Transition metal complexes with 2-(N-tosylamino)benzaldehyde 1-phthalazinylhydrazone

Article abstract of DOI:10.1134/S1070328411060078

2-(N-Tosylamino)benzaldehyde 1-phthalazinylhydrazone (H₂L) and its complexes with Cu(II), Ni(II), and Mn(II) were obtained. The acid-basic properties of the hydrazone were studied using potentiometry and spectrophotometry. The experimental data

Full text of DOI:10.1134/S1070328411060078

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 7, pp. 483–491. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © L.D. Popov, I.N. Shcherbakov, S.I. Levchenkov, Yu.P. Tupolova, A.S. Burlov, G.G. Aleksandrov, V.V. Lukov, V.A. Kogan, 2011, published in Koordinatꢀ
sionnaya Khimiya, 2011, Vol. 37, No. 7, pp. 483–491.
Transition Metal Complexes with 2ꢀ(NꢀTosylamino)benzaldehyde
1ꢀPhthalazinylhydrazone
L. D. Popova, I. N. Shcherbakova, S. I. Levchenkovb, *, Yu. P. Tupolovaa, A. S. Burlova,
G. G. Aleksandrovc, V. V. Lukova, and V. A. Kogana
a Southern Federal University, RostovꢀonꢀDon, Russia
b Southern Scientific Center, Russian Academy of Sciences, RostovꢀonꢀDon, Russia
c Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
*eꢀmail: physchem@yandex.ru
Received August 25, 2010
Abstract—2ꢀ(NꢀTosylamino)benzaldehyde 1ꢀphthalazinylhydrazone (H2L) and its complexes with Cu(II),
Ni(II), and Mn(II) were obtained. The acidꢀbasic properties of the hydrazone were studied using potentiomꢀ
etry and spectrophotometry. The experimental data were compared with the results of quantumꢀchemical
DFT calculations. The structure of the binuclear complex [Cu2L2] was determined using Xꢀray diffraction.
The broken symmetry approach was used to calculate the exchange coupling constant of the copper ions.
DOI: 10.1134/S1070328411060078
Hydrazones and azomethines of polyfunctional
carbonyl compounds are ligands under very intensive
study in modern coordination and supramolecular
chemistry [1–4]. These ligand systems tend to form
binuclear complexes with exchange couplings between
the metal ions. Such complexes allow relatively easy
variation in the electronꢀdonating centers, central
ions, and exogenous bridging groups and hence can
serve as convenient models for investigation of the
main factors that determine the character and strength
of exchange couplings between paramagnetic centers;
both antiferromagnetic and ferromagnetic exchange is
possible [5–9]. Magnetochemical analysis of such
exchangeꢀcoupled systems is an essential area of coorꢀ
dination chemistry; its ultimate priority is the design
of molecular magnetics (these are individual polynuꢀ
clear complex molecules with high magnetic moments
that can retain magnetization [10–15]).
EXPERIMENTAL
Synthesis of H2L Sodium acetate (0.002 mol) was
added to a hot suspension of 1ꢀhydrazinophthalazine
hydrochloride (0.002 mol) in ethanol (40 ml). Then a
.
hot solution of 2ꢀ(Nꢀtosylamino)benzaldehyde
(0.002 mol) in ethanol (10 ml) was added. The reacꢀ
tion mixture was refluxed for 4 h and diluted with disꢀ
tilled water (50 ml). The precipitate that formed was
filtered off, washed with water, and recrystallized from
a mixture of methanol (10 ml) and DMF (4 ml). The
yield of H2L was 60%.
Synthesis of transition metal complexes with H2L
(general procedure). A hot solution of an appropriate
metal salt in methanol was added to a hot solution of
H2L (0.001 mol) in methanol (20 ml). The reaction
mixture was refluxed for 3 h. The precipitate that
formed was filtered off, washed with hot methanol,
and recrystallized from dioxane or methanol–DMF.
The yields of the complexes were 45–70%.
Elemental analysis data and some other characterꢀ
In this work, we studied the physicochemical propꢀ
erties of 2ꢀ(Nꢀtosylamino)benzaldehyde 1ꢀphthalaziꢀ
nylhydrazone (H2L) and its transition metal comꢀ
plexes.
istics of H2L, [Cu2L2] (
[Cu(HL)(СН3ОН)Br] (III), [Cu(HL)(СН3ОН)]NO3
IV), [Ni(HL)2] ( , and [Mn(HL)2] (VI are given in
Table 1.
I), [Cu(HL)(СН3ОН)Cl] (II),
(
V)
)
1H NMR spectra were recorded on a Varian Unity
300 spectrometer (300 MHz) in DMSOꢀd6 with
HMDS as the internal standard; the pulse Fourier
mode was used. IR spectra were recorded on a Varian
Scimitar 1000 FTꢀIR instrument in the 400–
4000 cm–1 range (Nujol). Electronic absorption specꢀ
tra were recorded on a Varian Cary 50 Scan spectroꢀ
photometer. Thermal analysis was carried out on a
Ts
NH
H
N
N
N
N
(H2L)
483

484
POPOV et al.
Table 1. Elemental analysis data for H2L and complexes
I–VI
(Percentage (found/calculated), %
Compound Empirical formula
Color
Yellow
T
m, °C
167
C
H
N
M
H2L
I
C22H19N5O2S
62.9/63.3
55.0/55.2
50.1/50.5
47.0/46.7
46.9/48.1
58.8/59.3
59.7/59.5
4.48/4.59
3.39/3.58
3.98/4.05
3.84/3.75
3.99/3.86
4.14/4.07
3.96/4.09
16.4/16.8
14.9/14.6
12.5/12.8
11.6/11.8
14.4/14.6
15.2/15.7
15.5/15.8
C22H17N5O2SCu
C23H22ClN5O3SCu
C23H22BrN5O3SCu
C23H22N6O6SCu
C44H36N10O4S2Ni
C44H36N10O4S2Mn
13.0/13.3 Brown
11.2/11.6 Brown
10.5/10.7 Brown
11.5/11.1 Brown
6.49/6.58 Brown
6.04/6.19 Yellow
>250
>250
>250
>250
>250
>250
II
III
IV
V
VI
Diamond TG/DTA instrument (Perkin Elmer); samꢀ Specific magnetic susceptibility was measured using
the relative Faraday method in the 77.4–300 K range.
The temperature dependence of the magnetic suscepꢀ
tibility of the binuclear complexes was theoretically
interpreted in terms of the isotropicꢀexchange
Heisenberg–Dirac–van Vleck model [16, 17].
ples were heated to 650°С at a rate of 10 K/min. Molar
conductivity was determined with a Pꢀ38 slidewire
bridge for 0.001 M solutions of the complexes in DMF.
Table 2. Crystallographic parameters and the data collecꢀ
Xꢀray diffraction study of complex I was performed
on a Bruker Smart CCD Apex II diffractometer
tion and refinement statistics for structure
I
(
MoKα radiation, graphite monochromator). An
Parameter
Value
absorption correction was applied with the SMART
program. The structure was solved by the direct
method and refined anisotropically (for nonꢀhydrogen
Empirical formula
M
C45H37N10O4.50S2Cu2
997.08
Fh2kl
atoms) on
by the fullꢀmatrix leastꢀsquares
Crystal dimensions, mm
Temperature, K
0.32 × 0.12 × 0.12
method. The hydrogen atoms were located geometriꢀ
cally and refined using a riding model ( iso(H) =
nUiso(C), where = 1.5 for the methyl C atoms and 1.2
296(2)
U
λ, Å
0.71073
n
Crystal system
Space group
Monoclinic
2/
for the other C atoms). All calculations were perꢀ
formed with the SHELXLꢀ97 program package [18].
Crystallographic parameters and the data collection
C
c
a
, Å
, Å
, Å
, deg
, Å3
24.583(4)
11.8898(18)
17.271(3)
106.952(4)
4828.6(13)
4
and refinement statistics for structure
I are summaꢀ
b
rized in Table 2. Selected bond lengths and bond
angles are given in Table 3. The atomic coordinates
and thermal parameters have been deposited with the
Cambridge Crystallographic Data Collection
(no. 787801; deposit@ccdc.cam.ac.uk or http://www.
ccdc.cam.ac.uk).
c
β
V
Z
ρcalcd, g/cm3
1.372
Electronic and spatial structures of the complexes
were determined using the ab initio quantumꢀchemical
DFT calculations (Table 3). For organic compounds,
we used the hybrid exchangeꢀcorrelation functional
B3LYP [19] with the Becke exchange functional [20]
and the Lee–Yang–Parr correlation functional [21].
The geometries of the complex molecules were preopꢀ
timized over all natural variables without symmetry
constraints. The minima at the potential energy surꢀ
face were identified for each structure by calculating a
force constant matrix and normal vibrational frequenꢀ
μ
, mm–1
(000)
θmax, deg
Ranges of
1.042
F
2044
2
50.06
h
,
k
, and
l
indices
–29 <
–14 <
–20 <
h
k
l
< 26
< 14
< 20
Number of measured reflections
13892
4265
Number of independent reflections
Number of parameters refined
300
cies. The splitꢀvalence basis 6ꢀ311G(d,p) was used as a
basis set. The electronic absorption spectra were calꢀ
culated in terms of the TDDFT method (B3LYP/6ꢀ
311G(d,p)) [22, 23].
All quantumꢀchemical calculations were perꢀ
formed with the Gaussian'03 program [24]. For data
R1
0.0630
0.1534
0.999
wR2
GOOF
Δρmax
/
Δρmin
,
e
Å–3
0.717/–0.567
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
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TRANSITION METAL COMPLEXES
485
Table 3. Selected interatomic distances and bond angles in the coordination polyhedra of the copper atoms in structure
I
Distance
d
, Å
Angle
ω, deg
Cu(1)–Cu(1#)
Cu(1)–N(1)
Cu(1)–N(5)
Cu(1)–N(2)
Cu(1)–N(4#)
3.367(1)
1.934(7)
1.937(8)
1.944(8)
2.014(8)
N(1)Cu(1)N(5)
N(1)Cu(1)N(2)
N(5)Cu(1)N(2)
N(1)Cu(1)N(4#)
N(5)Cu(1)N(4#)
N(2)Cu(1)N(4#)
160.8(3)
94.3(3)
78.8(4)
100.7(3)
95.2(3)
143.5(3)
preparation, presentation graphics, and visualization tains signals at
of the calculated results, the ChemCraft program was 2.48 ppm (s, 3H, Me). Signals at
used [25]. and 8.33 ppm (d, 1H, H(8), = 7.5 Hz) were assigned
The exchange coupling constant
δ
8.01 (s, 1H, azomethine) and
δ
8.38 (s, 1H, H(4))
J
to two protons of the phthalazine fragment. The other
aromatic protons are manifested as two multiplets at
2J for complex I
was calculated according to a tried and tested proceꢀ
dure [26, 27], which is based on the broken symmetry
approach proposed by Ginsberg, Noodleman, and
Yamaguchi [28, 29] under the assumption of a strong
magnetic orbital overlap. The exchange coupling conꢀ
stant is calculated as the difference between the enerꢀ
gies of two singleꢀdeterminant states defined in the
context of the infinite Kohn–Sham scheme (BP86/6ꢀ
δ
7.55–7.73 (6H) and 7.09–7.26 ppm (5H).
The IR spectrum of H2L shows an absorption band
at 1636 cm–1
(
ν
(С=N)azometh), two bands at 1595
(С=N)phthal), and two bands at
3440 and 3120 cm–1
(N–Н)) (Table 4).
and 1584 cm–1
(ν
(
ν
The position of the absorption peak of the phthalaꢀ
zine NH group suggests thatH2L exists as phthalazone
tautomer (a), which is also characteristic of other
hydrazones derived from hydrazinophthalazine [7, 32,
33].
These data agree with the electronic absorption
spectra of H2L. The spectral pattern depends on the
solvent nature. In ethanol, H2L absorbs at 295 and 375
nm. In dioxane and DMF, the longerꢀwavelength
band experiences slight bathochromic shifts by 5 and
10 nm, respectively. In acetone, acetonitrile, and
DMSO, the position of this band remains unchanged,
while chloroform causes its hypsochromic shift by
15 nm. The position and shape of the shorterꢀwaveꢀ
length band are virtually the same in ethanol, dioxane,
acetonitrile, and DMF. In chloroform, this band expeꢀ
riences a bathochromic shift by 10 nm.
311D(
d
)
level) [30, 31]: triplet (
S = 1) and singlet (low
= 0). For the latter state, it is assumed that the
MO symmetry may be lower than the molecular symꢀ
metry (broken symmetry state):
spin,
S
E
BS(S = 0) − E(S = 1)
1 + s2
(1)
2J =
,
where
MOs;
s
s
is the overlap integral for the interacting spin
is taken to be unity in the limit of large overlap
and zero in the limit of small overlap. The tripletꢀstate
geometry was optimized over all geometrical parameꢀ
ters without symmetry constraints in the DFT context
BP86/6ꢀ311G(d)). The energy of the singlet state was
calculated using the fixed geometry obtained for the
triplet state.
(
RESULTS AND DISCUSSION
Table 4. IR spectra of H2L and complexes I–VI
The structure of H2L in solutions and in the solid
state was examined by elemental analysis, IR spectrosꢀ
copy, H2L NMR spectroscopy, electronic absorption
spectroscopy, and quantumꢀchemical modeling.
Because of the acidity of the NH protons,
the ligand H2L can exist as a number of tautomers
(Fig. 1, a–c).
ν
(C=N)azometh
,
ν
(C=N)arom
,
ν
(NH),
Compound
cm–1
cm–1
cm–1
H2L
I
1646
1616
1620
1625
1625
1628
1620
1595, 1584
1592
3120, 3440
II
1590
3171
3176
3217
3176
3183
The 1H NMR spectrum of H2Lin DMSOꢀd6 shows
III
IV
V
1599
signals for the NH protons at
δ 11.8 (s, 1H) and
1598
10.7 ppm (s, 1H); their chemical shifts and disappearꢀ
ance upon the addition of D2O suggest the exchange
character of both the protons. The spectrum also conꢀ
1597
VI
1595
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
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2011

486
POPOV et al.
Ts
Ts
Ts
N
NH
NH
H
H
N N
N N
N
N
H
NH
N N
N
N
N
а
b
c
d
e
f
Fig. 1. Tautomers (
a
)–(
c
) of H L. Molecular structure of H L and the total energies of its protonated forms: –1633.487819 (d),
2
2
–1633.461955 (e), and –1633.459727 au (f).
The relative stabilities of tautomers (
calculated using the DFT approach (B3LYP/6ꢀ
311G(d,p ) without and with consideration to the solꢀ
vent effect in the polarizable continuum model
(PCM). The calculated data are given in Table 5.
a)–(c) were potentiometry and spectrophotometry. An analysis of
the potentiometric titration curve suggests the protoꢀ
nation of the hydrazone molecule; the calculated
basicity constant is рKb = 3.60. In the basic range up to
)
pH 12.5, no proton abstraction was detected.
Phthalazone form (a) is much more stable than the
The presence of the sole equilibrium associated
with the ligand protonation (cation formation) in the
pH range from 2 to 12 was confirmed by spectrophoꢀ
tometric data. In neutral and basic media, the elecꢀ
tronic absorption spectra of the solutions are nearly
identical; the longerꢀwavelength band appears at
375 nm. At pH < 3, this band experiences a hypsochꢀ
romic shift to 355–350 nm. The position of the band
at 295 nm is virtually pHꢀindependent.
two other tautomers in the gas phase and in both solꢀ
vents; the energy differences between the tautomers in
polar (ethanol) and nonpolar solvents (chloroform)
are nearly the same. Quinonoid form (
more favorable than amino hydrazone (
phase and is considerably stabilized in the polar solꢀ
vent (ethanol). In chloroform, however, tautomer (
is the highestꢀenergy structure. Therefore, H2L exists
in solution only as phthalazone tautomer ( ).
c
) is somewhat
b) in the gas
c
)
a
To elucidate the nature of the resulting monocaꢀ
tion, we performed quantumꢀchemical DFT calculaꢀ
tions of the structures and total energies of a number of
The protolytic properties of a ligand are crucial for
its complexing ability [34–36]. We studied the proꢀ
tolytic equilibria of H2L in aqueous ethanol using isomeric protonated forms of H2L (Fig. 1, d–f).
Table 5. Calculated total energies
E
(au) and relative stabilities
Δ
E
(kcal/mol) of the tautomers (
a
)–(c
) of H2L in the gas
phase and in ethanol and chloroform (B3LYP/6ꢀ311G(
d
,p
), PCM)
Gas
Ethanol
CHCl3
Tautomer
E
Δ
E
E
Δ
E
E
ΔE
a
b
c
–1633.092293
–1633.073509
–1633.080041
0.0
11.8
7.7
–1633.109925
–1633.095433
–1633.101878
0.0
9.1
5.0
–1633.104875
–1633.089489
–1633.087491
0.0
9.7
10.9
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
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TRANSITION METAL COMPLEXES
487
Table 6. Calculated wavelengths
strengths
λ
(nm) and oscillator
The hydrazoneH2L is preferentially protonated at
the phthalazone N atom ( ). Structure ( ) and the
presence of monocation ( ) in solution are confirmed
f
of the electron transitions for tautomer (
a
) and
d
a
monocation (
d)
d
by comparison of the TDDFTꢀcalculated and experiꢀ
mental electronic absorption spectra of these comꢀ
a
d
Transition
λ
, nm
f
λ, nm
f
pounds. The calculated wavelengths (
intensities (oscillator strengths, ) of the first five elecꢀ
tron transitions are given in Table 6. According to our
calculations, tautomer ( ) absorbs strongly (
λ, nm) and the
f
1
2
3
4
5
382
371
346
326
318
0.5981
0.0882
0.0191
0.0026
0.1067
378
343
339
326
325
0.1945
0.3984
0.0109
0.0382
0.0110
a
f =
0.5981) at 382 nm, which is close to the observed
absorption peak at 375 nm in basic and neutral media.
The other transitions in the range up to 320 nm have
low intensities. At the same time, monoprotonated
form (
while its absorption at 382 nm is substantially weaker.
Thus, the protolytic equilibrium between tautomers tautomer. In the IR spectra of all the complexes, the
) and ( ) accurately describes the observed evolution
absorption band ν(С=N)azometh is shifted to 1616–
d) should absorb best at 343 nm (f = 0.3984),
explained by the coordination of H2L as the hydrazone
(
a
d
1625 cm–1, which provides evidence for the coordinaꢀ
tion of the azomethine N atom to the copper(II) ion.
of the electronic absorption spectrum at low pH valꢀ
ues.
We obtained a number of transition metal comꢀ
plexes with H2L using the following reaction scheme:
The effective magnetic moment µeff of complex I at
room temperature (1.23 µB) is appreciably lower than
the spin magnetic moment (1.73 µB) and decreases to
0.18 µB upon cooling to the boiling temperature of liqꢀ
uid nitrogen (Table 7). These data suggest a very strong
antiferromagnetic exchange between the paramagꢀ
netic centers in this complex. The exchange coupling
Cu(CH3COO)2
CuL (
Cu(HL)(CH3OH)Cl (II
Cu(HL)(CH3OH)Br (III
Cu(HL)(CH3OH)NO3 (IV
Ni(HL)2 (
Mn(HL)2 (VI
I)
CuCl2
)
CuBr2
)
Cu(NO3)2
Ni(CH3COO)2
Mn(CH3COO)2
H2L
)
V)
constant in complex I was calculated in terms of the
)
isotropicꢀexchange Heisenberg–Dirac–van Vleck
model [16, 17] using the Bleaney–Bowers equation
[40]:
The molecular formulas and structures of the comꢀ
plexes were determined by elemental analysis, therꢀ
mogravimetry, IR spectroscopy, conductometry, and
magnetochemical measurements.
Reactions of H2L with cupric acetate, cupric chloꢀ
ride, and cupric bromide gave complexes of the forꢀ
mulas CuL and Cu(HL)(СН3ОН)X (L2– and HL– are
diꢀ and monodeprotonated forms of H2L; X = Cl or
Br) (Table 1). According to TG data, the last two comꢀ
plexes contain innerꢀsphere methanol molecules
because the endothermic weight loss at 130–150°С
corresponds to one methanol molecule [37, 38].
2
2NA g2β
'
χM
=
×
3kT
(2)
−1
⎡
⎤
1
−2J
⎡
)
⎢
⎣
⎤
×
1 − f 1 + exp
+ fS(S+1) + Nα,
(
(
)
⎢
⎣
⎥
⎦
⎥
⎦
3
kT
'
where
is the diamagnetismꢀcorrected molar magꢀ
χM
netic susceptibility, NA is Avogadro’s number,
Landé factor, is the Bohr magneton, is the Boltzꢀ
mann constant, is the exchange coupling constant,
g
is the
β
k
J
f
A reaction of H2L with cupric nitrate yielded the
complex Cu(HL)(СН3ОН)NO3 (IV).
is the mole fraction of the paramagnetic impurity, and
Conductometric data for 0.001 M solutions of the
complexes in DMF suggest that complex IV can be
classified among double electrolytes [39] (i.e., the
nitrate anion is an outerꢀsphere ligand in this comꢀ
plex).
Nα is the temperatureꢀindependent paramagnetism.
The exchange coupling constant
= 2.20, Nα = 120
10–6 cm3/mol, and
These data provide unambiguous evidence for the
2J
is –416 cm–1
= 0.009).
(g
×
f
According to IR spectra (Table 4), the ligand H2L dimeric structure of the complex. In this case, dimerꢀ
is doubly deprotonated in the complex with cupric
acetate and singly deprotonated in the complexes with
cupric halides and cupric nitrate. The IR spectra of
ization is possible only through the N atoms of the
phthalazine fragment: the N atom of the aldehyde
fragment can hardly serve as a bridge because of steric
complexes II
3190 cm–1
spectrum ofH2L. The noticeably changed position of
the band (N–Н)phthal in the spectra of the complexes
compared to that for the starting hydrazone can be (from –300 to –600 cm–1 [7, 41, 42]).
–
IV show an absorption band at 3130–
hindrances presented by the tosyl group. The
for complex is within the range characteristic of
binuclear copper(II) complexes with diazine bridges
2J value
(
ν(N–Н)), which is absent from the IR
I
ν
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
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488
POPOV et al.
Table 7. Magnetic properties of complexes
I–VI and the molar conductivities of their 0.001 M solutions in DMF
Complex
T
, K
293
77.4
293
77.4
293
77.4
293
77.4
293
77.4
293
77.4
μeff
,
μB
2
J
, cm–1
λ
,
Ω
–1 cm2 mol–1
9.3
I
1.23
0.18
2.02
1.88
2.12
2.03
1.81
1.79
2.93
2.87
5.95
5.87
–416
II
10
11
55
11
12
III
IV
V
VI
amid with the axial N(1) and N(5) atoms
(N(1)Cu(1)N(5), 160.9(3) ) and the equatorial N(2),
°
N(4#), and O(2) atoms. Although the Cu(1)–O(2)
bond is long, these atoms interact greatly, which is eviꢀ
dent from the virtually planar fragment Cu(1)–O(2)–
S(1)–N(1) (the deviations of the atoms are 0.002 Å).
The fiveꢀmembered chelate ring has an envelope conꢀ
formation with the copper atom as a flap projecting
out of the meanꢀsquare plane of the other four atoms
by 0.171(1) Å. The sixꢀmembered chelate ring is disꢀ
torted much more strongly because of inflections
along the lines N(1)–C(7) and N(1)–N(2). The strucꢀ
tures of the monomeric complex fragments are nearly
planar (except for the tosyl fragments in the flagpole
position with respect to the ligand plane). The aroꢀ
matic rings of the phthalazine and benzaldehyde fragꢀ
N
N
Cu
Ts
N N
N N
N
Cu
N
N
N
Ts
(I)
Structure
I determined from spectroscopic and
magnetochemical measurements was confirmed by
Xꢀray diffraction. The complex crystallizes as a 2 : 1
solvate with a disordered DMSO molecule. Since the
complex molecule has a symmetry axis С2 passing
ments are virtually coplanar, making an angle of 1.5
The Cu atom deviates from this plane by 0.294(1) Å.
The dihedral angle between the planes of two monoꢀ
meric fragments is 64.4°
As a result, in contrast to documented complexes
with phthalazine bridges [7], the sixꢀmembered
exchange fragment in complex is noticeably nonplaꢀ
°.
...
through the midpoint of the Cu Cu distance, two
mononuclear fragments CuL are fully identical. For
designation of symmetryꢀrelated atoms, we simply add
.
the character # (the molecular structure of complex
with atomic numbering is shown in Fig. 2). Crystalloꢀ
graphic parameters of structure are given in Table 2.
I
I
nar and has a boatꢀlike conformation with apical copꢀ
per atoms. This is due to steric repulsion between the
tosylaminobenzaldehyde fragment of one ligand and
the phthalazine fragment of the other ligand. The copꢀ
per atoms are spaced at 3.367(1) Å. Note that for the
binuclear copper(II) complex with 2ꢀacetylbenzimiꢀ
dazole 1ꢀphthalazinylhydrazone, in which steric hinꢀ
drances are less substantial, quantumꢀchemical calcuꢀ
lations lead to a similar structure for the exchange
fragment [27].
I
Selected bond lengths and bond angles are given in
Table 3.
In the binuclear complex, the copper ion is pentaꢀ
coordinated. The coordination sphere of Cu includes
three N atoms of one ligand (Cu(1)–N(1), 1.934(7) Å;
Cu(1)–N(2), 1.944(8) Å; and Cu(1)–N(5),
1.937(8) Å) and the N(4#) atom of the second ligand
at a noticeably longer distance from the copper ion
(Cu(1)–N(4#), 2.014(8) Å). The mononuclear fragꢀ
ments dimerize through this atom to form the sixꢀ
membered exchange ring Cu(1)–N(5)–N(4)–
Cu(1#)–N(5#)–N(4#). The coordination sphere is
completed by the tosyl O(2) atom (Cu(1)–O(2),
Because of steric repulsion, the phenyl rings of the
tosyl fragments in structure
I are virtually parallel to
each other, their planes making a dihedral angle of
~9
°
.
The great exchange integral for complex I, despite
2.774(7) Å), giving a strongly distorted trigonal bipyrꢀ the long distance between the copper ions and the
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
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2011

TRANSITION METAL COMPLEXES
(а)
489
O(1)
N(1)
C(2)
C(6)
C(3)
C(4)
S(1)
O(2)
C(1)
(b)
C(5)
Cu(1)
N(4)
N(5)
C(14)
C(9)
C(7)
N(2)
C(8)
N(3)
C(15)
@
@
@
@
N2
@
N4
Fig. 2. Structure
I with atomic thermal displacement ellipsoids (50% probability); the hydrogen atoms are omitted. The projecꢀ
tions (a) along and (b) normally to the line Cu–Cu.
1
nonplanar structure of the exchange fragment, can be in this approximation (–457 cm– ) is in
attributed to considerable delocalization of the magꢀ satisfactory agreement with the experimental value
1
netic orbitals over the N atoms of the phthalazine
bridges and the interacting copper atoms.
(
2J
= –416 cm– ).
The unpaired electrons are largely delocalized over
We performed quantumꢀchemical modeling of the electronꢀdonating atoms of the ligand in both the
exchange couplings in complex I in the context of the triplet and lowꢀspin states (Table 8). Near either Cu
broken symmetry approach. We found that the total atom, the spin density sign on all electronꢀdonating
energies and squared spin moments are –6545.352311 atoms in the lowꢀspin state is the same as on the metal
au and 2.0032 for the highꢀspin (HS) state and ion; the spin density sign in the exchange fragment is
⎯
6545.356476 au and 0.7372 for the lowꢀspin (LS) reversed between the phthalazine N atoms, which
state, respectively. The exchange coupling constant accounts for the considerable antiferromagnetic
calculated by formula (1) in the limit of strong overlap exchange in this complex.
is 457 cm–1.
The effective magnetic moments of complexes II
–
Both the spin MOs are substantially delocalized IV are close to the spin magnetic moments for the Cu2+
over the exchange fragment (Fig. 3). Either MO is ion and remain virtually unchanged upon cooling
considerably contributed by the
atoms and the
phthalazine fragment. This validates the use of the chemical data allows, with a high probability, their
d
σꢀАОs of both copper (Table 7). The absence of exchange couplings between
σ
ꢀАОs of the bridging N atoms of the the Cu2+ ions in combination with other physicoꢀ
large overlap limit (s = 1 in formula (1)). The antiferꢀ structures to be represented as the following monoꢀ
romagnetic exchange coupling constant calculated mers:
+
L'
Ts
Ts
L'
X
N
N
Cu
Cu
NO3–
N N
N
N N
N
NH
NH
II: X = Cl;
IV: L' = CH3OH
III: X = Br; L' = CH3OH
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 37
No. 7
2011

490
POPOV et al.
(b)
(а)
Fig. 3. Magnetic spin orbitals of the electrons with the αꢀ and βꢀorientations of the spin in the lowꢀspin state: (a) 237α (HOMO),
E
= –0.1689; (b) 237β (HOMO), E = –0.1689. The atoms of the tosyl fragments are omitted; their AOs are virtually not involved
in these spin MOs.
Reactions of H2L with nickel(II) acetate and manꢀ
ganese(II) acetate gave the complexes М(HL)2 ) and
Mn(HL)2 (VI) (HL– is a monodeprotonated H2L;
ACKNOWLEDGMENTS
(
V
This work was supported by the Federal Target Program
“Scientific and Pedagogical Personnel of the Innovative
Russia” (State Contract no. 02.740.11.0255).
Table 1). The IR spectra of complexes
V and VI show
an absorption band at ~3200 cm–1 (NH stretching
vibrations in the hydrazinophthalazine fragment). The
band
ν(С=N)azometh in their spectra is shifted to 1620–
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