Homo and heterodinuclear complexes derived from unsymmetrical macrocyclic ligands with two coordination sites: Removal of a pendant arm and migration of copper ion upon cyclization

Article abstract of DOI:10.1080/00958972.2012.687103

The dinucleating macrocyclic ligands (L^2a)^2- and (L^2b)^2- were prepared by [1:1] cyclic condensation of N,N′-dipropionitrile-N,N′-ethylene-di(5-methyl-3-formyl-2- hydroxybenzylamine or N,N′-dipropionitrile-N,N′-ethylene-di(5-bromo- 3-formyl-2-hydroxybenzylamine with 1,3-diaminopropane. The ligands include dissimilar N(amine)₂O₂ and N(imine)₂O ₂ coordination sites sharing two phenolic oxygen atoms and containing two propionitrile pendant arms on the amine nitrogen atoms. A series of mono- and dinuclear complexes were synthesized and characterized on the basis of elemental analysis, molar conductance measurement, X-ray crystallography, IR, NMR, and UV-Vis spectroscopies as well as cyclic voltammetric measurements. During the cyclization copper(II) migrates from the N(amine)₂O ₂ to the N(imine)₂O₂ coordination site and one of the propionitrile pendant arms is removed. The heterodinuclear complexes [ZnL²Cu(OAc)]⁺ were prepared by a transmetallation reaction. The characterization results showed that the two metal ions are bridged by two phenolic oxygen atoms and an acetate group, providing distorted five-coordinate geometries for both metals.

Full text of DOI:10.1080/00958972.2012.687103

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Homo and heterodinuclear complexes
derived from unsymmetrical
macrocyclic ligands with two
coordination sites: removal of a
pendant arm and migration of copper
ion upon cyclization
Hamid Golchoubian a , Davood Sadeghi Fateh b , Giuseppe Bruno c
& Hadi Amiri Rudbari c
a Department of Chemistry, University of Mazandaran,
47416-95447, Babol-sar, Iran
b Department of Chemistry, Mohammad Reza Hariri Science
Foundation, 47146-38474, Babol, Iran
c Dipartimento di Chimica Inorganica, Università di Messina,
Villaggio S Agata, Salita Sperone, 31, 98166 Messina, Italy
Version of record first published: 14 May 2012.
To cite this article: Hamid Golchoubian , Davood Sadeghi Fateh , Giuseppe Bruno & Hadi Amiri
Rudbari (2012): Homo and heterodinuclear complexes derived from unsymmetrical macrocyclic
ligands with two coordination sites: removal of a pendant arm and migration of copper ion upon
cyclization, Journal of Coordination Chemistry, 65:11, 1970-1991
To link to this article: http://dx.doi.org/10.1080/00958972.2012.687103
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Journal of Coordination Chemistry
Vol. 65, No. 11, 10 June 2012, 1970–1991
Homo and heterodinuclear complexes derived from
unsymmetrical macrocyclic ligands with two coordination
sites: removal of a pendant arm and migration
of copper ion upon cyclization
HAMID GOLCHOUBIAN*y, DAVOOD SADEGHI FATEHz,
GIUSEPPE BRUNOx and HADI AMIRI RUDBARIx
yDepartment of Chemistry, University of Mazandaran, 47416-95447, Babol-sar, Iran
zDepartment of Chemistry, Mohammad Reza Hariri
Science Foundation, 47146-38474, Babol, Iran
xDipartimento di Chimica Inorganica, Universita di Messina,
Villaggio S Agata, Salita Sperone, 31, 98166 Messina, Italy
(Received 18 November 2011; in final form 14 March 2012)
The dinucleating macrocyclic ligands (L2a 2ꢀ and (L2b 2ꢀ
) were prepared by [1 : 1] cyclic
)
condensation of N,N0-dipropionitrile-N,N0-ethylene-di(5-methyl-3-formyl-2-hydroxybenzyla-
mine or N,N0-dipropionitrile-N,N0-ethylene-di(5-bromo-3-formyl-2-hydroxybenzylamine with
1,3-diaminopropane. The ligands include dissimilar N(amine)2O2 and N(imine)2O2 coordina-
tion sites sharing two phenolic oxygen atoms and containing two propionitrile pendant arms
on the amine nitrogen atoms. A series of mono- and dinuclear complexes were synthesized
and characterized on the basis of elemental analysis, molar conductance measurement,
X-ray crystallography, IR, NMR, and UV-Vis spectroscopies as well as cyclic voltammetric
measurements. During the cyclization copper(II) migrates from the N(amine)2O2 to the
N(imine)2O2 coordination site and one of the propionitrile pendant arms is removed. The
heterodinuclear complexes [ZnL2Cu(OAc)]þ were prepared by a transmetallation reaction.
The characterization results showed that the two metal ions are bridged by two phenolic oxygen
atoms and an acetate group, providing distorted five-coordinate geometries for both metals.
Keywords: Heterodinuclear complex; Pendant arm ligand; Unsymmetrical compartmental
ligand; Macrocyclic ligand; Copper migration; Crystal structure
1. Introduction
Syntheses of macrocyclic unsymmetrical compartmental ligands and their dinuclear
complexes have received increasing interest due to unique physicochemical properties
associated with metal–metal interactions [1–5], their potential to mimic the active sites
of the metalloenzymes [6], their ability to stabilize unusual oxidation states [7], their
catalytic properties [8], and also their possibilities for mutual influences of two metal
centers on the electronic, magnetic, and electrochemical properties [9]. Among the
*Corresponding author. Email: h.golchobian@umz.ac.ir
Journal of Coordination Chemistry
ISSN 0095-8972 print/ISSN 1029-0389 online ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/00958972.2012.687103

Homo and heterodinuclear complexes
1971
X
X
NC
N
Me
O-
O-
N
N
N
O-
O-
N
N
O-
O-
N
N
N
N
N
N
(CH2)n
(CH2)n
(CH2)m
(CH2)m
N
Me
N
NC
X
X
n, m = 2, 3
n, m = 2, 3, 4
2
X = Me, Br
3
X = Me, Br
1
Scheme 1. Phenol-based macrocyclic dicompartmental ligands with pendant arms.
various types of dinucleating ligands, phenol-based two compartmental ligands have
been attracted wide attention because of their capabilities to accommodate simulta-
neously two metal ions in close proximity [10–14]. Many unsymmetrical phenol-based
dinucleating ligands with shape and flexibility of the coordination compartment, the
nature of donors and their relative position, the number of donors and size of the
chelating ring have been developed. Special attention has focused on unsymmetrical
compartmental ligands containing two pendant arms as shown in scheme 1 (types 1
and 2) and their metal complexes [15–22]. The pendant arms could have additional
potential ligating groups. Okawa and coworkers introduced the unsymmetrical
dinucleating ligands type 1 (scheme 1) [23] whose pendant arms were inactive for
coordination to metal ions. However, elegant development of unsymmetrical
dicompartmental ligand by Bosnich and coworkers [12] made use of ligating picolyl
pendant arms attached to the nitrogen donors in one compartment as shown by 2 in
scheme 1.
In continuation of our research work on the generation of unsymmetrical ligands
with dissimilar compartments [24–29] we report here the synthesis of heterodinuclear
complexes with unsymmetrical macrocyclic ligand containing two propionitrile pendant
arms, shown as 3 in scheme 1. The idea behind this design was based on results that
showed acetonitrile coordinated to Co(II), Ni(II), and Cu(II) [30–32] in macrocyclic
complexes type 1 shown in scheme 1.
2. Experimental
2.1. Materials and measurements
All chemicals were of analytical grade. Solvents were purified by conventional methods.
Elemental analyses were performed by a LECO CHN-600 Elemental Analyzer.
Absolute metal percentages were determined by a Varian-spectra A-30/40 atomic

1972
H. Golchoubian et al.
absorption-flame spectrometer. Conductance measurements were made at 25ꢁC with a
Jenway 400 conductance meter on 1.00 ꢂ 10ꢀ3 mol Lꢀ1 samples in acetonitrile. 1H NMR
and 13C NMR spectra were measured with Bruker 500 and 400 DRX Fourier Transform
Spectrometers at room temperature. UV-Vis spectra were obtained on a Cicil CE5501
spectrophotometer at room temperature in acetonitrile and solid state. Infrared (IR)
spectra were recorded in KBr by a single beam Bruker VECTOR22 FTIR from 400 cmꢀ1
to 4000 cmꢀ1. Cyclic voltammograms were recorded using a EG&G Model 263 A
interfaced to a PC via a GPIB interface from þ2 V to ꢀ2 V in deaerated CH3CN with
0.1 mol Lꢀ1 n–Bu4NPF6 (TBAHFP) supporting electrolyte and 1.0 mmol Lꢀ1 sample.
Redox potentials were measured using a three-electrode system consisting of a glassy
carbon (working), platinum wire (auxiliary), and Ag/Agþ (non-aqueous (CH3CN),
reference) electrodes. All samples were dried to constant weight under high vacuum
prior to analysis. The compounds 2-hydroxy-3-chloromethyl-5-methylbenzaldehyde
and 2-hydroxy-3-chloromethyl-5-bromobenzaldehyde were prepared by standard
method [33].
2.2. Syntheses
2.2.1. N,N9-bis-(2-cyanoethyl)-ethylenediamine. To a deoxygenated aqueous solution
(20 mL) of ethylenediamine (13.35 mL, 0.20 mol) acrylonitrile (65.75 mL, 1.00 mol) was
added dropwise during 40 min at room temperature. The resultant pale yellow solution
was stirred for 30 min and the solvent was then removed under vacuum. The residual
of the water was further removed by passing the product through anhydrous CaCl2.
The desired diamine formed as a pale yellow liquid (4.9 g, 95%), sufficiently pure
for further treatment. IR (ꢀ/cmꢀ1): 2247 (CꢃN str.), 2915 and 2847 (C–H str.
Aliphatic), 3380 (N–H str.). UV-Vis (nm; "max) 258 (5360). 1H NMR (400 MHz in D2O)
ꢁ: 2.70 (t, 4 H, J ¼ 6.8 Hz, CCH2CN), 2.76 (s, 4 H, NCH2CH2N), 2.93 (t, 4 H,
J ¼ 6.8 Hz, NCH2CH2CN). 13C NMR (100.08 MHz in D2O) ꢁ: 17.46 (CCH2CN), 43.95
(NCH2CH2CN), 47.13 (NCH2CH2N), 120.60 (CH2CN). Mass spectrum showed the
dominant peak at m/e 114 corresponding to loss of two CN moieties from C8H14N4.
2.2.2. 1,6-Bis(2-cyanoethyl)-2,5-bis(2-hydroxy-3-formyl-5-methylbenzyl)-2,5-diazahexane,
L1aH2. 2-Hydroxy-3-chloromethyl-5-methylbenzaldehyde (0.92 g, 5.0 mmol) was dis-
solved in 1,3-dioxalane (25 mL) and anhydrous Na2CO3 (1.38 g, 13.0 mmol) was added.
To the resulting mixture, N,N0-bis-(2-cyanoethyl)-ethylenediamine (0.42 g, 2.50 mmol)
was added. The reaction mixture, after stirring at 100ꢁC for 6 h, was allowed to cool
to room temperature and was then filtered through Celite. Dioxalane was removed
in vacuum to give a thick orange-brown oil, which was treated with an aqueous solution
of HCl (4 mol Lꢀ1) in an ice-bath to reach pH ¼ 1. The yellow suspension was then
extracted by CH2Cl2 (3 ꢂ 20 mL). The aqueous layer was adjusted to pH ꢄ 7.0 with
aqueous NaOH (40%) and then to pH ꢄ 8.4 by the addition of a saturated aqueous
solution of NaHCO3. The oily mixture was extracted with CH2Cl2 (4 ꢂ 10 mL) and the
combined organic extracts were dried over Na2SO4. Filtration and concentration under
reduced pressure gave essentially pure L1aH2 as a pale brown oil, 1.07 g (93%).
Although the crude compound can be used in further treatment without any problem
it was purified as follows: to an ethanol solution (10 mL) of crude L1aH2 was added

Homo and heterodinuclear complexes
1973
1.4 mL Et3N (10.0 mmol) and 0.425 g LiCl (10.0 mmol) in absolute ethanol (10 mL)
which immediately resulted in a yellow solid. After stirring the reaction mixture for 1 h,
the resultant Li2L1a was collected, washed with ethanol (2 ꢂ 3 mL), Et2O (2 ꢂ 3 mL),
and pentane (2 ꢂ 3 mL) and dried under vacuum. Li2L1a was obtained as a pale yellow
solid. Li2L1a was converted to pure L1aH2 by dissolving it in dichloromethane (10 mL)
with HCl (gas) bubbled slowly through a stirred solution for 5 min. A colorless
precipitate formed almost immediately. The solid was separated by filtration. To the
colorless precipitate was added an aqueous saturated solution of NaHCO3 (20 mL) and
the mixture was then extracted with CH2Cl2 (4 ꢂ 10 mL). The resultant organic layers
were collected and dried through anhydrous Na2SO4. Filtration and concentration
under reduced pressure resulted in L1aH2 as a pale yellow oil. In purification almost
1
70% of the compound was lost. H NMR (500.13 MHz in CDCl3) ꢁ: 2.25 (s, 6H,
ArCH3), 2.50 (t, J ¼ 6.4 Hz, 4H, CH2–CN), 2.70 (s, 4H, N–CH2–CH2–N), 2.84
(t, J ¼ 6.4 Hz, 4H, NCCH2CH2–N), 3.69 (s, 4H, Ar–CH2–N), 7.27 (s, 2H, Ar–H), 7.34
(s, 2H, Ar–H), 9.91 (s, 2H, Ar–CHO), 11.01 (br, s, 2H, Ar–OH). 13C NMR (125 MHz in
CDCl3) ꢁ: 16.2 (CH2–CN), 20.7 (ArCH3), 44.3 (Ar–CH2–N), 50.2 (NCCH2CH2–N),
52.4 (N–CH2–CH2–N), 119.3 (CH2CN), 121.3 (Ar), 125.7 (Ar), 129.3 (Ar), 131.9 (Ar),
138.7 (Ar), 158.3 (Ar), 195.5 (Ar–CHO). When one drop of D2O was added to the
1H NMR sample, the broad signal at 11.01 ppm disappeared. IR (ꢀ/cmꢀ1): 1670 (C¼O
str.), 2248 (CꢃN str.), 2848 (C–H str. aliphatic), 3010 (C–H str. aromatic), 3430
(O–H str.).
2.2.3. 1,6-Bis(2-cyanoethyl)-2,5-bis(2-hydroxy-3-formyl-5-bromobenzyl)-2,5-diazahexane,
L1bH2. This compound was prepared (91%) by the method applied for L1aH2 except
that 2-hydroxy-3-chloromethyl-5-bromobenzaldehyde was used in place of 2-hydroxy-
3-chloromethyl-5-methylbenzaldehyde. 1H NMR (500.13 MHz in CDCl3) ꢁ: 2.57
(t, J ¼ 6.8 Hz , 4H, CH2–CN), 2.81 (s, 4H, N0–CH2–CH2–N), 2.91 (t, J ¼ 6.8 Hz, 4H,
NCCH2CH2–N), 3.76 (s, 4H, Ar–CH2–N), 7.69 (s, 2H, Ar–H), 7.70 (s, 2H, Ar–H), 9.98
(s, 2H, Ar–CHO), 11.25 (br, s, 2H, Ar–OH). 13C NMR (125 MHz in CDCl3) ꢁ: 16.5
(CH2–CN), 50.2 (Ar–CH2–N), 52.0 (NCCH2CH2–N), 52.2 (N–CH2–CH2–N), 112.1
(CH2CN), 119.0 (Ar), 122.7 (Ar), 128.8 (Ar), 134.3 (Ar), 139.8 (Ar), 159.3 (Ar), 194.5
(Ar–CHO). When one drop of D2O was added to the 1H NMR sample, the broad signal
at 11.25 ppm disappeared. IR (ꢀ/cmꢀ1): 1668 (C¼O str.), 2248 (CꢃN str.), 2831 (C–H
str. aliphatic), 3068 (C–H str. aromatic).
2.3. Metal complexes
All [ML1] complexes were prepared by
a general procedure described for
[ZnL1a(H2O)2]. All complexes are insoluble in common solvents used and cannot be
purified by recrystallization.
[ZnL1a(H2O)2]: To L1aH2 (1.12 g, 2.1 mmol) and Et3N (0.88 mL, 4.3 mmol) in ethanol
(20 mL) was added Zn(OAc)2 ꢅ 4H2O (0.44 g, 2.1 mmol) in methanol (10 mL). The initial
pale yellow solution turned yellow and a yellow precipitate formed almost immediately.
The reaction mixture was stirred for 6 h. The solid was collected with suction filtration
and washed with methanol (2 ꢂ 10 mL), Et2O (2 ꢂ 10 mL) and hexane (2 ꢂ 10 mL) and
dried in vacuum. [ZnL1a(H2O)2] was obtained as a yellow solid (0.60 g, 51%). Selected
IR data (ꢀ/cmꢀ1 using KBr): 3468 (m, O–H str.), 2931 and 2848 (w, C–H str.), 2249

1974
H. Golchoubian et al.
(w, CꢃN str.), 1659 (s, C¼O str.), 1457 (s, C¼C str. aromatic). Anal. Calcd for
C26H28N4O4Zn ꢅ 2H2O (Mw ¼ 561.94 g molꢀ1) (%): C, 55.57; H, 5.74; N, 9.97; Zn,
11.63. Found (%): C, 54.90; H, 6.18; N, 9.64; Zn, 11.31.
[ZnL1b(H2O)2]: This complex formed as a yellow solid with yield of 52%. Selected
IR data (ꢀ/cmꢀ1 using KBr): 3435 (m, O–H str.), 2926 and 2853 (m, C–H str.), 2248
(m, CꢃN str.), 1656 (s, C¼O str.), 1439 (s, C¼C str. aromatic). Anal. Calcd for
C24H22N4O4ZnBr2 ꢅ 2H2O (Mw ¼ 691.68 g molꢀ1) (%): C, 41.68; H, 3.79; N, 8.10;
Zn, 9.45. Found (%): C, 42.18; H, 4.07; N, 8.64; Zn, 9.27.
[CuL1a] ꢅ 2H2O was obtained as a blue solid (55%). Selected IR data (ꢀ/cmꢀ1
using KBr): 3431 (m, O–H str.), 2925 and 2840 (m, C–H str.), 2248 (m, CꢃN str.),
1651 (s, C¼O str.), 1614 (m, C¼C str. aromatic), 1461, 1269. Anal. Calcd for
C26H28N4O4Cu ꢅ 2H2O (Mw ¼ 560.11 g molꢀ1) (%): C, 55.75; H, 5.76; N, 10.00; Zn,
11.35. Found (%): C, 56.20; H, 6.12; N, 9.49; Zn, 11.17 .
[CuL1b] ꢅ 2H2O was obtained as a blue solid with yield of 53%. Selected IR data
(ꢀ/cmꢀ1 using KBr): 3422 (m, O–H str.), 2931 and 2847 (m, C–H str.), 2247 (m,
CꢃN str.), 1660 (s, C¼O str.), 1426 (s, C¼C str. aromatic). Anal. Calcd for
C24H22N4O4CuBr2 ꢅ 2H2O (Mw ¼ 689.85 g molꢀ1) (%): C, 41.79; H, 3.80; N, 8.12; Zn,
9.21. Found (%): C, 42.23; H, 4.39; N, 7.69; Zn, 9.00.
Demetallation of [CuL1a] ꢅ 2H2O: [CuL1a] ꢅ 2H2O (0.2 g, 0.36 mmol) was suspended
in 100 mL of chloroform and H2S gas was bubbled slowly through it and stirred for
30 min. The resulting black suspension of CuS was removed by filtration through Celite.
The chloroform was distilled from the solution under reduced pressure. The yellow
residue was dissolved in methanol (15 mL), sonicated, filtered through Celite, and
concentrated under reduced pressure to give the pure free ligand L1aH2 as a yellow oil
1
(14 g, 84%). The observed H NMR and 13C NMR spectra were identical with those
described for L1aH2.
[(Hþ)L3aCu]PF6: To stirred suspension of [CuL1a(H2O)2] (0.29 g, 0.63 mmol) in
ethanol (40 mL) was added dropwise over 45 min a solution of 1,3-diaminopropane
(0.055 mL, 0.63 mmol) and acetic acid (0.072 mL, 1.25 mmol) in ethanol (20 mL). After
the addition was complete, all starting materials were dissolved. The resulting blue
solution was then stirred for 3 h at room temperature. A dark blue solid precipitated
almost immediately after addition of a filtered saturated solution of NH4PF6 in ethanol.
The solid was collected and washed with ethanol (2 ꢂ 10 mL), Et2O (2 ꢂ 5 mL) and
hexane (2 ꢂ 5 mL). The crude compound was recrystallized by diffusion of diethyl ether
into CH3CN solution, yielding a blue solid (0.22 g, 53%). Crystals suitable for X-ray
crystal structure determination were grown by vapor diffusion of ethanol into a
CH3CN : C2H5OH solution of the complex. Selected IR data (ꢀ/cmꢀ1 using KBr): 3247
(m, N–H str.), 2923 and 2859 (m, C–H str.), 2247 (m, CꢃN str.), 1621 (s, C¼N str.),
1447 (s, C¼C Ar), 842 and 558 (s, PF6 str.). Anal. Calcd for C26H31N5O2CuPF6
(Mw ¼ 654.07 g molꢀ1) (%): C, 47.74; H, 4.78; N, 10.71; Cu, 9.72. Found (%): C, 47.41;
H, 5.12; N, 10.52, Cu; 10.01.
[(Hþ)L3bCu]PF6 was prepared by the same procedure described above except that
[CuL1b(H2O)2] was used in place of [CuL1a(H2O)2]. The product was obtained as
a blue solid with yield of 50%. Selected IR data (ꢀ/cmꢀ1 using KBr): 3237 (m, N–H
str.), 3054, 2927 and 2852 (m, C–H str.), 2248 (m, CꢃN str.), 1614 (s, C¼N str.), 1451
(s, C¼C Ar.), 843 and 558 (s, PF6 str.). Anal. Calcd for C24H25N5O2CuBr2PF6
(Mw ¼ 770.81 g molꢀ1) (%): C, 36.78; H, 3.21; N, 8.93; Cu, 8.11. Found (%): C, 37.05;
H, 3.51; N, 8.62; Cu, 8.14.

Homo and heterodinuclear complexes
1975
[ZnL2aZn(OAc)]PF6: [ZnL1a(H2O)2] (0.30 g, 0.63 mmol) was suspended in ethanol
(30 mL) and then a solution of 1,3-diaminopropane (0.055 mL, 0.63 mmol) and acetic
acid (0.072 mL, 1.25 mmol) in ethanol (20 mL) was added dropwise over 30 min. After
all starting materials dissolved, a solution of Zn(OAc)2 ꢅ 4H2O (0.138 g, 0.63 mmol)
in ethanol (10 mL) was added. The reaction mixture was stirred for 1 h and then a
saturated solution of NH4PF6 in ethanol was added. The resulting yellow solid was
collected and washed with ethanol (2 ꢂ 10 mL), ether (2 ꢂ 10 mL) and pentane
(2 ꢂ 10 mL). The crude compound was recrystallized by diffusion of diethyl ether
into CH3CN solution, yielding yellow-orange crystals (0.24 g, 46%). Crystals suitable
for X-ray crystal structure determination were grown by vapor diffusion of ethanol into
a CH3CN: ethanol solution of the complex. Anal. Calcd for C31H37N6O4PF6Zn2
(Mw ¼ 833.40 g molꢀ1) (%): C, 44.68; H, 4.47; N, 10.08; Zn, 15.69. Found: C, 44.48; H,
4.36; N, 9.94; Zn, 15.63. Selected IR data (ꢀ/cmꢀ1 using KBr): 3053 (w, C–H str.
aromatic), 2925, 2859, and 2746 (m, C–H str.), 2249 (m, CꢃN str.), 1653 (s, C¼N str.),
1571, and 1463 (s, C¼O str. OAc), 1442 (m, C¼C str. aromatic), 1327 (s, Ph–O str.) 843,
1
and 558 (s, PF6 str.). H NMR (500 MHz, CD3CN), 1.96 (s, 3H, CH3–COO), 2.21
(m, 2H), 2.28 (s, 6H, ArCH3), 2.75 (m, 4H), 2.97 (m, 2H), 3.15 (m, 4H), 3.28, (m, 2H),
3.66 (s, 1H), 3.68 (s, 1H), 3.99 (m, 4H), 4.31 (s, 1H), 4.33 (s, 1H), 7.21 (s, 2H, Ar), 7.25
(s, 2H, Ar), 8.32 (s, 2H, ArCH¼N). 13C NMR (125 MHz in CD3CN) ꢁ: 10.06, 14.79,
19.15, 28.97, 46.34, 50.42, 55.64, 61.89, 118.17, 118.61, 123.12, 126.02, 136.67, 137.29,
162.78, 166.19, 170.96.
[ZnL2bZn(OAc)]PF6 was prepared with the same procedure as [ZnL2aZn(OAc)]PF6
except that [ZnL1b(H2O)2] was used instead of [ZnL1a(H2O)2] giving a yellow solid
with yield of 53%. Anal. Calcd for C29H31N6O4PF6Br2Zn2 (Mw ¼ 963.14 g molꢀ1) (%):
C, 36.17; H, 3.24; N, 8.73; Zn, 13.58. Found: C, 36.51; H, 3.02; N, 9.02; Zn, 13.48.
Selected IR data (ꢀ/cmꢀ1 using KBr): 3033 (w, C–H str. aromatic), 2931, 2850 and 2749
(m, C–H str.), 2248 (m, CꢃN str.), 1655 (s, C¼N str.), 1573 and 1460 (s, C¼O str.
OAc), 1446 (m, C¼C str. aromatic), 1324 (s, Ph–O str.), 844 and 558 (s, PF6 str.).
1H NMR (400 MHz, CD3CN), 1.83 (s, 3H, CH3COO), 2.75 (m, 4H), 3.02 (m, 3H,), 3.16
(m, 4H), 3.28 (m, 2H), 3.40 (s, 1H), 3.73, (s, 1H), 3.97 (m, 5H), 4.34 (s, 1H), 4.38 (s, 1H),
7.58 (d, AB system, 2H, Ar), 7.60 (s, AB system, 2H, Ar), 8.32 (s, 2H, ArCH¼N).
13C NMR (100 MHz in CDCl3) ꢁ: 10.14, 22.76, 28.62, 46.39, 50.39, 55.13, 61.99, 107.06,
117.33, 118.13, 120.59, 125.82, 138.38, 138.63, 164.06, 169.86.
All heterodinuclear complexes were prepared by a general procedure described
for [ZnL2aCu(OAc)]PF6.
[ZnL2aCu(OAc)]PF6 ꢅ CH3CN: To a solution of [ZnL2aZn(OAc)]PF6 (178 mg,
2.0 mmol) in CH3CN (10 mL) was added a solution of Cu(OAc)2 ꢅ H2O (48 mg,
2.4 mmol) in ethanol (10 mL). The brown reaction mixture was stirred for 1 h. A satu-
rated solution of NH4PF6 in ethanol was added to the resultant solution. The solution
was partially concentrated at room temperature to reduce CH3CN content; ethanol was
then added in portions of (2 ꢂ 10 mL) and the solution was allowed to stand overnight.
The solid was collected and washed with ethanol (2 ꢂ 10 mL), ether (2 ꢂ 10 mL), and
pentane (2 ꢂ 10 mL). The crude compound was recrystallized by diffusion of diethyl
ether into CH3CN solution, which yielded blue crystals (0.11 g, 63%). Crystals suitable
for X-ray crystal structure determination were grown by vapor diffusion of ethanol into
a CH3CN : C2H5OH solution of the complex. Selected IR data (ꢀ/cmꢀ1 using KBr):
2925 and 2839 (m, C–H str.), 2248 (m, CꢃN str.), 1623 (s, C¼N str.), 1572 and 1403

1976
H. Golchoubian et al.
(s, C¼O str. OAc), 1440 (s, C¼C str. aromatic), 1329 (s, Ph–O str.), 844 and
558 (s, PF6 str.). Anal. Calcd for C33H40N7O4PF6ZnCu (Mw ¼ 872.62 g molꢀ1) (%):
C, 45.42; H, 4.62; N, 11.24; Zn, 7.49; Cu, 7.28. Found: C, 45.01; H, 4.73; N, 11.45;
Zn, 7.60; Cu, 7.43.
[ZnL2bCu(OAc)]PF6 was obtained as a blue solid with yield of 65%. Selected IR
data (ꢀ/cmꢀ1 using KBr): 2926 (m, C–H str.), 2251 (m, CꢃN str.), 1623 (s, C¼N str.),
1573 and 1444 (s, C¼O str. OAc), 1399 (m, C¼C str. aromatic), 1304 (s), 845 and 559
(s, PF6 str.). C29H31N6O4PF6Br2ZnCu (Mw ¼ 961.30 g molꢀ1) (%): C, 36.23; H, 3.25;
N, 8.74; Zn, 6.80; Cu, 6.61. Found: C, 36.58; H, 2.99; N, 8.91; Zn, 6.62; Cu, 6.53.
[ZnL3aCu(OAc)]PF6 was obtained as a blue solid with yield of 75%. Selected IR data
(ꢀ/cmꢀ1 using KBr): 3282 (m, N–H str.), 2935 (m, C–H str.), 2254 (m, CꢃN str.), 1623
(s, C¼N str.), 1588 and 1567 (m, C¼O str. OAc), 1447 (s, OAc), 1400 (s, C¼C str.),
1332 (m, Ph–O str.), 1305 (s), 844 and 558 (s, PF6 str.). C28H32N5O4PF6ZnCu
(Mw ¼ 776.48 g molꢀ1) (%): C, 43.31; H, 4.15; N, 9.02; Zn, 8.42; Cu, 8.18. Found (%):
C, 43.66; H, 3.87; N, 8.84; Zn, 8.25; Cu, 8.00.
[ZnL3bCu(OAc)]PF6 was obtained as a blue solid with yield of 77%. Selected IR data
(ꢀ/cmꢀ1 using KBr): 3282 (m, N–H str.), 2930 and 2848 (m, C–H str.), 2254 (m, CꢃN
str.), 1627 (s, C¼N str.), 1577 and 1440 (s, C¼O str. OAc), 1401 (s, C¼C str.), 1334
(s, Ph–O str.), 844 and 558 (PF6 str.). C26H26N5O4Br2PF6ZnCu (Mw ¼ 906.22 g molꢀ1
)
(%): C, 34.46; H, 2.89; N, 7.73; Zn, 7.21; Cu, 7.01. Found: C, 34.13; H, 3.09; N, 7.62;
Zn, 7.48, Cu, 7.33.
[CuL3aCu(OAc)]PF6 ꢅ 1.5 H2O was obtained as a blue solid with yield of 78%.
Selected IR data (ꢀ/cmꢀ1 using KBr): 3278 (m, N–H str.), 2925 and 2852 (m, C–H str.),
2253 (m, CꢃN str.), 1623 (s, C¼N str.), 1575 (s, C¼O str. OAc), 1448 (s, C¼C str.),
1334 (s, Ph–O str.), 844 and 558 (s, PF6 str.). C28H37Cu2F6N5O5 ꢅ 5 P (Mw ¼
815.70 g molꢀ1) (%): C, 42.70; H, 4.57; N, 8.50; Cu, 15.58. Found: C, 43.04; H, 4.25;
N, 8.18; Cu, 15.44.
2.4. X-ray crystallographic study
The X-ray measurement of [(Hþ)L3aCu]PF6, [ZnL2aZn(OAc)]PF6, [ZnL2aCu(OAc)]PF6,
and [CuL3aCu(OAc)]PF6 were made on a Bruker-Nonius X8 ApexII diffractometer
equipped with a CCD area detector by using graphite-monochromated Mo-Ka radiation
˚
(ꢂ ¼ 0.71073 A) generated from a sealed tube source. Data were collected and reduced
by SMART and SAINT software [34] in the Bruker packages. The structures
were solved by direct methods [35] and then developed by least-squares refinement
on F2 [36, 37]. The complete conditions of data collection and structure are given in
table 1.
All hydrogen atoms were refined in isotropic approximation in riding model with
Uiso(H) parameters equal to 1.2Ueq(Ci), for methyl groups equal to 1.5Ueq(Cii), where
U(Ci) and U(Cii) are, respectively, the equivalent thermal parameters of the carbon
atoms to which corresponding hydrogen atoms are bonded. Refinement of F2 was
against all reflections. The weighted R-factor wR and goodness-of-fit S are based on F2,
conventional R-factors are based on F, with F set to zero for negative F2. The threshold
expression of F2 4 2ꢃ(F2) is used only for calculating R-factors(gt) etc., and is not
relevant to the choice of reflections for refinement.

Homo and heterodinuclear complexes
1977

1978
H. Golchoubian et al.
3. Results and discussion
3.1. Synthesis
The amine of the precursor dialdehyde acyclic ligand L1H2 was prepared by reactions
depicted in scheme 2. Condensation of one part of ethylenediamine and two parts
of acrylonitrile resulted in the desired diamine compound with 95% yield (scheme 2,
reaction 1). Subsequently, introduction of two molecules of 4-substituted-2-formyl-6-
chloromethylphenol and a diamine molecule in dioxalan at reflux resulted in the
formation of the precursor dialdehyde L1H2 as a viscous oil (scheme 2, reaction 2).
The crude compound was purified through replacement of protons of the phenols by
lithium ions that resulted in solid Li2L1. Subsequent acidification of the solids yields
purified L1H2 (scheme 2, reaction 3); 70% of yield is lost in the purification process.
Acidification was done here to recover the organic ligand; however, this is not always
necessary because we have also been successful in directly using Li2L1 in preparations
of the mononuclear complexes.
Mononuclear ZnIIL1 and CuIIL1 were readily obtained as solids by allowing L1H2
(or Li2L1) to react with the metal acetate and triethylamine in ethanol (scheme 2,
reaction 4). The metal in the acyclic MIIL1 complex can bind at either the N(amine)2O2
or at the O4 coordination site of the ligand. The IR spectrum and the solid state visible
spectral data (discussed later) indicate that the metal ion resides in the N(amine)2O2
coordination site. The MIIL1a and MIIL1b complexes were nearly insoluble in all
solvents investigated, hindering characterization and establishment of the purity of
these compounds.
Having the structure of MIIL1 as shown in scheme 2, which fixes the orientation of
the two aldehydes, it was expected that MIIL1 would condense with 1,3-diaminopro-
pane to give the desired macrocyclic complex. This proves to be the case but the results
were dependent on the nature of M(II). Thus addition of an equivalent of 1,3-
diaminopropane to ZnL1 under acid catalysis yielded the unexpected dinuclear
macrocyclic product [ZnL2Zn(OAc)]þ instead of mononuclear compound (scheme 2,
reaction 6) with yield of 35%. All attempts to obtain mononuclear [ZnL2(Hþ)2]2þ by
varying the reaction conditions have failed. However, the analogous ligand system with
two pyridine pendant arms in place of the propionitrile generates the macrocyclic
mononuclear complex [ZnL2(Hþ)2]2þ [10–13]. As a result, to improve the yield of the
reaction an extra equivalent of Zn(OAc)2 was used that resulted an increase in the yield
of the reaction (50%). The mononuclear Cu(II) complex, [(Hþ)L3Cu]þ, was prepared
by a rather unusual route involving migration of copper from N(amine)2O2 site to the
N(imine)2O2 site along with bond rupture of a propionitrile pendant arm and formation
of a secondary amine (scheme 2, reaction 7). The characterization results confirm the
presence of a proton in the vacant N(amine)2O2 site. Removal of the propionitrile
pendant arm in introduction of Cu(OAc)2 to the free ligand L1H2 was ruled out by
lack of the N–H vibration in the IR spectra of CuL1a and CuL1b complexes and also
by similarity of their IR spectra with those of the ZnL1a and ZnL1b complexes. This
was further confirmed by demetallation of the acyclic copper(II) complex, CuIIL1a by
H2S gas (scheme 2, reaction 5). Characterization of the isolated ligand by NMR
spectroscopy revealed both propionitrile pendant arms in the demetallated ligand.
The driving force in the migration of Cu(II) may be related to the nature of the donors
of the compartments. Cu(II) migrates to occupy the relatively rigid N(imine)2O2

Homo and heterodinuclear complexes
1979
CN
CN
NH2
NH
NH
1
+
2
NH2
CN
X
X
NC
X
NC
CN
+
NH
NH
N
N
OH
OH
O
O
N
N
OH
OH
O
O
2
3
2
Cl OH
O
CN
NC
crude L 1H
NC
2 X
X
4
L1aH2 , X=CH3
L1bH2 , X=Br
5
X
X
X
CH3
NC
NC
CN
C
H2O
PF6
O
O
N
N
O
O
N
N
O
O
O
N
N
O
N
N
PF6
7
6
Zn
Zn
M
H+ Cu
O
N
N
O
H2O
H
NC
NC
X
X
[(H+)L3aCu]PF6
[(H+)L3bCu]PF6
X
[ZnL 2aZn( OAc)]PF
[ZnL 2bZn(µ−OAc)]PF6
ZnL1a, CuL1a
ZnL1b, CuL1b
µ−
6
8
9
X
X
CH3
O
CH3
C
NC
NC
C
O
O
O
N
M
O
N
N
O
O
N
N
N
PF6
PF6
Cu
Zn
Cu
N
H
O
N
NC
X
X
[ZnL 2aCu( OAc)]PF
µ−
[ZnL3aCu(OAc)]PF 6
[ZnL3bCu(OAc)]PF 6
[CuL3aCu(OAc)]PF 6
6
[ZnL 2bCu(µ−OAc)]PF6
Scheme 2. Synthetic transformations. The following reagents/solvents were used. Reaction 1: ambient
conditions in aqueous solution. Reaction 2: reflux in dioxalane in the presence of anhydrous Na2CO3. Reaction
3: (a) LiCl (2 equiv.), Et3N (2 equiv), in methanol and ethanol; (b) HCl (gas) in dichloromethane, followed by
the addition of NaHCO3 (aq), extraction of the ligand in dichloromethane. Reaction 4: Zn(OAc)2 ꢅ 4H2O or
Cu(OAc)2 ꢅ H2O, triethylamine (2 equiv), methanol, and ethanol. Reaction 5: [CuL1a], H2S gas, CHCl3.
Reaction 6: [ZnL1], 1,3-diaminopropane, acetic acid (2 equiv), and Zn(OAc)2 (an equiv) in ethanol followed by
the addition of NH4PF6 (satur.). Reaction 7: [CuL1], 1,3-diaminopropane, acetic acid (2 equiv) in ethanol
followed by the addition of NH4PF6 (satur.). Reaction 8: [ZnL2Zn(OAc)]PF6, Cu(OAc)2 ꢅ H2O, in acetonitrile/
ethanol followed by the addition of NH4PF6 (satur.). Reaction 9: [(Hþ)L3Cu]PF6, Zn(OAc)2 ꢅ 4H2O, or
Cu(OAc)2 ꢅ H2O, triethylamine (1 equiv) in acetonitrile/ethanol followed by the addition of NH4PF6 (satur.).

1980
H. Golchoubian et al.
coordination site, which provides the preferred square-planar environment, but Zn(II)
resides in the more flexible N(amine)2O2 site [30]. Migration of copper ion from aminic
to iminic site in the formation of the mononuclear macrocyclic complex type 1 in
scheme 1 was reported previously by Bouyagui et al. [38]. However, their procedure
involved utilization of macro-acyclic CuL complex, diamine link, and Er(NO3)2 in
which Er(II) was not engaged in coordination with the macrocyclic complex.
The heterodinuclear complexes incorporating copper(II) in the N(imine)2O2 and
zinc(II) ion in the N(amine)2O2 coordination sites were prepared through two
different routes. Mononuclear [(Hþ)L3Cu]þ is an ideal precursor for mild synthesis of
[ZnL3Cu(OAc)]þ. The reaction depicted in equation (1) can be driven to the right by
addition of an exceptionally mild base since incorporation of the second metal depends
on the fast removal of the cavity protons. Under such circumstances coordination of the
second metal would be much faster than site scrambling of the metals [10]. Starting from
the mononuclear complexes, the heterodinuclear complexes [ZnL3aCu(OAc)]PF6 and
[ZnL3bCu(OAc)]PF6 were prepared by the method illustrated in scheme 2 (reaction 9).
In the second route, [ZnL2aCu(OAc)]þ and [ZnL2bCu(OAc)]þ were synthesized
by transmetallation. The reaction was carried out by the addition of Cu(OAc)2 to
dinuclear [ZnL2Zn(OAc)]þ at room temperature (scheme 2, reaction 8) with moderate
yield. It was found that the optimum mole ratio of the reactants between
[ZnL2Zn(OAc)]þ and Cu(OAc) is 1 : 1.2.
ꢀ
ꢁþ
ꢀ
ꢁ
ðHþÞL3Cu þZnðOAcÞ2! ZnL3CuðOAcÞ þþHOAc:
ð1Þ
Okawa and co-workers carried out extensive work on coordination-position isomers
of heterodinuclear complexes using the macrocyclic ligands as shown by 1 in scheme 1
[39]. Site specificity of metal ions at the N(amine)2O2 site or N(imine)2O2 site of Cu(II)–
Zn(II) complexes depend on the synthetic procedure and the nature of the counter-
anion. For instance, the reaction of macrocyclic mononuclear Cu(II) complexes with
ZnCl2 provided the heterodinuclear complexes with Cu(II) residing in the N(imine)2O2
compartment and the Zn(II) occupied the N(amine)2O2 site. Transmetallation of Pb(II)
in Pb(II)–Cu(II) for a Zn(II) ion afforded Zn(II)–Cu(II) perchlorate complexes in which
Cu(II) migrates from the N(imine)2O2 site to the N(amine)2O2 site; migration is
kinetically controlled by geometrical characteristic of the macrocyclic ligand.
3.2. Physical characterization
3.2.1. Electronic absorption spectra. The electronic absorption spectra of the mono-
and dinuclear complexes were recorded in acetonitrile solutions from 200 nm to 900 nm,
including d–d transition and some metal-ligand charge transfer bands. In the spectra, the
charge transfer bands overlap with d–d bands of Cu(II). A d–d band is observed in the
solid state spectrum at 665 nm for [CuL1a] and 660 nm for [CuL1b], indicative of Cu(II)
in the N(amine)2O2 coordination site [23]. Cu(II) in a N(amine)2O2 coordination site
with square-planar geometry shows a d–d transition around 645–670 nm [40, 41]. A d–d
transition is observed for [(Hþ)L3aCu]þ and [(Hþ)L3bCu]þ at 584–581 nm. The d–d band
of [(Hþ)L3Cu]þ is comparable to those of N,N0-1,3-trimethylenesalicylideneaminato
copper(II) (602 in nujol mull) [42] and copper(II) complexes with similar structures
(600 nm in DMF) [23]. These results support that copper(II) shifts from N(amine)2O2

Homo and heterodinuclear complexes
1981
Table 2. Electronic absorption maxima (nm) and intensities (mol Lꢀ1 cmꢀ1) of
the charge transfer and d–d transitions for Cu(II) complexes in CH3CN.
Compound
[CuL1a
ꢇ–ꢇ*
285
281
371 (9430)
351 (9840)
351 (7670)
352 (6790)
360 (7340)
350 (6680)
352 (8250)
d–d
]
665
660
[CuL1b
]
[(Hþ)L3aCu]PF6
584 (190), 690 sh (58)
581 (214), 690 sh (85)
674 (125)
670 (140)
678 (130)
[(Hþ)L3bCu]PF6
[ZnL2aCu(OAc)]PF6
[ZnL2bCu(OAc)]PF6
[ZnL3aCu(OAc)]PF6
[ZnL3bCu(OAc)]PF6
[CuL3aCu(OAc)]PF6
673 (138)
676 (142)
Electronic absorption spectra for [CuL1a] and [CuL1b] were taken in solid state.
coordination site to the N(imine)2O2 coordination site upon cyclization of [CuL1] and the
N(amine)2O2 coordination site is free from coordination (see scheme 2). This is proved
by X-ray crystallography for [(Hþ)L3aCu]PF6 as described below. The d–d band in
[ZnL2Cu(OAc)]PF6 and [ZnL3Cu(OAc)]PF6 moves to a longer wavelength (674 and
678 nm, respectively) relative to the corresponding mononuclear copper(II) complexes
due to square-pyramidal geometry about copper(II) [30]. The intense band at 360 nm in
macrocyclic complexes is assigned to the ꢇ–ꢇ* transition associated with azomethine
linkages [39]. Table 2 lists the positions and intensities of the phenolate charge-transfer
and the d–d bands observed in the spectra of the complexes.
3.2.2. IR spectra. The IR spectrum of N,N0-bis-(2-cyanoethyl)-ethylenediamine shows
a strong ꢀ(CꢃN) at 2247 cmꢀ1 and a sharp band with medium intensity at 3380 cmꢀ1
due to N–H vibration. The former band appears with minor change in the IR spectra
of L1aH2 and L1bH2 but the latter is not present in the free ligands. IR spectra of all
mononuclear dialdehyde [ML1a] and [ML1b] complexes are nearly identical irrespective
of the metal ions used and ꢀ(CꢃN) appears in the same position as the free ligands
indicating that nitrogen of the propionitrile pendant arms are not involved in
coordination. The [ZnL1] and [CuL1] complexes show an intense ꢀ(C¼O) of the formyl
at 1660 cmꢀ1. The main spectral differences between the acyclic dialdehyde and the
macrocyclic diimine complexes in the spectra are the emergence of two sharp bands at
840 and 560 cmꢀ1, attributed to the anti-symmetric stretching and anti-symmetric
bending vibrations of PFꢀ6 , respectively [43, 44]. Strong evidence that the aldehydes had
been completely converted into imine groups was provided by the disappearance of the
aldehyde C¼O stretch and the appearance of a strong band at 1640 cmꢀ1 assigned to
C¼N stretch [45, 46]. Emergence of a band near 3240 cmꢀ1, attributed to N–H stretch
of the quaternized amine, for [(Hþ)L3Cu]þ and also the presence of the ꢀ(CꢃN) at
2247 cmꢀ1 indicate dissociation of an aminonitrile pendant arm. Strong evidence
for coordination of the second metal in the N(imine)2O2 or N(imine)2O2 coordination
site is the appearance of the phenolic stretch at 1320–1334 cmꢀ1, which is absent in this
region in the mononuclear complexes [47].
IR spectra of the dinuclear complexes show anti-symmetric and symmetric ꢀ(COO)
vibrations of acetate at 1572 and 1462 cmꢀ1, respectively. The small separation between
the two vibration modes (5150 cmꢀ1) indicates bridging acetate in the complex [48].

1982
H. Golchoubian et al.
Table 3. Molar conductivities of the complexes in acetonitrile.a
Ãm of the complexes
(ꢀꢀ1cm2 molꢀ1, at 25ꢁC)
Compound
[(Hþ)L3aCu]PF6
123
134
[(Hþ)L3bCu]PF6
[ZnL2aZn(OAc)]PF6
[ZnL2bZn(OAc)]PF6
[ZnL2aCu(OAc)]PF6
[ZnL2bCu(OAc)]PF6
[ZnL3aCu(OAc)]PF6
[ZnL3bCu(OAc)]PF6
[CuL3aCu(OAc)]PF6
1 : 1 electrolytes
146
155
119
151
129
145
137
120–160
220–300
1 : 2 electrolytes
aConcentration: ca 1.0 ꢂ 10ꢀ3 mol Lꢀ1
.
The ꢀas(COOꢀ) and ꢀs(COOꢀ) in the heterodinuclear complexes at 1570 cmꢀ1 and
1440 cmꢀ1, respectively, confirm bidentate acetate.
3.2.3. Conductometric data. Molar conductance data, Ãm, of all of the ionic
complexes determined in acetonitrile at 25ꢁC are presented in table 3. The values are
accurate to ꢆ5 ꢀꢀ1 cm2 molꢀ1. The standard values of 1 : 1 and 1 : 2 electrolytes
in acetonitrile are shown in the same table [43]. The results are in agreement with the
expected range of the values for two- and three-ion electrolytes, consistent with their
formulae [49].
3.2.4. NMR spectra. The NMR spectra of L1aH2 are very similar to L1bH2. The only
difference is the absence of singlets at 2.25 ppm in the 1H NMR and at 20.7 ppm in the
13C NMR spectra of the latter. In both compounds the signals belonging to the protons
of the phenolic hydroxy groups were broad, indicating acidic protons and suggesting
formation of O–H–N hydrogen bonds. This has been observed in similar systems [14].
1
The H NMR spectra of [ZnL2aZn(OAc)]PF6 have a single resonance at 2.28 ppm,
attributed to the six tolyl methyls and indicate that the two methyls are equivalent.
13C NMR spectra of the dizinc macrocyclic complexes show signals for one half of
the molecule. These results are consistent with symmetrical structures for [ZnL2a
Zn(OAc)]PF6 and [ZnL2bZn(OAc)]PF6.
3.2.5. Electrochemical properties. Electrochemical properties of copper(II) complexes
were studied by cyclic voltammetry in acetonitrile. Typical examples of cyclic
voltammograms are provided in ‘‘Supplementary material’’ and the numerical data
are provided in table 4. In the sweep to negative potential, complexes containing La and
Lb demonstrate a reversible or quasi-reversible couple at ꢀ0.82 ꢆ 0.03 V and
ꢀ0.97 ꢆ 0.01 V (vs. Ag/Agþ), respectively, that is attributed to Cu(II)/Cu(I) process in
the iminic N2O2 coordination site. The reduction potential for complexes with Lb is
lower relative to those of La due to electron withdrawing of bromine in the phenyl ring
that reduces the electron density around copper. Also, [CuL3aCu(OAc)]PF6 showed

Homo and heterodinuclear complexes
1983
Table 4. Redox potentials and peak separations for copper complexes.
E
a, V(Epa ꢀ Epc, V)
½
N2O2 site Cu(II)/
Cu(I) couple
N2O2 site Cu(II)/
Cu(I) couple
Complexes
[(Hþ)L3aCu]PF6
ꢀ0.82 (0.12)
ꢀ0.96 (0.14)
ꢀ0.83 (0.06)
ꢀ0.98 (0.05)
ꢀ0.85 (0.05)
ꢀ0.98 (0.06)
ꢀ0.80 (0.05)
–
–
–
–
–
–
[(Hþ)L3bCu]PF6
[ZnL2aZn(OAc)]PF6
[ZnL2bZn(OAc)]PF6
[ZnL3aCu(OAc)]PF6
[ZnL3bCu(OAc)]PF6
[CuL3aCu(OAc)]PF6
ꢀ0.42 (0.09)
a1.0 mmol Lꢀ1 sample, 0.1 mol Lꢀ1 n-Bu4NPF6 in CH3CN. Scan rate: 100 mVsꢀ1
. Solutions
were deaerated with Ar for 10 min prior to each run. Condition: Glassy carbon working,
Pt auxiliary, Ag/Agþ reference electrodes.
another reduction couple at ꢀ0.42 V that is attributed to the Cu(II)/Cu(I) reduction
in the aminic N4O2 compartment. The high Cu(II)/Cu(I) potential in the aminic site
compared with that of the iminic site is due to more flexibility of the former to provide
a non-planar environment preferred for Cu(I) [30].
3.2.6. X-ray structure. Crystal structure of [(Hþ)L3aCu]PF6. The structure is shown
in figure 1 and selected bond lengths and angles are provided in table 5.
The cation comprises (L3)2ꢀ and one Cu(II). The hexafluorophosphate is not
coordinated. X-ray crystallography clearly demonstrates that Cu(II) resides in the
N(imine)2O2 site and a proton at the N(amine)2O2 site, indicating that migration
occurred in which Cu(II) shifts from the N(amine)2O2 site to the N(imine)2O2 site of
(L2)2ꢀ in the cyclization process. During the cyclization one propionitrile pendant is
lost. Another propionitrile pendant arm is positioned in the apical site of the basal plane
˚
with Cu(1)–N(5) distance 2.897(4) A, coordinated weakly to copper(II) because of the
strong Jahn–Teller effect and can be driven out from the coordination sphere by
solvent. The [CuN(imine)2O2] chromophore involved in the aromatic moieties is nearly
coplanar with deviations from the least-squares plane through CuN2O2 of N(1) ꢀ0.126,
˚
N(2) 0.127, O(1) 0.151, O(2) ꢀ0.152 A, and Cu(II) resides in the plane. The Cu–N and
˚
Cu–O bond distances are 1.985(15) and 1.920(7) A. The N(1)–Cu(1)–N(2) bite angle
[96.76(14)ꢁ] is significantly larger than 90ꢁ and the opposite O(1)–Cu(1)–O(2) angle
[80.89(11)ꢁ] is smaller than 90ꢁ. The cavity at the unfilled site of the ligand has
˚
˚
‘‘diagonal’’ distances of 3.532 A (O(1)–N(4)) and 4.162 A (O(2)–N(3)), suitable for a
first row divalent transition metal ion, for which M–N and M–O bond distances are
˚
generally close to 2 A. The 1,3-diaminopropane fragment is disordered and located
in two positions with a skew conformation. N(1) and N(2) are above and below of the
mean macrocyclic plane.
Crystal structure of [ZnL2aZn(OAc)]PF6. The crystal structure of this compound
is shown in figure 2 together with the numbering scheme. Selected bond distances and
angles are given in table 6. The compound consists of two monomers in asymmetric
units, which are different from a crystallographic point of view. The conformations
of the two independent complexes are almost the same, with only differences in bond

1984
H. Golchoubian et al.
Figure 1. ORTEP diagram of [(Hþ)L3aCu]PF6.
þ
Table 5. Selected bond lengths (A) and angles ( ) for [(H )L3aCu]PF6.
ꢁ
˚
Cu(1)–O(1)
Cu(1)–O(2)
Cu(1)–N(1)
Cu(1)–N(2)
N(3)–C(15)
1.913(3)
1.927(3)
1.974(3)
2.010(3)
1.461(6)
Cu(1)–N(5)
N(5)–C(26)
N(3)–C(20)
N(4)–C(22)
2.897(4)
1.141(5)
1.478(5)
1.495(5)
O(1)–Cu(1)–O(2)
O(1)–Cu(1)–N(1)
O(2)–Cu(1)–N(1)
O(1)–Cu(1)–N(2)
O(2)–Cu(1)–N(2)
N(1)–Cu(1)–N(2)
80.89(11)
92.68(12)
168.48(12)
168.45(13)
90.84(13)
96.76(14)
O(1)–Cu(1)–N(5)
O(2)–Cu(1)–N(5)
N(1)–Cu(1)–N(5)
N(2)–Cu(1)–N(5)
N(5)–C(26)–C(25)
78.51(11)
82.82(12)
105.39(13)
92.55(14)
179.1(5)

Homo and heterodinuclear complexes
1985
Figure 2. ORTEP diagram of [ZnL2aZn(OAc)]PF6.
distances and angles. Each cation has (L2)2ꢀ, two Zn(II) and one acetate. One Zn(II)
resides at the N(amine)2O2 site and another at the N(imine)2O2 site. The pair of zinc
ions is bridged by two phenolic oxygen atoms and an acetate, providing distorted five-
˚
˚
coordination. The Zn–Zn separation is 2.9514(4) A and 2.9688(4) A for two asymmetric
units. The geometry around Zn(1) bound to the N(amine)2O2 can be regarded as a
square pyramid: the parameter ꢈ [50] discriminating between square pyramid (ꢈ ¼ 0)
and trigonal bipyramid (ꢈ ¼ 1) is 0.024. The equatorial Zn(1)–N(amine)2O2 bond
˚
distances fall in the range 2.0079(19)–2.131(2) A and the axial Zn(1)–O(3) bond is
˚
1.960(2) A. The deviation of the Zn(1) from the basal N(amine)2O2 least-square plane
˚
toward O(3) is 0.544(4) A. The [Zn(2)N(imine)2O2] site is almost square pyramidal
˚
(ꢈ ¼ 0.154) with basal Zn(2)–O and Zn(2)–N bond distances Zn(2)–O(1) ¼ 2.0755(18) A,
˚
˚
˚
Zn(2)–O(2) ¼ 2.0394(19) A, Zn(2)–N(3) ¼ 2.026(2) A, and Zn(2)–N(4) ¼ 2.039(3) A,
which are shorter than the corresponding basal Zn(2)–O and Zn(2)–N bond distances.
˚
Instead, the apical Zn(2)–O(4) is long (2.011(2) A). Because of the acetate bridge, the
N(amine)2O2 and the N(imine)2O2 least-square plane are bent at the O(1)–O(2) edge of
165.87(4)ꢁ. The deviation of Zn(2) from the basal N(imine)2O2 least-squares plane
2a
toward O(4) is 0.453 A. The [ZnL Zn] entity assumes a saddle-like shape with a
˚
bridging acetate on the saddle. The O(1)–C(1) and the O(2)–C(18) bonds make an angle
of 161.89ꢁ. The dihedral angle between the least-squares plane defined by Zn(1), O(1),

1986
H. Golchoubian et al.
Table 6. Selected bond lengths (A) and angles ( ) for [ZnL2aZn(OAc)]PF6.
ꢁ
˚
Zn(1)–O(1)
Zn(1)–O(2)
Zn(1)–O(3)
Zn(1)–N(1)
Zn(1)–N(2)
Zn(1)–Zn(2)
Zn(2)–O(1)
Zn(2)–O(2)
Zn(2)–O(4)
Zn(2)–N(3)
Zn(2)–N(4)
N(3)–C(12)
N(4)–C(8)
2.0459(19)
2.0079(19)
1.960(2)
2.131(2)
2.117(2)
2.9514(4)
2.0755(18)
2.0394(19)
2.011(2)
2.026(2)
2.039(3)
1.274(4)
1.281(4)
1.138(5)
1.162(9)
Zn(10)–O(10)
Zn(10)–O(20)
Zn(10)–O(30)
Zn(10)–N(10)
Zn(10)–N(20)
Zn(10)–Zn(20)
Zn(20)–O(10)
Zn(20)–O(20)
Zn(20)–N(40)
Zn(20)–N(30)
Zn(20)–N(40)
N(30)–C(120)
N(40)–C(80)
C(230)–N(50)
C(290)–N(60)
2.0578(19)
2.017(2)
1.959(2)
2.121(2)
2.120(2)
2.9688(4)
2.0831(19)
2.033(2)
2.035(3)
2.039(3)
2.035(3)
1.278(4)
1.275(4)
1.124(5)
1.17(2)
C(23)–N(5)
C(29)–N(6)
O(3)–Zn(1)–O(2)
O(3)–Zn(1)–O(1)
O(2)–Zn(1)–O(1)
O(3)–Zn(1)–N(2)
O(2)–Zn(1)–N(2)
O(1)–Zn(1)–N(2)
O(3)–Zn(1)–N(1)
O(2)–Zn(1)–N(1)
O(1)–Zn(1)–N(1)
N(2)–Zn(1)–N(1)
O(4)–Zn(2)–N(3)
O(4)–Zn(2)–N(4)
N(3)–Zn(2–N(4)
O(4)–Zn(2)–O(2)
N(3)–Zn(2)–O(2)
N(4)–Zn(2)–O(2)
O(4)–Zn(2)–O(1)
N(3)–Zn(2)–O(1)
N(4)–Zn(2)–O(1)
O(2)–Zn(2)–O(1)
N(6)–C(29)–C(28)
N(5)–C(23)–C(22)
O(3)–C(30)–O(4)
106.19(9)
O(30)–Zn(10)–O(20)
O(30)–Zn(10)–O(10)
O(20)–Zn(10)–O(10)
O(30)–Zn(10)–N(20)
O(20)–Zn(10)–N(20)
O(10)–Zn(10)–N(20)
O(30)–Zn(10)–N(10)
O(20)–Zn(10)–N(10)
O(10)–Zn(10)–N(10)
N(20)–Zn(10)–N(10)
O(40)–Zn(20)–N(30)
O(40)–Zn(20)–N(40)
N(40)–Zn(20)–N(30)
O(40)–Zn(20)–O(20)
O(20)–Zn(20)–N(30)
O(20)–Zn(20)–N(40)
O(40)–Zn(20)–O(10)
N(30)–Zn(20)–O(10)
N(40)–Zn(20)–O(10)
O(20)–Zn(20)–O(10)
N(60)–C(290)–C(280)
N(50)–C(230)–C(220)
O(40)–C(300)–O(30)
106.17(10)
100.77(9)
75.15(8)
104.78(10)
148.30(9)
92.58(8)
108.68(10)
89.82(8)
149.73(8)
86.67(9)
114.08(11)
98.26(11)
98.42(11)
99.36(10)
88.53(9)
156.44(10)
96.42(9)
147.20(9)
88.34(9)
74.27(8)
101.69(9)
75.09(8)
105.00(9)
148.20(9)
92.73(8)
106.85(9)
89.39(8)
150.39(8)
87.44(8)
112.05(10)
99.95(11)
98.15(10)
98.58(9)
88.63(9)
156.15(10)
98.90(9)
146.46(9)
88.58(9)
73.79(8)
179.5(5)
178.3(5)
125.8(3)
176.5(2)
179.0(5)
125.8(3)
and O(2) and the least-squares plane defined by Zn(2), O(1), and O(2) is 49.67ꢁ. The
bridging O(2) has a planar configuration: the sum of the Zn(1)–O(2)–Zn(2), Zn(1)–
O(2)–C(18), and Zn(2)–O(2)–C(18) angles is 358.5ꢁ. O(2) has a non-planar configura-
tion with the sum of the Zn(1)–O(1)–Zn(2), Zn(1)–O(1)–C(1), and Zn(2)–O(1)–C(1)
angles of 338.7ꢁ. The two N-propionitrile pendant arms attached to N(1) and N(2) are
cis with respect to the mean molecular plane and on the same side as the bridging
acetate.
Crystal structure of [ZnL2aCu(OAc)]PF6 ꢅ CH3CN. The structure is presented in
figure 3 and selected bond lengths and angles are provided in table 7. This structure
is similar to the analogous complex reported by Okawa [51, 52]. The compound is a
heterodinuclear macrocyclic complex, a PFꢀ6 and an acetonitrile trapped in the crystal
lattice. The Cu(II) is located in the N(imine)2O2 and Zn(II) in the N(amine)2O2
sites. Two phenolic oxygen atoms and an acetate bridge the two metal ions. The
geometries around both metal ions are square pyramidal but with different degrees of
deviations. The discriminating parameter ꢈ is 0.025 for copper(II) and 0.201 for zinc(II).

Homo and heterodinuclear complexes
1987
Figure 3. ORTEP diagram of [ZnL2aCu(OAc)]PF6 ꢅ CH3CN.
Table 7. Selected bond lengths (A) and angles ( ) for [ZnL2aCu(OAc)]PF6 ꢅ CH3CN.
ꢁ
˚
Zn(1)–O(3)
Zn(1)–N(3 A)
Zn(1)–O(1)
Zn(1)–O(2)
Zn(1)–N(4)
Zn(1)–N(3)
1.940(3)
2.005(12)
2.022(3)
2.061(3)
2.099(4)
2.179(6)
Cu(1)–O(2)
Cu(1)–N(1)
Cu(1)–O(1)
Cu(1)–N(2)
Cu(1)–O(4)
Zn(1)–Cu(1)
1.940(4)
1.973(5)
1.976(3)
1.982(5)
2.260(3)
2.9345(8)
O(3)–Zn(1)–N(3 A)
O(3)–Zn(1)–O(1)
N(3 A)–Zn(1)–O(1)
O(3)–Zn(1)–O(2)
N(3 A)–Zn(1)–O(2)
O(1)–Zn(1)–O(2)
O(3)–Zn(1)–N(4)
N(3A)–Zn(1)–N(4)
O(1)–Zn(1)–N(4)
O(2)–Zn(1)–N(4)
O(3)–Zn(1)–N(3)
O(1)–Zn(1)–N(3)
110.6(4)
109.10(14)
95.3(2)
105.22(14)
144.2(4)
73.09(14)
107.46(16)
78.1(3)
142.79(16)
90.96(16)
99.42(19)
94.12(15)
O(2)–Zn(1)–N(3)
N(4)–Zn(1)–N(3)
O(2)–Cu(1)–N(1)
O(2)–Cu(1)–O(1)
N(1)–Cu(1)–O(1)
O(2)–Cu(1)–N(2)
N(1)–Cu(1)–N(2)
O(1)–Cu(1)–N(2)
O(2)–Cu(1)–O(4)
N(1)–Cu(1)–O(4)
O(1)–Cu(1)–O(4)
N(2)–Cu(1)–O(4)
154.82(18)
86.5(2)
166.42(17)
76.77(14)
91.97(16)
91.6(2)
99.1(2)
167.9(2)
95.73(14)
92.01(16)
91.08(13)
93.36(17)

1988
H. Golchoubian et al.
Figure 4. ORTEP diagram of [CuL3aCu(OAc)]PF6 ꢅ 1.5 H2O.
The copper(II) is located in the basal plane made by O(1), O(2), N(1), and N(2) and its
deviation from the least-squares plane is N(1) ꢀ0.029, N(2) 0.029, O(1) 0.036, O(2)
˚
ꢀ0.036, Cu(1) 0.103 A. However, the Zn(II) ion is moved toward the acetate bridge,
O(3), so that its deviation from the basal (amine)2O2 (N(3), N(4), O(1), and O(2)) least-
˚
squares plane is 0.546 A. Because of the acetate bridge, N(amine)2O2 and the
N(imine)2O2 planes are bent at the O(1)–O(2) edge. The angle between the two
planes is 157.65(4)ꢁ. The two N-propionitrile pendant arms attached to N(3) and N(4)
are situated cis with regard to the mean molecular plane and on the same side of the
bridging acetate group.
Crystal structure of [CuL3aCu(OAc)]PF6 ꢅ 1.5H2O. The crystal structure of this
compound is shown in figure 4 together with the numbering scheme. Selected bond
distances and angles are given in table 8. The compound consists of a cation dicopper
macrocyclic complex, a PFꢀ6 , 1.5 molecules of water, and an acetate. The cation includes
a macrocyclic ligand which has one N-propionitrile pendant arm. Both compartments
are occupied by Cu(II) with square-pyramidal structures as a result of the presence of a
bridging acetate in the apical position of the two copper ions. The copper(II) ions move
from basal planes toward oxygen atoms of acetate. The deviation of Cu(1) in the
N(imine)2O2 compartment from the basal plane made by N(1), N(2), O(1), and O(2) is
˚
˚
0.152(10) A; this deviation for Cu(2) in N(amine)2O2 coordination site is 0.734(11) A.
The two planes are bent at the O(1)–O(2) edge and the angle between them is 160.66(4)ꢁ.

Homo and heterodinuclear complexes
1989
Table 8. Selected bond lengths (A) and angles ( ) for [CuL3aCu(OAc)]PF6 ꢅ 1.5 H2O.
ꢁ
˚
Cu(1)–O(2)
Cu(1)–O(1)
Cu(1)–N(1)
Cu(1)–N(2)
Cu(1)–O(4)
Cu(1)–Cu(2)
1.963(4)
1.968(3)
1.969(5)
1.979(4)
2.248(4)
2.9322(8)
Cu(2)–O(1)
Cu(2)–O(2)
Cu(2)–N(4A)
Cu(2)–N(4)
Cu(2)–N(3)
Cu(2)–O(3)
1.953(3)
1.962(3)
1.972(7)
1.973(7)
2.012(4)
2.125(4)
O(2)–Cu(1)–O(1)
O(2)–Cu(1)–N(1)
O(1)–Cu(1)–N(1)
O(2)–Cu(1)–N(2)
O(1)–Cu(1)–N(2
N(1)–Cu(1)–N(2)
O(2)–Cu(1)–O(4)
O(1)–Cu(1)–O(4)
N(1)–Cu(1)–O(4)
N(2)–Cu(1)–O(4)
O(2)–Cu(2)–O(3)
N(4A)–Cu(2)–O(3)
N(4)–Cu(2)–O(3)
76.86(14)
166.00(16)
91.46(16)
91.01(18)
165.34(18)
99.3(2)
96.06(16)
93.08(14)
92.21(17)
96.41(17)
96.77(16)
107.7(6)
O(1)–Cu(2)–O(2)
O(1)–Cu(2)–N(4A)
O(2)–Cu(2)–N(4A)
O(1)–Cu(2)–N(4)
O(2)–Cu(2)–N(4)
N(4A)–Cu(2)–N(4)
O(1)–Cu(2)–N(3)
O(2)–Cu(2)–N(3)
N(4A)–Cu(2)–N(3)
N(4)–Cu(2)–N(3)
O(1)–Cu(2)–O(3)
N(3)–Cu(2)–O(3)
77.23(14)
153.9(6)
97.9(2)
165.2(3)
94.4(2)
14.1(4)
95.86(16)
163.46(17)
81.7(3)
88.9(3)
98.36(18)
99.12(18)
94.7(3)
The C(1), C(2), and N(4) of the ethylenediamine are disordered and occupy two
positions in the crystal structure.
4. Conclusion
The dinucleating macrocyclic ligands containing N(amine)2O2 and N(imine)2O2
coordination sites with two propionitrile pendant arms were synthesized by a stepwise
method. The synthetic objective of this research was preparation of homo- and
heterodinuclear complexes, but in the course of the synthetic studies an unusual
bond rupture of one propionitrile pendant arm along with shift of Cu(II) from the
N(amine)2O2 to the N(imine)2O2 coordination site occurred during cyclization of the
acyclic mononuclear copper(II) complexes. To achieve our primary objective, that is
the preparation of dicompartmental ligands possessing contiguous six- and four-
coordination sites the ligand system requires modification in order to bring the pendant
arms in coordination. The –CN moieties of the pendant arms are not able to coordinate
to metal ions but it seems possible to transform –CN into –COOꢀ or CH2–NH2 groups
which contain better donors. Although difficult, the presence of the metal ion could
facilitate these transformations. The synthesis of these types of ligands is currently in
progress in our lab.
Supplementary material
CCDC 806686, 806685, 822549, and 822548 contain the supplementary crystallographic
data for [(Hþ)L3aCu]PF6, [ZnL2aZn(OAc)]PF6, [ZnL2aCu(OAc)]PF6 ꢅ CH3CN, and
[CuL3aCu(OAc)]PF6 ꢅ 1.5H2O. These data can be obtained free of charge via

1990
H. Golchoubian et al.
www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: þ44 1223 3366033 or
E-mail: deposit@ccdc.cam.uk.
Acknowledgments
We are grateful to Mazandaran University of the Islamic Republic of Iran for the
financial support. We also express our appreciation to Dr Sahar Rashid Nadimi for
measuring the cyclic voltammogram of the samples.
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