1 INTRODUCTION

The macrocyclic ligand is a major theme of contemporary coordination chemistry, frequently proven to be of great utility[1-2]. Metal template condensation reactions involving amines and formaldehyde often provide selective routes toward products that can not be obtainable in the absence of metal ions, which have been utilized for the preparation of polyaza macrocyclic complexes[3-5].Square planar macrocyclic complexes can be employed as useful metal building blocks since they act as linear linkers for the organic ligand, which makes the design and assembly of network simple and easy[6-8]. Herein, we report two new macrocyclic compounds: 1 and 2, and the synthesis route is depicted in Scheme 1.

Scheme 1. Synthesis route of compounds (1) and (2)

2 EXPERIMENTAL

2.1 Reagents and instruments

The IR spectra were measured from KBr pellets on a Nicolet Avatar 370 FT-IR spectrometer.Elemental analyses were performed using a Vario ELIII CHNS/O elemental analyzer. The powder X-ray diffraction measurements were performed on a Bruker D8 ADVANCE X-ray diffractometer. All other chemicals were commercially available and used without further purification.

2.2 Synthesis

[Cu2(L)2](ClO4)4·2CH3OH 1 To a methanol solution (100 mL) of Cu(CH3COO)2·H2O (10 g, 0.05 mol) was added triethylenetetramine (8.0 g, 0.05 mol), 1,2-diaminocyclohexane (5.7 g, 0.05 mol) and 37% formaldehyde (16.2 g, 0.2 mol). After reflux for 24 h, the solution was cooled to room temperature and filtered to remove any insoluble solid. The solution was left at room temperature until the red-violet crystals formed. The product was filtered.Yield: 60%. Anal. Calcd. for C34H72Cl4Cu2N12O18(%): C, 33.86; H, 6.02; N, 13.94. Found: C, 33.80; H,6.15; N, 13.82%.

[Cu(L)](ClO4)2·2H2O 2 Compound 1 was subsequently recrystallized from aqueous solution to obtain compound 2. Yield: 50%. Anal. Calcd. for C17H33Cl2CuN5O10(%): C, 43.05; H, 8.03; N, 16.74.Found: C, 43.18; H, 8.15; N, 16.62%.

2.3 Crystal structure determination

The crystals of compounds with approximate dimensions were selected and mounted on a glass fiber. The intensity data were collected on a Bruker Smart APEX CCD-based diffractometer equipped with a graphite-monochromatic MoKα radiation (λ =0.71073 ?) by using a φ-ω scan mode at 293(2) K.The empirical absorption was applied to the intensity data. The intensities were corrected for Lorentz and polarization effects as well as for empirical absorption based on the multi-scan technique. The structure was solved by direct methods with SHELXS-97 program and refined by full-matrix least-squares techniques on F2with SHELXL-97[9-10]. All non-H atoms were refined with anisotropic displacement parameters. The hydrogen atoms were located theoretically and refined with riding model position parameters as well as fixed isotropic thermal parameters. It should be noted that oxygen atoms of(ClO4)2-in compound 2 were treated by disorder and these atoms were refined anisotropically with the application of restrains (ISOR O(6) and O(8) in SHELXL). The crystal data are summarized in Table 1.

Table 1. Crystallographic Data and Collection Parameters of Compounds 1 and 2

To be continued

3 RESULTS AND DISCUSSION

The crystal structures of compounds 1 and 2 are given in Fig. 1. The selected bond lengths and bond angles are listed in Table 2.

Fig. 1. Molecular structures of compounds 1 (a) and 2 (b)

Table 2. Selected Bond Lengths (?) and Bond Angles (°) for the Compounds

Compound 1 X-ray crystallographic analysis shows that compound 1 consists of two[Cu(L)]- (ClO4)2fragments and two methanol solvents. For the Cu(1) segment, the copper atom is six-coor- dinated by two secondary and two tertiary amines of the macrocycle and two oxygen atoms of (ClO4)2-(Fig. 1a). The Cu–N bond distances in the CuN4plane range from 2.001(5) to 2.014(5) ?, and the average of the four distances is 2.058 ?. The axial bond distances are 2.715 ? for Cu(1)–O(16) and 2.756 ? for Cu(1)–O(10), far from the normal range. Due to the Jahn-Teller effect, the Cu–O bond is longer than Cu–N. Thus, the coordination model of copper atom at the axial positions can be regard as semi-coordination[11]. The N–Cu–N angles of the tetragonal planes (N(1)–Cu(1)–N(4) = 86.58(19)°and N(1)–Cu(1)–N(6) = 94.4(2)°) somewhat deviated from the ideal square-planar angles (90°). For the Cu(2) segment, the distances between Cu(2) and coordinated nitrogen atoms fall in the range of 1.992–2.014 ?. Due to the Jahn-Teller effect, the axial Cu–O bonds (Cu(2)–O(5) = 2.602 ?, Cu(2)–O(12) = 2.942 ?) are longer than the Cu–N bond.Two ethyl substituents are on both sides of the CuN(4) plane, which shows that the macrocycle is not a plane-symmetric structure.

Compound 2 In the crystal structure of com- pound 2, only one [Cu(L)](ClO4)2fragment was observed in the asymmetric unit (Fig. 1b).The Cu–N bond distances of compound 2 are similar to those of 1 (Cu(1)–N(1) = 2.017(3) ?,Cu(1)–N(2) = 2.007(3) ?, Cu(1)–N(3) = 2.003(3) ? and Cu(1)– N(4) = 1.997(3) ?). The axial Cu(1)–O(2) and Cu(1)–O(8) separations of 1.6067 and 2.8554 suggest coordination coupling effect by Jahn-Teller. Additionally,strong intermolecular hydrogen bonds are also observed in the structure (Table 3). The molecules are assembled to form a three-dimen- sional structure via intermolecular hydrogen bonding interactions, as illustrated in Fig. 2. X-ray powder diffraction patterns of the two compounds (Fig. 3) were recorded to confirm the purity of the as- synthesized bulk materials. The experimental XRD patterns match well with the calculated lines from the crystal structures.Symmetry codes: #1: –x+1, –y+1, –z+1, #2: –x+1/2, –y+1/2, –z+1

Fig. 2. View down the a-axis: 3-D arrangement of compounds 1 (a) and 2 (b)

Table 3. Hydrogen Bonds for the Title Compounds (?, °)

Fig. 3. Comparison of the experimental and simulated XRD patterns.In each group, the top is the experimental pattern and the bottom is the simulated one

Obviously, the successful syntheses of com- pounds 1 and 2 reveal that the molecular structure was influenced dramatically by solvent. This report gives a clear example that the two procedures may cause two different compounds.

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