КООРДИНАЦИОННАЯ ХИМИЯ, 2015, том 41, № 7, с. 403-408
УДК 541.49
SELF-ASSEMBLY, CRYSTAL STRUCTURE, AND SPECTROSCOPY
PROPERTIES OF TWO NEW COMPLEXES WITH 1,10-PHENANTHROLINE-5,6-DIONE AND SCN LIGANDS © 2015 J. P. Song1, 2, Q. Ma1, *, S. M. Shuang2, Y. Guo1, and C. Dong 2, *
1College of Chemistry and Environmental Engineering, Institute of the Applied Chemistry, Shanxi Datong University, Datong,
Shanxi, 037009 P.R. China 2Institute of Environmental Science, Shanxi University, Taiyuan, 030006 P.R. China
*E-mail: maqihx@163.com Received January 12, 2015
Two new complexes [Co(Pdon)(SCN)2(H2O)2] (I) and [Hg(Pdon)2Br2] (II) (Pdon = 1,10-phenanthroline-5,6-dione) have been synthesized and characterized by element analysis, IR and single crystal X-ray diffraction (CIF files CCDC nos. 793904 (I) and 783209 (II)). Compounds I and II are mononuclear complexes obtained by the self-assembly of Pdon, SCN- and metal ion Co2+ and Hg2+, which are further in close contacted forming a two dimensional supramolecular framework via O—H---S and O-H-O hydrogen bonding interactions interactions between adjacent molecules.
DOI: 10.7868/S0132344X15070099
INTRODUCTION
1,10-Phenanthroline-5,6-dione (Pdon) is a versatile ligand for the assembly of metal organic materials [1, 2]. It may serve as a terminal or planar bridging ligand in the construction of multinuclear complexes and has the ability to form stable complexes with a wide variety of metal ions analogous to 1,10-phenan-throline (Phen) and carries an o-quinone moiety with pH-dependent electroactivity. So, metal complexes with the ligand potentially allow for the variation and control of redox properties over a wide range as well as the fine tuning of potentials through pH changes [3, 4]. The diketone functionality can also easily be transformed to other chelating groups, such as diamine or dioxime [5, 6]. Moreover, it is also a versatile organic linker that can form bridges through amine condensation or a combination of coordination and condensation [7—9]. The SCN- ligand is a linear ligand with two donor atoms and may coordinate through terminal modes or bridging modes or both, with great potential in building coordination network [10]. It can adopt end-to-end (EE) and end-on (EO) fashions via the nitrogen and sulfur atoms to build coordination networks as well as interlink the 1D or 2D molecules into frameworks via the non-covalent interactions [11, 12]. A series of new coordination polymers with interesting structures based on the bridging SCN- ligand along with their magnetic properties have been reported [13]. The significance of this research work is to report the self-assembly synthesis of Pdon, SCN- and d10 metal ion (Hg2+).
Based on our interesting of the self-assembly of Pdon, SCN- and different metal ions, in this research
work, two complexes [Co(Pdon)(SCN)2(H2O)2] (I) and [Hg(Pdon)2Br2] (II) were designed and synthesized. It is noted that two crystal structures exhibit different coordination forms comparable to the our reported similar complexes [14]. Herein, we report the synthesis, crystal structure and spectroscopy properties of complexes I and II.
EXPERIMENTAL
Materials and methods. All chemicals were of reagent grade and commercially available, and were used without further purification. The Infrared spectra were recorded as KBr pellets on a Shimadzu 8300 FT-IR spectrometer. Samples for elemental analysis were dried under vacuum, and the analysis was performed with a CHN-O-Rapid instrument.
Pdon was oxidated from its parent compound 1,10-phenanthroline. The processes of preparation and purify were easily followed to the literature [2]. Pure products were yellow-orange needles, m.p. = = 257°C.
IR data (v, cm-1): 3457 s, 1689 s, 1559 s, 1460 m, 1415 s, 1291 m, 1206 w, 1115 w, 1063 w, 926 w, 808 w, 736 m, 671 w, 613 w, 541 w.
Synthesis of complex I. CoCl2 (0.1 mmol) dissolved in 5.0 mL of aqueous solution was added to a methanol solution (10 mL) containing Pdon (0.021 g, 0.1 mmol) dropwise at room temperature and the mixture was reacted with stirring for 0.5 h. Then, KSCN (0.0195 g, 0.2 mmol) was slowly added dropwise with a constant stirring. The insoluble components were removed by filtration, and the filtrate was allowed to stand at room
temperature. The orange red crystals were collected after slow evaporation at room temperature for about 2 weeks in a yield of 16.7%.
IR data (v, cm-1): 3444 s, 2073 s, 1695 s, 1571 s, 1470 w, 1421 s, 1298 w, 1121 w, 1027 w, 925 w, 834 w, 736 m, 697 w, 456 w.
For C14H10N4O4S2Co anal. calcd., %: C, 39.91; Found, %: C, 39.32;
H, 2.39; N, 13.30. H, 2.35; N, 13.33.
CoCl-
N
+ KSCN-N
MCo(Pdon)(SCN)2(H2O)2]
HgBr^[Hg(Pdon)2Br2]
Synthesis of complex II was carried out by the same way as for I, using HgBr2 instead of CoCl2. The yield was 49%.
IR data (v, cm-1): 3444 s, 1703 s, 1579 m, 1467 s,1424 m, 1313 w, 1258 w, 1206 w, 1130 w, 1024 w, 823 w, 731 w, 691 w, 626 w.
For C24H12N4O4Br2Hg
anal. calcd., %: C, 36.92; H, 1.55; N, 7.18. Found, %: C, 36.14; H, 1.35; N, 7.21.
X-ray diffraction study. The single crystal diffraction data of I and II were collected on a Bruker Smart Apex II diffractometer equipped with 1K CCD instrument by using a graphite monochromator utilizing Mo^a radiation (X = 0.71073 A) at room temperature. Cell parameters were determined using SMART software [15]. Data reduction and corrections were performed using SAINTPlus. Absorption corrections were made via SADABS [16]. The structures were solved by direct methods with the program SHELXS-97 and refined by full-matrix least-squares methods on all F2 data with SHELXL-97 [17]. The non-hydrogen atoms were refined anisotropically. Hydrogen atoms attached C were added theoretically and treated as riding on the concerned atoms. H atoms of coordina-tional water molecule in I were located from difference Fourier maps and refined their global Uiso value. The final cycle of full-matrix least-squares refinement was based on observed reflections and variable parameters. Details of the crystal parameters, data collection and refinement are summarized in Table 1. Selected bond lengths and bond angles were given in Table 2. The geometrical parameters of the hydrogen bonds are listed in Table 3.
Supplementary material for structures I and II has been deposited with the Cambridge Crystallographic Data Centre (nos. 793904 and 783209, respectively; deposit@ ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
RESULTS AND DISCUSSION
General method for the preparation of complexes I and II is given below:
The self-assembly process of I and II was achieved from three reacting reagents (Pdon, thiocyanate and CoCl2/HgBr2) in aqueous-ethanol solution at room temperature. The crystal structures of complexes I and II indicate that under synthesis condition of this work, Pdon acted only as a terminal ligand and occupied two coordinated sites of the metal ions. Despite this recipe adopted the same condition of synthesis, complexes I and II still exhibit different coordination mode. The architecture may relate to crystal and ionic radii (Á, C.N. 6) of metal ions, Co (0.79, 0.65) and Hg (1.16, 1.02) [18]. The infrared absorption spectrum shows a small shift to higher energy of C=O stretching of the pdon in I, II and the free ligand at 1703 and 1689 cm-1, respectively. The C=N stretching of thiocyanate in complex I was at 2073 cm-1. The bond lengths of C=O ranging from 1.191 to 1.222(8) Á (Table 1) exhibit character of double bond, indicating Pdon participate in coordination mainly in the form of quinone. The products are further confirmed by elemental analyses.
X-ray crystallographic analysis revealed that complex I is a mononuclear species with one Pdon ligand, two coordinated water molecules and two c/s-SCN-anions, as shown Fig. 1a. The metal centre is six-coordinated in slightly distorted octahedron with a coordination environment of CoN4O2, in which four N atoms came from one Pdon ligand and two c/s-SCN- anions, two O atoms came from two coordination water molecules. The both Co-N(Pdon) distances are 2.154(4) Á, which are longer comparable to the corresponding bond distances in [Co(Phen)2(H2O)2](NO3)3 • 2H2O (1.934-1.952 Á) [19]. The Co-N(SCN-) distances of I are 2.061(4) and 2.083(4) Á. The NCoN chelated angle formed by each Pdon is 76.45(13)°, which are slightly bigger than the corresponding angles found in c/s-[Co(Bipy)2(SCN)2] (75.4°) [20]. The NCoN angle formed by SCN- is 93.82(17)°; NCS- ligand acts as a terminal coordination mode. The Co(1)N(3)C(13) and Co(1)N(4)C(14) angles of 161.9(4)° and 174.3(4)°, respectively, indicate that the terminal NCS anions are coordinated in an almost linear fashion. The S(1)C(13)N(3) and S(2)C(14)N(4) angles of NCS (179.3(5)° and 178.3(5)°, respectively) are significantly in close to linear terminal NCS groups.
Hydrogen bonding interactions are usually important in the synthesis of supramolecular architecture. There are persistent O-H—S and O-H—O hydrogen bonding interactions between crystal molecules (Fig. 2). The three kinds of the O—O distances are in the range of2.867(5) to 3.049(5) Á and O—S bond distance is the
Table 1. Crystallographic data and structural refinement details of complexes I and II
Parameter Value
I II
M 421.31 780.79
Temperature, K 298(2) 298(2)
Crystal system Monoclinic Orthorhombic
Space group P21 Fdd2
a, A 8.8845(11) 42.485(4)
b, A 10.3264(14) 8.469(8)
c, A 9.6862(13) 13.1831(12)
P, deg 96.817(1) 90
V, A3 885.5(2) 4744(5)
Crystal size, mm 0.43 x 0.32 x 0.19 0.40 x 0.37 x 0.13
Z 2 8
Pcalcd g cm-3 1.299 1.552
p., mm-1 1.23 9.90
/(000) 426 1078
9 Range, deg 3.1-25.0 2.90-25.02
Limiting indices -6 < h < 6, -9 < k < 9, -14 < l < 15 -9 < h < 8, -15 < k < 14, -25 < l < 25
GOOF(/2) 1.08 1.13
Reflections measured 4402 5499
Reflections unique 2800 2030
Rint 0.028 0.057
Final R (I> 2ct(T)) R1 = 0.037 wR2 = 0.087 R1 = 0.0573 wR2 = 0.1278
R (all data
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