Home Physical Sciences A tetranuclear ruthenium complex with bridging pyridine-2,4-dicarboxylato ligands forming a square metallamacrocycle
Article Publicly Available

A tetranuclear ruthenium complex with bridging pyridine-2,4-dicarboxylato ligands forming a square metallamacrocycle

  • Yu-Feng Xie , Ai-Quan Jia , Hang Zhu , Hua-Tian Shi and Qian-Feng Zhang EMAIL logo
Published/Copyright: January 20, 2016
Download Article (PDF)
Become an author with De Gruyter Brill
Author Information Explore this Subject
Zeitschrift für Naturforschung B
From the journal Zeitschrift für Naturforschung B Volume 71 Issue 2

Abstract

Treatment of [RuCl2(PPh3)3] with equimolar amounts of 2,4-pyridinedicarboxylic acid (2,4-dipicH2) in the presence of Et3N afforded a tetranuclear complex [Ru(μ-2,4-dipic)(PPh3)2]4 (1) as red crystals. The crystal and molecular structure of [Ru(μ-2,4-dipic)(PPh3)2]4·CHCl3·8H2O (1·CHCl3·8H2O) was determined by single-crystal X-ray diffraction. Each ruthenium center in 1 is six-coordinated with two phosphorus atoms from triphenylphosphine ligands, one nitrogen atom from a pyridyl moiety and three oxygen atoms from two 2,4-dipic2– ligands. 2,4-Pyridinedicarboxylate dianions (2,4-dipic2–) act as bridging ligands to form the stable tetranuclear metallamacrocyclic compound. The electrochemical properties of 1 were also investigated.

Keywords: crystal structure; metalla rectangle; pyridinedicarboxylic acid; ruthenium

1 Introduction

Pyridinedicarboxylic acids (dipicH2) are known for their various biomedical applications based on their various coordination modes [1–4]. In particular, 2,4-pyridinedicarboxylic acid (2,4-dipicH2) shows immune-suppressive and fibro-suppressive properties and is capable of protecting certain enzymes from heat inactivation [5]. In addition, 2,4-, 2,5- and 2,6-dipicH2 acids have been found to be widely functioning as bidentate, tridentate, meridional and bridging ligands to form stable chelates with transition metal ions in simple coordination complexes and macrocyclic homo- and hetero-nuclear systems [6–9]. Although first row transition-metal complexes containing dipic2– ligands have been documented, few related ruthenium compounds have been reported to date [10–16]. Self-assembly of polypyridyl ligands with dinuclear arene-ruthenium building blocks bridged by chloro-, oxalato- or benzoquinonato ligands has allowed the construction of a wide range of cationic metallo complexes possessing different architectures and functionalities, of which metalla rectangles show host-guest possibilities and intramolecular template-controlled photochemical dimerization reactions [17–19]. We previously reported a novel metallamacrocyclic p-iPrC6H4Me–ruthenium complex with alternating hydroxyl and 4,4′-bipy (4,4′-bipy = 4,4′-bipyridine) bridges between the ruthenium atoms [20]. Such tetranuclear rectangular ruthenium complexes did not show an intact electrochemistry under the oxidation–reduction conditions at room temperature because ruthenium(II) was oxidized to ruthenium(III), and the p-iPrC6H4Me moieties dissociate from the ruthenium centers. To further explore polynuclear ruthenium-based macrocyclic complexes, we were interested in investigating the interaction of a typical ruthenium staring material such as [RuCl2(PPh3)3] with 2,4-dipicH2, whereby a tetranuclear ruthenium-based compound with bridging 2,4-dipic2– ligands, [Ru(μ-2,4-dipic)(PPh3)2]4, was unexpectedly isolated. The initial results of synthesis, structure and electrochemical properties are presented in this paper.

2 Experimental section

2.1 General

All synthetic manipulations were carried out under dry nitrogen by standard Schlenk techniques. 2,4-Pyridinedicarboxylic acid (dipicH2) and triethylamine were purchased from Alfa Aesar Ltd. and used as supplied. [RuCl2(PPh3)3] was prepared according to the literature method [21]. The NMR spectrum was recorded on a Bruker ALX 400 Plus spectrometer operating at 400 MHz for 1H, and chemical shifts (δ, ppm) were reported with reference to SiMe4 (1H). Infrared spectra (KBr) were recorded on a Perkin-Elmer 16 PC FT-IR spectrophotometer with the use of pressed KBr pellets. Cyclic voltammetry was performed with a CHI 660 electrochemical analyzer. A standard three-electrode cell was used with a glassy carbon working electrode, a platinum counter electrode and an Ag/AgCl reference electrode under nitrogen atmosphere at 25 °C. Formal potentials (Eo) were measured in CH2Cl2 solutions with 0.1 m [nBu4N]PF6 as supporting electrolyte and reported with reference to the ferrocenium–ferrocene couple (Cp2Fe+/0). In the –0.5 to +1.2 V region, a potential scan rate of 100 mV s–1 was used. Elemental analyses were carried out using a Perkin-Elmer 2400 CHN analyzer.

2.2 Synthesis of [Ru(μ-2,4-dipic)(PPh3)2]4·CHCl3·8H2O (1·CHCl3·8H2O)

To a slurry of [RuCl2(PPh3)3] (95.8 mg, 0.10 mmol) in THF (10 mL) was dropwise added a solution of 2,4-dipicH2 (16.7 mg, 0.10 mmol) and Et3N (0.10 mL) in THF (5 mL), and then the mixture was heated at reflux with stirring for 2 h, during which there was a color change from light yellow to dark red. The solvent was removed in vacuo and the residue was washed with diethyl ether and hexane. Recrystallization from CHCl3–diethyl ether (1:2) afforded red block-shaped crystals of 1·CHCl3·8H2O in 3 days. Yield: 176 mg, 54 % (based on Ru). – 1H NMR (CDCl3, ppm): δ = 1.56 (br, 16H, H2O), 6.84–7.17 (m, 120H, H in PPh3), 7.92 (t, J = 6.8 Hz, 4H, H in dipic2–), 8.13 (d, J = 7.2 Hz, 4H, H in dipic2–), 8.27 (d, J = 7.0 Hz, 4H, H in dipic2–). – IR (KBr disk, cm–1): v(C=O) = 1650 (vs) and 1609 (vs), v(py ring) = 1573 (s), v(C–O) = 1481(s) and 1433(s), δ(py ring) = 773(s), 742(s) and 696(s). – Anal. for C172H132N4O16P8Ru4·(CHCl3)·8(H2O): calcd. C 60.64, H 4.38, N 1.64; found C 60.27, H 4.32, N 1.61.

2.3 X-ray structure determination

A suitable single crystal of [Ru(μ-2,4-dipic)(PPh3)2]4·CHCl3·8H2O (1·CHCl3·8H2O) was selected and mounted on a Bruker SMART Apex CCD area detector diffractometer, using graphite-monochromatized MoKα (λ = 0.71073 Å) radiation at room temperature. Data were measured using ω scans of 0.5° per frame, such that a hemisphere was collected. Cell parameters were retrieved using the Smart software and refined using Saint on all observed reflections. Data reduction was performed with the Saint software which corrects for Lorentz polarization and decay [22]. An absorption correction was applied using Sadabs [23]. The structure was solved by Direct Methods using Shelxtl-97 and refined by least squares on F2 (Shelxtl-97) [24, 25]. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were placed in idealized positions and refined employing a riding model with displacement parameters 1.5× or 1.2× those of the bound carbon atoms. One of the phenyl rings exhibiting disorder was fixed as an idealized rigid group. The solvent molecules of chloroform and water were refined isotropically without hydrogen atoms due to heavy disorder, which probably resulted in the relatively high R values in the final refinement. The largest peak in the final difference map had a height of 1.59 e Å–3 and is in the vicinity of the ruthenium atom. A summary of crystallographic data and experimental details for 1 are summarized in Table 1.

Table 1

Crystallographic data and experimental details for [Ru(μ-2,4-dipic)(PPh3)2]4·CHCl3·8H2O (1·CHCl3·8H2O).

Empirical formulaC173H149N4O24Cl3P8Ru4
Formula weight3426.35
Crystal systemMonoclinic
Space groupC2/c
a, Å44.439(8)
b, Å10.1248(18)
c, Å43.015(8)
β, deg115.186(4)
V, Å317 514(5)
Z4
Dcalcd, g cm–31.30
Temperature, K293(2)
F(000), e7016
μ(MoKα ), mm–10.5
Refl. total/unique/Rint54 934/19 887/0.0770
Ref. parameters963
R1a/wR2b (I > 2σ(I))0.0836/0.2132
R1a/wR2b (all data)0.1209/0.2347
GoFc1.046
Δρfin (max/min), e Å–3+1.59/–1.46

aR(F) = Σ||Fo| – |Fc||/Σ|Fo|.

bwR(F2) = [Σw(Fo2 – Fc2)2/Σw(Fo2)2]1/2; w = [σ2(Fo2) + (AP)2 + BP]–1, where P = (Max(Fo2, 0) + 2Fc2)/3.

cGoF = S = [Σw(Fo2 – Fc2)2/(nobs – nparam)]1/2.

CCDC 1035021 (1·CHCl3·8H2O) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre viawww.ccdc.cam.ac.uk/data_request/cif.

3 Results and discussion

Interaction of [RuCl2(PPh3)3] and 2,4-pyridinedicarboxylic acid in a 1:1 molar ratio in the presence of Et3N in THF solution led to the isolation of the tetranuclear compound [Ru(μ-2,4-dipic)(PPh3)2]4 (1) as red block crystals 1·CHCl3·8H2O in 54 % yield (Scheme 1). The construction of ruthenium-based metallamacrocyclic complexes generally includes the use of arene-ruthenium building blocks (arene = C6H6, C6Me6, p-iPrC6H4Me, C6HMe5) [17], while the usage of phosphine-ruthenium units as metallo corners to prepare supramolecular species has been rare reported, apart from one study in which [RuCl2(dppb)]2(μ-dppb) (dppb = bis(diphenylphosphine)butane) was adopted to synthesize the tetranuclear structure compound [RuCl2(dppb)(μ-4,4′-bipy)]4 [26]. The tetramer [RuCl2(dppb)(μ-4,4′-bipy)]4 was constructed by four bridging neutral 4,4′-bipy ligands. In 1 four di-anionic ligands are used to construct the square structure. Previously, Jin reported the preparation of the tetranuclear metallacycle [(p-iPrC6H4Me)Ru(L3)]4·(OTf)4 (L3 = 1-(3-pyridinyl)butane-1,3-dione, OTf = SO3CF3), as well as the hexanuclear metallacycles {[(p-iPrC6H4Me)Ru(L1)]6(OTf)}·(OTf)5 (L1 = 3-(4-pyridyl)-pentane-2,4-dione) and {[(p-iPrC6H4Me)Ru(L1)]6(PF6)}·(PF6)5 showing encapsulation of the counteranions. The arene-ruthenium fragments were connected by mono-anionic pyridyl-substituted dionate ligands in the three complexes [27].

Scheme 1: Synthesis of the neutral tetranuclear compound 1.
Scheme 1:

Synthesis of the neutral tetranuclear compound 1.

The C=O and C–O stretching vibrations of 2,4-dipic2– in 1 were expectedly found in the regions of 1650–1609 cm–1 and 1481–1433 cm–1, respectively, of its infrared spectrum, indicating different coordination modes (η1 and η2) of the two carboxylates [28]. The 1H NMR spectrum of 1 displayed pyridyl proton resonances at 7.92, 8.13 and 8.27 ppm, whereas the chemical shifts of phenyl groups in triphenylphosphine ligands were found in the 6.84–7.17 ppm regions.

Compound 1·CHCl3·8H2O crystallizes in the monoclinic space group C2/c with Z = 4. There are four tetranuclear compound molecules 1 along with the solvent molecules in the lattice. The tetranuclear unit [Ru(μ-2,4-dipic)(PPh3)2]4 (1) has crystallographic 2 (C2) symmetry. The molecular structure of [Ru(μ-2,4-dipic)(PPh3)2]4 with atom numbering is depicted in Fig. 1. The packing of 1 in the unit cell of 1·CHCl3·8H2O is displayed in Fig. 2.

Fig. 1: Structure of [Ru(μ-2,4-dipic)(PPh3)2]4 with the atomic numbering. Hydrogen atoms are omitted for clarity. Selected distances (Å) and angles (deg): Ru(1)–P(1) 2.252(2), Ru(1)–P(2) 2.337(2), Ru(1)–N(1) 2.087(5), Ru(1)–O(1) 2.086(4), Ru(1)–O(8A) 2.128(4), Ru(1)–O(7A) 2.279(4), Ru(2)–P(3) 2.322(2), Ru(2)–P(4) 2.250(2), Ru(2)–N(2) 2.095(5), Ru(2)–O(5) 2.069(4), Ru(2)–O(4) 2.138(4), Ru(2)–O(3) 2.269(4), C(1)–O(1) 1.278(7), C(1)–O(2) 1.233(7), C(2)–O(3) 1.254(7), C(2)–O(4) 1.268(7), P(1)–Ru(1)–P(2) 98.62(6), N(1)–Ru(1)–O(1) 77.98(18), O(7A)–Ru(1)–O(8A) 59.64(15), P(3)–Ru(2)–P(4) 99.82(6), N(2)–Ru(2)–O(5) 79.18(18), O(3)–Ru(2)–O(4) 59.34(15).
Fig. 1:

Structure of [Ru(μ-2,4-dipic)(PPh3)2]4 with the atomic numbering. Hydrogen atoms are omitted for clarity. Selected distances (Å) and angles (deg): Ru(1)–P(1) 2.252(2), Ru(1)–P(2) 2.337(2), Ru(1)–N(1) 2.087(5), Ru(1)–O(1) 2.086(4), Ru(1)–O(8A) 2.128(4), Ru(1)–O(7A) 2.279(4), Ru(2)–P(3) 2.322(2), Ru(2)–P(4) 2.250(2), Ru(2)–N(2) 2.095(5), Ru(2)–O(5) 2.069(4), Ru(2)–O(4) 2.138(4), Ru(2)–O(3) 2.269(4), C(1)–O(1) 1.278(7), C(1)–O(2) 1.233(7), C(2)–O(3) 1.254(7), C(2)–O(4) 1.268(7), P(1)–Ru(1)–P(2) 98.62(6), N(1)–Ru(1)–O(1) 77.98(18), O(7A)–Ru(1)–O(8A) 59.64(15), P(3)–Ru(2)–P(4) 99.82(6), N(2)–Ru(2)–O(5) 79.18(18), O(3)–Ru(2)–O(4) 59.34(15).

Fig. 2: Packing diagram of the tetranuclear unit [Ru(μ-2,4-dipic)(PPh3)2]4 in the unit cell.
Fig. 2:

Packing diagram of the tetranuclear unit [Ru(μ-2,4-dipic)(PPh3)2]4 in the unit cell.

Each ruthenium atom is six-coordinated by two phosphorus atoms from two triphenylphosphine ligands, one nitrogen atom from a pyridyl moiety, and three oxygen atoms from two 2,4-dipic2– ligands. Alternating 4,4′-bipy and 2,4-dipic2– ligands lead to a somewhat distorted square structure, with a dimension of 8.88 × 8.86 Å2, as defined by the ruthenium centers, which is obviously shorter than the dimension of the related tetranuclear complex [RuCl2(dppb)(μ-4,4′-bipy)]4 (11.38 × 11.49 Å2) [26]. The average Ru···Ru diagonal distance in 1 is 12.25(1) Å. The average Ru···Ru···Ru angle in 1 is 89.15(5)°. The average Ru–P bond length of 2.290(2) Å in 1 is similar to that in [RuCl2(dppb)(μ-4,4′-bipy)]4 (2.314(3) Å) [26]. The average Ru–N bond length of 2.091(5) Å in 1 compares well with that in the related compound [(p-iPrC6H4Me)RuCl(2,4-dipicH)] (2.101(3) Å) [5]. The average Ru–O(N,O-chelate) bond length of 2.078(4) Å is a little shorter than that of 2.099(2) Å in [(p-iPrC6H4Me)RuCl(2,4-dipicH)] [5]. The bond length of C(1)–O(1) (1.278(7) Å) in η1-carboxylate is longer than C(1)–O(2) (1.233(7) Å), suggesting that the C(1)–O(1) bond is more likely to be a C–O single bond. On the other hand, the bond lengths of C(2)–O(3) (1.254(7) Å) and C(2)–O(4) (1.268(7) Å) ascribed to the 4-position η2-carboxylate are similar to each other. The average chelate angle of N–Ru–O is 78.58(18)°, which is near to that in [(p-iPrC6H4Me)RuCl(2,4-dipicH)] (77.94(10)°) [5]. The average chelate angle of O–Ru–O of 59.49(15)° in 1 is a little larger than that in 4-picolinic acid-derived ruthenium complex [Ru(IMes)2(CO)(η2-O2CC5H4N)H] (57.67(6)°) [29]. Relatively weak interactions exist between phenyl rings of PPh3 ligands and carboxylates of 2,4-dipic2– moieties via the C–H···O hydrogen bonds with the C–H···O distance of 3.578(3) Å.

As displayed in Fig. 3, the cyclic voltammogram of 1 in CH2Cl2 solution with 0.1 mol L–1 [nBu4N][PF6] as supporting electrolyte at room temperature showed one obviously reversible couple at 0.15 V versus Cp2Fe+/0, which is assigned as the metal-centered RuIII–RuII couple because both PPh3 and 2,4-dipic2– ligands are redox inactive at this potential. Another reversible couple at 0.24 V is tentatively attributed to RuIII–RuIV oxidation. The origin of the wave at –1.2 V is not quite clear. The irreversible oxidation wave is tentatively attributed to the RuII–RuIII oxidation. It is thus understood that the CV of compound 1 presents two quasi-reversible processes, which were attributed to the four electrons for the RuIII–RuII and RuIII–RuIV couples as suggested by pulse differential voltammetry experiments. Usually, only one quasi-reversible process is observed for related tetranuclear metallamacrocycles such as [RuCl2(dppb)(μ-4,4′-bipy)]4 [26] and [(p-iPrC6H4Me)4Ru4(μ-C10H4O4)2 (μ-L)]4·(Tf)4 (L = trans-[(4-pyridyl-ethynyl)2Pt(PEt3)2]) [30]. The strong pyridine-2,4-dicarboxylato donor is expected to increase the energy of the empty eg set of the low-spin Ru(II) compound. The reduction at 0.15 V for 1 most likely corresponds to this wave, as the ruthenium centers should be less susceptible to reduction in the presence of strong donors [30]. It is likely that this reduction event is due to the larger . system introduced by the electron-rich 2,4-dipic2– moieties.

Fig. 3: Cyclic voltammogram of the tetranuclear compound [Ru(μ-2,4-dipic)(PPh3)2]4 (0.001 m) in CH2Cl2 at 25 °C at 100 mV s–1 scan rate.
Fig. 3:

Cyclic voltammogram of the tetranuclear compound [Ru(μ-2,4-dipic)(PPh3)2]4 (0.001 m) in CH2Cl2 at 25 °C at 100 mV s–1 scan rate.

In summary, a synthetic protocol for a neutral tetranuclear ruthenium complex has been presented. [Ru(μ-2,4-dipic)(PPh3)2]4 with eight triphenylphosphine donors and four bridging 2,4-pyridinedicarboxylates has a square molecular structure. Compared with the 4,4′-bipyridine bridged tetramer complex [RuCl2(dppb)(μ-4,4′-bipy)]4 [26] and the cationic tetranuclear arene-ruthenium metallacycles [30], compound 1 shows richer electrochemical property possibly due to the electron-rich π system of the 2,4-dipic2– ligands. Using this synthetic methodology, more novel organic phosphine-ruthenium-based metallamacrocycles with controlled structures and predicted electrochemical properties will be synthesized in the laboratory extending this work.

Corresponding author: Qian-Feng Zhang, Institute of Molecular Engineering and Applied Chemistry, Anhui University of Technology, Ma’anshan, Anhui 243002, P.R. China, Fax: +86-555-2311059, E-mail:

Acknowledgments

This work was supported by the Natural Science Foundation of China (21372007).

References

[1] H. Ilkimen, C. Yenikaya, M. Sari, M. Bulbul, E. Tunca, Y. Suzen, Polyhedron2013, 61, 56.10.1016/j.poly.2013.05.040Search in Google Scholar

[2] P. Lainé, A. Gourdon, J.-P. Launay, J.-P. Tuchagues, Inorg. Chem.1995, 34, 5150.10.1021/ic00125a012Search in Google Scholar

[3] L. Yang, D. C. Crans, S. M. Miller, A. la Cour, O. P. Anderson, P. M. Kaszynski, M. E. Godzala III, L. D. Austin, G. R. Willsky, Inorg. Chem. 2002, 41, 4859.10.1021/ic020062lSearch in Google Scholar

[4] B. Zhao, P. Cheng, X. Chen, C. Cheng, W. Shi, D. Liao, S. Yan, Z. Jiang, J. Am. Chem. Soc.2004, 126, 3012.10.1021/ja038784eSearch in Google Scholar

[5] S. Grgurić-Šipka, I. Ivanović, G. Rakić, N. Todorović, N. Gligorijević, S. Radulović, V. B. Arion, B. K. Keppler, Ž. Lj. Tešić, Eur. J. Med. Chem. 2010, 45, 1051.10.1016/j.ejmech.2009.11.055Search in Google Scholar

[6] P. S. Mukherjee, N. Das, Y. K. Kryschenko, A. M. Arif, P. J. Stang, J. Am. Chem. Soc.2004, 126, 2464.10.1021/ja039235bSearch in Google Scholar

[7] S. Noro, H. Miyasaka, S. Kitagawa, T. Wada, T. Okubo, M. Yamashita, T. Mitani, Inorg. Chem. 2005, 44, 133.10.1021/ic049550eSearch in Google Scholar

[8] S.-L. Huang, L. Zhang, Y.-J. Lin, G.-X. Jin, CrystEngComm2013, 15, 78.10.1039/C2CE26072GSearch in Google Scholar

[9] Y.-G. Huang, M.-Y. Wu, W. Wei, Q. Gao, D.-Q. Yuan, F.-L. Jiang, M.-C. Hong, J. Mol. Struct. 2008, 885, 23.10.1016/j.molstruc.2007.10.002Search in Google Scholar

[10] S. M. Couchman, J. M. Dominguez-Vera, J. C. Jeffery, C. A. McKee, S. Nevitt, M. Pohlman, C. M. White, M. D. Ward, Polyhedron1998, 17, 3541.10.1016/S0277-5387(98)00145-4Search in Google Scholar

[11] D. Sukanya, R. Prabhakaran, K. Natarajan, Polyhedron2006, 25, 2223.10.1016/j.poly.2006.01.023Search in Google Scholar

[12] M. K. Tse, S. Bhor, M. Klawonn, G. Anilkumar, H. Jiao, C. Döbler, A. Spannenberg, W. Mägerlein, H. Hugl, M. Beller, Chem. Eur. J.2006, 12, 1855.10.1002/chem.200501261Search in Google Scholar

[13] V. W. Manner, A. G. DiPasquale, J. M. Mayer, J. Am. Chem. Soc.2008, 130, 7210.10.1021/ja801672wSearch in Google Scholar

[14] L. Duan, Y. Xu, M. Gorlov, L. Tong, S. Andersson, L. Sun, Chem. Eur. J.2010, 16, 4659.10.1002/chem.200902603Search in Google Scholar

[15] M. Trivedi, R. Nagarajan, A. Kumar, N. K. Singh, N. P. Rath, J. Mol. Struct. 2011, 994, 29.10.1016/j.molstruc.2011.02.044Search in Google Scholar

[16] S. Jameh-Bozorghi, H. Esfandiari, H. Saravani, F. R. Charati, B. W. Skelton, M. Makha, J. Coord. Chem. 2012, 65, 994.10.1080/00958972.2012.665160Search in Google Scholar

[17] B. Therrien, Eur. J. Inorg. Chem. 2009, 2445.10.1002/ejic.200900180Search in Google Scholar

[18] Y.-F. Han, W.-G. Jia, Y.-J. Lin, G.-X. Jin, Organometallics2008, 27, 5002.10.1021/om800490sSearch in Google Scholar

[19] H. Yan, G. Süss-Fink, A. Neels, H. Stoeckli-Evans, J. Chem. Soc., Dalton Trans.1997, 4345.10.1039/a704658hSearch in Google Scholar

[20] Q.-F. Zhang, R. D. Adams, W.-H. Leung, Inorg. Chim. Acta2006, 359, 978.Search in Google Scholar

[21] T. A. Stephenson, G. Wilkinson. J. Inorg. Nucl. Chem.1966, 28, 945.10.1016/0022-1902(66)80191-4Search in Google Scholar

[22] Smart and Saint+ for Windows NT (version 6.02a), Bruker Analytical X-ray Instruments Inc., Madison, WI (USA) 1998.Search in Google Scholar

[23] G. M. Sheldrick, Sadabs, University of Göttingen, Göttingen (Germany) 1996.Search in Google Scholar

[24] G. M. Sheldrick, Shelxtl (version 5.1) Software Reference Manual, Bruker Analytical X-ray Instruments Inc., Madison, WI (USA) 1997.Search in Google Scholar

[25] G. M. Sheldrick, Acta Crystallogr.2008, A64, 112.10.1107/S0108767307043930Search in Google Scholar

[26] S. L. Queiroz, E. Kikuti, A. G. Ferreira, M. O. Santiago, A. A. Batista, E. E. Castellano, J. Ellena, Supramol. Chem. 2004, 16, 255.10.1080/1061027042000201644Search in Google Scholar

[27] G. L. Wang, Y. J. Lin, H. Berke, G.-X. Jin, Inorg. Chem. 2010, 49, 2193.10.1021/ic902011vSearch in Google Scholar

[28] T. S. Kamatchi, N. Chitrapriya, H. Lee, C. F. Fronczek, F. R. Fronczek, K. Natarajan, Dalton Trans.2012, 41, 2066.10.1039/C1DT11273BSearch in Google Scholar

[29] R. F. R. Jazzar, P. H. Bhatia, M. F. Mahon, M. K. Whittlesey, Organometallics2003, 22, 670.10.1021/om020684eSearch in Google Scholar

[30] V. Vajpayee, Y. H. Song, Y. J. Yang, S. C. Kang, T. R. Cook, D. W. Kim, M. S. Lah, I. S. Kim, M. Wang, P. J. Stang, K.-W. Chi, Organometallics2011, 30, 6482.10.1021/om200908cSearch in Google Scholar PubMed PubMed Central

Received: 2015-9-21
Accepted: 2015-11-26
Published Online: 2016-1-20
Published in Print: 2016-2-1

©2016 by De Gruyter

Articles in the same Issue

  1. Frontmatter
  2. In this Issue
  3. Salaterpene E, a eudesmane-type sesquiterpene from Salacia longipes var. camerunensis
  4. N-Acyl-N-(4-chlorophenyl)-4-nitrobenzenesulfonamides: highly selective and efficient reagents for acylation of amines in water
  5. Synthesis and characterization of Cu(II)-halide 1-methylimidazole complexes
  6. Highly selective naked-eye anion sensors based on thioureido or amido calix[4]arenes
  7. A tetranuclear ruthenium complex with bridging pyridine-2,4-dicarboxylato ligands forming a square metallamacrocycle
  8. Ab initio studies of the structural, electronic, and optical properties of quaternary BxAlyGa1–x–yN compounds
  9. Activation of P4 by Li[SitBu3]: generation of lithium bis(supersilyl)heptaphosphanortricyclanide Li[P7(SitBu3)2]
  10. Metal-free oxidative coupling of aminopyridines with nitroolefins to imidazo[1,2-a]pyridine in the presence of I2–TBHP–pyridine
  11. La3Cu4P4O2 and La5Cu4P4O4Cl2: synthesis, structure and 31P solid state NMR spectroscopy
  12. Notes
  13. Synthesis and single-crystal structure of the pseudo-ternary compounds LiA[N(CN)2]2 (A = K or Rb)
  14. The first pseudo-ternary thiocyanate containing two alkali metals – synthesis and single-crystal structure of LiK2[SCN]3
https://doi.org/10.1515/znb-2015-0158
Keywords for this article
crystal structure; metalla rectangle; pyridinedicarboxylic acid; ruthenium

Articles in the same Issue

  1. Frontmatter
  2. In this Issue
  3. Salaterpene E, a eudesmane-type sesquiterpene from Salacia longipes var. camerunensis
  4. N-Acyl-N-(4-chlorophenyl)-4-nitrobenzenesulfonamides: highly selective and efficient reagents for acylation of amines in water
  5. Synthesis and characterization of Cu(II)-halide 1-methylimidazole complexes
  6. Highly selective naked-eye anion sensors based on thioureido or amido calix[4]arenes
  7. A tetranuclear ruthenium complex with bridging pyridine-2,4-dicarboxylato ligands forming a square metallamacrocycle
  8. Ab initio studies of the structural, electronic, and optical properties of quaternary BxAlyGa1–x–yN compounds
  9. Activation of P4 by Li[SitBu3]: generation of lithium bis(supersilyl)heptaphosphanortricyclanide Li[P7(SitBu3)2]
  10. Metal-free oxidative coupling of aminopyridines with nitroolefins to imidazo[1,2-a]pyridine in the presence of I2–TBHP–pyridine
  11. La3Cu4P4O2 and La5Cu4P4O4Cl2: synthesis, structure and 31P solid state NMR spectroscopy
  12. Notes
  13. Synthesis and single-crystal structure of the pseudo-ternary compounds LiA[N(CN)2]2 (A = K or Rb)
  14. The first pseudo-ternary thiocyanate containing two alkali metals – synthesis and single-crystal structure of LiK2[SCN]3
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2026 De Gruyter Brill
Downloaded on 24.1.2026 from https://www.degruyterbrill.com/document/doi/10.1515/znb-2015-0158/html
Scroll to top button