Electrochemical synthesis and crystal structures of nickel(II), copper(II), zinc(II) and cadmium(II) complexes with N,N′-bis[(4-methylphenyl)sulfonyl]ethylenediamine

Article abstract of DOI:10.1016/S0020-1693(01)00726-5

The electrochemical oxidation of anodic metal (nickel, copper, zinc and cadmium) in acetonitrile solutions containing N,N′-bis[(4-methylphenyl)sulfonyl]ethylenediamine H₂L and an additional nitrogen coligand, such as 1,10-phenanthroline, yielde

Full text of DOI:10.1016/S0020-1693(01)00726-5

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Inorganica Chimica Acta 328 (2002) 111–122
Electrochemical synthesis and crystal structures of nickel(II),
copper(II), zinc(II) and cadmium(II) complexes with
N,N%-bis[(4-methylphenyl)sulfonyl]ethylenediamine
Jose´ Sa´nchez-Piso a, Jose´ A. Garc´ıa-Va´zquez a,*, Jaime Romero a, Mar´ıa L. Dura´n a,
Antonio Sousa-Pedrares a, Elena Labisbal a, Otaciro R. Nascimento b
a Departamento de Qu´ımica Inorga´nica, Uni6ersidad de Santiago de Compostela, 15706 Santiago de Compostela, Spain
b Instituto de F´ısica de Sao Carlos, Uni6ersidade de Sao Paulo, CP 369, 13560-250 Sao Carlos, SP, Brazil
Received 18 June 2001; accepted 28 September 2001
Abstract
The electrochemical oxidation of anodic metal (nickel, copper, zinc and cadmium) in acetonitrile solutions containing
N,N%-bis[(4-methylphenyl)sulfonyl]ethylenediamine H2L and an additional nitrogen coligand, such as 1,10-phenanthroline, yielded
mixed complexes of general formula [ML(phen)2] (M=Ni, Cu, Zn and Cd). The compounds have been characterized by
1
microanalysis, IR and UV–Vis (Ni, Cu complexes) spectroscopy, FAB mass spectrometry, H NMR spectroscopic studies (Zn,
Cd complexes) and EPR spectroscopy (Cu and Ni complexes). All compounds have also been characterized by single crystal X-ray
diffraction. The molecular structures of these compounds consist of individual monomeric molecules in which the metal atom is
in an [MN6] distorted octahedral environment. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Tosyl amide complexes; Electrochemical synthesis; X-ray crystal structures
amide proton by a metal ion is not an easy process [21],
in the case of a sulfonamide group the electron-with-
drawing effect of the sulfonyl group increases the acid-
ity of the amide hydrogen and makes the substitution
of the proton easier [22].
As a result of our continuing interest in the electro-
chemical synthesis of amide complexes, we describe
here the electrochemical synthesis of the nickel, copper,
zinc and cadmium(II) complexes [ML(phen)2] with
N,N%-bis[(4-methylphenyl)sulfonyl]ethylenediamine
(H2L).
1. Introduction
The application of an electrolytic procedure for the
synthesis of metal complexes has been widely used,
especially in the cases of weakly acidic organic ligands
in which the acid group is usually a hydroxyl [1–6], an
NH pyrrole [7–14] or a thiol group [15–20].
We have now extended our previous work to include
the electrochemical synthesis of complexes of ligands of
type (I) Scheme 1 bearing two secondary amide groups.
Although it is well known that replacement of the
2. Experimental
Acetonitrile, ethylenediamine, tosyl chloride, 1,10-
phenanthroline and all other reagents were commercial
products (Aldrich) and were used without further
purification. Nickel, copper, zinc and cadmium (Ega
Chemie) were used as plates (ca. 2×2 cm). The ligand
H2L Scheme 1, was prepared by slow addition of
Scheme 1.
* Corresponding author. Tel.: +34-81-563 100; fax: +34-81-594
912.
E-mail address: qijagv@usc.es (J.A. Garc´ıa-Va´zquez).
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00726-5

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J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
C7H7ClO2S (6.4 g, 33.4 mmol) to a stirred ice-cold
solution of C2H8N2 (1 g, 16.7 mmol) in Py (6 cm3).
After addition of cold water (10 cm3), the mixture was
stirred for 1 h. After this time, the oily organic phase
was separated and water (10 cm3) and EtOH (10 cm3)
were added. The solid formed was filtered off and
recrystallized from a mixture (1:1) of water–EtOH. The
purity of the product was checked by elemental analy-
1120 (s); 1098 (s); 1078 (s); 1020 (w); 1008 (w); 875 (w);
865 (w); 842 (s); 802 (s); 788 (w); 722 (s); 660 (s); 635
(w); 595 (w); 555 (s); 545 (w); 498 (w); 462 (w); 420 (w);
290 (w); 260 (w).
Crystals suitable for X-ray diffraction studies were
obtained by crystallisation from CH3OH–CH3CN.
2.1.2. [CuL(phen)2]
1
sis, IR and H NMR spectroscopy. Anal. Found: C,
An experiment similar to that described above, with
Cu as the anode and a solution of H2L (0.137 g, 0.372
mmol), 1,10-phenanthroline (0.148 g, 0.747 mmol) and
tetramethylammonium perchlorate (ca. 10 mg) in
MeCN (50 cm3), at 10 mA and 6 V for 2 h, dissolved 45
mg of Cu (Ef=0.95). At the end of the experiment the
pale green crystalline solid was filtered off, washed with
hot MeCN, Et2O and dried in vacuo. The compound
was characterized as [CuL(phen)2]·CH3CN. Anal.
Found: C, 60.6; H, 2.9; N, 10.8; S, 7.6. Calc. for
[C42H37CuN7O4S2]: C, 60.7; H, 4.5; N, 11.8; S, 7.7%. IR
(KBr, cm−1): 3040 (w); 3005 (w); 2980 (w); 2930 (w);
2880 (w); 2820 (w); 1615 (w); 1582 (s); 1565 (s); 1500
(s); 1480 (s); 1445 (w); 1420 (s); 1375 (w); 1352 (w);
1340 (w); 1312 (w); 1250 (s); 1215 (s); 1140 (s); 1120 (s);
1090 (s); 1020 (s); 1008 (s); 980 (w); 970 (w); 945 (w);
882 (w); 860 (w); 840 (s); 800 (s); 785 (s); 768 (s); 724
(s); 660 (s); 630 (w); 595 (s); 560 (s); 540 (s); 525 (s); 500
(w); 465 (w); 415 (w); 355 (w); 280 (w); 260 (w); 235 (w).
53.0; H, 5.7; N, 7.6; S, 17.7. Calc. for [C16H20N2O4S2]:
C, 52.2; H, 5.5; N, 7.6; S, 17.4%. IR (KBr, cm−1): 3275
(s); 3060 (w); 3040 (w); 2970 (w); 2925 (w); 2870 (w);
1915 (w); 1590 (s); 1485 (w); 1455 (s); 1445 (s); 1405 (s);
1330 (s); 1305 (s); 1290 (s); 1235 (w); 1180 (w); 1150 (s);
1090 (s); 1075 (s); 1060 (s); 1015 (w); 872 (s); 815 (s);
750 (s); 705 (w); 665 (s); 610 (w); 565 (s); 550 (s); 495
(w); 475 (w); 410 (w); 395 (w); 310 (w). 1H NMR
(CDCl3, ppm) 2.43 s (ꢀCH3); 3.05 s (CH2); 7.30 m, 7.71
m (C6H6 ring).
2.1. Preparation of complexes
The complexes were obtained using an electrochemi-
cal procedure. The cell consisted of a tall-form beaker
with a rubber bung through which the electrochemical
leads entered into the cell. An MeCN solution of the
ligand H2L and 1,10-phenanthroline (50 cm3), contain-
ing about 10 mg of tetramethylammonium perchlorate
as a current carrier, was electrolysed using a platinum
wire as the cathode and a metal plate as the sacrificial
anode. Applied voltages of 10–15 V allowed sufficient
current flow for smooth dissolution of the metal. As the
electrolysis proceeded, the colour of the solution
changed and hydrogen gas evolved from the cathode.
The cells can be summarised as Pt(−)/CH3CN+H2L/
M(+), where M is Ni, Cu, Zn or Cd.
2.1.3. [ZnL(phen)2]
Electrochemical oxidation of a Zn anode in a solu-
tion of H2L (0.206 g, 559 mmol), 1,10-phenanthroline
(0.222 g, 1.120 mmol) and tetramethylammonium per-
chlorate (ca. 10 mg) in MeCN (50 cm3), at 20 V and 10
mA for 3 h, caused 33 mg of Zn to be dissolved
(Ef=0.45). At the end of the experiment the brown
crystalline solid was filtered off, washed with hot
MeCN, Et2O and dried in vacuo. The compound was
characterized as [ZnL(phen)2]·CH3CN. Anal. Found: C,
60.6; H, 4.5; N, 11.5; S, 8.1. Calc. for
[C42H37N7O4S2Zn]: C, 60.5; H, 4.5; N, 11.8; S, 7.7%. IR
(KBr, cm−1): 3045 (w); 3010 (w); 2920 (w); 2880 (w);
2820 (w); 2240 (w); 1945 (w); 1910 (w); 1880 (w); 1820
(w); 1750 (w); 1615 (w); 1585 (s); 1568 (s); 1502 (s);
1482 (s); 1445 (w); 1420 (s); 1375 (w); 1340 (w); 1315
(w); 1280 (w); 1255 (s); 1240 (s); 1215 (s); 1185 (w);
1140 (s); 1120 (s); 1095 (s); 1080 (s); 1045 (w); 1020 (s);
1008 (s); 975 (w); 942 (w); 880 (w); 860 (w); 843 (s); 805
(s); 788 (s); 770 (w); 722 (s); 657 (s) 635 (w); 595 (w);
550 (s); 525 (w); 498 (w); 460 (w); 415 (w); 395 (w); 355
(w); 280 (w); 235 (w). 1H NMR (CDCl3, ppm) 2.00
(ꢀCH3); 3.51 (CH2); 6.21, 6.45 (C6H6 ring); 8.30 (2,9),
7.82 (4,7), 7.69 (5,6), 7.61 (3,8) (phen).
The crystalline solids formed at the bottom of the cell
were collected, washed with MeCN, Et2O and dried in
vacuo. In some cases concentration of the resulting
solution was required in other to obtain a solid
product.
2.1.1. [NiL(phen)2]
Electrolysis of a solution (50 cm3) of H2L (0.206 g,
0.559 mmol), 1,10-phenanthroline (0.222 g, 1.120
mmol) and tetramethylammonium perchlorate (ca. 10
mg) in MeCN, at 20 V and 10 mA for 3 h, dissolved 28
mg of Zn (Ef=0.43). At the end of the experiment the
brown crystalline solid was filtered off, washed with hot
MeCN, Et2O, and dried in vacuo. The compound was
characterized as [NiL(phen)2]·CH3CN. Anal. Found: C,
61.5; H, 4.6; N, 11.9; S, 8.5. Calc. for [C42H37N7-
NiO4S2]: C, 61.0; H, 4.5; N, 11.9; S, 7.8%. IR (KBr,
cm−1): 3050 (w); 3010 (w); 2920 (w); 2880 (w); 2815
(w); 1620 (w); 1590 (w); 1570 (w); 1503 (w); 1480 (w);
1440 (w); 1408 (s); 1340 (w); 1250 (s); 1240 (s); 1140 (s);
2.1.4. [CdL(phen)2]
The electrochemical oxidation of Cd in a solution of
the ligand H2L (0.206 g, 0.559 mmol) and 1,10-phenan-

J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
113
throline (0.222 g, 1.120 mmol) in MeCN (50 cm3), using
a 10 mA current for 3 h, resulted in the dissolution of
57 mg of the metal (Ef=0.45). At the end of the
electrolysis the yellow solid was filtered off, washed
with MeCN, Et2O and dried in vacuo. The compound
was characterized as [CdL(phen)2]. Anal. Found: C,
56.9; H, 4.1; N, 10.2; S, 7.3. Calc. for [C40H34CdN6-
O4S2]: C, 57.24; H, 4.08; N, 10.0; S, 7.6%. IR (KBr,
cm−1): 3060 (w); 3030 (w); 2970 (w); 2925 (w); 2880
(w); 2820 (w); 2240 (w); 1930 (w); 1890 (w); 1610 (w);
1580 (w); 1560 (w); 1500 (s); 1482 (s); 1435 (w); 1417
(s); 1370 (w); 1355 (w); 1339 (w); 1295 (w); 1250 (s);
1215 (s); 1140 (s); 1120 (s); 1100 (s); 1077 (s); 1040 (w);
1020 (s); 1005 (s); 854 (s); 840 (s); 802 (s); 782 (s); 766
(s); 720 (s); 659 (s); 635 (s); 595 (s); 550 (s); 538 (s); 520
(s); 490 (w); 460 (w); 415 (w); 395 (w); 350 (w); 275 (w);
mation. ORTEP diagrams of the molecules are shown in
Figs. 1–4.
2.4. EPR measurements of [CuL(phen)2] and
[NiL(phen)2]
The powder and frozen THF solution spectra of
[CuL(phen)2] and the powder spectrum of [NiL(phen)2]
were obtained using an EMX EPR spectrometer from
Bruker, equipped with a rectangular resonant cavity
and 100 kHz field modulation and N2 Temperature
Controller system. The EPR spectra were obtained at
120 K (room temperature for the Ni compound) under
the following conditions: 0.1 mT (0.4 mT) amplitude
modulation, 10 mW microwave power, and first and
second harmonic detection. In order to improve the
signal-to-noise ratio of the second harmonic measure-
ments, an average of 64 scans was recorded and a
detailed superhyperfine splitting from nitrogen nuclei
interactions was obtained. A g-marker of MgO–Cr(III)
(g=1.9797) was used to obtain the microwave fre-
quency for both samples. The positions and linewidths
of the resonance for the Cu compound were calculated
by numerical simulation of the powder spectra using
the QPOW program [26,27] with the Spin Hamiltonian
composed of Zeeman, Hyperfine and Superhyperfine
interactions. For the Ni compound the Spin Hamilto-
nian involves the zero field splitting and Zeeman inter-
action and to estimate the value of the zero field
splitting it was also necessary to measure the EPR
spectrum at the Q-band using a Varian E-line spec-
trometer. EPR spectra and simulations for the copper
compound are shown in Fig. 5 and the EPR parameters
are given in Table 6. The EPR spectra for the nickel
compound at both frequencies (X- and Q-band) are
shown in Fig. 6.
1
238 (w); 215 (w). H NMR (CDCl3, ppm) 1.99 (ꢀCH3);
3.33 (CH2); 6.28, 6.77 (C6H6 ring); 9.21 (2,9), 8.34 (4,7),
7.86 (5,6) and 7.70 (3,8) (phen).
2.2. Physical measurements
Microanalyses were performed using a CHNS Carlo
Erba 1108 elemental analyser. IR spectra were recorded
in KBr mulls on a Bruker IFs 66v spectrophotometer.
FAB mass spectra were recorded on a Kratos-MS-50T
spectrometer connected to a DS90 data system using
1
3-nitrobenzylalcohol (3-NBA) as a matrix. H and 13C
NMR spectra were recorded on a Bruker WM 350
MHz using CDCl3 or DMSO-d6 as solvents. Chemical
shifts were determined against TMS. Solid state elec-
tronic spectra were recorded on a Shimadzu UV 3101
PC. Magnetic measurements were made using a DMS
VSM 1160 instrument.
2.3. Crystal structure determination
Crystals of [NiL(phen)2], [CuL(phen)2], [ZnL(phen)2]
and [CdL(phen)2] were mounted on glass fibres on a
SIEMENS Smart CCD area-detector diffractometer.
Data collections were carried out under ambient condi-
3. Results and discussion
,
tions using Mo Ka radiation (u=0.71073 A, graphite
3.1. Electrochemical synthesis of complexes
monochromator).
All the structures were resolved by direct methods
and refined by full-matrix least-squares based on F2
[23]. Data were corrected for absorption using SADABS
[24]. No anomalies were encountered in the refinement
of any of the structures. Neutral atom scattering factors
and anomalous dispersion factors were taken from the
International Tables for X-ray Crystallography [25].
The crystal data and summary of data collection and
structure refinement for these compounds are given in
Table 1. Significant bond distances and angles for
The anodic oxidation of nickel, copper, zinc or cad-
mium in the presence of H2L and 1,10-phenanthroline
is a simple and efficient route to obtain compounds of
composition [ML(phen)2], where L is the dianion result-
ing of the deprotonation of the two amide groups of
ligand H2L. In all cases, the product formed was easily
separated as a crystalline product by filtration. These
compounds are insoluble in common organic solvents
and have melting points greater than 250 °C.
The values of the electrochemical efficiency, defined
as the amount of metal dissolved per Faraday of
charge, were close to 0.5 in the cases of the Ni, Zn and
Cd complexes. This fact, along with the evolution of
[NiL(phen)2],
[CuL(phen)2],
[ZnL(phen)2]
and
[CdL(phen)2] are given in Tables 2–5. Complete crys-
tallographic details are given in the Supporting Infor-

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J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
Table 1
Summary of crystal data and structure refinement
Compound
[NiL(phen)2]
[CuL(phen)2]
[ZnL(phen)2]
[CdL(phen)2]
Empirical formula
Formula weight
Temperature (K)
C42H37N7NiO4S2
826.62
293(2)
C42H37CuN7O4S2
831.44
293(2)
C42H37N7O4S2Zn
833.28
293(2)
C40H34CdN6O4S
839.26
293(2)
,
Wavelength (A)
0.71073
monoclinic
Cc
0.71073
monoclinic
C2
0.71073
monoclinic
C2
0.71073
monoclinic
C2/c
Crystal system
Space group
Unit cell dimensions
,
a (A)
9.53490(10)
16.4785(3)
25.0886(4)
90.00(–)
94.0817(4)
90.00(–)
3931.94(10)
4
17.32590(10)
9.31180(10)
13.2776(2)
90.00(–)
113.0240(10)
90.00(–)
1971.50(4)
2
17.1584(5)
9.4354(3)
13.3009(3)
90.00(–)
113.1350(10)
90.00(–)
1980.20(10)
2
20.9098(2))
13.4262(2)
14.6961(2)
90.00(–)
122.7430(10)
90.00(–)
3470.20(8)
4
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Dcalc (mg m−3
)
1.396
1.401
1.398
1.606
Absorption coefficient
(mm−1
F(000)
0.652
0.712
0.777
0.804
)
1720
862
864
1712
Crystal size (mm)
Colour
q range for data collection (°) 1.63–28.26
0.45×0.30×0.05
Brown–red
0.40×0.30×0.15
Green
2.44–28.27
0.20×0.15×0.10
Light brown
1.66–28.27
0.45×0.40×0.20
Yellow
1.91–28.27
Index ranges
−125h512, −95k521, −225h521, −115k512, −225h520, −125k510, −185h527, −175k514,
−335l533
13 226
−125l−517
6809
−165l−517
6810
−195l517
12 422
Reflections collected
Reflections observed
13 226
6809
6810
12 422
Independent reflections
Criterion for observation
Data/restraints/parameters
Final R indices [I\2|(I)]
Goodness-of-fit on F2
8886 [Rint=0.0508]
I\2|(I)
8886/2/508
0.0433/0.0867
0.793
4023 [Rint=0.0219]
I\2|(I)
4023/1/255
0.0298/0.0650
0.979
4013 [Rint=0.0484]
I\2|(I)
4013/1/260
0.0522/0.0826
1.003
4280 [Rint=0.0195]
I\2|(I)
4280/0/308
0.0237/0.0592
1.026
Largest difference peak and 0.485 and −0.665
0.388 and −0.270
0.289 and −0.455
0.336 and −0.486
−3
,
hole (e A
)
3.2. Structure of [NiL(phen)2]
hydrogen from the cathode, is compatible with the
mechanism:
Fig. 1 shows the molecular structure of [NiL(phen)2]
together with the atom labelling scheme adopted. Se-
lected bond distances and angles are given in Table 2.
The complex crystallises with four formula units and
four acetonitrile molecules in the cell.
Cathode: H2L+2e−“L−2+H2
Anode:
M+L−2+2 phen“[ML(phen)2]+2e−
M=Ni, Zn, Cd.
An Ef value close to 1.0 mol F−1 was found in the
synthesis of the copper complex, and this shows that
the anodic oxidation leads initially to a Cu(I) com-
pound. However, the analytical data show that the
complex is [CuL(phen)2]. This observation suggests that
the ligand oxidises the Cu(I) to Cu(II) in solution as
soon as it is formed.
As can be seen in Fig. 1, monomeric [NiL(phen)2] has
a highly distorted octahedral coordination around
Ni(II). The coordination sphere involves four nitrogen
atoms belonging to two bidentate 1,10-phenanthroline
ligands and two amide nitrogen atoms of the dianionic
ligand N,N%-bis(p-toluenesulfonyl)ethylenediamide.
The arrangement of the 1,10-phenanthroline ligands
is such that the equatorial plane is formed by two
nitrogen atoms of one phenanthroline molecule, one
nitrogen atom of the other phenanthroline molecule
and one of the nitrogen atoms from the dianionic
ligand. The inner coordination sphere is completed by
two additional nitrogen atoms, one from the dianionic
ligand and other from a phenanthroline molecule. The
four ‘in plane’ atoms N(2), N(3), N(5) and N(6) are not
Cathode: H2L+1e−“1/2H2(g)+HL−
Anode:
Cu“Cu++1e−
HL−+Cu++phen“[CuL(phen)2]+1/2H2(g)
This behaviour has been previously observed in the
synthesis of other copper complexes by an electrochem-
ical procedure [6].

J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
115
Table 2
coplanar; N(3) and N(5), which are trans to each other,
,
Selected bond lengths (A) and angles (°) for [NiL(phen)2]
,
lie −0.094(1) and −0.107(1) A, respectively, below the
least-squares plane through the four atoms, while N(2)
Bond lengths
,
and N(6) are +0.092(1) and +0.109(1) A, respec-
Ni(1)ꢀN(2)
Ni(1)ꢀN(5)
Ni(1)ꢀN(4)
S(1)ꢀO(2)
S(1)ꢀN(1)
S(2)ꢀO(3)
S(2)ꢀN(2)
N(1)ꢀC(1)
N(3)ꢀC(17)
N(4)ꢀC(26)
N(5)ꢀC(29)
N(6)ꢀC(38)
2.083(3)
2.109(3)
2.131(3)
1.446(3)
1.571(3)
1.450(2)
1.573(3)
1.473(4)
1.315(4)
1.317(5)
1.321(4)
1.314(4)
Ni(1)ꢀN(1)
Ni(1)ꢀN(3)
Ni(1)ꢀN(6)
S(1)ꢀO(1)
S(1)ꢀC(3)
S(2)ꢀO(4)
S(2)ꢀC(10)
N(2)ꢀC(2)
N(3)ꢀC(21)
N(4)ꢀC(22)
N(5)ꢀC(33)
N(6)ꢀC(34)
2.085(3)
2.116(3)
2.135(3)
1.458(2)
1.785(4)
1.452(3)
1.795(3)
1.480(4)
1.365(4)
1.368(4)
1.369(4)
1.367(4)
tively, above this plane; the nickel atom lies nearly in
,
the plane, sitting 0.063(1) A above it. This lack of
planarity gives rise to N(3)ꢀNiꢀN(5) and N(2)ꢀNi(1)ꢀ
N(6) angles of 166.42(10) and 172.71(11)°, respectively.
Further distortion is provided by the small bite of the
1,10-phenanthroline ligands [78.70(10) and 78.53(10)°]
and the dianionic ligand [NamideꢀNiꢀNamide, 80.89(10)°].
This situation causes the angles defined by the two
trans nitrogen atoms and the nickel atom to be very
different from the expected values of 180° [166.42(10)
and 172.94(11)°] and also means that the angles deter-
mined by the Ni and two cis nitrogen atoms differ from
90° [78.53(10)–97.05(10)°].
Bond angles
N(2)ꢀNi(1)ꢀN(1)
N(1)ꢀNi(1)ꢀN(5)
C(1)ꢀN(1)ꢀNi(1)
S(1)ꢀN(1)ꢀNi(1)
N(2)ꢀNi(1)ꢀN(4)
N(1)ꢀNi(1)ꢀN(4)
N(5)ꢀNi(1)ꢀN(4)
C(17)ꢀN(3)ꢀNi(1) 127.9(2)
C(21)ꢀN(3)ꢀNi(1) 113.5(2)
N(5)ꢀNi(1)ꢀN(6)
N(3)ꢀNi(1)ꢀN(6)
N(4)ꢀNi(1)ꢀN(6)
80.89(10)
95.51(11)
109.84(19)
129.07(16)
96.93(10)
172.92(11)
91.37(10)
N(2)ꢀNi(1)ꢀN(5)
N(2)ꢀNi(1)ꢀN(3)
N(1)ꢀNi(1)ꢀN(3)
N(5)ꢀNi(1)ꢀN(3)
C(2)ꢀN(2)ꢀNi(1)
S(2)ꢀN(2)ꢀNi(1)
N(3)ꢀNi(1)ꢀN(4)
N(2)ꢀNi(1)ꢀN(6)
N(1)ꢀNi(1)ꢀN(6)
C(26)ꢀN(4)ꢀNi(1) 129.4(2)
C(22)ꢀN(4)ꢀNi(1) 112.7(2)
C(29)ꢀN(5)ꢀNi(1) 128.0(2)
C(38)ꢀN(6)ꢀNi(1) 129.7(2)
94.62(10)
95.68(11)
94.79(11)
166.45(11)
109.74(18)
129.88(16)
78.68(11)
172.72(11)
97.05(10)
The NiꢀNamide bond distances [2.083(3) and 2.085(3)
,
A] do not differ significantly from those of the octahe-
dral 1,10-phenanthroline complex bis{[(4-methyl-
phenyl)sulfonyl]-2-pyridylamide}nickel(II), 2.095(6) and
,
2.096(6) A [28], but they are significantly greater than
78.58(10)
91.43(10)
85.92(10)
those found in tetracoordinated nickel(II) amide com-
,
plexes; for example, 1.916(3) A in the tetrahedral com-
plex [N,N% - bis(2% - pyridinecarboxamido)-1,2-ethane]-
C(33)ꢀN(5)ꢀNi(1) 113.9(2)
C(34)ꢀN(6)ꢀNi(1) 113.0(2)
,
nickel(II) [29] and 1.904(3) A in the square–planar
complex bis{4-methyl-N-(2-pyridin-2-yl-ethyl)benzene-
sulfonamide}nickel(II) [30]. This change in bond length
is due to a change in the coordination number from 4
to 6. The NiꢀNphen bond distances, 2.116(3), 2.131(3),
,
2.109(3) and 2.134(3) A, are similar to those found in
other octahedral nickel(II) phenanthroline complexes;
Table 3
,
Selected bond lengths (A) and angles (°) for [CuL(phen)2]
,
for example, 2.121(5) and 2.136(5) A in 1,10-phenan-
throline bis{[2-(2-pyrrole)methylimino]-4-methylpheno-
lato}nickel (II) [31].
The 1,10-phenanthroline ligands are essentially pla-
nar, with no atom deviating from the least-squares
plane by more than 0.046 A. The bond lengths and
angles within the ligand are similar to those found in
other 1,10-phenanthroline complexes. The Nphen
Bond lengths
Cu(1)ꢀN(1)
Cu(1)ꢀN(3)
S(1)ꢀO(2)
2.020(2)
2.3489(17) S(1)ꢀO(1)
1.4491(17) S(1)ꢀN(1)
1.784(2)
1.331(3)
1.316(3)
1.403(3)
1.343(4)
1.124(9)
Cu(1)ꢀN(2)
2.1142(19)
1.4445(17)
1.571(2)
1.467(3)
1.359(3)
1.347(3)
1.522(5)
1.378(4)
S(1)ꢀC(2)
N(1)ꢀC(1)
,
N(2)ꢀC(9)
N(3)ꢀC(18)
C(17)ꢀC(18)
C(19)ꢀC(20)
N(90)ꢀC(90)
N(2)ꢀC(13)
N(3)ꢀC(14)
C(1)ꢀC(1)c1
C(2)ꢀC(3)
ꢀ
NiꢀNphen angles of 78.70(10) and 78.53(10)° are similar
to those reported for other bidentate complexes of
Bond angles
phenanthroline
[28,31,32].
The
phenanthroline
N(1)ꢀCu(1)ꢀN(1)c1 82.30(11) N(1)ꢀCu(1)ꢀN(2)
N(1)c1ꢀCu(1)ꢀN(2) 97.65(7) N(1)c1ꢀCu(1)ꢀ
N(2)c1
168.21(7)
168.21(7)
molecules are almost perpendicular to one another,
with a dihedral angle of 80.13(4)°, and form dihedral
angles with the equatorial plane of 6.98(11) and
81.94(5)°.
N(2)ꢀCu(1)ꢀN(2)c1 84.82(10) N(1)ꢀCu(1)ꢀN(3)
N(1)c1ꢀCu(1)ꢀN(3) 97.13(7) N(2)ꢀCu(1)ꢀN(3)
93.96(7)
74.32(7)
N(2)c1ꢀCu(1)ꢀN(3) 94.64(7) N(3)ꢀCu(1)ꢀN(3)c1 165.26(9)
C(1)ꢀN(1)ꢀCu(1)
S(1)ꢀN(1)ꢀCu(1)
C(9)ꢀN(2)ꢀCu(1)
C(13)ꢀN(2)ꢀCu(1)
C(18)ꢀN(3)ꢀCu(1)
C(14)ꢀN(3)ꢀCu(1)
N(90)ꢀC(90)ꢀC(91)
110.51(14) N(3)ꢀC(14)ꢀC(13)
129.56(12) C(15)ꢀC(14)ꢀC(13)
123.39(16) C(16)ꢀC(15)ꢀC(14)
118.68(15) C(16)ꢀC(15)ꢀC(20)
130.12(15) C(17)ꢀC(16)ꢀC(15)
111.35(14) C(16)ꢀC(17)ꢀC(18)
180.00(4)
117.66(2)
119.6(2)
117.0(2)
123.1(2)
119.9(2)
119.0(2)
3.3. Structure of [CuL(phen)2]
Fig. 2 shows the molecular structure of [CuL(phen)2]
together with the labelling scheme used. Selected bond
distances and angles with estimated standard deviations
are given in Table 3.
In [CuL(phen)2] the copper atom is located on a
twofold axis and is hexacoordinated by the two amide
Symmetry transformations used to generate equivalent atoms: c1,
−x, y, −z.

116
J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
Table 4
,
greater, 2.3489(17) A, than the other four, 2.020(2)–
,
Selected bond lengths (A) and angles (°) for [ZnL(phen)2]
,
2.1142(19) A. Therefore, in the [CuL(phen)2] complex
the coordination polyhedron is best described as an
octahedron with the longer CuꢀN distances associated
with the axial nitrogen atoms. Thus, the equatorial
plane is formed by the two amide nitrogen atoms of the
tosylamide ligand and two other nitrogen atoms, one
from each phenanthroline molecule; the axial positions
are occupied by the other nitrogen atoms of each
phenanthroline.
The N(1), N(1)*, N(2) and N(2)* atoms of the equa-
torial plane deviate considerably from planarity. The
trans equatorial atoms N(1) [N(1*)] and N(2) [N(2*)]
are both above (below) the least-squares plane by +
Bond lengths
Zn(1)ꢀN(1)
Zn(1)ꢀN(3)
S(1)ꢀO(1)
S(1)ꢀC(2)
N(2)ꢀC(9)
N(3)ꢀC(18)
2.092(4)
2.247(4)
1.446(3)
1.781(4)
1.331(5)
1.335(6)
Zn(1)ꢀN(2)
S(1)ꢀO(2)
S(1)ꢀN(1)
N(1)ꢀC(1)
N(2)ꢀC(13)
N(3)ꢀC(14)
2.202(3)
1.445(3)
1.556(4)
1.471(6)
1.354(5)
1.352(5)
Bond angles
N(1)ꢀZn(1)ꢀN(1)c1 81.7(2)
N(1)ꢀZn(1)ꢀN(2)
99.90(14)
99.90(13)
N(1)ꢀZn(1)ꢀN(2)c1 95.35(13) N(1)c1ꢀZn(1)ꢀ
N(2)c1
N(2)ꢀZn(1)ꢀN(2)c1 159.81(19) N(1)ꢀZn(1)ꢀN(3)
c1
169.59(14)
90.44(13)
98.61(12)
N(1)c1ꢀZn(1)ꢀN(3) 98.61(12) N(2)ꢀZn(1)ꢀN(3)
,
,
0.218(1) A [−0.203(1) A], leading to an N(1)ꢀCuꢀN(2)
angle of 168.21(7)°. The copper atom lies in the best
square plane formed by the equatorial atoms. The angle
between the apical nitrogen atoms and the copper atom
is 165.26(9)°, whereas those formed by the metal and
two cis ligands differ from 90°, with values in the range
82.30(11)–97.6(7)°.
c1
c1
N(2)c1ꢀZn(1)ꢀN(3) 74.32(13) N(1)ꢀZn(1)ꢀN(3)
c1
N(1)c1ꢀZn(1)ꢀN(3) 69.59(14) N(2)ꢀZn(1)ꢀN(3)
N(2)c1ꢀZn(1)ꢀN(3) 90.44(13) N(3)c1ꢀZn(1)ꢀ
N(3)
74.32(13)
83.0(2)
C(1)ꢀN(1)ꢀZn(1)
C(9)ꢀN(2)ꢀZn(1)
C(18)ꢀN(3)ꢀZn(1)
108.9(3)
125.3(3)
128.6(3)
S(1)ꢀN(1)ꢀZn(1)
C(13)ꢀN(2)ꢀZn(1)
C(14)ꢀN(3)ꢀZn(1)
128.7(2)
116.3(3)
114.6(3)
Two of the bond distances between the copper atom
and the four nitrogen atoms of the 1,10-phenanthroline
,
molecules are significantly longer, 2.3489(17) A, than
Symmetry transformations used to generate equivalent atoms: c1,
−x+2, y, −z+2; c2, −x+2, y, −z+1.
,
the other two, 2.1142(19) A. The longer distances are
associated with the apical nitrogen atoms. The value of
,
2.1142(19) A can be considered as normal and is similar
to those found in other copper complexes with biden-
Table 5
,
Selected bond lengths (A) and angles (°) for [CdL(phen)2]
tate 1,10-phenanthroline or 2,2%-bipyridine ligands
[33,34]. However, the distance of 2.3489(17) A is unusu-
Bond lengths
,
Cd(1)ꢀN(1)
Cd(1)ꢀN(3)
Cd(1)ꢀN(2)
S(1)ꢀO(1)
S(1)ꢀO(2)
S(1)ꢀN(1)
S(1)ꢀC(2)
N(1)ꢀC(1)
2.2827(14) N(2)ꢀC(9)
2.3866(14) N(2)ꢀC(20)
2.4103(14) N(3)ꢀC(18)
1.4410(14) N(3)ꢀC(19)
1.4481(14) C(1)ꢀC(1)c1
1.5669(14) C(2)ꢀC(3)
1.7817(17) C(2)ꢀC(7)
1.465(2)
1.323(2)
1.354(2)
1.326(2)
1.350(2)
1.518(3)
1.381(2)
1.391(3)
ally high and is similar to the longest CuꢀN distance
found in [Cu(phen)3]2+, a compound with a very pro-
nounced Jahn–Teller distortion [34]. The CuꢀNamide
,
bond length, 2.020(2) A, is significantly shorter than
those generally observed in other hexacoordinated cop-
per complexes with tosylamides, such as bis[(N-4-tolue-
nesulfonyl-2-pyridylaminato-N,N%)-pyridyl] copper(II)
[35], 2.548 and 2.387 A. This bond is slightly longer
than those reported for tetracoordinated copper com-
Bond angles
N(1)ꢀCd(1ꢀN(1)c1
,
77.08(7) N(1)ꢀCd(1)ꢀN(3)
104.74(5)
N(1)c1ꢀCd(1)ꢀN(3) 95.74(5) N(3)ꢀCd(1)ꢀN(3)c1 153.81(7)
N(1)ꢀCd(1)ꢀN(2)c1 164.42(5) N(1)c1ꢀCd(1)ꢀN(2) 100.81(5)
c1
,
plexes involving sulfonamides. For example, 1.999(2) A
in square planar bis{4-methyl-N-(2-pyridin-2-yl-
ethyl)benzenesulfonamide}copper(II) [30]. However, it
is similar to that found in pentacoordinated copper(II)
complexes; e.g. 2.041(5) and 2.031(5) A in [CuL2dmf],
where HL is N-(p-tolylsulphonyl)-o-phenylenediamine
[36], or 2.044(3) A in {(1,10-phenanthroline)[N-2(oxo-
phenyl)-methylidine]-N%-tosylbenzene-1,2-diaminato}-
copper(II) [32].
Each of the phenanthroline ligands is planar within
experimental error; the intraligand bond lengths and
angles are similar to those found in other complexes
and will not be discussed further.
N(3)ꢀCd(1)ꢀN(2)c1 90.82(5) C(1)ꢀN(1)ꢀCd(1)
N(3)c1ꢀCd(1)ꢀN(2) 69.66(5) S(1)ꢀN(1)ꢀCd(1)
c1
107.75(10)
126.46(8)
,
N(3)c1ꢀCd(1)ꢀN(2) 90.82(5) C(9)ꢀN(2)ꢀC(20)
N(2)c1ꢀCd(1)ꢀN(2) 85.27(7) C(9)ꢀN(2)ꢀCd(1)
118.54(15)
125.23(12)
116.21(11)
,
O(1)ꢀS(1)ꢀO(2)
116.71(9) C(20)ꢀN(2)ꢀCd(1)
Symmetry transformations used to generate equivalent atoms: c1
−x+2,y,−z+1/2
nitrogen atoms of the dianionic ligand and by four
nitrogen atoms of two bidentate 1,10-phenanthroline
molecules. This environment is similar to that found in
[NiL(phen)2], but with an important difference. In the
[NiL(phen)2] compound all the NiꢀN distances are
quite similar, 2.083(3)–2.134(3) A, whereas in the cop-
per complex two of the CuꢀN bond distances are
3.4. Structure of [ZnL(phen)2]
,
The molecular structure of [ZnL(phen)2], along with
the atom labelling scheme, is illustrated in Fig. 3.

J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
117
Selected bond lengths and angles, with estimated stan-
dard deviations are given in Table 4. The zinc atom is
located on a crystallographic twofold axis and is coordi-
nated to the two amide nitrogen atoms of the dianionic
tosylamide ligand and to four nitrogen atoms of two
phenanthroline molecules. The coordination polyhedron
around the zinc atom is distorted octahedral. The small
bite angles of the ligands, particularly in the case of the
neutral 1,10-phenanthroline ligand, are the main reason
for the distortion. Thus, the values of the NphenꢀZnꢀ
Nphen and NamideꢀZnꢀNamide angles are 74.32(2) and
81.7(2)°, respectively. One of the amide nitrogen atoms,
N(1), and one nitrogen atom, N(3)%, of a phenanthroline
molecule are in trans positions and, consequently,
if these are considered as the apical positions then
the equatorial plane is formed by the other amide
nitrogen atom of the tosylamide ligand and the other
three nitrogen atoms of the 1,10-phenanthroline
molecules. Two of the nitrogen atoms of this plane,
N(1)* and N(3), are below the best equatorial square
,
plane by 0.112(2) and 0.138(2) A, respectively, while
,
N(2) and N(2)* are above it by 0.138(2) and 0.113(2) A,
,
respectively. The zinc atom is 0.125(2) A out of this
equatorial plane. The NꢀZnꢀN bond angles within the
equatorial plane differ markedly from those of a regular
octahedron; cis, 74.32(13)–99.90(13)° and trans,
159.81–169.59(14)°. The axial positions form an angle
NꢀZnꢀN of 169.59(14)°. This distortion is caused mainly
by the small bite angle, 74.32(13)°, of the phenanthroline
ligands.
Two different ZnꢀN bond distances are observed; the
,
bonds involving amide nitrogen atoms, 2.092(4) A, are
Fig. 1. Perspective view of [NiL(phen)2] (50% probability displacement ellipsoids).
Fig. 2. Perspective view of [CuL(phen)2] (50% probability displacement ellipsoids).

118
J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
Fig. 3. Perspective view of [ZnL(phen)2] (50% probability displacement ellipsoids).
Fig. 4. Perspective view of [CdL(phen)2] (50% probability displacement ellipsoids).
significantly shorter than those involving phenanthro-
other 1,10-phenanthroline complexes. The phenanthro-
line molecules are almost perpendicular to one another,
dihedral angle of 80.26(5)°, and form dihedral angles
with the equatorial plane of 81.12(6) and 7.86(13)°.
,
line nitrogen atoms, 2.202(3) and 2.247(4) A. These
latter bonds are slightly longer than those found in
other octahedral zinc compounds that contain phenan-
throline; e.g. in [Zn(pyS)2phen] [37] [average value
,
,
2.182(7) A] or in [Zn(O2C6H4)(phen)2] [38] (2.189 A).
3.5. Structure of [CdL(phen)2]
,
The ZnꢀNamide bond distances, 2.092(4) A, are greater
than those found in tetrahedral compounds containing
anionic nitrogen atoms; e.g. 1.962(5) A in bis{N-[(2-
pyrrolyl)methylidyne]-N%-tosylbenzene-1,2-diaminato}-
zinc(II) [39]. However, this distance is shorter than
those found in the octahedral amide zinc(II) complex
[Zn(C7H4NO3S)2(H2O)4], 2.201(2) A, where C7H4NO3S
is the anion of saccharine [40].
Each 1,10-phenanthroline ligand is essentially planar,
with no atom deviating from the least-squares plane by
more than 0.050 A. In addition, the bond lengths and
A perspective view of the molecular structure of
[CdL(phen)2], along with the atom labelling scheme, is
illustrated in Fig. 3. Selected bond distances and angles
with estimated standard deviations are given in Table 5.
The structure of [CdL(phen)2] shows that the cad-
mium atom is located on a twofold axis and is coordi-
nated to the nitrogen atoms of two bidentate
1,10-phenanthroline molecules and to the amide nitro-
gen atoms of the dianionic ligand in a distorted octahe-
dral [CdN6] coordination environment. The CdꢀNamide
,
,
,
,
bond lengths are shorter, 2.2827(14) A, than the
angles within the ligand are similar to those found in

J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
119
,
CdꢀNphen bond lengths, 2.3866(14) and 2.4103(14) A,
cadmium(II) [41]. The CdꢀNphen bond lengths,
,
probably because in the former case the ligand is an-
ionic, whereas the other ligands are neutral.
The CdꢀNamide bond length is quite similar to those
found in other hexacoordinated complexes of cadmiu-
2.3866(14) and 2.4103(14) A, are slightly longer than
those found in the above complex, 2.304(11) and
,
2.374(10) A.
The trans atoms N(1%) and N(2) of the equatorial
,
m(II); e.g. 2.234(12) and 2.280(10) A in 1,10-phenan-
throlinebis{[(4-methylphenyl)sulfonyl]-2-pyridylamide}-
plane described by [N(2)N(3)N(1%)N(3%)] are below the
,
least-squares plane by −0.1689(5) and −0.23338(8) A,
Fig. 5. EPR spectra of the [CuL(phen)2] as: (a) solid state powder sample and (b and c) as a tetrahidrofurane (THF) solution. Spectra were
measured at 120 K, 0.1 mT of amplitude modulation as a first and second harmonic and 10 mW of microwave power. The second harmonic
measurement was done with 64 scans to improve signal-to-noise ratio. The spectral simulations are presented as dot lines.
Table 6
EPR parameters extracted by computing simulation from EPR spectra of the sample [CuL(phen)2] as a powder and THF solution
Type of
sample
Nuclei
gx90.0003 gy90.0003 gz90.0003 Ax (MHz) Ay (MHz) Az (MHz) DHx (MHz) DHy (MHz) DHz (MHz)
Powder
Cu(II)
N-equatorial
N-apical
2.0470
2.0530
2.1030
2.0860
2.2580
2.2830
5
20
5
5
12
5
408
5
15
45
25
50
25
360
25
THF solution Cu(II)
N-equatorial
N-apical
5
35
5
5
35
5
438
5
35
The Cu(II) ion are coordinated by four equatorial nitrogen nuclei and two apical nitrogen nuclei. The EPR measurements was done at
temperature of 120 K.

120
J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
of one phenanthroline ligand from the initial species
(m/z 605, 610, 611 and 661, respectively, for M=Ni,
Cu, Zn and Cd). The spectra also show a peak for the
[M(phen)2] fragment (m/z 418, 423, 424 and 473, re-
spectively, for M=Ni, Cu, Zn and Cd) formed by loss
of the amide ligand and another peak for [Mphen] [m/z
238 (100%), 243 (100%), 244 (67%) and 294 (100%), for
M=Ni, Cu, Zn and Cd, respectively] formed by loss of
both the amide ligand and one of the phenanthroline
molecules.
In the cases of the zinc and cadmium complexes, the
1H NMR spectra provide further evidence for the
above conclusions. The spectrum of the ligand shows
one singlet at 5.30 ppm, which is assigned to the amide
proton, and signals at 3.05 and 2.43 ppm, assigned to
the methylene and methyl protons, respectively. A mul-
tiplet due to the aromatic hydrogen atoms is observed
in the range 7.7–7.3 ppm. The spectra of [ZnL(phen)2]
and [CdL(phen)2] show that the signal due to the amide
proton is absent, reinforcing the conclusion drawn form
the IR spectra that the ligands are coordinated to the
metal in their dianionic form.
On the other hand, the signals due to the methylene
groups are shifted to low field and the signals due to the
1,10-phenanthroline hydrogen atoms to high field. This
can be taken as further evidence for coordination of the
amide ligand and coordination of the phenanthroline to
the metal centre. This conclusion is supported by the
X-ray diffraction structures of [ML(phen)2].
Fig. 6. EPR spectra of the [NiL(phen)2] as a solid state powder
sample: is the spectrum at X-band (a) and (b) Q-band. Spectra were
measured at 293 K, 0.4 mT of amplitude modulation and 10 mW of
microwave power. A Cr(III), as impurity in MgO crystal, was used as
g-marker.
The solid reflectance spectrum of the [CuL(phen2)]
complex shows an asymmetric band around 13 600
cm−1, which is typical of copper(II) species with a
hexacoordinated geometry [43] and is in agreement with
the structure of [CuL(phen)2] established by X-ray dif-
fraction. The magnetic moment of the copper(II) com-
plex (1.91 BM) is close to the spin value for one
unpaired electron and within the general range for
Cu(II) complexes.
respectively, while N(3) and N(3%) are above it by
,
+0.2309(8) and +0.1718(6) A, respectively. This situa-
tion leads to an N(1)ꢀCdꢀN(2%) angle of 164.42(5)°. The
,
cadmium atom is 0.140(1) A out of the equatorial
plane.
The 1,10-phenanthroline ligands are planar, with di-
hedral angles between them of 77.81° and dihedral
angles between them and the equatorial plane of 8.92(6)
and 81.19(3)°.
The solid state powder EPR spectrum at 120 K is
shown in Fig. 5(a). The main feature is the presence of
a non-resolved broad signal in the low field region. This
spectrum can be assigned to a distorted octahedral
complex with three different g values, as described in
Table 6. When the powder sample is dissolved in te-
trahydrofuran (THF) and frozen at 120 K, the EPR
spectrum shows a detailed hyperfine splitting from the
interaction of the unpaired electron spin with the cop-
per nuclear spin and superhyperfine splitting from the
nuclear spin of the surrounding nitrogen atoms. Fig.
5(b and c) show these results with the best simulations.
The parameters of the best fit are shown in Table 6.
The simulation was obtained on the assumption that
the four equatorial nitrogen atoms are equivalent and
that the two apical ones are equivalent but different
from the equatorial ones. The isotropic values Ao=
3.6. Spectroscopic studies
The w(NH) band in the free ligands appears at 3275
cm−1 but is not observed in the IR spectra of the
complexes. This observation indicates that the amide
hydrogen atoms are lost during the electrochemical
process. In addition, the spectra of the complexes also
show bands at 1510, 850, and 730 cm−1 due to the
coordinated phenanthroline molecules [42]. All these
data are in accordance with a hexacoordinated geome-
try for these complexes.
The FAB mass spectra of the compounds show, in all
cases, the molecular ion [ML(phen)2] (m/z 785, 790, 791
and 839, respectively, for M=Ni, Cu, Zn and Cd), as
well as a peak associated with [MLphen] formed by loss

J. Sa´nchez-Piso et al. / Inorganica Chimica Acta 328 (2002) 111–122
121
(Ax+Ay+Az)/3 for the superhyperfine interactions
show that the unpaired electron is more concentrated
on the equatorial nitrogen nuclei (Ao=25 MHz) than
on the apical nuclei (Ao=15 MHz), as expected from
the crystal data. The Az value for the hyperfine interac-
tion with the copper nuclear spin is smaller (Az=438
MHz, or 13.8 mT) than the values found in other
copper compounds containing nitrogen ligands [43–45].
This could be due to delocalization of the unpaired
electron over the six surrounding nitrogen atoms. The
unpaired electron could be described as occupying a
accord with a hexacoordinate environment around the
nickel atom.
Acknowledgements
We thank the X. de G. (Xuga 20302B97 and
PGIDT00PXI20305PR) for financial support.
References
dx
orbital mixed with the four in-plane p orbitals
2
2
−y
of the equatorial nitrogen atoms and a dz orbital
2
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