Crystal structure of a nickel(ii) complex with macrocyclic tetraamine

Transcription

1 Journal of Chemical Crystallography, Vol. 34, No. 7, July 2004 ( C 2004) Crystal structure of a nickel(ii) complex with macrocyclic tetraamine Jun Li, (1,2) Yan-Wei Ren, (2) Jin-Hua Zhang, (2) and Pin Yang (1) Received January 22, 2004 A new compound [Ni(cyclen)(η 2 -CH 3 CO 2 )]BF 4 (cyclen = 1,4,7,10-tetraazacyclododecane) has been synthesized and characterized structurally. It crystallizes in the orthorhombic system, space group Pnnm with a = (5), b = (6), c = 8.913(4) Å, V = (12) Å 3, and Z = 4. The nickel(ii) ion has a distorted octahedral geometry with four secondary amines of the macrocycle and two oxygen atoms of the bidentate acetate group. TGA curve shows its thermal stability is up to 280 C. KEY WORDS: Crystal structure; nickel(ii) complex; macrocycle; acetate group. Introduction The coordination chemistry of macrocyclic compounds has been receiving considerable attention recently, because of its importance in the biological processes. 1 Especially, chemical design of efficient and selective host molecules for various biologically important types of phosphate anion guests has been attracting great interest. 2 Kimura group has studied the function of the zinc(ii) complexes with 1,4,7- triazacyclononane, 1,5,9-triazacyclododecane, and 1,4,7,10-tetraazacyclododecane as synthetic nucleic hydrolases, and the results have shown that these complexes can efficientes catalytically hydrolyze phosphoester. 3,4 However, these compounds formed by macrocyclic polyamine and other physiological metals are less (1) Institute of Molecular Science, Shanxi University, Taiyuan , People s Republic of China. (2) Chemistry Department, Northwest University, Xi an , People s Republic of China. To whom correspondence should be addressed; junli@nwu.edu.cn. reported, and crystal structure data are very limited. To our knowledge, only a few complexes with such ligands have been crystallographically studied. 5 9 We are quite interested in the synthesis of the macrocyclic tetraamine nickel(ii) complexes and have obtained a new nickel(ii) compound with acetate group in the experiments. In this paper, we described the synthesis and crystal structure of [Ni(cyclen)(η 2 -CO 2 )]BF 4 (cyclen = 1,4,7,10-tetraazacyclododecane), together with the results of IR, UV Vis spectra, and thermal analysis. Experimental Materials The macrocycle 1,4,7,10-tetraazacyclododecane(cyclen) was prepared as described previously in the literature. 10 The other reagents were of analytical grade from commercial sources and were used without any further purification /04/ /0 C 2004 Plenum Publishing Corporation

2 410 Li, Ren, Zhang, and Yang Physical measurements Elemental analysis was performed by Vario EL-III instrument. Infrared spectrum was recorded on an Equinox55 spectrophotometer in the range of cm 1 using a powdered sample on a KBr pellet. Electronic spectrum was recorded on TU-1800 spectrophotometer. Thermal analysis was performed on a Netzsch STA 449C instrument, with a heating rate of 10 C/min in nitrogen. Synthesis of the compound [Ni(cyclen)(η 2 -CH 3 CO 2 )]BF 4 To an ethanol/water (v/v, 1:1) (20 ml) of Ni(CH 3 CO 2 ) 2 4H 2 O (0.43 g, 1.7 mmol) and NaBF 4 (0.19 g, 1.7 mmol) was added cyclen (0.30 g, 1.7 mmol). The mixture was adjusted to ph 7 by the solution of NaOH (2 mol/l). Then the solution was filtered and stored in a refrigerator until the violet crystals formed. The product was filtered off, washed with diethyl ether, and dried in air. Yield: g (72%). Anal. Calcd for C 10 H 23 BF 4 N 4 O 2 Ni: C, 31.84; H, 6.10; N, 14.86%. Found: C, 32.21; H, 5.93; N, 14.71%. IR (KBr, cm 1 ): 3183[ν(NH)], 1553[ν as (COO )], and 1446[ν s (COO )]. X-ray crystallography The diffraction data were collected on a Brucker SMART APEX CCD area detector employing graphite monochromated Mo Kα radiation (λ = Å) with ϕ and ω scan mode. The sample selected for investigation has dimensions of mm. 3 The data were collected at room temperature. The intensities were corrected for Lorentz and polarization (L p ) effects, and empirical absorption correction based on a series of scans was applied. A total of 1482 unique data (R int = ) were used to solve the structure by a direct method 11 and subsequent difference Fourier syntheses. The bond distances of B1 F1, B1 F2, and B1 F3 were restrained for the least squares on F 2 in refine- Table 1. Crystal Data and Structural Refinement Compound [Ni(L)(η 2 -CH 3 CO 2 )]BF 4 CCDC deposit no. CCDC Chemical formula C 10 H 23 BF 4 N 4 O 2 Ni Formula weight Temperature, K 298(2) Crystal system Orthorhombic Space group Pnnm Unit cell dimensions a = (5) Å b = (6) Å c = 8.913(4) Å α = β = γ = 90 Volume, Å (12) Z 4 Density (calculated), g/cm Absorption coefficient, mm Diffractometer/scan Brucker Smart Apex CCD Area detector/ω-scans F(000) 784 Crystal size, mm θ range for data collection, deg Index ranges 14 h 11, 16 k 17, 10 l 9 Reflections collected/unique 7893(R int = ),1482 Absorption correction -scan Max. and min. transmission and Refinement method Full-matrix least squares on F 2 Data/restraints/parameters 1482/3/115 Goodness of fit on F Final R indices [I > 2σ (I )] R 1 = , wr 2 = R indices (all data) R 1 = , wr 2 = Largest diff. peak and and hole, e/å 3 ment. The final cycle of refinement led to a final convergence at R = , wr 2 = The crystal data of [Ni(cyclen)(η 2 -CH 3 CO 2 )]BF 4 are given Table 1. All calculations were carried out using SHEXTL-97 program. 12 All non-hydrogen atoms were refined anisotropically and hydrogen atoms were placed in calculated positions with respect to the isotropic displacement parameters. Final atomic coordinates and equivalent isotropic displacement parameters are given in Table 2. Results and discussion Structural description An ORTEP view with the atomic labeling scheme is shown in Fig. 1. The selected bond

3 Crystal structure of a nickel(ii) complex 411 Table 2. Atomic Coordination (10 4 ) and Equivalent Isotropic Displacement Parameter (10 3 Å 2 ) Atom x Y z U eq Ni(1) 5618(1) 1800(1) 0 46(1) B(1) 7582(6) 5699(4) (2) F(1) 8146(8) 6464(6) (4) F(2) 8132(10) 5022(8) (8) F(3) 6986(7) 5782(6) 8832(7) 276(4) N(1) 5337(5) 3168(3) 0 57(1) N(2) 5391(3) 1951(3) 2320(4) 65(1) N(3) 4047(4) 1301(3) 0 54(1) O(1) 6474(3) 585(3) 0 60(1) O(2) 7409(4) 1829(3) 0 62(1) C(1) 7388(5) 983(4) 0 53(1) C(2) 8437(5) 466(5) 0 71(2) C(3) 5820(5) 3463(4) 1403(6) 80(2) C(4) 5338(5) 2923(4) 2647(6) 78(1) C(5) 4341(4) 1462(4) 2665(6) 77(1) C(6) 3519(4) 1582(3) 1395(6) 67(1) distances and angles are listed in Table 3. The molecular structure consists of [Ni(cyclen)(η 2 - CH 3 CO 2 )] + cation and BF 4 anion. Each nickel(ii) ion is six-coordinated with four N atoms of the macrocyclic ligand and two O atoms of the bidentate acetate group, giving a distorted octahedron configuration. The atoms of Fig. 1. An ORTEP view of [Ni(cyclen)(η 2 -CH 3 CO 2 )] + cation. Hydrogen atoms are not shown for the sake of clarity. Probability ellipsoids are 30%. O(1),O(2),C(1),C(2),N(1),N(3),Ni(1) are approximately coplanar, and the acetate group is symmetrically disposed with respect to a pairs of nitrogen atoms (N(2), N(2A)) of the cyclen. The average Ni N and Ni O distances are and Å, respectively, which are similar to the bond distances previously reported for other nickel(ii) compounds with macrocyclic tetraamine, bipyridine, and nicotinate. 9,13 15 Furthermore, it is well within the general trend that the weaker nickel(ii) nitrogen bonds are observed in the octahedral species (Ni N = Å) than in squareplanar species (Ni N = Å). 16 The N1 Ni N2, N2 Ni N3, and O1 Ni O2 bond angles are 82.69(11), 85.30(11), and 61.47(15), respectively. The deviation of these angles from the ideal octahedral geometry is due to the facts that a four-member chelate ring is formed by the bidentate acetate group, as well as the four fivemember chelate rings are formed by macrocycle cyclen. The distortion is also reflected in the bond angles of N1 Ni O1, N2 Ni N2A, and N3 Ni O2, which are (19), 160.5(2), and (17), respectively. Therefore, the fourand five-member chelate rings provide a very distorted Ni(II) octahedron configuration. The oxygen atoms of the acetate group form hydrogen bonds with secondary amines of the macrocycle from adjacent the molecule [N(3) O(1); Å, N(3) H O(1); ; symmetry code: (iv) x + 1, y, z]. There are two N(3) O(1) hydrogen bonds between every two adjacent molecules, forming an eight-member ring (Fig. 2). The fluorine atoms of BF 4 also form hydrogen bonds with the secondary amines of the macrocycle [N(1) F(3); Å, N(1) H F(3), and N(2) F(1); Å, N(2) H F(1), , symmetry codes: (i) x + 1, y + 1, z 1, (ii) x + 1, y + 1, z + 1, (iii) x + 3/2, y 1/2, z + 3/2] (Table 4). The N(3) O(1) hydrogen bond distances of Å is obvious shorter than those of N(1) F(3) (2.583 Å) and N(2) F(1) (2.241 Å). Perhaps because of the hydrogen bond N(3) H O(1), the Ni(1) O(2) bond distance (2.157(4) Å) is

4 412 Li, Ren, Zhang, and Yang Table 3. Selected Bond Distances (Å) and Angles ( ) Bond distances Ni(1) N(3) 2.034(5) Ni(1) N(2) 2.098(4) Ni(1) N(1) 2.066(4) Ni(1) O(2) 2.157(4) Ni(1) O(1) 2.084(4) O(1) C(1) 1.251(7) Ni(1) N(2)# (4) O(2) C(1) 1.261(7) Bond angles N(3) Ni(1) N(1) 102.1(2) N(2)#1 Ni(1) N(2) 160.5(2) N(3) Ni(1) O(1) 98.19(18) N(3) Ni(1) O(2) (17) N(1) Ni(1) O(1) (19) N(1) Ni(1) O(2) 98.3(2) N(3) Ni(1) N(2)# (11) O(1) Ni(1) O(2) 61.47(15) N(1) Ni(1) N(2)# (11) N(2)#1 Ni(1) O(2) 97.37(11) O(1) Ni(1) N(2)# (11) N(2) Ni(1) O(2) 97.37(11) N(3) Ni(1) N(2) 85.30(11) O(1) C(1) Ni(1) 58.0(3) N(1) Ni(1) N(2) 82.69(11) O(2) C(1) Ni(1) 61.4(3) O(1) Ni(1) N(2) 99.08(11) O(1) C(1) O(2) 119.4(5) clearly longer than that of the Ni(1) O(1) bond (2.084(4) Å). IR and UV Vis spectrum The IR spectrum of the compound displays characteristic strong sharp band at 3183 cm 1, indicating the presence of N H stretching vibration. The strong bands at 1553 and 1446 are assigned to U as ( CO 2 ) and U s( CO 2 ) for the acetate group, respectively, which are finally confirmed by an X-ray diffraction analysis. The UV Vis spectrum has a absorption band at 233 nm, assigned to the charge transfer of O > Ni 2+. In the visible region, there are three absorption bands, the maximum absorption are 358, 560, and 809 nm, which attributed to the d d transition of 3 A 2g > 3 T 1g (p), 3 A 2g > 3 T 1g, and 3 A 2g > 3 T 2g of Ni(II), respectively. Thermal analysis Fig. 2. A crystal packing diagram. Hydrogen bonds are indicated by dotted lines. Hydrogen atoms are omitted for clarity. The thermal decomposition behavior of the compound [Ni(cyclen)(η 2 -CH 3 CO 2 )]BF 4 is studied from 30 to 750 C. The TG curve (Fig. 3) indicates that the compound is stable until 280 C. It shows two steps of weight loss. The first step is at about 280 C. It decomposed and lost the ligand cyclen (the lost weight is 46.08%, calculated value is 45.69%). The second step lost C 2 H 3 OBF 4 group between 380 and 670 C (the lost weight is 34.29%; the calculated value is 34.18%). The residue is NiO after decomposition at high temperature of 750 C (the residue value is 19.66%, calculated value is 19.82%).

5 Crystal structure of a nickel(ii) complex 413 Table 4. Hydrogen Bonding Parameters a D H A D H(Å) H A(Å) D A(Å) D H A (deg) N(1) H(1)...F(3) i N(1) H(1)...F(3) ii N(2) H(2)...F(1) iii N(3) H(3)...O(1) iv a Symmetry codes: (i) x + 1, y + 1, z 1; (ii) x + 1, y + 1, z + 1; (iii) x + 3/2, y 1/2, z + 3/2; (iv) x + 1, y, z. Acknowledgments This research was supported by grants from the National Natural Science Foundation of China (No ) and Shanxi Natural Science Foundation (No. 2002B04). Supplementary material Tables with atomic coordinates, bond lengths, bond angles, and thermal parameters for all atoms, including hydrogen atoms, may be obtained from the authors on request. Crystallographic data for the structure of compound [Ni(cyclen)(η 2 - Fig. 3. TG curve of [Ni(cyclen)(η 2 -CH 3 CO 2 )]BF 4. CH 3 CO 2 )]BF 4 have been deposited with the Cambridge Crystallographic Data Center as supplementary No. CCDC References 1. Eric, L.H.; Judith, N.B. Coord. Chem. Rev. 1998, 173, Kimura, E.; Shin, Aoki, T.; Koike, Motoo, S. J. Am. Chem. Soc. 1997, 119, Kimura, E.; Takeshi, S.; Tohru, K.; Motoo, S. J. Am. Chem. Soc. 1990, 112, Shionoya, M.; Kimura, E.; Shiro, M. J. Am. Chem. Soc. 1993, 115, Karl, W.; Ingolf, T.; Willy, H. Inorg. Chem. 1985, 24, Ronald, H.; Hans, J.S. J. Am. Chem. Soc. 1997, 119, Xian, H.B.; Shou, L.L.; Ruo, H.Z.; Dai, Z.L. Inorg. Chim. Acta 2000, 298, Iitaka, Y.; Shina, M.; Kimura, E. Inorg. Chem. 1974, 13, Andrea, B.; Antonio, B.; Enrique, G.E.; Yves, J.; Miguel, J.; Victor, M.; Michele, P.L. Inorg. Chem. 1990, 29(5), Jack, E.R.; Thomas, J.A. J. Am. Chem. Soc. 1974, April 3, Sheldrick, G.M. Acta Crystallogr. Sec. A 1990, 46, Sheldrick, G.M. SHELXL97, Program for the Refinement of Crystal Structure; University of Gottingen: Germany, Richard, C.H.; Evgenij, A.E.; Feben, T.G. Inorg. Chem. 1996, 35, Basiuk, E.V.; Basiuk, V.A.; Hernandez-Ortega, O.S.; Martinez- Garcia, G.M.; Saniger-Blesa, J.M. Acta. Crystallogr. Sec. C. 2001, 57, Whimp, P.O.; Marcia, F.B.; Curtis, N.F. J. Am. Chem. Soc. (A) 1970, Martin, L.Y.; Sperati, C.R.; Busch, D.H. J. Am. Chem. Soc. 1977, 99, 2968.