano or nitro groups. Significantly, in the absorption spectra of the complexes, there is little variation in the energy of the MLCT band, suggesting that the character of the ligand orbital involved in the transition contains no character from the N-substituent. We have addressed this by carrying out a complementary DFT and TD-DFT study. Calculated absorption spectra predict a red shift in λ(max) on going from [Ru(pytpy)(2)](2+) to [RuL(2)](4+), and little variation in λ(max) within the series of [RuL(2)](4+) complexes; these results agree with experimental observations. Analysis of the compositions of the MOs involved in the MLCT transitions explain the experimental observations, showing that there is no contribution from orbitals on the N-alkyl substituents, consistent with the fact that the nature of the N-substituents has little influence on the energy of the MLCT band. The theoretical results also reveal satisfactory agreement between calculated and crystallographic data for [Ru(1)(2)](4+) (1 = 4'-(4-(1-benzylpyridinio))-2,2':6',2'-terpyridine) and [Ru(4)(2)](4+).     

基于3,5-二((4'-羧基苄基)氧)苯甲酸和4'-(4-吡啶基)-2,2':6',2"-三联吡啶为混合配体的两个配合物的水热合成与晶体结构

在水热条件下,以3,5-二（（4''-羧基苄基）氧）苯甲酸（H3bcb）和4''-（4-吡啶基）-2,2''：6'',2"-三联吡啶（PYTPY）为混合配体构筑了2个过渡金属配合物[Co（H₂bcb）₂（PYTPY）]_n （1）和[Mn（H₂bcb）₂（PYTPY）]_n （2）,利用元素分析、红外光谱以及单晶X射线衍射表征其结构。分析表明配合物1和2为一维链状结构。此外,2个配合物展示了优良的热稳定性。磁化率的测试结果表明,配合物1和2在2 K和8 K以下时展示了反铁磁相互作用。     

A simple synthesis of 4-amino-6-methyl-1,1,1-trifluoro(trichloro)hepta-3,5-dien-2-ones and 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyridone

Treatment of 2,2-dimethyl-6-trifluoro(trichloro)methyl-2,3-dihydro-4-pyrones with ammonia gives 4-amino-1,1,1-trifluoro(trichloro)-6-methylhepta-3,5-dien-2-ones. Under similar conditions 1,1,1-trifluoro-2-hydroxy-6-methylhepta-2,5-dien-4-one and 6-chloro-1, 1,1-trifluoro-2-hydroxy-6-methylhept-2-en-4-one cyclize into 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyridone. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2263–2265, December, 1997.     

New active ruthenium(II) complexes based N3,N3′-bis(diphenylphosphino)-2,2′-bipyridine-3,3′-diamine and P,P′-diphenylphosphinous acid-P,P′-[2,2′-bipyridine]-3,3′-diyl ester ligands for transfer hydrogenation of aromatic ketones by propan-2-ol

The dimeric starting material [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ reacts with N3,N3′-bis(diphenylphosphino)-2,2′-bipyridine-3,3′-diamine, 1 and P,P′-diphenylphosphinous acid-P,P′-[2,2′-bipyridine]-3,3′-diyl ester, 2 ligands to afford bridged dinuclear complexes [C₁₀H₆N₂{NHPPh₂-Ru(η⁶-p-cymene)Cl₂}₂], 3 and [C₁₀H₆N₂{OPPh₂-Ru(η⁶-p-cymene)Cl₂}₂], 4 in quantitative yields. These bis(aminophosphine) and bis(phosphinite) based Ru(II) complexes serve as active catalyst precursors for the transfer hydrogenation of acetophenone derivatives in 2-propanol and especially 4 acts as a good catalyst, giving the corresponding alcohols in 99% yield in 20 min (TOF ? 280 h⁻¹).     

3-烷基/芳基-6-(2', 4'-二氯苯基)-7H-1, 2, 4-三唑[3, 4-b]- 1, 3, 4-噻二 嗪的合成及波谱性质

以间二氯苯与氯乙酰氯反应,生成ω-氯代-2,4-二氯苯乙酮(1),再使之分别与3-烷基/芳基-4-氨基-5-巯基-1,2,4-三唑(2a～2l)反应,合成了12种新的3-烷基/芳基-6-(2',4'-二氯苯基)-7H-1,2,4-三唑并[3,4-b]1,3,4-噻二嗪(4a～4l)。利用EA,IR,^1HNMR确定了其结构,并提出该反应的可能机制。     

Cu(NO3)2.3H2O-mediated synthesis of 4'-(2-pyridyl)-2,2':6',2' '-terpyridine (L2) from N-(2-pyridylmethyl)pyridine-2-methylketimine (L1). A C-C bond-forming reaction and the structure of {[Cu(L2)(OH)(NO3)][Cu(L2)(NO3)2]}.2H2O

N-(2-Pyridylmethyl)pyridine-2-methylketimine (L1) was synthesized from equimolar quantities of (2-pyridyl)methylamine and 2-acetylpyridine. Methanolic solution of L1 reacted readily with Cu(NO3)2.3H2O in air, affording green solid of composition {[Cu(L2)(OH)(NO3)][Cu(L2)(NO3)2]}.2H2O, where L2 is 4'-(2-pyridyl)-2,2':6',2' '-terpyridine. Oxidation of the active methylene group of L1 to an imide and then condensation with 2-acetylpyridine involving a C-C bond-forming reaction, mediated by a Cu2+ ion, are the essential steps involved in the conversion of L1 to L2. L2 is isolated by extrusion of Cu2+ with EDTA(2-). The copper center in [Cu(L2)(OH)(NO3)] has a mer-N3O3 environment, and that in [Cu(L2)(NO3)2] has a distorted trigonal-bipyramidal geometry. Two H2O molecules held by C-H...O interactions are present in the predominantly hydrophobic channels of approximate cavity dimension 7.60 x 6.50 A created by aromatic rings through pi-pi interactions.     

Asymmetric reduction of 2,2-dimethyl-6-(2-oxoalkyl/oxoaryl)-1,3-dioxin-4-ones and application to the synthesis of (+)-yashabushitriol

The asymmetric transfer hydrogenation of a series of 2,2-dimethyl-6-(2-oxoalkyl)-1,3-dioxin-4-ones and 2,2-dimethyl-6-(2-oxoaryl)-1,3-dioxin-4-ones was achieved in high enantiomeric excess using a Ru(II) catalyst. The aryl substrates were most compatible with the methodology and this process facilitated a total synthesis of enantiomerically pure (+)-yashabushitriol.     

A pyrazolyl-terminated 2,2′:6′,2″-terpyridine ligand: Iron(II), ruthenium(II) and palladium(II) complexes of 4′-(3,5-dimethylpyrazol-1-yl)-2,2′:6′,2″-terpyridine

The preparation of 4′-(3,5-dimethylpyrazol-1-yl)-2,2′:6′,2″-terpyridine (2) under acidic conditions results in the formation of the salts [H₂2][MeOSO₃]₂ and [H₂2][EtOSO₃]₂, treatment of which with base leads to neutral 2. The structure of [H₂2][EtOSO₃]₂ · H₂O has been established by single crystal X-ray diffraction. The complexes [Fe(2)₂][PF₆]₂ and [Ru(2)₂][PF₆]₂ have been prepared and characterized, and the single crystal structure determination of [Ru(2)₂][PF₆]₂ is reported; [Fe(2)₂][PF₆]₂ is isostructural with [Ru(2)₂][PF₆]₂. Treatment of [Fe(2)₂]²⁺ with PdCl₂ produces [Pd(2)Cl]⁺, isolated and structurally characterized as the hexafluoridophosphate salt, illustrating that metal exchange within the tpy-binding domain occurs in preference to palladium(II) coordination by the N-donor atom of the pendant 3,5-dimethylpyrazol-1-yl unit in 2. [Pd(2)Cl]²⁺ can also be prepared from PdCl₂ and [H₂2][MeOSO₃]₂ in refluxing methanol.