헥사아자 거대 두고리, 8-메틸- 및 8-에틸-1, 3, 6, 8, 10, 13-헥사아자 바이시클로[11. 3. 1] 헵타데칸의 합성과 성질

김 성 권

(주) 세풍 공학 연구소

Synthesis and Properties of Ni(II) and Cu(II) Complexes of the hexaaza Macrobicycles, 8-methyl-and 8-ethyl-1, 3, 6, 8, 10, 13-Hexaazabicyclo[11. 3. 1] heptadecane

Sung Kwon Kim

Sepoong Engineering R&D Center

Introduction

Metal template synthesis often provide selective routes toward products that are not obtainable in the absence of metal ion. Especially, template reactions involving formadehyde and amine macrocyclic, and preparation of saturated polyaza multidentate macrocyclic and macropolycyclic complexes.1, 2 In these reactions, formaldehyde links two amine moieties in the cyclization to yield methylenediamine(N-CH2-N) linkage. For example, Ni(II) and Cu(II) complexes of 1 were prepared from the template condensation reactions as described in eq. 13.

The ligand 1 highly interesting because they contain six nitrogen atoms in the macrocyclic framework but acting as tetradentates. Particularly, ligand 1 contains rarely occurring both a methyl pendant arm at the uncoordinated nitrogen atom and one 1, 2-diazacyclopentane small ring moiety. It has been known that the size of small-ring moieties toward to the macrocyclic ligand and various alkyl pendant arms at the uncoordinated nitrogen atom significantly affect the metal-donor distance as well as the spectroscopic and electrochemical properties of the complexes.4-5 Therefore, we have attempted to prepare the complex of 3,8-Alkyl-1,3,6,8,10,13-hexaazabicyclo[11.3.1] heptadecane, from the condensation reaction of N-(2-aminoethyl)-1,3- propanediamine, ethylenediamine, formaldehyde and appropriate primaryalkylamine(methylamine for 2 and ethylamine for 3) in the presence of Ni(II) and Cu(II) ion to see how the spectroscopic properties by the nature of the small ring moieties and various alkyl pendant arms moieties fused to the 14-membered macrocyclic framework.

This paper presents the synthesis and properties of the new Ni(II) and Cu(II) complexes of 2 and 3, Comparisons which those of the complexes of 1 are also described.

Experimental Section

[Ni(2)][ClO4]2. To a stirred methanol solution (60ml) of NiCl2.6H2O (5.0g) were slowly added N-(2-aminoethyl-1, 3-propanediamine(3.6ml), ethylenediamine(1.9ml), 40% methylamine(2.5 ml) and 36%-aqueous formaldehyde(9.2ml) with stirring. The mixture was heated at reflux for 32h until a dark orange solution resulted. The solution was filtered to remove insoluble material and cooled to room temperature. A saturated methanol solution of excess LiClO4.3H2O was added to the filtrate, and the solution was stored in refrigerator until orange crystals formed. The crystals were filtered, washed with methanol, and dried in vacuo. The crystals were recrystallized from hot water. Yield: -30%, Anal. Calcd for NiC12H28N6Cl2O8: C, 27.55 ; H, 5.39; N,16.06. Found: C, 27.45; H, 5.38; N, 15.92.

[Ni(3)][ClO4]2. This compound was prepared by a method similar to that for [Ni(2)][ClO4]2 except that 70% ethylamine(2.3 ml) was used instead of methylamine. Yield: -25%. Anal Calcd for NiC13H30N6Cl2O8: C, 29.45; H, 5.63; N, 15.64. Found: C, 29.18; H, 5.90; N, 15.29.

[Cu(2)][ClO4]2. This compound was prepared by a method similar to that for [Ni(2)][ClO4]2 except that Cu(OAc)2.H2O was used instead of NiCl2.6H2O. The red crystals of square-planar complexes were filterered out, which were mixed with a trace amount of five-coordinated complexes, the products were fractionally free of blue solid were obtained. Yield: -20%. Anal Calcd for CuC12H28N6Cl2O8: C,27.30; H, 5.34; N, 15.92. Found: C, 27.11; H, 5.26; N, 15.86.

[Cu(3)][ClO4]2. This compound was prepared by a method similar to that for [Cu(2)][ClO4]2. Yield: -18%. Anal Calcd for CuC13H30N6Cl2O8: C, 29.30; H, 5.67; N, 15.77. Found: C, 28.95; H, 5.49; N, 15.32.

Results and Discussion

New hexaaza macrobicyclic complexes [M(L)][ClO4]2 (L=2, 3: M=Ni(II), Cu(II)) were prepared by the template condensation of N-(2-aminoethyl)-1, 3- propanediamine, ethylenediamine, formaldehyde and primaryalkylamine (methylamine for 2 and ethylamine for 3) in the presence of metal ion, followed by addition of excess lithium perchlorate. The value of molar conductance (Table 1) indicate that [M(L)][ClO4]2 (M=Ni(II), Cu(II); L=2, 3) are 1:2 electrolytes in aqueous solutions.

[Ni(L)][ClO4]2 and [Cu(L)][ClO4]2 (L=2, 3) are extremely stable in the crystalline state and are relatively stable against ligand dissociation even in highly acidic solutions. Spectra of aqueous solutions of [Ni(2)]2+(5.9 x 10-3 M) and those of [Ni(3)]2+ (5.0 x 10-3 M) indicate that 18% and 20%, respectively, of the complexes were decomposed in 10h at 25oC upon the addition of HNO3(0.3M). With the same conditions, only 10% of [Cu(2)]2+ and 13% of [Cu(3)]2+ were decomposed  in 18h. Other Ni(II) and Cu(II) complexes of macrocyclic ligands with 5-6-5-6 chelate ring sequence were also reported to decompose slowly even in highly acidic solutions. 4, 6

The infrared spectra (Table 1) of the Ni(II) and Cu(II) complexes of 2 and 3 show a single absorption around 3200cm-1, which is attributed to □NH of the coordinated secondary amines. A much higher □NH value(3210 cm-1) for [Ni(2)][ClO4]2 than that (3181cm-1) for [Ni(1)][ClO4)2 indicate that the Ni-N interaction in [Ni(2)][ClO4]2 containing 1, 3-diazacyclohexane ring moieties in the macrocycle is much weaker than in [Ni(1)][ClO4]2 containing 1, 3-diazacyclopentane ring moieites. The electronic absorption spectra (Table 1) of [Ni(2)]2+ and [Ni(3)]2+ show that the complexes have square-planar Ni(II)- N4 chromophore.7, 8

Equilibrium between [Ni(L)]2+ and [Ni(L)](H2O)2]2+(L=2, 3) in water. Some tetraaza macrocyclic Ni(II) complexes exist in water as equilibrium mixtures of yellow diamagnetic square-planar [Ni(L)]2+ and blue(or violet) paramagnetic octahedral [Ni(L)(H2O)2]2+ species. 9, 10

K

[Ni(L)]2+	[Ni(L)(H2O)2]2+

The equilibrium has been reported to be dependent on temperature, ionic strength, and the nature of the added electrolyte. Thermodynamic data for the equilibrium process are listed in Table 2. The equilibrium constant [k=□/□lim-□)] were determined at different temperature, and □Ho values were obtained from a lnK vs 1/T plot, and □So value from □Go=□Ho-T□So. Although stronger Ni-N bonds are involved in the square-planar species than in octahedral species11 ,this endothermic effect is exceeded by exothermic effect resulting from the formation of the two axial Ni-OH2 bonds, making □Ho values negative. The value of □So for various ligand system nearly correspond to those expected for the loss of freedom of two water molecules in the octahedral species (30-40) x 2 JK-1mol-1, The value of □Ho and □So for the square-planar/octahedral conversion of Ni(II) complexes are much more negative for 3 than for 2. The reason for the steric effect is not clear. However, interaction of solvent molecules with the square-planar and the octahedral complexes(eg. at uncoordinated nitrogens) could be affected by the alkyl substituents.

References

1. Harrowfield, J. B.; Lay, P. A.; Sargeson, A. M. J. Am. Chem. Soc. 1983, 105, 5503.

2. Geue, R. J.; Sargeson, A.; M. Inorg. Chem. 1985, 24, 1607.

3. Kang, S. G.; Jung, S.; Kwon, J. Bull. Kor. Chem. Soc. 1990, 11, 431.

4. Busch, D. H. Acc. Chem, Res. 1978, 11, 392.

5. Fabbrizzi, L. J. Chem. Soc. Dalton Trans. 1979, 1857,

6. Lin, C. T.; Margerum, D. W.; Inorg. Chem. 1975, 14, 919.

7. Hay, R. W.; Bembi, R, Inorg. Chim. Acta. 182, 59, 147.

8. Fabbrizzi, L. Inorg. Chem. 1977, 16, 2667.

9. Hay, R. W.; Piplani, D. P. J. Chem. Soc. Dalton Trans. 1977, 1956.

10. Fabbrizzi, L. Inorg. Chem. 1977, 18, 438.

11. Ito, T.; Toriumi, K. Chem. Lett. 1978, 1395.

Table I. Spectral and Conductance Data for Hexaaza Macrocyclic Ni(II) and Cu(II) Complexes

complex	IR, cm-1	electronic spectraa □max, nm (□, M-1cm-1)	□Ma M-1cm-1M-1
[Ni(2)][ClO4]2 [Ni(3)][ClO4]2 [Ni(1)][ClO4]2c [Cu(2)][ClO4]2 [Cu(3)][ClO4]2 [Cu(1)][ClO4]2c	3210 3260, 3245, 3205 3181 3250 3260 3235	472(78)b, 454(57) 460(80)b, 458(56) 446(69)b, 448(77) 516(99)b, 500(96) 502(105)b, 521(119) 506(109)b, 490(102)	215 205 210 204 202 210

aIn aqueous solutions at 25oC unless otherwise specfied. bIn nitro methane solutions. cRef. 3

Table II. Thermodynamic Data for the Equilibrium

[Ni(L)]2+ + 2H2O	[Ni(L)](H2O)2]2+

L	K25oC	-□Ho KJmol-1	-□So JK-1mol-1	ref
2 3 1	0.58 0.62 0.12	18.3 20.2 11.3	69.2 79.8 52.3	this work this work 3