The title compound, [N-(2-pyridylmethyl)-(L)-alanine]Co(III) thiocyanate ( 1 ) was obtained from the reaction of Co(OOCH3)2·H2O with the tridentate reduced Schiff base ligand, N-(2-pyridylmethyl)-(L)-alanine (L) and NH4SCN and characterized by elemental analysis, IR, UV-visible, TGA and single- crystal X-ray diffraction. Structural and spectroscopic analyses reveal [Co(L)2)]SCN to be monomeric with Cobalt(III) adopting a pseudo-octahedral geometry, coordinating to two reduce Schiff base ligands. In the crystal lattice, the thiocyanate anion forms an intermolecular SCN···HNamine hydrogen bond, while adjacent monomers are linked by intermolecular Ocarboxyl···HNamine···H-bonds to form a supramolecular network. This work is therefore undertaken in an attempt to construct coordination framework structures of varying properties using the mixed-ligand strategy involving reduced Schiff bases and the thiocyanate ion .
Cobalt complexes of Schiff base ligands are an important class of coordination compounds due to their structural diversity which display geometries ranging from tetrahedral, bipyramidal, square pyramidal to octahedral [
Reduced Schiff base ligands have been found to be relatively inert towards air oxidation and are strongly coordinating due to the reduction of the N=C bond, giving rise to flexible multidentate ligands [
Recent attention has been focused on the study of the coordination compounds of cobalt due to its varied oxidation states and their interesting structural, magnetic, electronic and optoelectronic properties [
Elemental analysis for carbon, nitrogen and hydrogen were carried out on a FLASH 2000 Organic Elemental Analyzer, CHNS-O analyser by Thermo Scientific. Thermo Scientific iCAP 6000 SERIES duo ICAP Spectrometer was used to determine the metal content. Thermogravimetric analysis was investigated using a Mettler Toledo TGA/DSC1 STAR System; Infrared spectra were recorded on a Perkin-Elmer model IR-457 spectrometer and a spectrum 100 FT-IR Perkin Perkin-Elmer spectrometer, while the UV/Vis spectrum was recorded using an Agilent HP8453 Diode Array UV/Vis Spectrometer. The magnetic susceptibility measurement was made using the Sherwood Scientific magnetic susceptibility balance; while X-ray diffraction was carried using a Bruker APEX diffractometer.
N-(2-pyridylmethyl)-(L)-alanine) (L)(0.361 g, 2 mmol) in 10 mL aqueous ethanol was added drop wise to a 5 ml aqueous solution of Co(OOCH3)2∙H2O (0.249 g, 1 mmol,) while stirring at room temperature. After stirring for a further 10 minutes,
Scheme 1. Synthesis and structure of N-(2-pyridylmethyl)-L-alanine) isothiocyanate Cobalt(III).
NH4SCN, (0.16 g, 2 mmol,) in 2 mL distilled water was added drop wise and stirring continued for a further two hours. Rectangular reddish brown crystals suitable for X-ray analysis were obtained from the solution by slow evaporation. Yield: 81%; anal. Calc. (Found) for C19H22N5O4SCo; C:48.00 (47.92); H:4.66 (4.78); N: 14.73 (14.72); S: 6.74 (6.69); Co: 12.40 (12.28). The synthesis of N-(2-pyridylmethyl)-L-alanine) isothiocyanate Cobalt(III) is summarized in Scheme 1.
A suitable single crystal of the title compound was mounted on a glass fiber on the goniometer head of a Bruker APEX diffractometer and data were collected using graphite monochromated Cu-Kα radiation (λ = 1.54178 Å, operating at 50 kV and 40 mA) at a temperature of 100 K. Crystal data, data collection and structure refinement details are summarized in
The structure was solved by direct methods and refined by full-matrix least squares on F2 [
In the IR spectrum of the Co(III) complex, a very strong infrared absorption band at 1609 cm−1 is attributed to υC=C and υC=N of the pyridyl ring, while the strong band at 2098 cm−1 suggest the presence of N=C=S stretch [
The thermal behaviour of the title compound (
Empirical formula Formula weight Temperature Wavelength Crystal system Space group Unit cell dimensions Volume Z Density (calculated) Absorption coefficient F(000) Crystal size Theta range for data collection Index ranges Reflections collected Independent reflections Completeness to theta = 67.00˚ Absorption correction Max. and min. transmission Refinement method Data/restraints/parameters Goodness-of-fit on F2 Final R indices [I > 2sigma(I)] R indices (all data) Absolute structure parameter Largest diff. peak and hole | C19H22CoN5O4S 475.41 100(2) K 1.54178 Å Monoclinic P2(1) a = 9.8179(4) Å α = 90˚. b = 7.3412(3) Å β = 106.813(3)˚. c = 14.4414(6) Å γ = 90˚. 996.37(7) Å3 2 1.585 Mg/m3 8.064 mm−1 492 0.20 × 0.08 × 0.03 mm3 3.20˚ to 72.11˚. −12 ≤ h ≤ 10, −9 ≤ k ≤ 8, −17 ≤ l ≤ 17 4709 3009 [R(int) = 0.0497] 98.4% Semi-empirical from equivalents 0.7939 and 0.584652 Full-matrix least-squares on F2 3009/1/281 0.776 R1 = 0.0408, wR2 = 0.0819 R1 = 0.0539, wR2 = 0.0861 −0.010(5) 0.587 and −0.350 e.Å−3 |
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organic ligands [calc. 75.2% (found 75.8%)]. The final residue of [24.15% (calc. 24.61%)) represents a mixture of Cobalt oxides, CoO and Co2O3.
The peak at m/z = 474.1 corresponds to C19H22N5O4SCo (calc. 475.41) which confirms the molecular weight of the compound. The effective magnetic moment, μeff was found to be consistent with a d6 low-spin configuration with some degree of spin-orbit coupling.
The structure of the title compound (I) is represented in Scheme 1 and comprise the [Co(L)2]+ cation and the NCS− anion with the resulting complex having the composition [Co(L)2]+NCS−. The two L ligands are bonded to the cobalt centre via their two pyridyl nitrogen atoms (Co(1)-N(1), 1.931(3) Å; Co(1)-N(3), 1.929(3) Å), two secondary amine nitrogen atoms (Co(1)-N(2), 1.971(4)Å; Co(1)-N(4), 1.967(3) Å) and two carboxylate oxygen atoms (Co(1)-O(2), 1.884(3) Å; Co(1)-O(4), 1.891(3) Å) to give a pseudo octahedral geometry around the cobalt atom (
Co(1)-O(2) Co(1)-O(4) Co(1)-N(3) Co(1)-N(1) Co(1)-N(4) Co(1)-N(2) O(3)-C(18)-O(4) N(5)-C(19)-S(1) O(2)-Co(1)-O(4) O(2)-Co(1)-N(3) O(4)-Co(1)-N(3) O(2)-Co(1)-N(1) O(4)-Co(1)-N(1) N(3)-Co(1)-N(1) O(2)-Co(1)-N(4) O(4)-Co(1)-N(4) N(3)-Co(1)-N(4) N(1)-Co(1)-N(4) O(2)-Co(1)-N(2) O(4)-Co(1)-N(2) N(3)-Co(1)-N(2) N(1)-Co(1)-N(2) N(4)-Co(1)-N(2) | 1.884(3) 1.891(3) 1.929(3) 1.931(3) 1.967(3) 1.971(4) 122.9(4) 178.9(4) 86.73(14) 91.93(13) 88.55(17) 93.53(13) 93.77(18) 174.18(16) 171.62(16) 86.88(17) 82.50(14) 92.29(14) 86.41(15) 172.66(16) 94.30(18) 84.03(18) 100.19(18) |
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D-H...A | d(D-H) | d(H...A) | d(D...A) | <(DHA) |
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N(4)-H(4A)...N(5)#1 N(2)-H(2A)...O(3)#2 | 0.87(4) 0.88(5) | 2.03(5) 2.26(5) | 2.892(5) 2.997(5) | 174(4) 141(4) |
Symmetry transformations used to generate equivalent atoms: #1 x − 1, y, z #2 x, y − 1, z.
We have isolated a Co(III) Isothiocyanate metal-organic framework containing the chiral ligand, N-(2-pyridylmethyl)-L-alanine (pyala). Spectroscopic studies and the x-ray structure show that the compound is a monomer in which Cobalt(III) adopts a pseudo octahedral geometry, coordinating to two molecules of the ligand. Adjacent monomeric centres are linked by N-H…O, N-H…S hydrogen bonds which stabilize the compound thus forming a 3D supramolecular networks.
The authors thank the Royal Society―DFID capacity building initiative program for mobility bursary to (NS-JE).
The authors declare that there is no conflict of interest.
Ntum, S.-J.E., Paboudam, A.G., Conde, A.M., Nyamen, L.D., Mohamadou, A., Raftery, J. and Ndifon, P.T. (2017) Synthesis and Crystal Structure of N-(2-Pyridylmethyl)-L-Alanine) Isothiocyanate Cobalt(III). Crystal Structure Theory and Applications, 6, 39-56. https://doi.org/10.4236/csta.2017.63004
[N-(2-pyridylmethyl)-(L)-alanine]Co(III)thiocyanate
Computing details
Data collection: Bruker Apex diffractometer; Data collection: Graphite monochromated Cu-kα radiation (λ = 1.54178 Å); structure solved by: Direct methods; refined by: Full matrix least square method; all calculations were carried out by: SHELXTL package.
Crystal data
Data collection
Refinement
x | y | z | U(eq) | |
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C(1) C(2) C(3) C(4) C(5) | 1690(5) 583(5) −123(5) 331(5) 1451(5) | 4175(7) 3899(7) 5428(7) 7165(8) 7319(7) | 3505(3) 3909(3) 4109(3) 3942(3) 3555(3) | 15(1) 21(1) 22(1) 22(1) 19(1) |
C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) Co(1) N(1) N(2) N(3) N(4) N(5) O(1) O(2) O(3) O(4) S(1) | 2428(4) 5010(5) 6004(5) 5752(5) 4486(4) 5308(5) 6703(4) 7235(5) 6361(4) 2951(4) 1945(5) 404(5) 2918(5) 9040(5) 3622(1) 2112(3) 3808(4) 5000(3) 2268(3) 9758(4) 6903(3) 5048(3) 3036(3) 3549(3) 8003(1) | 2659(6) 3078(7) 1571(6) 4892(7) 5285(6) 5304(6) 5895(8) 6450(6) 6430(6) 4702(7) 7696(6) 8204(7) 9048(6) 2628(7) 5922(1) 5869(7) 3315(5) 5844(6) 5787(6) 3657(6) 4966(5) 6324(4) 10,609(5) 8482(4) 1191(2) | 3169(3) 3978(3) 3869(3) 4298(3) 1065(3) 431(3) 772(3) 1727(3) 2313(3) 800(3) 1036(3) 948(4) 1701(3) 1589(3) 2717(1) 3327(2) 3055(3) 2000(2) 1414(2) 1330(3) 4911(2) 3892(2) 1433(2) 2563(2) 1938(1) | 14(1) 17(1) 23(1) 18(1) 16(1) 19(1) 19(1) 20(1) 18(1) 16(1) 18(1) 21(1) 16(1) 20(1) 12(1) 15(1) 14(1) 15(1) 14(1) 23(1) 20(1) 14(1) 21(1) 15(1) 29(1) |
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x | y | z | U(eq) | |
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H(2) H(3) H(4) H(5) H(6A) H(6B) H(7) H(8A) H(8B) H(8C) H(11) H(12) H(13) H(14) | 317 −912 −124 1766 1821 2603 4574 5467 6754 6434 4924 7294 8195 6723 | 2706 5289 8219 8501 2191 1651 2689 433 1410 1892 4923 5920 6841 6841 | 4045 4359 4093 3445 2543 3645 4493 3699 4481 3358 −221 354 1972 2962 | 25 26 26 23 17 17 21 35 35 35 23 23 24 22 |
H(15A) H(15B) H(16) H(17A) H(17B) H(17C) H(4A) H(2A) | 2479 2881 2097 −238 225 236 1490(50) 4030(50) | 4941 3384 7774 7380 9460 8097 5220(60) 2630(80) | 106 923 381 489 716 1582 1400(30) 2620(40) | 20 20 21 32 32 32 7(11) 20(15) |
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U11 | U22 | U33 | U23 | U13 | U12 | |
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C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) C(17) C(18) C(19) Co(1) N(1) N(2) N(3) N(4) N(5) O(1) O(2) O(3) O(4) S(1) | 17(2) 23(2) 19(2) 25(2) 21(2) 16(2) 17(2) 21(2) 21(2) 17(2) 23(2) 22(2) 15(2) 17(2) 19(2) 21(2) 19(2) 22(2) 15(2) 14(1) 14(2) 18(2) 16(2) 10(1) 19(2) 22(2) 18(1) 32(2) 19(2) 35(1) | 15(3) 17(3) 30(3) 22(3) 12(2) 10(2) 15(3) 14(3) 22(3) 9(2) 13(2) 16(2) 20(3) 20(3) 13(2) 13(2) 18(3) 13(2) 26(3) 10(1) 16(2) 11(2) 11(2) 14(2) 29(3) 19(2) 12(2) 12(2) 10(2) 24(1) | 11(2) 21(2) 16(2) 17(2) 21(2) 18(2) 18(2) 29(2) 15(2) 22(2) 22(2) 24(2) 25(2) 18(2) 16(2) 19(2) 28(2) 16(2) 17(2) 13(1) 17(2) 16(2) 18(2) 16(2) 20(2) 16(2) 12(1) 20(1) 16(2) 32(1) | 2(2) 5(2) −4(2) −6(2) −3(2) 2(2) 6(2) −6(2) −2(2) 2(2) 2(2) 3(2) 1(2) 3(2) −4(2) 3(2) 3(2) 1(2) −3(2) 0(1) 0(2) −1(2) 2(2) −2(2) −2(2) 2(1) 0(1) 2(1) 0(1) −2(1) | 2(2) 5(2) 5(2) 5(2) 2(2) 7(2) 3(2) 0(2) 8(2) 5(2) 6(2) 14(2) 5(2) 6(2) 3(2) 7(2) 9(2) 8(2) 3(2) 4(1) 6(1) 6(2) 6(1) 4(1) 6(2) −2(1) 4(1) 9(1) 6(1) 18(1) | 0(2) 1(2) −4(2) 3(2) −2(2) 3(2) 0(2) 5(2) 3(2) 0(2) 4(2) 6(2) 0(2) −1(2) −2(2) 2(2) −1(2) 2(2) 4(2) 0(1) −3(2) −1(2) 0(2) −4(2) −3(2) 1(1) −1(1) −1(1) 1(1) −8(1) |
C(1)-N(1) C(1)-C(2) C(1)-C(6) C(2)-C(3) C(2)-H(2) C(3)-C(4) C(3)-H(3) C(4)-C(5) C(4)-H(4) C(5)-N(1) C(5)-H(5) C(6)-N(2) C(6)-H(6A) C(6)-H(6B) C(7)-N(2) C(7)-C(8) C(7)-C(9) C(7)-H(7) C(8)-H(8A) C(8)-H(8B) C(8)-H(8C) C(9)-O(1) C(9)-O(2) C(10)-N(3) C(10)-C(11) C(10)-C(15) C(11)-C(12) C(11)-H(11) C(12)-C(13) C(12)-H(12) C(13)-C(14) C(13)-H(13) C(14)-N(3) C(14)-H(14) C(15)-N(4) C(15)-H(15A) C(15)-H(15B) C(16)-N(4) C(16)-C(18) C(16)-C(17) C(16)-H(16) C(17)-H(17A) C(17)-H(17B) | 1.359(6) 1.388(7) 1.484(6) 1.393(7) 0.9500 1.394(7) 0.9500 1.375(6) 0.9500 1.337(6) 0.9500 1.491(5) 0.9900 0.9900 1.513(5) 1.513(6) 1.524(6) 1.0000 0.9800 0.9800 0.9800 1.218(5) 1.301(6) 1.361(5) 1.384(6) 1.505(6) 1.385(6) 0.9500 1.387(6) 0.9500 1.369(6) 0.9500 1.350(5) 0.9500 1.489(6) 0.9900 0.9900 1.505(6) 1.514(6) 1.527(6) 1.0000 0.9800 0.9800 |
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C(17)-H(17C) C(18)-O(3) C(18)-O(4) C(19)-N(5) C(19)-S(1) Co(1)-O(2) Co(1)-O(4) Co(1)-N(3) Co(1)-N(1) Co(1)-N(4) Co(1)-N(2) N(2)-H(2A) N(4)-H(4A) N(1)-C(1)-C(2) N(1)-C(1)-C(6) C(2)-C(1)-C(6) C(1)-C(2)-C(3) C(1)-C(2)-H(2) C(3)-C(2)-H(2) C(2)-C(3)-C(4) C(2)-C(3)-H(3) C(4)-C(3)-H(3) C(5)-C(4)-C(3) C(5)-C(4)-H(4) C(3)-C(4)-H(4) N(1)-C(5)-C(4) N(1)-C(5)-H(5) C(4)-C(5)-H(5) C(1)-C(6)-N(2) C(1)-C(6)-H(6A) N(2)-C(6)-H(6A) C(1)-C(6)-H(6B) N(2)-C(6)-H(6B) H(6A)-C(6)-H(6B) N(2)-C(7)-C(8) N(2)-C(7)-C(9) C(8)-C(7)-C(9) N(2)-C(7)-H(7) C(8)-C(7)-H(7) C(9)-C(7)-H(7) C(7)-C(8)-H(8A) C(7)-C(8)-H(8B) H(8A)-C(8)-H(8B) C(7)-C(8)-H(8C) | 0.9800 1.226(5) 1.288(5) 1.166(6) 1.643(5) 1.884(3) 1.891(3) 1.929(3) 1.931(3) 1.967(3) 1.971(4) 0.88(5) 0.87(4) 122.1(4) 114.8(4) 122.9(4) 117.8(5) 121.1 121.1 119.8(4) 120.1 120.1 118.6(5) 120.7 120.7 122.5(5) 118.8 118.8 109.8(4) 109.7 109.7 109.7 109.7 108.2 110.8(4) 110.4(4) 113.9(4) 107.2 107.2 107.2 109.5 109.5 109.5 109.5 |
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H(8A)-C(8)-H(8C) H(8B)-C(8)-H(8C) O(1)-C(9)-O(2) O(1)-C(9)-C(7) O(2)-C(9)-C(7) N(3)-C(10)-C(11) N(3)-C(10)-C(15) C(11)-C(10)-C(15) C(10)-C(11)-C(12) C(10)-C(11)-H(11) C(12)-C(11)-H(11) C(11)-C(12)-C(13) C(11)-C(12)-H(12) C(13)-C(12)-H(12) C(14)-C(13)-C(12) C(14)-C(13)-H(13) C(12)-C(13)-H(13) N(3)-C(14)-C(13) N(3)-C(14)-H(14) C(13)-C(14)-H(14) N(4)-C(15)-C(10) N(4)-C(15)-H(15A) C(10)-C(15)-H(15A) N(4)-C(15)-H(15B) C(10)-C(15)-H(15B) H(15A)-C(15)-H(15B) N(4)-C(16)-C(18) N(4)-C(16)-C(17) C(18)-C(16)-C(17) N(4)-C(16)-H(16) C(18)-C(16)-H(16) C(17)-C(16)-H(16) C(16)-C(17)-H(17A) C(16)-C(17)-H(17B) H(17A)-C(17)-H(17B) C(16)-C(17)-H(17C) H(17A)-C(17)-H(17C) H(17B)-C(17)-H(17C) O(3)-C(18)-O(4) O(3)-C(18)-C(16) O(4)-C(18)-C(16) N(5)-C(19)-S(1) O(2)-Co(1)-O(4) O(2)-Co(1)-N(3) | 109.5 109.5 123.5(5) 121.3(4) 115.1(4) 122.2(4) 113.3(4) 124.5(4) 118.3(4) 120.8 120.8 119.6(4) 120.2 120.2 119.3(4) 120.4 120.4 122.1(4) 118.9 118.9 106.7(4) 110.4 110.4 110.4 110.4 108.6 110.6(4) 110.9(4) 108.7(4) 108.9 108.9 108.9 109.5 109.5 109.5 109.5 109.5 109.5 122.9(4) 120.8(4) 116.2(4) 178.9(4) 86.73(14) 91.93(13) |
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O(4)-Co(1)-N(3) O(2)-Co(1)-N(1) O(4)-Co(1)-N(1) N(3)-Co(1)-N(1) O(2)-Co(1)-N(4) O(4)-Co(1)-N(4) N(3)-Co(1)-N(4) N(1)-Co(1)-N(4) O(2)-Co(1)-N(2) O(4)-Co(1)-N(2) N(3)-Co(1)-N(2) N(1)-Co(1)-N(2) N(4)-Co(1)-N(2) C(5)-N(1)-C(1) C(5)-N(1)-Co(1) C(1)-N(1)-Co(1) C(6)-N(2)-C(7) C(6)-N(2)-Co(1) C(7)-N(2)-Co(1) C(6)-N(2)-H(2A) C(7)-N(2)-H(2A) Co(1)-N(2)-H(2A) C(14)-N(3)-C(10) C(14)-N(3)-Co(1) C(10)-N(3)-Co(1) C(15)-N(4)-C(16) C(15)-N(4)-Co(1) C(16)-N(4)-Co(1) C(15)-N(4)-H(4A) C(16)-N(4)-H(4A) Co(1)-N(4)-H(4A) C(9)-O(2)-Co(1) C(18)-O(4)-Co(1) | 88.55(17) 93.53(13) 93.77(18) 174.18(16) 171.62(16) 86.88(17) 82.50(14) 92.29(14) 86.41(15) 172.66(16) 94.30(18) 84.03(18) 100.19(18) 119.0(4) 126.0(4) 114.9(3) 111.6(3) 108.6(3) 108.8(3) 108(3) 106(3) 114(4) 118.5(4) 126.1(3) 115.1(3) 111.5(3) 107.5(2) 108.3(3) 106(3) 110(3) 113(3) 116.0(3) 115.2(3) |
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Symmetry transformations used to generate equivalent atoms.
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