Reactions between Cu(II) halide complexes of 2,2′-dipyridylamine and nitrophenolates. X-ray diffraction structure of the [bis(2,2′-dipyridylamine)di(p-nitrophenolato)di(μ-methoxo) dicopper(II)], [Cu(dipyam)(pnp)(μ-OCH3)]2, a dimeric complex containing axial phenoxo ligands in square-pyramidal arrangements

Article abstract of DOI:10.1016/S0020-1693(03)00082-3

The reaction between the [Cu(dipyam)Br₂] complex (dipyam=2,2′-dipyridylamine) and nitrophenolates gave products of exchange reactions between halides and phenolates. Starting from [Cu₂(dipyam)₂(OH)₂(H₂O)]Cl ₂·2H₂O, o- and p-nitrophenolate complexes with the same rough formula Cu(dipyam)(OR)(OCH₃) (OR=o- or p-nitrophenolate) but a different chemical behaviour have been obtained. The X-ray diffraction analysis shows that the derivative of the p-nitrophenolate is an interesting dimer [Cu(dipyam)(pnp)(μ-OCH₃)]₂ (pnp=p-nitrophenolate), with two centrosymmetrically related five-coordinated copper(II) ions, having a distorted square-pyramidal geometry defined by axial phenolate ligands and by equatorial dipyam nitrogens and μ-methoxo oxygen bridges. The bridging arrangement forms a Cu₂O₂ core, with a Cu?Cu separation of 3.062(2) A?. The crystal structures of the [Cu(dipyam)(pnp)₂]·2H₂O and [Cu(dipyam)(onp)₂] complexes (onp=o-nitrophenolate) are also reported.

Full text of DOI:10.1016/S0020-1693(03)00082-3

Inorganica Chimica Acta 349 (2003) 128ꢁ134
/
www.elsevier.com/locate/ica
Reactions between Cu(II) halide complexes of 2,2?-dipyridylamine
and nitrophenolates. X-ray diffraction structure of the [bis(2,2?-
dipyridylamine)di(p-nitrophenolato)di(m-methoxo)dicopper(II)],
[Cu(dipyam)(pnp)(m-OCH3)]2, a dimeric complex containing axial
phenoxo ligands in square-pyramidal arrangements
Annamaria Camus a,*, Alessandro Facchinetti a, Nazario Marsich a,
Anna Maria Manotti Lanfredi b,*, Chiara Massera b, Franco Ugozzoli b
a Dipartimento di Scienze Chimiche, Universita` degli Studi di Trieste, Via Giorgieri 1, 34127 Trieste, Italy
b Dipartimento di Chimica Generale e Inorganica, Chimica Analitica, Chimica Fisica, Universita` degli Studi di Parma, Parco Area delle Scienze 17/A,
43100 Parma, Italy
Received 4 October 2002; accepted 15 January 2003
Abstract
The reaction between the [Cu(dipyam)Br2] complex (dipyamꢀ
exchange reactions between halides and phenolates. Starting from [Cu2(dipyam)2(OH)2(H2O)]Cl2×
complexes with the same rough formula Cu(dipyam)(OR)(OCH3) (ORꢀo- or p-nitrophenolate) but a different chemical behaviour
have been obtained. The X-ray diffraction analysis shows that the derivative of the p-nitrophenolate is an interesting dimer
[Cu(dipyam)(pnp)(m-OCH3)]2 (pnpꢀp-nitrophenolate), with two centrosymmetrically related five-coordinated copper(II) ions,
having a distorted square-pyramidal geometry defined by axial phenolate ligands and by equatorial dipyam nitrogens and m-
/
2,2?-dipyridylamine) and nitrophenolates gave products of
/
2H2O, o- and p-nitrophenolate
/
/
˚
Cu separation of 3.062(2) A. The crystal
methoxo oxygen bridges. The bridging arrangement forms a Cu2O2 core, with a Cu
structures of the [Cu(dipyam)(pnp)2]×2H2O and [Cu(dipyam)(onp)2] complexes (onpꢀ
# 2003 Elsevier Science B.V. All rights reserved.
/
ꢀ ꢀ ꢀ
/
/
/
o-nitrophenolate) are also reported.
Keywords: Crystal structures; Copper IIꢁ2,2? dipyridylamine complexes; Phenolate complexes
/
1. Introduction
of monophenols to o-diphenols or quinones promoted
by the tyrosinase enzyme [3]. A product with the same
rough formula, but with a different chemical reactivity,
was obtained with the o-nitrophenolate (onp).
During the preparation of some (dipyam)(carboxyla-
to)(pnp)copper(II) [1] complexes (dipyamꢀ2,2?-dipyr-
/
idylamine: pnp-p-nitrophenolate) our attention was
attracted by the formation of a side product, the dimer
[Cu(dipyam)(pnp)(m-OCH3)]2 (II). Its rather rare struc-
ture, with a phenolate coordinating axially to each
copper atom, could represent a model of intermediate
in the catalytic reactions between Cu(II) amine systems
and phenols [2] or in the mechanism of o-hydroxylation
2. Experimental
2.1. Reagents
[Cu(dipyam)Br2] [4] and [Cu2dipyam2(OH)2(H2O)]-
2H2O [5,6] were synthesized as reported in the
Cl2×
/
literature. The other chemicals employed were commer-
cial products of 99% purity. The sodium phenolates
were prepared by reaction of the phenols with NaOH in
1:1 ratio 15 min before their use.
* Corresponding authors. Fax: ꢂ
/
39-040-558 3903 (A.C.); fax: ꢂ39-
/
0521-90 5557 (A.M.M.L.).
E-mail addresses: camus.annamaria@tiscali.it (A. Camus),
manotti@unipr.it (A. Manotti Lanfredi).
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00082-3

A. Camus et al. / Inorganica Chimica Acta 349 (2003) 128ꢁ
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129
2.2. Syntheses
(ii) II could be obtained easily also by refluxing a
suspension in methanol of the Cu(dipyam)(pnp)2 com-
plex. The reagent underwent a partial solubilization, but
the dimer began to precipitate almost immediately. The
reaction was complete in a few minutes.
The crystals used for X-ray diffraction were obtained
from a [Cu(dipyam)(pnp)2] solution prepared in situ by
adding slowly 2.55 mmol of Na(pnp) in 50 ml of
methanol to a stirred suspension of 0.500 g (1.27
mmol) of [Cu(dipyam)Br2] in 50 ml of hot methanol.
2.2.1. [Cu(dipyam)(pnp)2] (I)
A green solution of 0.50 g (1.27 mmol) of [Cu(di-
pyam)Br2] in 50 ml of hot water was treated with an
excess (5.00 mmol) of pnp in the same volume of water.
The solution darkened immediately and a solid began to
precipitate after 10 min. The product was filtered and
washed repeatedly with water. Recovered 0.559 g (86.1%
yield) of a microcrystalline powder, insoluble in ether,
acetonitrile, toluene, chlorinated solvents, ethyl acetate
and reacting with methanol (Section 2.2.2(ii)). Dec.p.:
The greenꢁ
resting well formed crystals. Dec.p.: 204ꢁ
/
black solution, filtered clear, separated by
205 8C with
/
gas evolution.
228ꢁ229 8C. Calc. for C22H17CuN5O6: C, 51.74; H,
/
3.35; Cu, 12.44, N, 13.71%. Found: C, 51.4; H, 3.2; Cu,
12.4; N, 13.5%.
2.2.3. Cu(dipyam)(Br)(onp) (III)
IR (cmꢃ1): 1640 m, 1615 w; 1580 s; 1531 mw; 1485 s,
br, 1434 mw, 1333 s, 1310 vs, 1280 w; 1249, 1235 w; 1166
m; 1113 ms, sh; 1018, 998 w, 867 mw, 845 m, 828 w; 763
ms; 701, 652 mw; 520, 470 br, 421 w.
An orange solution of 0.50 mmol of Na(opn) (0.070 g
of o-nitrophenol and 0.5 ml of NaOH N in 5 ml of
MeOH) was added to a suspension of [Cu(dipyam)Br2]
(0.200 g, 0.507 mmol in 20 ml of methanol) without
apparent alteration, After 1 h at reflux the solution was
filtered clear from traces of unreacted [Cu(dipyam)Br2]
and concentrated by evaporation at room temperature,
leaving aggregates of big brown needles: 0.204 g; Yield:
The crystals used for the X-ray structure were
obtained as greenꢁblack needles by slow evaporation
/
of a water solution and contained two solvent water
molecules.
88.7%. Dec.p.: 220ꢁ221 8C. Calc. for C16H13BrCuN4O3:
/
C, 42.44; H, 2.89; Br, 17.65; Cu, 14.04; N, 12.38%.
Found: C, 42.3; H, 2.8; Br, 17.8; Cu, 14.0; N, 12.3%. III
is moderately soluble in hot methanol, acetone and
acetonitrile.
IR (cmꢃ1): 1643 m; 1606, 1591 m; 1546 m, 1531 w;
1483 s, br, 1460 sh; 1437 sh, 1425 m; 1384 w; 1364 w;
1325 m; 1242, 1205 m; 1160, 1137 mw; 1081, 1065 w;
1022 mw; 908, 883, 854, 828 w; 778 m, 767, 753 w; 700
w; sh, 654 mw, sh; 573 mw; 528 mw; 471 w, 427 mw.
2.2.2. [(Cu(dipyam)(pnp)(m-OCH3)]2 (II)
(i) A solution of 0.87 mmol of Na(pnp) in 5 ml of
methanol was added to a suspension of 0.248 g (0.43
mmol) of [Cu2(dipyam)2(OH)2(H2O)]Cl2×/2H2O in 25 ml
of methanol and the mixture was refluxed under stirring.
In a few minutes the copper reagent disappeared and II
began to precipitate as a green powder. After half an
hour the product was filtered off, washed with water and
acetone and dried in vacuo. Yield: g 0.270, 70.3%.
Dec.p.: 200ꢁ201 8C. Calc. for C34H32Cu2N8O8 C, 50.7;
H, 3.99; Cu, 15.73; N, 13.87%. Found: C, 50.7; H, 4.0;
/
2.2.4. [Cu(dipyam)(onp)2] (IV)
IV was prepared like III, but using a double amount
of Na(opn). A new fluffy precipitate began to form
immediately at the mixing of the reagents. After 1 h at
reflux the hot mixture was filtered and the solid washed
with water and methanol. 0.209 g; Yield: 80.4%. Calc.
for C22H17CuN5O6: C, 51.74; H, 3.35; Cu, 12.44; N,
13.71%. Found: C, 51.5; H, 3.3; Cu, 12.6; N, 13.5%.
Cu(dipyam)(onp)2 is sparingly soluble in hot metha-
nol, moderately in chloroform and fairly soluble in
acetone and acetonitrile. Recrystallization from hot
acetone gave brown black square parallelepipeds, with
Cu, 15.5; N, 13.9%.
IR (cmꢃ1): 1659 m; 1600 sh, 1579 s, 1540 mw; sh,
1481 s, 1460 sh; 1428 m; 1384 w; 1299 vs; 1215 w, 1237
m; 1173, 1157 mw; 1112 s, sh; 1052 m; 1017, 1009, 991
w; 912 w; 870 w, 848 m, br; 820 sh, 805 w, 767 s; 704 w;
673 mw; 642 s, 610 w; 534, 522, 502 w; 483 mw; 431, 413
w; 381 w.
The complex is insoluble in ether, acetone, acetoni-
trile, benzene, chlorinated solvents and sparingly soluble
in water, ethanol, THF, nitromethane, DMF. heating
by the solutions decompose. In ethyl acetate the product
shows initially a good solubility, but a Cu(dipyam)(ace-
tate)2 complex1 precipitates after a few minutes. Free p-
nitrophenol was found in the mother liquor.
IR spectrum unchanged and Dec.p.: 223.8ꢁ224 8C.
/
lR (cmꢃ1): 1648 m; 1609, 1589 m; sh, 1544 m, sh; 1501
m, 1483 vs; 1434. 1421 m; 1363 mw; 1328 m; 1252, 1241,
1220 s; 1158 mw; 1137 m; 1083, 1062 w; sh, 1023 mw, sh;
910 w, 883 mw; 856, 821 w; 779 m, 766, 744 m; 700 w;
656 w; 570 w; 535, 528 w; 423 w.
2.2.5. Cu(dipyam)(onp)(OCH3) (V)
A solution of Na(onp) (0.098 mmol) in 5 ml of
methanol was added dropwise to a suspension of 0.314 g
1
Identified by analysis and comparison of its IR spectrum with that
of an authentic sample prepared from copper(II)acetate and dipyam.
See also Ref. [7].

130
A. Camus et al. / Inorganica Chimica Acta 349 (2003) 128ꢁ134
/
Table 1
Crystallographic data for compounds I, II and IV
I
II
IV
Formula
C
546.983
22H17CuN5O6×
/
2H2O
C34H32Cu2N8O8
403.884
293(2)
C22H17CuN5O6
510.952
293(2)
Formula weight
Temperature (K)
Crystal system
Space group
293(2)
monoclinic
C2/c
triclinic
¯
P1
monoclinic
P21/n
8.054(4)
/
˚
a (A)
14.925(5)
26.590(5)
6.636(5)
8.243(5)
9.507(5)
11.736(5)
83.987(5)
74.290(5)
72.128(5)
842.4(8)
1
˚
b (A)
10.722(5)
24.763(3)
˚
c (A)
a (8)a
b (8)
g (8)
94.002(5)
93.37(2)
3
˚
V(A )
2627(2)
4
2135(1)
4
Z
Dcalc(g cmꢃ3
F (0 0 0)
)
1.3829
1124
0.8837
1.592
414
1.328
1.5898
1044
1.074
Linear absorption coefficient (mmꢃ1
Index range
)
ꢃ
/
160
270
30l 0
1.57ꢁ23.26
3444
1472 (Rint
/
h 0
/10,
ꢃ
/
100
120
140
1.80ꢁ27.03
9476
3648 (Rint
/
h 0
k 0
l 015
/
10,
ꢃ
/
110
150
240
1.65ꢁ30.72
/
h 0
k 0
l 035
/
11,
ꢃ
/
/k 0
/28,
ꢃ
/
/
/
12,
ꢃ
/
/
/
14,
ꢃ/
/
/7
ꢃ/
/
/
ꢃ/
/
/
2u Range(8)
Reflections measured
/
/
/
16 974
Unique data
Data/restraints/parameters
ꢀ/0.0768)
ꢀ
/
0.0364)
5918 (Rint
ꢀ/0.0484)
1412/0/166
827
3648/1/243
2373
5918/1/377
3392
Observed reflection [Iꢀ 2s(I)]
/
Final R indices b
R indices (all data)
Goodness-of-fit
R1ꢀ
R1ꢀ
0.921
1.129, ꢃ
/0.0802, wR2ꢀ
/0.1943
R1ꢀ
R1ꢀ
0.668
0.402, ꢃ
/
0.0398, wR2 0,1011
R1ꢀ
R1ꢀ
0.917
0.438, ꢃ
/
0.0525, wR2ꢀ
/
0.1124
0.1285
/0.1344, wR2ꢀ
/0.2127
/
0.0719, wR2ꢀ0.1153
/
/0.1148, wR2ꢀ
/
Highest peak, deepest hole
˚
in final difference map (e A
/0.431
/
0.335
/0.562
ꢃ3
)
a
Unit cell parameters were obtained by least-squares analysis of the setting angles of 30 reflections found in a random search on the reciprocal
space.
b
R1ꢀ
/
ajjFojꢃ
/
jFcjj/ajFoj, wR2ꢀ
/
[aw(Fo2ꢃ
/
Fc2)2/awFo4]1/2. Goodness-of-fitꢀ
/
[Sw(Fo2ꢃ
/
Fc2)2/(nꢃp)]1/2, where n is the number of reflections and p
/
the number of parameters.
(0.5 mmol) of [Cu2(dipyam)2(OH)2(H2O)]Cl2×
45 ml of methanol, under stirring. The parent complex
changed slowly to a gelatinous pale brown product,
/
2H2O in
IR (cmꢃ1): 1662 m; 1605, 1585 m; 1540 ms; sh, 1483
vs; 1430 m; 1385 w; 1355 m, 1335 ms; 1258, 1236 ms;
1172 w, 1153 m; 1079 w; 1045 mw, 1031, 1019, 1007 w;
878 mw; 840 w; 784 mw, 764, 751 m; 703, 679 w; 657,
650 w; 565 w; 534, 520, 509 w; 432, 417 w.
while a yellowꢁgreen microcrystalline powder began to
/
precipitate after a few minutes. The transformation of
the copper reagent was apparently complete in half an
hour, but the formation of the green product increased
until 1.5 h at least. The average yields of the final
product (ten runs) was near 74%. It decomposed sharply
2.3. Apparatus
2.3.1. IR spectra
in the range 165.5ꢁ166.5 8C, with gas evolution. V is
/
IR spectra were registered on a Perkinꢁ
2000 spectrometer as KBr pellets. The data reported
above for each complex are relative to the 2000ꢁ400
cmꢃ1 region.
/
Elmer System
scarcely soluble in the tested solvents and in all of them
a partial decomposition occurs, more or less rapid
depending on the temperature of the suspension. A
treatment in hot ethyl acetate gave again Cu(dipyam)(a-
cetate)2 as main product.
As consequence of the impossibility to recrystallize
the product, the analyses, although indicative of the
reported formula, are not well reproducible: usually the
copper percentage is a little higher and that of nitrogen a
little lower than the theoretical ones. GPC gave, after
/
2.3.2. X-ray data collection and structure determination
of I, II and IV
Crystal data, experimental details for data collection
and structure refinement for compound I, II and IV are
reported in Table 1.
The crystal structures were determined by X-ray
diffraction methods. Intensity data and cell parameters
were recorded at room temperature (25 8C) on a Bruker
treatment with diluted sulphuric acid, 7.1ꢁ
/
7.4% of
methanol.

A. Camus et al. / Inorganica Chimica Acta 349 (2003) 128ꢁ
/134
131
calculations were carried out on a DIGITAL Alpha
Station 255 computer.
3. Results and discussion
The dimer [Cu(dipyam)(pnp)(m-OCH3)]2 was pre-
viously repeatedly isolated as side-product in reactions
between Cu(II)(dipyam)(OOCR)Br complexes and p-
nitrophenolate in hot methanol. Once identified it was
synthesized in a more rational manner, following the
methods reported in Section 2. The introduction of ꢀ
/
OCH3 groups in copper complexes is rather common in
the presence of methanol and a basic environment, and
in the case of [Cu2(dipyam)2(OH)2(H2O)]Cl2×
/
2H2O it
was already observed at reagent level [13], but the
stability of II is unusual, the alkoxy groups being not
hydrolized in water suspension for at least 2 days at
25 8C and for some hours at 70 8C. A suspension of II in
diluted sulphuric acid, however, gave methanol quanti-
tatively, as proved by a gas-chromatographic analysis
(MeOH: Calc. 7.93, Found: 7.5%). The stability to
hydrolysis is remarkably lower for the isomer with
onp, a sample of which released 0.5% of methanol
during the first hour in water suspension and was
hydrolized for 87% after 24 h. A puzzling fact is the
different behaviour of II and V relatively to the
corresponding Cu(dipyam)(OR)2 complexes: II is ob-
tained easily by heating a methanol suspension of
[Cu(dipyam)(pnp)2] whereas on the contrary V, in hot
methanol, decomposes slowly forming [Cu(dipya-
m)(onp)2]. Extractions in Soxhlet of V with acetone
for some hours yielded [Cu(dipyam)(onp)2] quantita-
Fig. 1. ORTEP view (at 20% probability) of the dinuclear complex II,
with the atomic numbering scheme in the symmetry independent
moiety.
AXS Smart 1000 single-crystal diffractometer (Mo Ka
radiation) equipped with a CCD area detector for
compounds I and IV, and on a Philips PW 1100
diffractometer using graphite monochromated Mo Ka
tively, leaving as residues of the reaction greenꢁbrown
/
˚
0.71069 A) and a v/2u scan technique for
radiation (lꢀ
/
solids with a copper content of about 40% and a IR
spectrum characterized by two strong absorptions at
compound II. In the case of compounds I and IV, the
raw frame data were processed using SAINT and SADABS
to yield the reflection data file [8]. The structures were
solved by Direct methods using the SIR-92 program [9]
and refined on Fo2 by full-matrix least-squares proce-
dures, using the SHELXL-97 program [10]. All non-
hydrogen atoms were refined with anisotropic atomic
displacements except for the oxygen atoms of the two
water molecules in compound I. The hydrogen atoms
3521 and 3428 cmꢃ1 2
.
Another difference between the Cu(II) dipyam com-
plexes with the tested nitrophenolates is the fact that,
whereas Cu(dipyam)Br(onp) is easily prepared and
recovered also in little amounts from the mother liquors
of [Cu(dipyam)(onp)2] syntheses, we were unable to
isolate the corresponding pnp complex, both under the
preparative conditions for Cu(dipyam)Br(onp) and at
room temperature. We obtained instead the [Cu(di-
were included in the refinement at idealized geometry
˚
pyam)(pnp)2] and [Cu2(drpyam)2(OH)2(H2O)]Br2×
/2H2O
(Cꢀ
/
Hꢀ0.95 A) and refined ‘riding’ on the correspond-
/
complexes, in a ratio of approximately 1:0.5.
ing parent atoms. The weighting scheme used in the last
cycle of refinement was wꢀ
1/[s2Fo2ꢂ(0.1000P)2], wꢀ
1/[s2Fo2ꢂ(0.1000P)2] and wꢀ1/[s2Fo2ꢂ(0.0569P)2ꢂ
1.34P] (where Pꢀ
(Fo2ꢂ2Fe 2)/3) for I, II and IV
respectively.
/
/
/
2
/
/
/
/
We consider this product responsible for the unsatisfactory
analytical results of V: in fact a small decomposition during the
synthesis of this complex was unavoidable also at 0 8C and, while the
soluble Cu(dipyam(onp)2 is easily washed away, the coproduct remains
inglobed in V. In agreement with this suggestion small absorptions at
3521 and 3428 cmꢃ1 were sometimes observed in the IR spectrum of
samples of V.
/
/
Molecular geometry calculations were carried out
using the PARST-97 program [11]. Drawings were
obtained by ORTEP3 in the WinGX suite [12]. All

132
A. Camus et al. / Inorganica Chimica Acta 349 (2003) 128ꢁ134
/
3.1. X-ray diffraction structure of II, I and IV
Table 2
˚
Relevant bond distances (A) and angles (8) for [Cu(dipyam)(pnp)(m-
OCH3)]2 (II)
The structure of II consists of centrosymmetric di-
nuclear complexes (Fig. 1) in which two Cu(di-
pyam)(pnp) units are held together by two symmetry
related m-metoxo oxygen bridges. The relevant bond
distances and angles are reported in Table 2. Each
copper atom is in a distorted square-pyramidal coordi-
nation environment with the basal plane defined by the
Cuꢀ
Cuꢀ
Cuꢀ
Cuꢀ
Cuꢀ
Cu
N1ꢀ
N1ꢀ
N3ꢀ
N3ꢀ
N2ꢀ
/
N1
N2
O1
O4
O4?
1.982(2)
2.088(3)
2.145(3)
1.923(2)
2.004(3)
3.062(2)
1.346(4)
1.358(4)
1.377(4)
1.374(4)
1.352(4)
N2ꢀ
O4ꢀ
O1ꢀ
/
C10
1340(4)
1.392(5)
1.293(4)
1.422(5)
1.408/6)
1.386(5)
1.384(6)
1.444(4)
1.221(6)
1.234(5)
/
/C17
/
/C11
/
C11ꢀ
C11ꢀ
C14ꢀ
C14ꢀ
C14ꢀ
/
C12
C16
C15
C13
N4
/
/
/
ꢀ ꢀ ꢀ
/Cu?
/
/
C5
C1
C5
C10
C6
/
pyridyl nitrogens from a chelating dipyam ligand (Cuꢀ
/
/
/
˚
/
N4ꢀ
/
O2
N1ꢀ
/
1.982(2) and Cuꢀ
/
N2ꢀ
/
2.088(3) A) and the oxy-
O4ꢀ1.923(2)
2.004(3) A). The Cuꢀ ꢀ ꢀCu? separation is
3.062(2) A and the angles CuꢀO4ꢀCu? and O4ꢀCuꢀO4?
/
N4ꢀ
/
O3
gens from two m-methoxo bridges (Cuꢀ
/
/
/
˚
and Cuꢀ
/
O4?ꢀ
/
N1ꢀ
N2ꢀ
O4ꢀ
O4?ꢀ
N2ꢀCuꢀ
N1ꢀCuꢀ
O1ꢀCuꢀ
O1ꢀCuꢀ
O1ꢀCuꢀ
O1ꢀCuꢀ
CuꢀO4ꢀ
/
Cuꢀ
Cuꢀ
Cuꢀ
Cuꢀ
/
N2
O4
O4?
91.1(1)
95.3(1)
77.5(1)
95.0(1)
129.2(1)
172.2(1)
88.1(1)
106.3(1)
94.4(1)
95.0(1)
102.5(1)
Cuꢀ
Cuꢀ
Cuꢀ
Cuꢀ
Cuꢀ
Cuꢀ
O1ꢀ
C14ꢀ
C14ꢀ
O2ꢀN4ꢀ
/
N1ꢀ
N1ꢀ
N2ꢀ
N2ꢀ
O4ꢀ
O1ꢀ
C11ꢀ
N4ꢀ
N4ꢀ
/
C1
115.2(2)
127.5(2)
118.2(2)
124.5(2)
121.4(2)
124.6(2)
121.9(3)
118.8(3)
118.7(3)
122.5(4)
˚
/
/
/
/
/
/
/
/C5
are 102.5(1) and 77.5(l)8, respectively. The oxygen from
the pnp ligand completes the coordination environment
of each metal center in the axial position at a distance of
/
/
/
/C6
/
/
N1
/
/C10
/
/O4?
/
/C17
˚
2.145(3) A. Although unusual this distance fits the axial
/
/O4
/
/C11
/
/
N1
N2
O4
/
/
C12
O2
˚
copper(II) bond distance (2.164(6) A) found
in the previously investigated mononuclear copper(II)
phenolateꢁ
/
/
/
/
/
/
/
/
/O3
complex [Cu(dipyam)(OOCCH3)(dcp)] (dcpꢀ2,6-di-
/
/
/
O4?
Cu?
/
/O3
/
/
chlorophenolate) [1]. Both compounds show in the
coordination sphere of copper the sequence of atoms
present in the nuclear core of the galactose oxidase [14].
The four basal donor atoms N1, N2, O4 and O4? are out
Relevant hydrogen bonds
C12ꢀH12ꢀ ꢀ ꢀO4?
H12 O4?
ꢀ ꢀ ꢀ
˚
/
/
/
3.556(5) A C12ꢀ
/
H12ꢀ
H3Nꢀ
H7ꢀO3ƒ?
/O4?
155(1)8
169(1)8
155(1)8
˚
2.66(1) A
/
/
˚
N3ꢀH3Nꢀ ꢀ ꢀ
H3N O1ƒ
ꢀ ꢀ ꢀ
C7ꢀH7ꢀ ꢀ ꢀO3ƒ?
H7 O3ƒ?
ꢀ ꢀ ꢀ
C15ꢀH15ꢀ ꢀ ꢀ
H15 O3ƒƒ
ꢀ ꢀ ꢀ
Symmetry codes: (?) 2ꢃ
1ꢃy, 2ꢃz; (ƒƒ) 1ꢃx, 1ꢃ
/
/
/
O1ƒ
2.758(4) A N3ꢀ
/
/
O1ƒ
of their mean plane of 0.465(3), ꢃ
/
0.441(3), 0.394(2) and
˚
1.79(2) A
/
/
˚
0.402(2) A respectively, thus indicating a significant
ꢃ
/
˚
/
/
/
3.443(4) A C7ꢀ
/
/
distortion to the tetrahedral arrangement, with the metal
˚
center displaced of 0.451(l) A towards the apex of the
pyramid. The dipyam ligand is nearly planar with the
two pyridine rings mutually bent only of 5.3(1)8.
Compound II belongs to a rare class of dinuclear (m-
alkoxyde)2 copper(II) complexes containing a phenoxo
ligand axially coordinated to each copper(II) ion in a
square-pyramidal arrangement. To the best of our
knowledge the only other similar dinuclear copper(II)
˚
2.55(1) A
/
/
˚
/
/
/
O3ƒƒ
3.349(6) A C15ꢀ
/
H15ꢀO3ƒƒ 152(1)8
/
˚
2.47(1) A
/
/
/
x, 1ꢃ
/
y, 2ꢃ
/
z; (ƒ) 2ꢃ
/x, ꢃ
/y, 2ꢃ
/
z; (ƒ?) 1ꢃx,
/
/
/
/
/
y, 1ꢃ
/z.
Fig. 2. ORTEP view (at 20% probability) of the dinuclear complexes II interacting, through Nꢀ
/
H
/
ꢀ ꢀ ꢀ
/
O hydrogen bonds, in a supramolecular array.

A. Camus et al. / Inorganica Chimica Acta 349 (2003) 128ꢁ
/134
133
complexes containing the metal atoms doubly bridged
by oxygen atoms and containing phenol or phenolate
ligand axially coordinated to each copper(II) ion are the
atom exhibits a flattened tetrahedral arrangement of the
N2O2 donor set formed by the pyridyl nitrogens from
˚
Nꢀ1.967(8) A) and the phenolic oxygens
dipyam (Cuꢀ
/
/
cation [Cu2(H2bbppnol)(OAc)(H2O)2]2ꢂ (H3bbppnolꢀ
/
˚
from two pnp (Cuꢀ
/
Oꢀ1.917(7) A). The molecular
/
N,N?,N,N?-bis[(2-hydroxybenzyl)(methylpyridyl)]-2-ol-
1,3-propanediamine) [3] and the neutral [Cu2(dnc)2]×
2CH3CN (dncꢀduncamine, a tripod chelate ((2-pyr-
idylmethyl)[(2-hydroxy-3,5-dimethylphenyl)methyl] [(2-
hydroxy-5-methyl-3-methylthio)phenyl)-methyl]amine)
[15]. The complex cation, which contains the copper
centers bridged by an alkoxide oxygen from the
H2bbppnolꢃ ligand and by an additional bidentate
acetate, shows the metals in distorted octahedral
CuN2O4 geometries with the phenol groups axially
geometry of I, together with the observation that its
structure is not stabilized by intramolecular interactions,
lead to conclude that there are no structural barriers
which prevent the formation of the dimer, thus justify-
ing the reaction properties of the complex with methanol
to give the dinuclear species [Cu(dipyam)(pnp)(m-
OCH3)]2. On the contrary the configuration of complex
[Cu(dipyam)(onp)2], which shows the opn acting as
unsymmetrical chelating ligands, could explain the
unsuccessful reactions of IV with methanol. A distorted
octahedral coordination (Fig. 4) is observed around the
copper(II): four short in-plane bonds involve two
/
/
coordinated to each copper(II) ion. The Cuꢀ
bonds, in cis position with respect to the Cu
ꢀ ꢀ ꢀ
are trans with respect to the CuꢀOwater distances. In
spite of the similarity of the equatorial CuN2O2
chromophores, the CuꢀOphenol bonds (2.43(1) and
/Ophenolate
/
/
Cu axis,
/
mutually cis pyridyl nitrogens from dipyam (1.980(3)ꢁ
/
˚
2.024(3) A) and two mutually cis phenolic oxygens from
˚
1.970(3) A). The orientation of the
two opn ligands, nearly parallel to each other and
/
two opn (1.915(2)ꢁ
/
˚
˚
Cu separation (3.40(1) A) in
2.445(9) A) and the Cu
the complex cation are significantly longer than the Cuꢀ
Ophenolate and CuꢀCu distances found in II. The neutral
/
ꢀ ꢀ ꢀ
/
/
/
complex, in which the copper atoms of the CuN2O3
chromophores are doubly bridged by oxygens from the
phenolates of the dimethylphenol side chains, shows two
five-coordinated metal ions in a distorted trigonal
bipyramidal geometry defined by trans-axial phenolate
ligation with short bond distances (1.887(10) and
˚
1.949(9) A). The bridging groups originate a Cu2O2
˚
core in which the Cuꢀ ꢀ ꢀCu separation (3.054(2) A) is
strictly similar to that observed in II, while the Cuꢀ
/
Ophenolate distances, which contribute to the complex
stability, are shorter than the one found in our complex
˚
(2.145(3) A).
In II the trans-axial arrangement of the phenolate
ligands, each involved by the ortho-CH group in an
intramolecular hydrogen bond (Table 2) with the
adjacent m-metoxo oxygen, seem to play a significant
role in determining the stability of the complex.
In the crystal the dinuclear units interact with each
other through the dipyam secondary amine groups,
which form Nꢀ
/
H
/
ꢀ ꢀ ꢀ
/
O hydrogen bonds with coordinated
oxygens from adjacent phenolates (Table 2), thus
originating supramolecular arrays (Fig. 2); the self-
assembling partially overlaps the dipyam ligands leaving
an interplanar spacing between the dipyam moieties of
˚
O interactions
3.383(1) A. Weak intermolecular Cꢀ
/
H
/
ꢀ ꢀ ꢀ
/
between Cꢀ
/
H groups and nitrophenolate oxygens from
different arrays determine the crystal packing.
To investigate the different reaction properties of the
mononuclear Cu(II)dipyam-nitrophenolate complexes
with respect to methanol we have undertaken the crystal
structure analyses of I and IV. In the complex
[Cu(dipyam)(pnp)2]×
metry due to a two-fold axis passing through the metal
center and the amino nitrogen from dipyam, the metal
/
2H2O (Fig. 3), which has C2 sym-
Fig. 3. ORTEP view (at 20% probability) of the mononuclear complex
I, with the atomic numbering scheme in the symmetry independent
moiety (crystallization water molecules not shown).

134
A. Camus et al. / Inorganica Chimica Acta 349 (2003) 128ꢁ134
/
Fig. 4. ORTEP view (at 20% probability) of the mononuclear complex IV, with the atomic numbering scheme.
[2] G. Davies, M.A. El-Sayed, in: K.D. Karlin, J. Zubieta (Eds.),
Copper Coordination Chemistry: Biochemical and Inorganic
Perspectives, Adenine Press, NY, 1982, p. 281.
[3] A. Neves, L.M. Rossi, I. Vencato, V. Drago, W. Haase, R.
Werner, Inorg. Chim. Acta 281 (1998) 111 (and references
therein).
almost orthogonal to the least-squares plane through
the N2O2 donor set, allows the formation of the two
axial bonds involving an oxygen of the monodentate
˚
2.443(3) A).
NO2 groups (Cuꢀ
/
Oꢀ
/
2.430(3)ꢁ
/
[4] N. Ray, S. Tyagy, B. Hathaway, J. Chem. Soc., Dalton Trans. 2
(1982) 143.
[5] M.S. Garozzo, N. Marsich, A. Camus, Gazz. Chim. Ital. 123
(1993) 697.
4. Supplementary material
[6] P.L. Wu, M.E. Keniry, B. Hathaway, Acta Crystallogr. C 48
(1992) 35.
[7] (a) M.C. Munoz, J.M. La´zaro, J. Faus, M. Julve, Acta Crystal-
Crystallographic data (excluding structure factors) for
the structural analysis have been deposited with the
Cambridge Crystallographic Data Center, CCDC Nos.
194 338 (I), 194 339 (II) and 194 340 (IV). Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
˜
logr. C 49 (1993) 1756;
(b) A.M. Atria, E. Spodine, M.T. Garland, J. Manzur, R. Baggio,
O. Pena, Bol. Soc. Chil. Quim. 41 (1996) 79.
˜
[8] (a) SAINT Software Users Guide, Version 6.0; Bruker Analytical
X-ray Systems: Madison, WI, 1999.;
(b) G.M. Sheldrick, SADABS v2.03: Area-Detector Absorption
1EZ, UK (fax: ꢂ44-1223-336-033, e-mail: deposit@
/
Correction, University of Gottingen, Gottingen, Germany, 1999.
¨ ¨
ccdc.cam.ac.uk).
[9] A. Altomare, G. Cascarano, C. Giacovazzo, A. Gualiardi, M.C.
Burla, G. Polidori, M. Camalli, J. Appl. Crystallogr. 27 (1994)
435.
[10] G.M. Sheldrick, SHELX-97, Program for Crystal Structure Re-
Acknowledgements
finement, University of Gottingen, Gottingen, Germany, 1997.
¨ ¨
Available from http://www.shelx.uni-ac.gwdg.de/shelx/index.
html.
This work was supported by the Italian Murst. We
thank P. de Baseggio for recording the IR spectra and
for the elemental analyses.
[11] M. Nardelli, PARST97, updated version of PARST95, J. Appl.
Crystallogr. 28 (1995) 659.
[12] ORTEP3 in the WinGX suite, L.J. Farrugia, J. Appl. Crystallogr.
30 (1997) 565.
[13] N. Marsich, A. Camus, F. Ugozzoli, A.M. Manotti Lanfredi,
Inorg. Chim. Acta 236 (1995) 117.
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