Synthesis, stability and structural characterization of a new macrocyclic ligand with four neutral pendent groups: 1,4,7,10-tetrakisbenzyl-1,4,7,10-tetraazacyclo dodecane (L) and its Co and Cu complexes

Article abstract of DOI:10.1016/S0020-1693(02)01065-4

Two new divalent metal complexes of general formula: M(NO₃)₂(L)nH₂O [M = Co (1), n = 0; M = Cu (2), n = 2] which coordinated to a new macrocyclic ligand, 1,4,7,10-tetrakisbenzyl-1,4,7,10-tetraazacyclododecane (L) have been synthesized and characterized structurally by X-ray diffraction. In complex 1, the central Co atom coordinately bonds to four nitrogen atoms of the macrocyclic ligand and two oxygen atoms of a nitrate anion, to form a slightly distorted octahedron. X-ray diffraction indicated that the bonds lengths of Co-N(1) and Co-N(2) are 2.212(7), 2.230(7) ?, respectively. Bond lengths between Co and two oxygen atoms are the same: Co-O(1) 2.142(7) ?. In complex 2 four nitrogen atoms of macrocyclic ligand coordinated to copper atom together with an oxygen atom from water molecule, which defined a five-coordinated tetragonal pyramid. The distances between Cu and nitrogen atoms are Cu-N(1) 2.020(7) ? and Cu-N(2) 2.030(6) ?, respectively. The bond length of Cu-O(1) is 2.126(6) ?. Potentiometric measurements were determined in 1,4-dioxane-water for L, Co and Cu complexes with the formation constants: log K[ML] = 19.79 for Co and 15.61 for Cu.

Full text of DOI:10.1016/S0020-1693(02)01065-4

Inorganica Chimica Acta 340 (2002) 133ꢁ138
/
www.elsevier.com/locate/ica
Synthesis, stability and structural characterization of a new
macrocyclic ligand with four neutral pendent groups:
1,4,7,10-tetrakisbenzyl-1,4,7,10-tetraazacyclo dodecane (L) and
its Co and Cu complexes
Deyuan Kong a,*, Xiaoying Huang b, Yuyuan Xie c
a Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA
b Department of Chemistry, Rugters University, NJ 08102, USA
c Shanghai Institute of Materia Medica, Taiyuan Road 294, Shanghai 200031, People’s Republic of China
Received 20 February 2002; accepted 2 May 2002
Abstract
Two new divalent metal complexes of general formula: M(NO3)2(L)nH2O [Mꢀ
coordinated to a new macrocyclic ligand, 1,4,7,10-tetrakisbenzyl-1,4,7,10-tetraazacyclododecane (L) have been synthesized and
/
Co (1), nꢀ
/
0; Mꢀ
/
Cu (2), nꢀ2] which
/
characterized structurally by X-ray diffraction. In complex 1, the central Co atom coordinately bonds to four nitrogen atoms of the
macrocyclic ligand and two oxygen atoms of a nitrate anion, to form a slightly distorted octahedron. X-ray diffraction indicated that
˚
N(1) and CoꢁN(2) are 2.212(7), 2.230(7) A, respectively. Bond lengths between Co and two oxygen atoms
the bonds lengths of Coꢁ
/
/
˚
O(1) 2.142(7) A. In complex 2 four nitrogen atoms of macrocyclic ligand coordinated to copper atom together
with an oxygen atom from water molecule, which defined a five-coordinated tetragonal pyramid. The distances between Cu and
are the same: Coꢁ
/
˚
˚
˚
O(1) is 2.126(6) A.
nitrogen atoms are Cuꢁ
Potentiometric measurements were determined in 1,4-dioxaneꢁ
log K[ML]ꢀ19.79 for Co and 15.61 for Cu.
# 2002 Elsevier Science B.V. All rights reserved.
/
N(1) 2.020(7) A and Cuꢁ
/
N(2) 2.030(6) A, respectively. The bond length of Cuꢁ
/
/
water for L, Co and Cu complexes with the formation constants:
/
Keywords: Cobalt; Copper; Tetraazamacrocyclic Ligand; Stability constants; X-ray structures
1. Introduction
versatile applications have stimulated research in the
synthesis of novel Cyclen-based ligands with varying
types and numbers of pendent arms in an attempt to
find new ligands having different chemical, biological or
catalytic properties.
The successful application of several 1,4,7,10-tetra-
azacyclododecane (Cyclen) precursors in the synthesis of
macrocyclic complexes stems mainly from their use as
models for proteinꢁ
systems [1], and as selective complexing agents for metal
ions [2ꢁ4], such as therapeutic reagents for the treat-
/metal binding sites in biological
/
ment of metal toxicity [5,6]. Nowadays interest is
focused on the synthesis of macrocyclic complexes
with potential medicinal applications, as contrast-en-
hancing agents in magnetic resonance imaging (MRI)
[7,8], as NMR shift and relaxation reagents [9,10], and
as RNA cleavage catalysts [11,12]. These potential and
In this paper we describe the synthesis of macrocyclic
cobalt(II), copper(II) complexes with a new type of
Cyclen-based ligand having four neutral pendent groups
at N residuals, which have shown high anti-tumor
activities in an MTT assay to HL-60 tumor cell lines
in our former reports [13]. Structures of Co and Cu
* Corresponding author. Tel.: ꢂ
4719
E-mail address: kong@mail.chem.tamu.edu (D. Kong).
/
1-979-845-2732; fax: ꢂ1-979-845-
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 0 6 5 - 4

134
D. Kong et al. / Inorganica Chimica Acta 340 (2002) 133ꢁ138
/
complexes are determined by X-ray diffraction. Also the
thermodynamic stability of these two complexes are
studied via potentiometric methods.
solution containing ligand plus other components (KCl
solution, metal solution) carried out experimental runs.
The p[H] range for accurate measurements was con-
sidered to be 2ꢁ
system, defined as ꢃ
strength employed, was found to be 16.00 for 1,4-
dioxaneꢁwater (70:30 v/v).
/
12. The pKw for the mixed aqueous
/
log([Hꢂ][OHꢃ]) at the ionic
2. Experimental
/
2.1. Materials and methods
2.4. Computations
The ligand was synthesized as reported previously
[13]. GR grade 1,4-dioxane, H2SO4, HBr, MeOH,
NaOH and KCl were purchased from EM Sciences
Protonation constants and stability constants from
the direct titrations were calculated from the potentio-
metric data with the program BEST developed by Martell
group. The error in the constants listed in Table 1 is
Industries Inc. Co(NO3)2×
Ni(NO3)2×6H2O were obtained from Aldrich. IR spectra
were recorded on a Perking Elmer 983G spectrometer in
the range of 4000ꢁ Vis
400 cmꢃ1 using KBr pellets. UVꢁ
/
6H2O, Cu(NO3)2×/6H2O and
/
estimated as 90.02 log unit on the basis of the sfit value,
/
/
/
which measures the deviation of the experimental curve
and the curve calculated from the equilibrium constants,
being less than 0.01 p[H] unit in all potentiometric
determinations. Species distribution diagrams were
computed from the measured equilibrium constants
spectra were recorded on a Shimadazu UV-240 spectro-
meter. Elemental analysis was performed on a P-E 240C
analyzer. All of the metal stock solutions for the
potentiometric studies were reagent grade nitrate salt
solutions prepared with doubly distilled water and
standardized with ion exchange resin. CO2-free Dilute-
it ampoules of KOH were obtained from J.T. Baker Inc.
KOH solutions (about 0.1 M) were prepared with
doubly distilled water and standardized against potas-
sium biphthalate with phenolphthalein as an indicator.
The extent of carbonate accumulation was checked
periodically by titration with a standard HCl solution.
with SPE and plotted with SPEPLOT
.
2.5. Synthesis of the cobalt and copper complexes
2.5.1. Co(C36H44N4)(NO3)2
To a suspension of L (226 mg,0.5 mmol) in EtOH (15
ml), Co(NO3)2×/6H2O (145 mg, 0.5 mmol) was added at
50 8C. The solution changed from pink to violet. The
reaction mixture was stirred overnight, then filtered, and
2.2. Potentiometric equipment
Table 1
Crystallographic data for the cobalt and copper complexes
A Corning 250 digital p[H] meter, fitted with Fisher
full-range blue-glass and Fisher calomel reference elec-
trodes, was used for potentiometric titrations. A Me-
trohm 10-ml capacity piston buret was used for precise
delivery of the standard KOH. The solution to be
studied was contained in a 75-ml jacketed glass cell
Molecular formula
Formula weight
C36H44N6O6Co
715.71
red, prismatic
C36H48N6O8Cu
756.34
blue, prismatic
Crystal color; habit
Crystal dimensions (mm3)
Crystal system
0.20ꢄ0.20ꢄ0.30 0.20ꢄ0.20ꢄ0.30
orthorhombic
monoclinic
thermostated at 2590.05 8C by a circulating constant-
/
Unit cell dimensions
˚
temperature water bath.
a (A)
˚
24.146(7)
8.080(5)
17.860(6)
9.542(2)
16.757(3)
11.323(2)
102.20(3)
1769.6(6)
P21/m
2
b (A)
˚
c (A)
2.3. Potentiometric determinations
b (8)
3
V (A )
˚
3484(5)
Cmc21
All p[H] calibrations were performed with standar-
dized HCl aqueous solutions to measure hydrogen ion
Space group
Z
4
1.364
concentrations directly (p[H]ꢀ
/
ꢃ
log[H]ꢂ). The ionic
/
Dcalc (g cmꢃ3
F(000)
)
1.419
798
1508.00
25
strength was adjusted to 0.100 M with KCl. The
electrodes were calibrated by taking the average calcu-
lated E8 of 20 separate titration points of a titration of
dilute standardized HCl. Titrations of the ligand in the
absence or presence of metal ions in aqueous solution
were conducted in the manner described by Martell and
Motekaitis [14]. Cell solutions (generally, 50 ml) were
purged with a purified argon stream to create an inert
atmosphere. Standard base was introduced into the
sample solutions with a Metrohm piston buret in small
increments. Adding increments of standard base to a
umax (8)
27
0.678
m (cmꢃ1
Function minimized
p-factor
)
5.47
a 6(jFojꢃjFcj)2
a 6(jFojꢃjFcj)2
0.03
0.03
1316
No. observations (I ꢀ2.5s(I) 1544
and I ꢀ2s(I))
No. variables
231
247
Residuals: R, Rw 0.074, 0.090
Goodness-of-fit 3.65
Maximum shift of final cycle 0.01
0.087, 0.1442
1.103
0.00
Peak, hole in final difference 0.47; ꢃ0.48
0.49; ꢃ0.45
ꢃ3
˚
map (e A
)

D. Kong et al. / Inorganica Chimica Acta 340 (2002) 133ꢁ
/138
135
Table 2
product was dried over CaCl2. Yield: 344 mg, 92%. M.p.
(dec.) 185 8C. Anal. Found: C, 57.91; H, 6.67; N, 11.78.
˚
Selected bond lengths (A) and bond angles (8) of
[(C36H44N4)Co(NO3)](NO3)
Calc. for Cu(C36H44N4)(NO3)2×
/
1.5H2O: C, 57.85; H,
6.34; N, 11.24%. IR spectrum (KBr pellet): 3425b,m,
1479m, 1385s, 1331s, 1057m, 949w, 706m cmꢃ1
Bond lengths
.
Coꢁ
Coꢁ
Coꢁ
/
O(1)
N(1)
N(2)
2.142(7) C(1)ꢁ
2.212(7) C(2)ꢁ
2.230(7) C(2)ꢁ
1.273(9) C(3)ꢁ
/
C(2)
C(3)
C(7)
C(4)
C(5)
C(6)
C(7)
C(9)
1.52(1)
1.38(1)
1.39(1)
1.38(1)
1.38(2)
1.35(2)
1.41(1)
1.25(2)
1.52(1)
1.38(1)
1.31(2)
1.34(2)
1.36(2)
1.44(2)
1.14(4)
/
/
/
/
O(1)ꢁ
O(2)ꢁ
O(3)ꢁ
O(4)ꢁ
O(5)ꢁ
N(1)ꢁ
N(1)ꢁ
N(1)ꢁ
N(2)ꢁ
N(2)ꢁ
N(2)ꢁ
/
N(3)
N(3)
N(4)
N(4)
N(4)
/
3. Crystallography
/
1.21(1)
1.24(2)
1.25(1)
1.22(2)
1.50(1)
1.49(2)
1.50(2)
1.46(1)
1.52(1)
1.43(2)
1.36(2)
1.31(3)
C(4)ꢁ
C(5)ꢁ
C(6)ꢁ
C(8)ꢁ
C(10)ꢁ
C(11)ꢁ
C(11)ꢁ
C(12)ꢁ
C(13)ꢁ
C(15)ꢁ
C(17)ꢁ
/
/
/
/
/
Red (cobalt) and blue (copper) crystals were obtained
from slow diffusion of ether into complex DMF
solution. Crystals have approximate dimensions of
/
/
/
C(1)
/
C(11)
C(12)
C(16)
C(13)
C(14)
C(16)
C(17)
/
C(8)
/
0.20ꢄ
/
0.20ꢄ
0.30 mm3 were mounted on a glass fiber.
Data were collected on a Rigaku AFC 7R diffract-
/
/
C(17)
/
/
C(9)
/
/
C(10)
/
ometer with graphite-monochromated Mo Ka radiation
/
C(18)
/
˚
(lꢀ
/
0.071069 A) using the technique v ꢁ
/
2u at 20 8C to
C(14)ꢁ
/
C(15)
C(18)
/
a maximum 2u value of 50.0 8C. An empirical correc-
tion, applied using the program DIFABS [15], resulted in
correction factors ranging from 0.89 to 1.00. The
structure was solved by direct methods and expanded
using Fourier techniques [16,17]. Some non-hydrogen
atoms were refined anisotropically, while the rest were
refined isotropically. All hydrogen atoms were intro-
duced in calculated positions. Scattering factors were
taken from the literature [18]. All calculations were
performed using the TEXSAN crystallographic software
package. Details of data collection and structure refine-
ment are listed in Table 1 [19]. Selected bond lengths and
bond distances, angles are listed in Tables 2 and 3,
respectively.
C(18)ꢁ
/
Bond angles
O(1)ꢁCoꢁ
O(1)ꢁCoꢁ
O(1)ꢁCoꢁ
O(1)ꢁCoꢁ
O(1)ꢁCoꢁ
O(1)ꢁCoꢁ
N(1)ꢁCoꢁ
N(1)ꢁCoꢁ
N(1)ꢁCoꢁ
N(2)ꢁCoꢁ
CoꢁO(1)ꢁ
CoꢁN(1)ꢁ
CoꢁN(1)ꢁ
CoꢁN(1)ꢁ
CoꢁN(2)ꢁ
CoꢁN(2)ꢁ
CoꢁN(2)ꢁ
C(1)ꢁ
N(2)ꢁ
C(8)ꢁN(1)ꢁ
C(12)ꢁ
C(11)ꢁ
C(11)ꢁ
/
/
O(1)
N(1)
N(1)
N(2)
N(2)
N(1)
60.0(4) C(9)ꢁ
91.2(3) C(10)ꢁ
132.6(3) N(1)ꢁC(1)ꢁ
92.7(2) C(1)ꢁC(2)ꢁ
133.0(3) C(1)ꢁC(2)ꢁ
132.6(3) C(3)ꢁC(2)ꢁ
82.2(5) C(2)ꢁC(3)ꢁ
80.0(3) C(3)ꢁC(4)ꢁ
131.4(3) C(4)ꢁC(5)ꢁ
78.9(4) C(5)ꢁC(6)ꢁ
92.8(6) C(2)ꢁC(7)ꢁ
113.5(5) N(1)ꢁC(8)ꢁ
105.7(7) N(2)ꢁC(9)ꢁ
102.6(7) C(1)ꢁN(1)ꢁ
106.7(7) C(10)ꢁ
110.9(5) C(10)ꢁ
107.8(6) C(12)ꢁ
110.0(1) C(13)ꢁ
116.5(7) N(1)ꢁC(17)ꢁ
116.0(2) N(2)ꢁC(18)ꢁ
119.0(1) C(9)ꢁN(2)ꢁ
122.0(1) C(14)ꢁC(15)ꢁ
120.0(1)
/
N(2)ꢁ
N(2)ꢁ
C(2)
/
C(18)
109.0(1)
113.0(1)
114.5(7)
120.2(8)
121.3(8)
118.4(8)
121.0(1)
120.0(1)
121.0(1)
119.0(1)
121.0(1)
124.0(1)
122.0(1)
108.8(9)
119.2(9)
122.0(1)
118.0(1)
123.0(1)
126.3(6)
122.2(6)
109.6(9)
117.0(1)
/
/
/
/C(18)
/
/
/
/
/
/
/
/
C(3)
C(7)
C(7)
C(4)
C(5)
C(6)
C(7)
C(6)
/
/
/
/
/
/
/
/
/
/
N(1)
N(2)
N(2)
N(2)
N(3)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C(1)
/
/
C(9)
C(8)
C(17)
/
/
C(8)
/
/
/
/
C(17)
/
/
/
/
C(9)
/
C(11)ꢁ
C(11)ꢁ
C(13)ꢁ
C(14)ꢁ
/C(12)
/
/
C(10)
/
/
C(16)
C(14)
C(15)
/
/
C(18)
/
/
4. Results and discussion
/N(1)ꢁ
/C(8)
/
/
/
C(10)ꢁ
/
C(11)
/
/C(17)
/
/C(17)
/
/C(18)
The reaction of the tetradentate ligand L with Co(II)
and Cu(II) salt in equimolar ratios gave crystalline
/
C(11)ꢁ
C(12)ꢁ
C(16)ꢁ
/C(16)
/
/C(10)
/
/C(13)
/
/C(16)
compounds having the general formula [ML](NO3)2×
nH2O (nꢀ0, MꢀCo; nꢀ1.5, MꢀCu, see below for
suggested structures of these two metal complexes).
/
/
/C(15)
/
/
/
/
the red residue was washed repeatedly with CH2Cl2 and
EtOH. The product was dried over P2O5 in vacuo.
Yield: 220 mg, 61%. M.p. (dec.) 215 8C. Anal. Found:
C, 60.21; H, 6.30; N, 11.38. Calc. for
Co(C36H44N4)(NO3)2: C, 60.41; H, 6.20; N, 11.74%.
IR spectrum (KBr pellet): 2841w, 1475m, 1385s, 1335s,
The electronic spectra of the complexes were recorded in
methanol solution. Absorption maxima in the 200ꢁ800
nm region are shown that the copper complex exhibited
/
1065m, 950w, 706m cmꢃ1
.
two strong absorption bands at 208, 262 nm which can
2.5.2. Cu(C36H44N4)(NO3)2×
/
1.5H2O
be assigned to pꢁ
/
p* intraligand transitions, and one
Cu(NO3)2×6H2O (121 mg, 0.5 mmol) was dissolved
/
absorption at 360 (oꢀ
/
664.5 Mꢃ1 cmꢃ1) which corre-
into EtOH (20 ml) at 60 8C with stirring. Then L (226
mg, 0.5 mmol) was added to this solution, meanwhile a
blue precipitate deposited quickly. The reaction mixture
slurry was stirred overnight. After filtration using a
sintered glass filter, dark blue crystals were obtained
which were washed twice with 1:1 Et2O:EtOH. The
spond to the charge transitions between ligand and
metal ion. The spectrum of the Cobalt complex is
indicative of a six coordination sphere, giving two bands
at 480 (oꢀ
cmꢃ1
nm which correspond to the transitions
4T1g(F)ꢃ4
/
16.5 Mꢃ1 cmꢃ1) and 560 (oꢀ40.2 Mꢃ1
/
)
4
/
T1g(P) and T1g(F)ꢃA2g(F) [20].
/

136
D. Kong et al. / Inorganica Chimica Acta 340 (2002) 133ꢁ138
/
Table 3
Bond
˚
(A)
lengths
and
bond
angles
(8)
of
[(C36H44N4)Cu(OH2)](NO3)2×(H2O)
Bond lengths
Cuꢁ
Cuꢁ
Cuꢁ
/
O(1)
N(1)
N(2)
2.126(6)
2.020(7)
2.030(6)
C(9)ꢁ
C(10)ꢁ
N(2)ꢁ
/
C(10)
C(12)
1.366(12)
1.354(12)
1.500(10)
1.510(14)
1.534(10)
1.387(11)
1.364(12)
1.376(11)
1.399(11)
1.391(10)
1.398(10)
1.371(11)
1.494(11)
1.516(9)
/
/
/
/
C(6)
O(3)ꢁ
O(4)ꢁ
O(5)ꢁ
O(6)ꢁ
O(7)ꢁ
O(8)ꢁ
N(1)ꢁ
C(3)ꢁ
C(5)ꢁ
C(7)ꢁ
C(7)ꢁ
C(8)ꢁ
/
N(3)
N(3)
N(3)
N(4)
N(4)
N(4)
1.217(12) N(2)ꢁ
1.238(12) C(1)ꢁ
1.268(12) C(14)ꢁ
1.258(12) C(15)ꢁ
1.251(13) C(16)ꢁ
1.180(12) C(17)ꢁ
1.440(12) C(13)ꢁ
1.294(13) C(13)ꢁ
1.517(10) C(11)ꢁ
/
C(4)
/
/
C(7)
/
/
C(15)
C(16)
C(17)
C(18)
C(18)
C(14)
C(12)
/
/
/
/
/
/
/
C(3)
C(4)
C(13)
C(11)
C(8)
C(9)
/
/
/
/
/
/
1.354(10) N(1)ꢁ
1.377(11) N(2)ꢁ
1.389(12) N(2)ꢁ
/
C(2)
C(1)
C(5)
/
/
/
/
1.478(9)
Bond angles
N(2)ꢁ
N(1)ꢁ
N(1)ꢁ
N(1)ꢁ
C(3)ꢁ
C(3)ꢁ
C(2)ꢁ
C(3)ꢁ
C(2)ꢁ
C(1)ꢁ
C(5)ꢁ
C(5)ꢁ
C(6)ꢁ
C(5)ꢁ
C(6)ꢁ
C(4)ꢁ
N(1)ꢁ
C(4)ꢁC(3)ꢁ
/
Cuꢁ
Cuꢁ
Cuꢁ
Cuꢁ
/
O(1)
O(1)
N(1)
N(2)
101.6(2)
106.7(2)
86.6(4)
C(8)ꢁ
C(7)ꢁ
C(10)ꢁ
C(12)ꢁ
C(7)ꢁC(11)ꢁ
C(10)ꢁC(12)ꢁ
C(18)ꢁC(13)ꢁ
C(18)ꢁC(13)ꢁ
C(14)ꢁC(13)ꢁ
C(15)ꢁC(14)ꢁ
C(16)ꢁC(15)ꢁ
C(15)ꢁC(16)ꢁ
C(17)ꢁ
C(18)ꢁ
C(5)ꢁ
C(11)ꢁC(7)ꢁ
C(11)ꢁC(7)ꢁ
C(4)ꢁ
/
C(7)ꢁ
C(8)ꢁ
C(9)ꢁ
C(10)ꢁ
C(12)
/
C(1)
C(9)
C(8)
C(9)
119.1(8)
121.1(8)
119.6(10)
119.4(10)
121.9(9)
120.5(9)
118.8(8)
121.6(8)
119.6(8)
121.0(9)
119.5(9)
120.9(9)
120.3(8)
119.5(8)
116.3(6)
117.5(8)
123.2(8)
118.6(10)
/
/
/
/
Fig. 1. ORTEP drawing of [Co(L)(NO3)](NO3) complex. Ellipsoids are
drawn at the 30% probability level, and the hydrogen atoms are
omitted for clarity.
/
/
/
/
/
/
151.6(3)
111.3(9)
111.5(7)
111.5(7)
104.0(6)
104.3(5)
113.8(5)
110.1(7)
107.5(8)
/
/
/
N(1)ꢁ
N(1)ꢁ
N(1)ꢁ
N(1)ꢁ
N(1)ꢁ
N(1)ꢁ
N(2)ꢁ
N(2)ꢁ
N(2)ꢁ
N(2)ꢁ
N(2)ꢁ
N(2)ꢁ
C(1)ꢁ
/
C(2)
C(1)
C(1)
Cu
/
/
/
/
/
/
C(11)
C(14)
C(5)
/
/
/
/
/
/
/
/
/
/Cu
/
/C(5)
/
/Cu
/
/
C(13)
C(14)
C(17)
C(18)
C(17)
/
/
C(6)
C(4)
C(4)
Cu
/
/
/
/
/
/
/
/
117.7(10) C(16)ꢁ
/
/
/
/
115.2(5)
102.8(5)
103.9(6)
115.5(7)
C(13)ꢁ
/
/
/
/Cu
N(2)ꢁ
/
/
C(13)
/
/Cu
/
/C(8)
/
/C(7)
/
/C(1)
/
/
N(1)
119.9(11) C(3)ꢁ
/
/N(2)
4.1. Structure of [CoL(NO3)](NO3)
Fig. 2. ORTEP drawing of [Cu(L)(H2O)](NO3)2H2O. Ellipsoids are
drawn at the 20% probability level, and the hydrogen atoms and lattice
water molecule are omitted for clarity.
X-ray quality crystals of the Co complex were grown
from DMF by slow diffusion of Et2O at room tempera-
ture for several days. The solid structure of a packing of
discrete [CoL(NO3)]ꢂ cations, and the other nitrate ion
as counter ion, as illustrated in Figs. 1 and 2. The X-ray
crystal data are summarized in Table 1. Selected bond
lengths and bond angles are listed in Table 2. The
central Co atom in the cation is in as six-coordinate
environment (N4O2), being coordinated by all four
nitrogen atoms of the macrocyclic ring and the two
oxygen atoms from nitrate which serves as a bidentate
ligand. The coordination geometry can be described as a
nearly perpendicular to each other. O(1) O(1)*, O(2) and
N(3) atoms, Co, N(1), N(2), C(8) and C(9) atoms are
coplanar. All carbon atoms of phenyl ring are in one
˚
plane with the mean deviation 0.0114 and 0.0295 A.
Dihedral angle between these two planes is 32.198. Four
phenyl rings adopt an counterclockwise geometry.
4.2. Structure of [CuL(H2O)](NO3)2
The structure of the copper complex consists of
[CuL]2ꢂ, NO3 anions and H2O molecules. The copper
ꢃ
distorted octahedron. Bond lengths of Coꢁ
/
N are almost
2.230(7) A range. Bond lengths for
˚
equal in the 2.212(7)ꢁ
/
atom is five-coordinated, with approximate square
pyramidal geometry, by the four nitrogen atoms of the
macrocyclic ring and one oxygen atom of water. One
water molecule crystallizes in lattice. In the cation, Cu
and O(1) reside on a crystallographic imposed mirror
˚
Coꢁ
are: O(1)ꢁ
O(1)ꢁCoꢁN(1) 91.2(3)8 O(1)ꢁ
/
O(1) are 2.142(7) A. Bond angles between O, Co, N
CoꢁN(1) 132.6(3)8 O(1)ꢁCoꢁN(2) 92.7(2)8
CoꢁN(2) 133.0(3)8. The
/
/
/
/
/
/
/
/
other bond angles around Co atom are slightly larger or
smaller than 908, which indicates that these atoms were
plane. Both Cuꢁ
/
N and CuꢁO distances are shorter than
/

D. Kong et al. / Inorganica Chimica Acta 340 (2002) 133ꢁ
/138
137
those of Coꢁ
/
N and Coꢁ
/
O. The unit cell contains two
molecule units, and two hydrogen bonds are formed
basicity of this ligand is lower than the other two ligands
for lone pairs electron density of nitrogen atom well
between the coordinated/uncoordinated water molecules
˚
delocalized in phenyl group via pꢁp conjugation effect.
/
and two nitrate counter ions: O(1)ꢁ
/
H(1)ꢀ ꢀ ꢀO(6) 2.737 A
Fig. 3 showed that three components are formed in the
protonation reaction of the ligand.
˚
and O(2)ꢁ
/
H(3)ꢀ ꢀ ꢀO(7) 2.952 A.
In these complexes the macrocycle ligand takes a
trans-I configuration in which all the lone pairs in the
four basal nitrogens are oriented on the same side of the
macrocyclic ligand plane[12] and the 12-membered ring
is folded by the coordination of the metal atoms. The
degrees of folding from the Co complex to the Cu
The stability constants of Co and Cu complexes with
this ligand are listed and compared with L? and Lƒ. The
species distribution diagram of Cobalt complexes is
shown in Fig. 4. The four coordinated [CoL]2ꢂ specie is
the most prominent component in the pH range of 2ꢁ
/8.
Then the first water molecule attacked the Coꢁ
/L
complex are presented by both increase in the N(1)ꢁ
/
Mꢁ
/
complex at pH 9.0 and another hydroxide species
formed at pH 10.52, which completed the six-coordi-
nated sphere around Co ion. Whereas, the Cu(OH)L
species exist in major component of this binary system,
N(1) angles and N(1)ꢁMꢁN(2) angles. All metal ions
/
/
are high above the mean plane formed by the four basal
macrocyclic nitrogens. Four phenyl rings attached with
nitrogen atoms are situated on one side of the macro-
cyclic ligand and imposed the coordinated water or
nitrate ion coordinated tightly with the central metal
ions.
which formed started from acidic area (pHB5). The
/
potentiometric studies showed that these two metal
complexes have different bind ability with the ligand
and form different type of coordination sphere toward
coordination saturation. This ligand shows higher
binding ability toward copper(II) than cobalt(II) ions.
4.3. Potentiometric titrations
The protonation constants of ligand and stabiltiy
5. Supplementary material
constants of Coꢁ
/
L, CuꢁL were determined by direct
/
titration of the corresponding mixed solutions (1,4-
dioxane-H2O 70:30 v/v for L and metal complexes
with 0.1 M KCl as the supporting material). The results
are shown in Table 4. Compared with the known parent
ligand Cyclen, the first protonation constants is 1.23 log
unit lower. This is ascribed to four benzyl pendent
groups, which form superconjugating system with amine
atoms and reduce the basicity of them. Marcos et al.
reported the existence of four naphthylmethyl pendent
groups also low its first protonation constant to 8.64 in
parent ligand Cyclam (1,4,8,11-tetraazacyclotetrade-
cane) [21]. Recently, we have reported the first proto-
nation constants of ligand (L?): 1,4,7,10-tetrakis(2-
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 153829 and 153830. Copies of
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (fax: ꢂ44-1223-336-033; e-mail: depos-
/
carbamoylethyl)-1,4,7,10-tetraazacyclododecane,
10.31, also lower than that of Cyclen, because of four
is
carbamoylethyl pendent groups [22]. The overall proto-
nation constants log bꢀ
/
16.02 which is lower than
18.48) about
5 or 2 log units, respectively. This indicates that the
Cyclen (log bꢀ21.70) [23] and L? (log bꢀ
/
/
Fig. 3. Species distribution diagram for the ligand.
Table 4
Logarithms of deprotonation constants of ligand and stability constants of complexes (mꢀ0.100 M KCl, tꢀ25 8C, under argon)
Equilibrium quotient, K
log K
L
L?
Cyclen (Lƒ)
Coꢁ
/
L
Cuꢁ
/
L
Coꢁ/L?
Cuꢁ/L?
Coꢁ
/
Lƒ
CuꢁLƒ
/
[HL]/[L][H]
[H2L]/[HL][H]
9.37
4.59
2.06
10.31
6.83
1.34
10.65
9.64
1.4
[H3L]/[H2L][H]
[ML]/[M][L]
19.79
ꢃ9.04
ꢃ10.52
15.61
17.11
ꢃ7.67
ꢃ6.59
15.00
ꢃ12.3
14.1
24.6
[ML(OH)][H]/[ML]
[ML(OH)2][H]/[ML(OH)]

138
D. Kong et al. / Inorganica Chimica Acta 340 (2002) 133ꢁ138
/
[5] R.A. Bullman, Struct. Bond. (Berlin) 67 (1987) 41.
[6] D. Bryee-Smith, Chem. Soc. Rev. 15 (1986) 93.
[7] J.L. Bousquet, S. Saini, D.D. Stark, P.F. Hahn, M. Nigam, J.
Wittenberg, J. Feerucci, J. Radiol. 166 (1983) 693.
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¨
¨
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Fig. 4. Species distribution diagrams indicating the species present as
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[12] B.F. Baker, H. Kahlili, N. Wei, J.R. Morrow, J. Am. Chem. Soc.
119 (1998) 38.
/
Co(II) at 25 8C, mꢀ
/
0.100 M (KCl). %ꢀ
/
percent of total concentra-
[13] D.Y. Kong, L.H. Meng, L. Song, Y.Y. Xie, Transition Met.
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tion of the ligand (1ꢄ
/
10ꢃ3 M) set at 100%.
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Stability Constants, 2nd ed., VCH, New York, 1992.
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Netherlands, 1992
Acknowledgements
Thanks for the Mr. Jie Sun of Shanghai Institute
Organic Chemistry, Chinese Academy of Sciences for
solving the crystal structure of the cobalt complex.
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/
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