Copper(II) complexes of isomeric aminophenylhydroxamic acids. A novel 'clam-like' dimeric metallacrown and polymeric helical structure containing interlinked unique copper(II) sites

Article abstract of DOI:10.1039/b102169i

The reaction of 3-aminophenylhydroxamic acid with CuSO₄·5H₂O in aqueous solution gives the novel helical polymer [Cu₃(3-Apha)₄(H₂O)SO₄] _n·8H₂O 1 the structure of which contains interlinked repeating units having three unique neutral, anionic and cationic copper(II) sites. In this complex the copper(II) sites are magnetically non-interacting. A similar reaction with 2-aminophenylhydroxamic acid gives the novel dimeric 'metallacrown' [Cu₅(2-AphaH_-1)₄(μ-SO₄)(H ₂O)₂]₂·10H₂O 2 which has a 'clam-like' structure showing strong antiferromagnetic behaviour. In contrast to the above ligands, 4-aminophenylhydroxamic acid gives the monomeric square planar complex Cu(4-Apha)₂·H₂O 3 which exhibits paramagnetic behaviour. Crystal structures of all three complexes are reported.

Full text of DOI:10.1039/b102169i

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Copper(II) complexes of isomeric aminophenylhydroxamic acids.
A novel ‘clam-like’ dimeric metallacrown and polymeric helical
structure containing interlinked unique copper(II) sites
Declan Gaynor,a Zoya A. Starikova,b Wolfgang Haasec and Kevin B. Nolan*a
a Department of Chemistry, Royal College of Surgeons in Ireland, 123 St. Stephen’s Green,
Dublin 2, Ireland. E-mail: kbnolan@rcsi.ie
b X-Ray Structure Centre, General and Technical Chemistry Division,
Academy of Sciences of Russia, Vavilov Str. 28, Moscow B-334, 117813, Russia
c Technische Universität Darmstadt, Institut für Physikalische Chemie, Petersenstr. 20,
D- 64287, Darmstadt, Germany
Received 7th March 2001, Accepted 15th March 2001
First published as an Advance Article on the web 12th April 2001
The reaction of 3-aminophenylhydroxamic acid with CuSO4ؒ5H2O in aqueous solution gives the novel helical
polymer [Cu3(3-Apha)4(H2O)SO4]nؒ8H2O 1 the structure of which contains interlinked repeating units having
three unique neutral, anionic and cationic copper() sites. In this complex the copper() sites are magnetically
non-interacting. A similar reaction with 2-aminophenylhydroxamic acid gives the novel dimeric ‘metallacrown’
[Cu5(2-AphaHϪ1)4(µ-SO4)(H2O)2]2ؒ10H2O 2 which has a ‘clam-like’ structure showing strong antiferromagnetic
behaviour. In contrast to the above ligands, 4-aminophenylhydroxamic acid gives the monomeric square planar
complex Cu(4-Apha)2ؒH2O 3 which exhibits paramagnetic behaviour. Crystal structures of all three complexes
are reported.
Introduction
Hydroxamic acids, a group of weak organic acids of general
formula RC(O)N(RЈ)OH, play a variety of roles in biology and
medicine, for example as siderophores for iron(),1 as potent
and selective inhibitors of enzymes such as peroxidases,2
ureases,3 matrix metalloproteinases,4 and as hypotensive,5,6 anti-
cancer, anti-tuberculous and anti-fungal agents.7 Many of these
roles are due largely to the complexing ability of the hydrox-
amate group which is usually bidentate4,8 but can also be
bridging9 or even monodentate.10 Usually these interactions
are stabilised by hydrogen bonding interactions involving
the hydroxamate group and other suitable groups present in
the molecule. The structures of the copper() complexes of the
isomeric aminophenylhydroxamic acids (AphaH), which are
reported herein, illustrate the diversity of structures which these
ligands can produce and how these are influenced by other
coordinating groups in the molecules. The structures include a
novel helical polynuclear complex involving three unique
copper() sites formed by 3-AphaH, a novel dimeric copper()-
metallacrown type complex formed by 2-AphaH,11 and a simple
mononuclear complex formed by 4-AphaH.
Fig. 1 ORTEP19 diagram of 1 (solvent molecules omitted for clarity)
showing a single repeating unit which contains the unique neutral
(Cu1), anionic (Cu2) and the incomplete cationic (Cu3) copper() sites.
The Cu3 site is completed by coordinated NH2 groups from N6 (normal
bond) and N2 (elongated bond) belonging to adjacent repeating units.
structure (Fig. 1, Table 1), in which the repeating units contain
three interlinked unique copper() sites i.e. the neutral square
planar Cu(3-Apha)2, the anionic square pyramidal [Cu(3-
Apha)SO4(NH2)(...NH2)]Ϫ and the cationic square pyramidal
[Cu(3-Apha)(H2O)(NH2)(...NH2)]+ where NH2 represents
amino groups from neighbouring molecules forming both
normal and elongated (...) bonds. The polymer chains are
linked by an extensive hydrogen bonding network involving
hydroxamate nitrogens and oxygens, sulfate oxygens and both
coordinated and solvent waters. This network gives the crystal
lattice a rigid structure (Fig. 2) featuring channels (dimensions
∼5.5 Å × ∼9 Å) which are occupied by the monodentate sulfate
groups and solvent (H2O).
Results and discussion
Synthesis and structures
The isomeric aminophenylhydroxamic acids were prepared
in good yields by the reaction of NH2OH, generated in situ
from (NH2OH)2ؒH2SO4, with the corresponding esters. The
complexes were obtained in high yield and in crystalline form,
either directly or by recrystallisation, by the reaction of the
hydroxamic acid with CuSO4ؒ5H2O in aqueous solution. Satis-
factory microanalyses were obtained. The structures of the
complexes were obtained by single crystal X-ray crystallo-
graphy.
The dark green crystalline complex [Cu5(2-AphaHϪ1)4-
(µ-SO4)(H2O)2]2ؒ10H2O 2, was obtained by the reaction of
2-AphaH with CuSO4ؒ5H2O in aqueous solution. Each mono-
meric unit of this dimer contains a square of copper() ions,
The complex [Cu3(3-Apha)4(H2O)SO4]nؒ8H2O 1, prepared
from 3-AphaH and CuSO4ؒ5H2O, has a helical polymeric
1578
J. Chem. Soc., Dalton Trans., 2001, 1578–1581
This journal is © The Royal Society of Chemistry 2001
DOI: 10.1039/b102169i

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Table 2 Selected bond lengths (Å) and angles (Њ) with estimated
standard deviations for [Cu5(2-AphaHϪ1)4(µ-SO4)(H2O)2]2ؒ10H2O 2
Table 1 Selected bond lengths (Å) and angles (Њ) with estimated
standard deviations for [Cu3(3-Apha)4(H2O)SO4]nؒ8H2O 1
CU(1)–O(4)
Cu(1)–O(2)
Cu(1)–O(3)
Cu(1)–O(1)
Cu(2)–O(5)
Cu(2)–O(4S)
Cu(2)–O(6)
Cu(2)–N(8)
Cu(2)–N(4)
Cu(3)–O(7)
Cu(3)–O(8)
Cu(3)–O(1W)
1.922(3)
1.927(3)
1.942(3)
1.951(3)
1.958(3)
1.964(3)
1.981(3)
2.034(3)
1.408(3)
1.956(3)
1.974(3)
1.980(3)
Cu(3)–N(6A)
Cu(3)–N(2A)
S–O(4S)
2.053(3)
2.405(3)
1.460(3)
1.293(5)
1.376(4)
1.290(5)
1.384(4)
1.383(4)
1.265(5)
1.372(4)
1.284(5)
Cu(1)–O(7)
Cu(1)–N(1)
Cu(1)–O(8)
Cu(1)–N(2)
Cu(1)–O(7S)
Cu(2)–O(1)
Cu(2)–O(2)
Cu(2)–N(3)
Cu(2)–N(4)
Cu(2)–O(2A)
Cu(3)–O(3)
Cu(3)–N(5)
Cu(3)–O(4)
1.901(5)
1.959(6)
2.006(5)
2.009(5)
2.154(5)
1.904(4)
1.959(4)
1.963(5)
1.977(5)
2.428(5)
1.915(5)
1.916(6)
1.945(5)
Cu(3)–N(6)
Cu(3)–O(8S)
Cu(4)–O(5)
Cu(4)–O(6)
Cu(4)–N(7)
Cu(4)–N(8)
Cu(4)–O(10)
Cu(5)–O(3)
Cu(5)–O(7)
Cu(5)–O(1)
Cu(5)–O(5)
Cu(5)–O(9)
O(2)–Cu(2A)
1.973(5)
2.430(6)
1.919(4)
1.947(4)
1.967(5)
1.960(5)
2.472(5)
1.900(4)
1.915(5)
1.937(4)
1.953(5)
2.258(6)
2.428(5)
O(1)–C(1)
O(2)–N(1)
O(3)–C(8)
O(4)–N(3)
O(5)–N(5)
O(6)–C(15)
O(7)–N(7)
O(8)–C(22)
O(4)–Cu(1)–O(2)
O(4)–Cu(1)–O(3)
O(2)–Cu(1)–O(3)
O(4)–Cu(1)–O(1)
O(2)–Cu(1)–O(1)
O(3)–Cu(1)–O(1)
175.83(14) O(4S)–Cu(2)–N(4)
84.66(12) O(6)–Cu(2)–N(4)
95.84(12) N(8)–Cu(2)–N(4)
94.81(12) O(7)–Cu(3)–O(8)
84.80(12) O(7)–Cu(3)–O(1W)
178.40(12) O(8)–Cu(3)–O(1W)
93.16(12)
94.46(11)
95.30(12)
83.20(11)
172.00(11)
92.05(12)
169.58(12)
89.71(13)
97.27(12)
93.41(11)
89.41(12)
96.88(12)
O(7)–Cu(1)–N(1)
O(7)–Cu(1)–O(8)
N(1)–Cu(1)–O(8)
O(7)–Cu(1)–N(2)
N(1)–Cu(1)–N(2)
O(8)–Cu(1)–N(2)
O(7)–Cu(1)–O(7S)
N(1)–Cu(1)–O(7S)
O(8)–Cu(1)–O(7S)
N(2)–Cu(1)–O(7S)
O(1)–Cu(2)–O(2)
O(1)–Cu(2)–N(3)
O(2)–Cu(2)–N(3)
O(1)–Cu(2)–N(4)
O(2)–Cu(2)–N(4)
N(3)–Cu(2)–N(4)
O(1)–Cu(2)–O(2A)
O(2)–Cu(2)–O(2A)
N(3)–Cu(2)–O(2A)
N(4)–Cu(2)–O(2A)
O(3)–Cu(3)–N(5)
O(3)–Cu(3)–O(4)
N(5)–Cu(3)–O(4)
O(3)–Cu(5)–O(9)
O(7)–Cu(5)–O(9)
O(1)–Cu(5)–O(9)
O(5)–Cu(5)–O(9)
Cu(2)–O(2)–Cu(2A)
86.0(2)
77.4(2)
156.7(2)
172.6(2)
86.8(2)
106.7(2)
87.6(2)
113.0(2)
84.6(2)
97.1(2)
81.8(2)
89.4(2)
170.5(2)
162.7(2)
99.2(2)
88.2(2)
100.3(2)
83.3(2)
101.8(2)
96.9(2)
92.4(2)
81.2(2)
163.2(2)
90.6(2)
100.9(2)
102.3(2)
98.7(2)
96.4(2)
O(3)–Cu(3)–N(6)
N(5)–Cu(3)–N(6)
O(4)–Cu(3)–N(6)
O(3)–Cu(3)–O(8S)
N(5)–Cu(3)–O(8S)
O(4)–Cu(3)–O(8S)
N(6)–Cu(3)–O(8S)
O(5)–Cu(4)–O(6)
O(5)–Cu(4)–N(7)
O(6)–Cu(4)–N(7)
O(5)–Cu(4)–N(8)
O(6)–Cu(4)–N(8)
O(5)–Cu(4)–O(10)
N(7)–Cu(4)–O(10)
N(8)–Cu(4)–O(10)
O(6)–Cu(4)–O(10)
N(7)–Cu(4)–N(8)
O(3)–Cu(5)–O(7)
O(3)–Cu(5)–O(1)
O(7)–Cu(5)–O(1)
O(3)–Cu(5)–O(5)
O(7)–Cu(5)–O(5)
O(1)–Cu(5)–O(5)
Cu(2)–O(1)–Cu(5)
Cu(5)–O(3)–Cu(3)
Cu(4)–O(5)–Cu(5)
Cu(1)–O(7)–Cu(5)
177.6(3)
88.7(2)
98.2(2)
87.8(2)
92.4(2)
102.9(2)
90.3(2)
82.2(2)
89.8(2)
171.8(2)
177.6(2)
99.4(2)
94.66(2)
97.64(2)
83.68(2)
84.66(2)
88.7(2)
168.4(2)
88.1(2)
88.9(2)
91.9(2)
86.9(2)
159.0(2)
117.1(2)
117.3(3)
112.1(2)
120.6(3)
O(5)–Cu(2)–O(4S) 170.53(12) O(7)–Cu(3)–N(6A)
O(5)–Cu(2)–O(6)
O(4S)–Cu(2)–O(6)
O(5)–Cu(2)–N(8)
O(4S)–Cu(2)–N(8)
O(6)–Cu(2)–N(8)
O(5)–Cu(2)–N(4)
82.97(11) O(1W)–Cu(3)–N(6A)
89.43(12) O(7)–Cu(3)–N(2A)
90.89(12) O(8)–Cu(3)–N(2A)
95.64(13) O(1W)–Cu(3)–N(2A)
168.74(12) N(6A)–Cu(3)–N(2A)
93.06(12)
Fig. 2 ORTEP diagram of the polymeric helical chain of 1 showing
only the Cu2–Cu3 backbone and a unit cell displaying channels
containing coordinated sulfate groups and solvent molecules (H2O).
Cu1–4 (Fig. 3, Table 2), linked by doubly deprotonated
hydroxamate ligands, 2-AphaHϪ1, and a central copper() ion,
Cu5, coordinated by four hydroxamate oxygens and the oxygen
of a bridging sulfate which is also weakly bonded to Cu4. A
similar complex but having a monomeric structure and belong-
ing to a family called ‘metallacrowns’ has previously been
reported by Pecoraro et al. and was prepared from Cu(OAc)2.12
The structure of 2 (Fig. 3), however, is a fused dimeric metal-
lacrown, having a novel ‘clam-like’ structure, the closed end of
which arises from the binding of ring coppers, Cu2 and Cu2A,
in two metallacrown units to oxygen atoms O2A and O2
respectively in adjacent units, and the open end of which
accommodates bridging sulfate ligands. The exterior faces of
the metallacrown dimer are involved in hydrogen bonding with
other metallacrown units through the hydroxamate nitrogens
and oxygens resulting in intermolecular Cu–Cu distances of
Fig. 3 ORTEP diagram of 2 (solvent molecules not shown). Only
selected atoms of one metallacrown unit and the atoms of the second
ring involved in binding the two metallacrowns are displayed.
∼3.9 Å. The only other previously reported dimeric metalla-
crown is a nickel() complex in which metallacrown rings are
almost parallel.13 In contrast to the above complex structures,
the reaction of 4-AphaH with CuSO4ؒ5H2O gave the simple
square planar Cu(4-Apha)2ؒH2O 3 (Fig. 4, Table 3).
J. Chem. Soc., Dalton Trans., 2001, 1578–1581
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strongly antiferromagnetically coupled and which dimerises by
Table 3 Selected bond lengths (Å) and angles (Њ) with estimated
standard deviations for Cu(4-Apha)2ؒH2O 3
weak O–Cu axial interactions. The relative positioning of the
amino and hydroxamate groups in 3-AphaϪ allows the form-
ation of helical complex 1, containing trimeric units having
unique copper() sites which are magnetically non-interacting.
In contrast to the above two ligands 4-AphaϪ forms a simple
square planar 2 : 1 complex.
Cu(1)–O(1)
Cu(1)–O(1A)
Cu(1)–O(2A)
Cu(1)–O(2)
1.9225(11) O(1)–N(1)
1.9225(11) O(2)–C(1)
1.9246(11) N(1)–C(1)
1.9246(11)
1.3854(16)
1.2864(17)
1.3116(19)
O(1)–Cu(1)–O(1A)
O(1)–Cu(1)–O(2A)
O(1A)–Cu(1)–Cu(2A)
O(1)–Cu(1)–O(2)
180.00(6)
95.10(4)
84.90(4)
84.90(4)
95.10(4)
O(2A)–Cu(1)–O(2) 180.00(6)
N(1)–O(1)–Cu(1)
C(1)–O(2)–Cu(1)
C(1)–N(1)–O(1)
O(2)–C(1)–N(1)
106.79(8)
109.94(9)
118.07(12)
119.37(13)
Experimental
Ligand synthesis
O(1A)–Cu(1)–O(2)
2-AphaH, 3-AphaH and 4-AphaH. The ligands were prepared
from the corresponding methyl esters by modification of a pre-
vious method.15 Methyl 3-aminobenzoate was synthesised using
a previously reported method.16 Methyl 2-aminobenzoate and
methyl 4-aminobenzoate were obtained from Aldrich.
An aqueous solution (40 cm3) of NaOH (10 g, 0.25 mol) was
added to a mixture of (NH2OH)2ؒH2SO4 (8.2 g, 0.05 mol) and
50 g of ice. Na2SO3 (1 g, 6mmol) and the corresponding ester
(7.55 g, 0.05 mol) were then added. The temperature of the
mixture was raised to 45 ЊC and stirred for 24 hours. The result-
ing solution was acidified with 10% H2SO4 to pH 6.0. Some
hydroxamic acid product precipitated at this point and was
collected by filtration. The filtrate was evaporated to dryness
under reduced pressure yielding a yellow solid from which a
further crop of hydroxamic acid was obtained by extraction
into hot MeOH and evaporation to dryness under reduced
pressure. Recrystallisation was performed from hot H2O.
2-AphaH. Yield: 5.4 g, 35 mmol, 71%. Calc. (found) for
C7H8N2O2: C, 54.26 (54.56); H, 5.26 (5.22); N, 18.42 (18.17)%.
1H NMR (d6-DMSO): δ 10.92 (s, 1H, OH), 8.85 (s, 1H, NH),
7.29 (d, J 8.2 Hz, 1H, H3/6), 7.09 (dd, J 7.6 Hz, 8.2 Hz, 1H, H4/5),
6.66 (d, J 8.2 Hz, 1H, H3/6), 6.44 (dd, J 7.6 Hz, 8.2 Hz, 1H, H4/5),
6.2 (s, 2H, NH2).
Fig. 4 ORTEP diagram of 3 displaying its simple square planar
structure.
3-AphaH. Yield: 4.5 g, 30 mmol, 60%. Calc. (found) for
C7H8N2O2: C, 54.26 (55.03); H, 5.26 (5.37); N, 18.42 (18.26)%.
1H NMR (d6-DMSO): δ 10.97 (s, 1H, OH), 8.88 (s, 1H, NH),
7.01 (dd, J 7.2 Hz, 7.6 Hz, 1H, H5), 6.93 (s, 1H, H2), 6.80 (d,
J 7.2 Hz, 1H, H4/6), 6.64 (d, J 7.6 Hz, 1H, H4/6), 5.21 (s, 2H,
NH2).
4-AphaH. Yield: 5.7 g, 38 mmol, 75%. Calc. (found) for
C7H8N2O2: C, 54.26 (54.83); H, 5.26 (5.32); N, 18.42 (18.23)%.
1H NMR (d6-DMSO): δ 10.71 (s, 1H, OH), 8.73 (s, 1H, NH),
7.46 (d, J 8.6 Hz, 2H, aromatic H), 8.52 (d, J 8.6 Hz, 2H,
aromatic H), 5.56 (s, 2H, NH2).
Fig. 5 Magnetic susceptibility results for 2 displayed as χ [10Ϫ6 cm3
molϪ1] µeff [µB] against T [K].
Magnetic behaviour
The room temperature magnetic moment of dimeric complex 2
is 4.0 µB, Fig. 5, and is considerably lower than the calculated
value of 5.82 µB for ten independent S = ¹ copper() ions
¯
²
(g assumed to be 2.125) due to antiferromagnetic coupling. This
compares with the value of 2.5 µB reported for the monomeric
metallacrown which contains five copper() ions12 indicating
increased inter-copper interactions in each metallacrown ring
of the dimeric structure. A noteworthy feature of the magnetic
behaviour is the considerable decrease in µeff between 10 K and
4 K. This behaviour has not previously been reported for
copper() metallacrown complexes12 and is probably due to
weak antiferromagnetically coupled inter-metallacrown ring
interactions through the copper and oxygen bridge connecting
the two metallacrown rings. The magnetic behaviour of com-
plex 2 is represented in Fig. 5 in terms of χ [10Ϫ6 cm3 molϪ1] and
µeff [µB] against T [K].
Complex synthesis
[Cu3(3-Apha)4(H2O)SO4]nؒ8H2O 1. To an aqueous solution
(25 cm3) of 3-AphaH (250 mg, 1.65 mmol) at 50 ЊC was added
CuSO4ؒ5H2O (309 mg, 1.24 mmol) and left to stand at 10 ЊC.
After 24 hours a bright green crystalline product was obtained
and this was collected by filtration. Yield: 218 mg, 0.206 mmol,
75%. Calc. (found) for C28H46N8O21S1Cu3: C, 31.93 (32.53); H,
4.41 (3.90); N, 10.63 (10.62); Cu, 18.10 (18.35)%.
[Cu5(2-AphaHϪ1)4(ꢀ-SO4)(H2O)2]2ؒ10H2O 2. To an aqueous
solution (25 cm3) of 2-AphaH (250 mg, 1.65 mmol) at 40 ЊC
was added CuSO4ؒ5H2O (515 mg, 2.06 mmol) and was left to
stand at room temperature. After 24 hours a dark green crystal-
line product was obtained and this was collected by filtration.
Yield: 330 mg, 0.145 mmol, 70%. Calc. (found) for C56H76N16-
O38S2Cu10: C, 29.48 (29.48); H, 3.33 (3.16), N, 9.83 (9.36), Cu,
27.88 (26.92)%.
In contrast to 2 the polymeric complex 1 was found to be
paramagnetic with a µeff value of 3.22 µB per tricopper repeating
unit which is close to the calculated value for three non-
interacting copper() centres. Complex 3 has a magnetic
moment of 1.82 µB consistent with the simple monomeric
square planar complex14 shown by X-ray crystallography.
Conclusion
Cu(4-AphaH)2ؒH2O 3. To an aqueous solution (25 cm3) of
4-AphaH (250 mg, 1.65 mmol) at 40 ЊC was added CuSO4ؒ
5H2O (205 mg, 0.825 mmol). The pH of the solution was then
raised to 7.0 using 0.2 M NaOH. The resulting light green
The isomeric aminophenylhydroxamic acids form structurally
diverse complexes with copper(). The ‘bite’ of 2-AphaHϪ1
allows the formation of a pentanuclear metallacrown, which is
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J. Chem. Soc., Dalton Trans., 2001, 1578–1581

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precipitate was filtered off, dried and recrystallised from hot
water. Yield: 255 mg, 0.769 mmol, 80%. Calc. (found) for the
monohydrate C14H16N4O5Cu {formula from crystal structure}:
C, 43.80 (42.82); H, 4.21 (3.95); N, 14.60 (14.30), Cu, 16.55
(16.05)%. Calc. for 1¹ hydrate: C, 42.80; H, 4.33; N, 14.27; Cu,
16.19%. The difference between the crystal structure formula
and the formula which best fits the found microanalysis may be
attributed to solvent loss.17
Research Committee, RCSI, Enterprise Ireland, the Irish
Government under its Programme for Research in Third Level
Institutions and EU COST D8 for financial support. We thank
the referees for their helpful comments.
¯
²
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E. C. O’Brien, S. Le Roy, J. Levaillain, D. J. Fitzgerald and
K. B. Nolan, Inorg. Chim. Acta, 1997, 266, 177; H. O. Davies,
D. A. Brown, A. I. Yanovsky and K. B. Nolan, Inorg. Chim. Acta,
1995, 237, 71.
9 S. Benini, W. R. Rypniewski, K. S. Wilson, S. Miletti, S. Ciurli and
S. Mangani, J. Biol. Inorg. Chem., 2000, 5, 110.
10 L. R. Scolnick, A. M. Clements, J. Liao, L. Crenshaw, M. Helberg,
J. May, T. R. Dean and D. W. Christianson, J. Am. Chem. Soc., 1997,
119, 850.
Crystal data and data-collection parameters. For 1.
C28H46N8O21S1Cu3, Mr = 1053.41, orthorhombic, space group
Pna21, a = 15.2049(12), b = 14.2017(11), c = 18.5719(14) Å,
V = 4010.3(5) Å3, F(000) = 2164, Z = 4, T = 100 K, µ(Mo-
Kα) = 1.722 mmϪ1
,
33960 reflections collected, 10045
independent, Rint = 0.0471. Refinement converged at wR2 value
of 0.0879, R1 0.0418 [for 7521 reflections with Fo > 2σ(F)].
For 2. C56H76N16O38S2Cu10, Mr = 2280.86, monoclinic, space
group C2/c, a = 13.9633(11), b = 27.574(2), c = 19.966(2) Å,
β = 95.795(2)Њ, V = 7648.3(10) Å3, F(000) = 4568, Z = 4, T = 100
K, µ(Mo-Kα) = 2.882 mmϪ1, 36014 reflections collected, 11017
independent, Rint = 0.1909. Refinement converged at wR2 value
of 0.0754, R1 0.0520 [for 2865 reflections with Fo > 2σ(F)].
For 3. C14H16N4O5Cu, Mr = 383.85, monoclinic, space
group C2/c, a = 17.7195(9), b = 5.6014(3), c = 15.5028(8) Å,
β = 109.6520(10)Њ, V = 1449.09(13) Å3, F(000) = 788, Z = 4,
T = 110 K, µ(Mo-Kα) = 1.544 mmϪ1, 6547 reflections collected,
2093 independent, Rint = 0.0334. Refinement converged at wR2
value of 0.0818, R1 0.0301 [for 1786 reflections with
Fo > 2σ(F)].
11 V. L. Pecoraro, A. J. Stemmler, B. R. Gibney, J. J. Bodwin, H. Wang,
J. W. Kampf and A. Barwinski, Metallacrowns: A New Class of
Molecular Recognition Agents in Progress in Inorganic Chemistry,
ed. K. D. Karlin, John Wiley and Sons, New York, 1997, vol. 45,
p. 83.
CCDC reference numbers 154909–154911.
See http://www.rsc.org/suppdata/dt/b1/b102169i/ for crystal-
lographic data in CIF or other electronic format.
12 B. R. Gibney, D. P. Kessissoglou, J. W. Kampf and V. L. Pecoraro,
Inorg. Chem., 1994, 33, 4840.
Magnetic measurements
13 C. P. Raptopoulou, A. N. Papadopoulos, D. A. Malamatari,
E. Ioannidis, G. Moisidis, A. Terzis and D. P. Kessissoglou,
Inorg. Chim. Acta., 1998, 272, 283.
14 B. J. Hathaway, in Comprehensive Coordination Chemistry,
eds. G. Wilkinson, R. D. Gillard and J. A. Mc Cleverty, Pergamon
Press, Oxford, 1987, vol. 5, ch. 53, p. 656.
15 B. D. Hosangadi and R. H. Dave, Tetrahedron Lett., 1996, 37, 6375.
16 B. van’t Riet, G. L. Wampler and H. L. Elford, J. Med. Chem., 1979,
22, 5, 589.
Magnetic measurements in the temperature range 4.2–300 K
were obtained using a CAHN D200 balance with a maximum
accuracy of 0.1 µg, a Leybold–Heraeus LTC60 temperature
regulator with a silicon-diode or a carbon-glass-(below 70 K)
resistor and in the temperature range 300–450 K using a
CAHN RG balance with a maximum accuracy of 0.3 µg, and
a nickel–chrome–nickel-thermometer.18
17 E. Bouwman, P. Evans, H. Kooijman, J. Reedijk and A. L. Spek,
J. Chem. Soc., Chem. Commun., 1993, 1746.
18 S. Gehring, P. Fleischhauer, H. Paulus and W. Haase, Inorg. Chem.,
1993, 32, 54.
19 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1976.
Acknowledgements
We thank Mr Karsten Falk, Technische Universität Darmstadt
for his assistance with magnetic measurements and the
J. Chem. Soc., Dalton Trans., 2001, 1578–1581
1581