Di-, tri-, tetra-, and hexanuclear copper(ll) mono-organophosphates: Structure and nuclearity dependence on the choice of phosphorus substituents and auxiliary n-donor ligands

Article abstract of DOI:10.1021/ic801532y

Reactions of 2,6-dimethylphenyl phosphate (dmppH₂) and 2,6-diisopropylphenyl phosphate (dippH₂) with copper(ll) precursors have been investigated in the presence of auxiliary N-donor ligands, and new structural types of copper phosph

Full text of DOI:10.1021/ic801532y

Inorg. Chem. 2009, 48, 183-192
Di-, Tri-, Tetra-, and Hexanuclear Copper(II) Mono-organophosphates:
Structure and Nuclearity Dependence on the Choice of Phosphorus
Substituents and Auxiliary N-Donor Ligands†
Ramaswamy Murugavel,*,‡,§ Subramaniam Kuppuswamy,‡ Amarendra Nath Maity,‡
and Mayank Pratap Singh‡
Department of Chemistry and Centre for Research in Nanotechnology and Science, Indian Institute
of Technology-Bombay, Powai, Mumbai-400076, India
Received August 11, 2008
Reactions of 2,6-dimethylphenyl phosphate (dmppH2) and 2,6-diisopropylphenyl phosphate (dippH2) with copper(II)
precursors have been investigated in the presence of auxiliary N-donor ligands, and new structural types of copper
phosphates have been isolated. Copper acetate reacts with dmppH2 in the presence of either 3,5-di-tert-butyl
pyrazole (dbpz) or 3,5-dimethyl pyrazole (dmpz), leading to the isolation of tetrameric complex [Cu(dmpp)(dbpz)]4
1 and hexanuclear cage complex [Cu6(PO4)(dmpp)3(OAc)3(dmpz)9] 2, respectively. Whereas compound 1 is a cubane-
shaped cluster whose Cu4O12P4 core resembles the double-4-ring (D4R) zeolite SBU, compound 2 is a novel
hexanuclear copper complex with an unprecedented structure in metal phosphate chemistry. Use of bulkier dippH2
in the above reactions, however, yielded metal-free acid-base complexes [(dippH)(dbpz)(dbpzH)] 3 and
[(dippH)(dmpz)(dmpzH)] 4, respectively. The reactions carried out between copper acetate and dmppH2 or dippH2
in the presence of chelating ligand 1,10-phenanthroline produced structurally similar dimeric copper phosphates
[Cu(phen)(dmpp)(CH3OH)]2 · 2CH3OH 5 and [Cu(phen)(dipp)(CH3OH)]2 · 2CH3OH 6 with a S4R SBU core. Changing
the copper source to [Cu2(bpy)2(OAc)(OH)(H2O)] · 2ClO4 and carrying out reactions both with dippH2 and with dmppH2
result in the formation of trinuclear copper phosphates [Cu3(bpy)3(dmpp)2(CH3OH)3] · 2ClO4 · 2CH3OH 7 and
[Cu3(bpy)3(dipp)2(CH3OH)3] · 2ClO4 · 2CH3OH 8. The three copper ions in 7 and 8 are held together by two bridging
phosphate ligands to produce a tricyclic derivative whose core resembles the 4)1 SBU of zeolites. Compounds
1-8 have been characterized by elemental analysis and IR, absorption, emission, and EPR spectroscopic techniques.
The crystal structures of compounds 1, 2, 4, 5, 6, and 8 have also been established by single-crystal X-ray diffraction
studies.
Introduction
preformed molecular precursors has led to an outburst of
activity in the synthesis of smaller metal phosphate (and
related phosphonate and siloxane) and similar molecules.3-6
The research on molecular metal phosph(on)ate chemistry
is also propelled by the quest of functional models for
phosphate ester hydrolysis and the search of newer single
Following the discovery of phosphate analogues of zeo-
lites, AlPOs with porous structures,1 research on extended
metal phosphate and similar framework structures gained
momentum in the last two decades.2 The recent realization
that larger framework solids can be rationally built from
* To whom correspondence should be addressed. E-mail: rmv@chem.iitb.ac.in.
Fax: +91-22-2572 3480.
(3) Murugavel, R.; Walawalkar, M. G.; Dan, M.; Roesky, H. W.; Rao,
C. N. R. Acc. Chem. Res. 2004, 37, 763.
†
Part of this work is described in the M.Sc. dissertation of Amerendra
Nath Maity submitted to IIT-Bombay, April 2003.
(4) (a) Anantharaman, G.; Walawalkar, M. G.; Murugavel, R.; Gabor,
B.; Herbst-Irmer, R.; Baldus, M.; Angerstein, B.; Roesky, H. W.
Angew. Chem., Int. Ed. 2003, 42, 4482. (b) Walawalkar, M. G.;
Murugavel, R.; Roesky, H. W.; Uson, I.; Kraetzner, R. Inorg. Chem.
1998, 37, 473. (c) Walawalkar, M. G.; Murugavel, R.; Roesky, H. W.;
Schmidt, H.-G. Organometallics 1997, 16, 516. (d) Murugavel, R.;
Shanmugan, S. Chem. Commun. 2007, 1257.
‡
Department of Chemistry.
Centre for Research in Nanotechnology and Science.
§
(1) Wilson, S. T.; Lok, B. M.; Messina, C. A.; Cannan, T. R.; Flanigen,
E. M. J. Am. Chem. Soc. 1982, 104, 1146.
(2) Murugavel, R.; Choudhury, A.; Walawalkar, M. G.; Pothiraja, R.; Rao,
C. N. R. Chem. ReV. 2008, 108, 3549.
10.1021/ic801532y CCC: $40.75  2009 American Chemical Society
Inorganic Chemistry, Vol. 48, No. 1, 2009 183
Published on Web 12/02/2008

Murugavel et al.
molecular magnets.6–8 Although phosphoric acid forms
extended (often framework) structures because of the pres-
ence of three acidic protons, derivatization of one or two
hydroxyl groups of the phosphoric acid by ester formation
((OR)P(O)(OH)2 and (OR)2P(O)(OH)) normally results in
the formation of metal complexes that are discrete molecules
or clusters.9 The diesters of phosphoric acid, (RO)2P(O)(OH),
are similar to carboxylic acids in some ways and, hence,
normally form either mononuclear or dinuclear metal phos-
phates more readily than larger clusters.10,11 However,
phosphate diesters do not exhibit a chelating mode of
coordination, which is very common among metal carboxy-
lates. Although bridging two adjacent metal ions is the most
preferred mode of coordination for the phosphate diesters,
there are a number of complexes where these molecules are
monodentate through the P-O- group, with dangling PdO
groups. Phosphate monoesters, on the other hand, due to the
presence of two acidic protons and one phosphoryl oxygen,
tend to embrace more metal ions around them and form
larger aggregates.9,10 Hence, the secondary building units
(SBUs) of several zeolitic structures can be modeled using
these monophosphate esters, as it has been demonstrated in
the past decade for the case of phosphonic acids.12
Among copper-containing phosphonates and phosphates,
layered copper phosphonates [Cu(RPO3)(OH2)]n have been
known for a long time.13 Discrete molecular compounds of
copper phosphonates, on the other hand, have been well-
investigated in recent years, producing a large number of
medium- to large-sized aggregates.14 In contrary, the majority
of the work carried out on copper phosphates has revolved
around the synthesis of dinuclear copper complexes with the
aim to synthesize functional models for phosphate diester
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to mimic the active sites of hydrolases.
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184 Inorganic Chemistry, Vol. 48, No. 1, 2009

Copper(II) Mono-organophosphates
Scheme 1. Synthesis of Tetranuclear and Hexanuclear Copper Phosphates 1 and 2
serves as a single-source precursor for the preparation of
ceramic [Cu(PO3)2] at low temperatures. The monomeric
Cu-dtbp complex, [Cu(dtbp)2(phen)(OH2)], prepared in the
presence of chelating phen (1,10-phenanthroline) ligand, has
thrown important mechanistic insights into phosphate diester
hydrolysis assisted by H-bonding.2 An interesting conversion
of a water-bridged, one-dimensional polymer to a tetrameric
cage phosphate was also unraveled during this study through
thesynthesisandstructuralcharacterizationof[Cu(dtbp)2(py)2(µ-
OH2)]n and [Cu4(µ-OH)2(dtbp)6].10c Inspired by the structural
diversity shown by copper di-tert-butyl phosphate complexes
and the fact that mono-organophosphate esters are better
ligands for assembling polynuclear metal phosphate cage
complexes,9 we have now investigated the reactions of
CuII-precursor complexes with two different mono-orga-
nophosphates in the presence of a variety of N-donor ligands.
have been used. Cu(OAc)2 · 2H2O and dimeric precursor
[Cu2(bpy)2(OAc)(OH)(H2O)] · 2ClO4 have been used as the
source of copper ions. To avoid the formation of insoluble,
extended polymeric structures, monodentate N-donor ligands
(substituted pyrazoles) and chelating N-donor ligands, 1,10-
phenanthroline and 2,2′-bipyridine, have been used as the
auxiliary ligands to block one or more coordination sites on
the metal.
Synthesis of Copper Phosphate with Pyrazole Li-
gands. The reaction of dmppH2 with copper acetate in the
presence of a pyrazole coligand is highly sensitive
to the substituents on the 3,5-positions of the pyrazole ring.
The reaction in the presence of bulkier 3,5-di-tert-butyl
pyrazole (dbpz) proceeds smoothly to yield the tetrameric
copper phosphate [Cu(dmpp)(dbpz)]4 1 as the only product
(Scheme 1). On the other hand, the use of less bulky 3,5-
dimethylpyrazole (dmpz) leads to the exclusive formation
of the novel hexanuclear copper phosphate [Cu6(PO4)-
(dmpp)3(OAc)3(dmpz)9] 2. Despite the fact that the syntheses
of both 1 and 2 have been carried out under almost identical
reaction conditions (in methanol at room temperature under
aerobic conditions), the products isolated in the two reactions
are quite different. Whereas in the case of 1 a 1:1:1
M/phosphate/pyrazole complex is formed, an interesting
phosphate monoester hydrolysis is observed to produce
hexanuclear complex 2. Although the formation of a
monomer was not anticipated in either case due to the ability
of the phosphate ligand to embrace more metal centers, the
selectivity of hexanuclear and tetranuclear structures for the
two pyrazole ligands used is somewhat puzzling. It could,
however, be argued that, although the presence of less bulky
Results and Discussion
To synthesize the new copper phosphates, two monoaryl
esters of phosphoric acid, viz. 2,6-dimethylphenyl phosphate
(dmppH2) and 2,6-diisopropylphenyl phosphate (dippH2),
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2003, 42, 5637. (b) Butcher, R. J.; Gultneh, Y.; Allwar, Acta
Crystallogr. 2005, E61, m818. (c) Itoh, T.; Hisada, H.; Usui, Y.; Fujii,
Y. Inorg. Chim. Acta 1998, 283, 51. (d) Itoh, M.; Nakazawa, J.; Maeda,
K.; Kano, K.; Mizutani, T.; Kodera, M. Inorg. Chem. 2005, 44, 691.
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V. M.; Ren, T. Inorg. Chem. 2006, 45, 7973. (f) Selmeczi, K.; Giorgi,
M.; Speier, G.; Farkas, E.; Reglier, M. Eur. J. Inorg. Chem. 2006,
1022. (g) Zeng, G.; Guo, X.; Wang, C.; Lin, Y.; Li, H. Wuli Huaxue
Xuebao 1992, 8, 778. (h) Rafizadeh, M.; Tayebee, R.; Amani, V.;
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Inorganic Chemistry, Vol. 48, No. 1, 2009 185

Murugavel et al.
substituents on the pyrazole ligand (dmpz) can result in
accommodating more than one pyrazole ligand per metal as
in 2, there is very little room around the metal ion to
accommodate more than one bulky dbpz ligand. To over-
come this coordinative unsaturation, the PdO group on dmpp
acts as a bridge between the dimeric eight-membered rings,
and, hence, a tetrameric aggregate is formed in the case of
1. An additional difference between the formation of 1 and
2 is the Cu2+ ion-promoted hydrolysis of dmppH2 to produce
3-
PO4 anion during the synthesis.
Compounds 1 and 2 have been characterized by the aid
of elemental analysis; IR, UV-visible, and EPR spectros-
copy; room temperature magnetic measurements; thermal
analysis; and single-crystal X-ray diffraction studies. The
single crystals obtained for 1 and 2 were found to be
analytically pure. The infrared spectra of both 1 and 2 are
devoid of any absorption in the region of 2300 cm-1,
indicating the complete deprotonation (neutralization) of
dmppH2 during the reaction, leaving no P-OH groups in
the product. The UV-visible spectrum of the hexanuclear
2 shows a weak absorption at 742 nm (ꢀ ) 67
L · mol-1 · cm-1) due to the spin-forbidden d-d transitions,
whereas the absorptions at 214 and 254 nm are assignable
to ligand-based transitions.
Molecular Structure of 1. The central core of this
tetrameric copper phosphate is made up of a Cu4O12P4 unit
that is somewhat similar to a number of metal phosphonates
with a M4O12P4 cubane core and metallosiloxanes with a
M4O12Si4 core (Figure 1).5b,9b,14a Compounds with this core
have assumed particular importance due to their resemblance
to the commonly observed D4R (double-four-ring) SBU of
zeolites and other framework solids. Among the molecular
metal phosphates, so far only zinc9b has been incorporated
in the D4R core; hence, 1 represents the first metal phosphate
cubane cluster involving a nontetrahedral metal in the
alternate vertices of the cubane cluster.14d
Figure 1. Molecular structure of 1 (lattice 1,4-dioxane molecules, phenoxide
groups on phosphorus atoms, and hydrogen atoms have been omitted for
clarity). Selected bond distances [Å]: Cu(1)-N(1) 1.970(3), Cu(1)-O(1)
1.919(3), Cu(1)-O(3) 1.930(3), Cu(1)-O(5) 1.978(3), Cu(2)-N(3) 1.984(3),
Cu(2)-O(2) 1.980(3), Cu(2)-O(6) 1.919(3), Cu(2)-O(7) 1.923(3), P(1)-O(1)
1.516(3), P(1)-O(2) 1.533(3), P(1)-O(3)#1 1.518(3), P(1)-O(4) 1.609(3),
P(2)-O(5) 1.545(3), P(2)-O(6) 1.514(3), P(2)-O(7)#1 1.515(3), P(2)-O(8)
1.600(3). Bond angles [°]: N(1)-Cu(1)-O(5) 91.4(1), O(1)-Cu(1)-N(1)
162.2(1), O(1)-Cu(1)-O(3) 96.0(1), O(1)-Cu(1)-O(5) 88.5(1), O(3)-
Cu(1)-N(1) 91.9(1), O(3)-Cu(1)-O(5) 153.6(1), O(2)-Cu(2)-N(3)
95.8(1), O(6)-Cu(2)-N(3) 90.8(1), O(6)-Cu(2)-O(2) 155.1(1), O(6)-
Cu(2)-O(7) 94.2(1), O(7)-Cu(2)-N(3) 161.6(1), O(7)-Cu(2)-O(2)
87.2(1), P(1)-O(1)-Cu(1) 145.3(2), P(1)-O(2)-Cu(2) 108.4(2), P(1)#1-
O(3)-Cu(1) 125.0(2), P(2)-O(5)-Cu(1) 109.8(2), P(2)-O(6)-Cu(2)
126.3(2), P(2)#1-O(7)-Cu(2) 143.9(2). Symmetry transformations used
to generate equivalent atoms: #1 -x + 1, -y + 1, z. Hydrogen bond
parameters: N2 · · ·O2 ) 2.873(4) Å, H2W · · ·O2 ) 2.030(3) Å, N2-H2W
) 0.890(3) Å, N2-H2W· · ·O2 ) 157.6(2)°; N4· · ·O5 ) 2.792(4) Å,
H4W· · ·O5 ) 1.970(3) Å, N4-H4W ) 0.865(3) Å, N4-H4W· · ·O5 )
158.1(2)°. Equivalent positions: (a) -x + 1, -y + 1, +z; (b) x, y, z.
The coordination geometry of copper ions in 1 can be best
described as distorted square-planar. Because of the presence
of four tetrahedral phosphorus centers and four square-planar
copper centers in the eight vertices of the cluster, the D4R
unit in 1 is distorted to a large extent (as compared to such
units in octasilsequioxanes (RSi)8O12 or borophosphonate
[RPO3BR′]4, where the corners are occupied by tetrahedral
main group elements such as B, Si, and P).4c,5b,18 The
irregularity of the cubic structure of 1 could be easily
understood by viewing the core structure down a-, b-, and
c-axes, as shown in Figure 2. For comparison, the core
structure of [(RO)PO3Zn · collidine]4 A,9b which is made up
of a regular cubic core, is also shown in Figure 2.
(average 139.9(2)°), very acute to wide-open Cu-O-P
angles are found in 1 (108.4(2)-145.3(2)°). These variations
explain the asymmetrical nature of the cubane core in 1
(Figure 2). Despite these distortions, the angles around both
Cu1 and Cu2 indicate a near square-planar geometry around
the metal ions. Similarly, the angles at phosphorus suggest
a slightly distorted tetrahedral geometry. The Cu-N (pyra-
zole) distances are considerably shorter (1.970(3) and
1.984(3) Å) than the Zn-N (collidine) distances in A
(2.087(4) Å). Finally, although the square-planar geometry
around Cull ions in 1 could be attributed to the asymmetric
nature of the cubane, an additional obvious reason for this
distortion appears to be the intramolecular hydrogen bonding
involving exocubane dbpz N-H protons and the cubane
oxygen atoms, which draws the O2 and O5 oxygen atoms
out of the ideal cubane geometry, resulting in enormously
decreased Cu-O-P angles around these two atoms. The
only example of a tetranuclear D4R cluster with a distorted
cubane structure similar to 1 has been recently reported for
[Cu(tBuPO3)(dbpz)]4 by Chandrasekhar and co-workers.14d
It is of interest to compare a few key structural parameters
in 1 to those of A.9b Whereas all three Zn-O(P) distances
around each zinc ion in A are almost equal, two types of
Cu-O(P) distances are found in 1 (Figure 1). Similarly,
whereas all the Zn-O-P angles within A are similar
(18) (a) Bassindale, A. R.; Pourny, M.; Taylor, P. G.; Hursthouse, M. B.;
Light, M. E. Angew. Chem., Int. Ed. 2003, 42, 3488. (b) Bassindale,
A. R.; Liu, Z.; MacKinnon, I. A.; Taylor, P. G.; Yang, Y.; Light,
M. E.; Horton, P. N.; Hursthouse, M. B. Dalton Trans. 2003, 2945.
186 Inorganic Chemistry, Vol. 48, No. 1, 2009

Copper(II) Mono-organophosphates
Figure 2. Comparison between the M4O12P4 core 1 (above) and [(RO)PO3Zn·collidine]4 A9b (below), viewed along a- (left), b- (middle), and c- (right)
axes.
Molecular Structure of [Cu6(PO4)(dmpp)3(OAc)3-
(dmpz)9] (2). As described above, the change of the auxiliary
ligand to less bulky 3,5-dimethyl pyrazole in the reaction
between Cu(OAc)2 · H2O and dmppH2 leads to the isolation
of the hexanuclear copper phosphate 2. The single crystals
of 2 were found to be unsuitable for single-crystal X-ray
diffraction experiments due to persistent twinning problems.
The skeletal molecular structure of the compound, however,
could be derived from poor diffraction data obtained from
one such crystal (Figure 3).19 Due to the poor quality of the
structure, a detailed description of the metric parameters is
not warranted at the present time. Apart from the fact that
compound 2 is a hexanuclear complex with an unprecedented
cluster architecture in metal phosph(on)ate chemistry, it
3-
boasts a PO4 ligand that has been produced in the course
of the reaction. Whereas the hydrolysis of activated esters
of phosphoric acid (e.g., bis(nitrophenyl)phosphate) by Cu(II)
or other transition-metal ions is fairly well-established under
favorable conditions,20 it is interesting to note that an
unactivated phosphate monoester (bearing a bulky aryl group)
has undergone facile hydrolysis to produce phosphoric acid.
This PO4 anion acts a template for the formation of the
Figure 3. The core structure of 2.
3-
hexanuclear complex by coordinating to all six metal ions
in a [6.2220] mode of coordination (Harris notation).21 In
(19) The twinning in the crystal could not be modeled.
(20) (a) Rossi, L. M.; Neves, A.; Bortoluzzi, A. J.; Hoerner, R.; Szpoganicz,
other words, each of the O- of the phosphate ion acts as a
bridging ligand to hold two copper ions while the phosphoryl
group (PdO) remains uncoordinated. Apart from the central
B.; Terenzi, H.; Mangrich, A. S.; Pereira-Maia, E.; Castellano, E. E.;
Haase, W. Inorg. Chim. Acta 2005, 358, 1807. (b) Jurek, P. E.; Martell,
A. E. Inorg. Chem. 1999, 38, 6003. (c) Young, M. J.; Wahnon, D.;
Hynes, R. C.; Chin, J. J. Am. Chem. Soc. 1995, 117, 9441. (d) Wall,
M.; Hynes, R. C.; Chin, J. Angew. Chem., Int. Ed. Engl. 1993, 32,
1633. (e) Maldonado Calvo, J. A.; Vahrenkamp, H. Inorg. Chim. Acta
2006, 359, 4079.
(21) Coxall, R. A.; Harris, S. G.; Henderson, D. K.; Parsons, S.; Tasker,
P. A.; Winpenny, R. E. P. J. Chem. Soc., Dalton Trans. 2000, 2349.
Inorganic Chemistry, Vol. 48, No. 1, 2009 187

Murugavel et al.
3-
PO4 ligand, there are three dmpp (ROPO32-) ligands that
hold the complex together. Each of these dmpp ligands
bridges three copper ions in a [3.111] fashion. Each of the
three acetate ligands in the molecule bridges two copper ions.
The coordinative unsaturation at the metal ions is overcome
by the complexation of auxiliary pyrazole ligands. In the
final structure, the copper ions attain a pentacoordination,
although they fall distinctly into two different types. In the
first type, the copper ions are surrounded by two dmpp
oxygen centers, one PO43- oxygen, one acetate oxygen, and
a dmpz ligand. In the second set, the three Cu2+ ions are
3-
surrounded by one dmpp oxygen, one PO4 oxygen, one
acetate oxygen, and two dmpz ligands.
Synthesis of Pyrazole-Diisopropylphenyl Phos-
phates [(dippH)(dbpz)(dbpzH)] (3) and [(dippH)(dmpz)-
(dmpzH)] (4). Following the synthesis of compounds 1 and
2 and the demonstration of the role played by auxiliary
pyrazole (dbpz or dmpz) ligands in determining the nuclearity
of the complex produced, the role played by the phosphate
ligand has been evaluated by changing the substituent on
phosphorus to a bulkier diisopropylphenyl group. Thus, the
reactions leading to compounds 1 and 2 were repeated with
dippH2. Because of the more bulky dipp group, there was
no reaction between Cu(OAc)2 · H2O and dippH2, and only
acid-base complexes [(dippH)(dbpz)(dbpzH)] 3 and [(dip-
pH)(dmpz)(dmpzH)] 4 were obtained (see Supporting In-
formation for details).
Figure 4. Molecular structure of 5 (lattice methanol molecules and
hydrogen atoms have been omitted for clarity). Selected bond distances
[Å]: Cu(1)-N(1) 2.012(2), Cu(1)-N(2) 2.012(2), Cu(1)-O(1) 1.913(2),
Cu(1)-O(3) 1.918(2), Cu(1)-O(5) 2.383(2), P(1)-O(1) 1.514(2), P(1)-O(2)
1.505(2), P(1)-O(3) 1.516(2), P(1)-O(4) 1.635(2). Bond angles [°]:
N(1)-Cu(1)-N(2) 81.42(8), N(1)-Cu(1)-O(5) 103.65(7), N(2)-Cu(1)-O(5)
87.38(7), O(1)-Cu(1)-N(1) 158.85(8), O(1)-Cu(1)-N(2) 91.01(8),
O(1)-Cu(1)-O(3) 98.40(7), O(1)-Cu(1)-O(5) 95.65(8), O(3)-Cu(1)-N(1)
89.38(7), O(3)-Cu(1)-N(2) 170.53(8), O(3)-Cu(1)-O(5) 92.68(7),
P(1)-O(1)-Cu(1) 131.1(1), P(1)#1-O(3)-Cu(1) 133.1(1).
Scheme 2. Synthesis of 5-8
Synthesis of Dimeric Copper Phosphates [Cu(phen)-
(dmpp)(CH3OH)]2 · 2CH3OH (5) and [Cu(phen)(dipp)-
(CH3OH)]2 · 2CH3OH (6). After evaluating the role of
monodentate pyridinic ligands (dmpz and dbpz) in copper
phosphate chemistry, the use of a bidentate ligand such as
1,10-phenanthroline has been investigated. It is well-known
that, in the reactions of polydentate ligands with metal ions,
the nuclearity of the complex can be considerably reduced
by the use of chelating ligands such as 2,2′-bipyridine and
1,10-phenanthroline, which occupy two cis-coordination sites
on the metal ion and, thus, impede the aggregation of metal
ions. Thus, the reaction of copper acetate with both dmppH2
and dippH2 in the presence of phen in methanol at
room temperature yields dinuclear copper phosphates
[Cu(phen)(dmpp)(CH3OH)]2 · 2CH3OH 5 and [Cu(phen)-
(dipp)(CH3OH)]2 · 2CH3OH 6 in good yield. Compounds 5
and 6 (Scheme 2) yielded satisfactory analytical data. The
absence of any absorption in the IR spectra of both
compounds in the range 2350-2400 cm-1 is indicative of
the fact that there are no unreacted P-OH groups left on
the phosphate ligands.
The UV-vis spectrum of 5 recorded in methanol shows
absorptions at 214, 271, and 673 nm. Whereas the strong
absorptions at 214 and 271 nm are ligand-centered transi-
tions, the very weak absorption at 673 nm (ꢀ ) 92
L · mol-1 · cm-1) is due to the d-d transition of d9 Cu2+ ion.
A similar spectral pattern with absorption maxima at 262,
304, 351, and 639 nm was observed in the solid-state diffuse
reflectance UV spectrum of 5. The EPR spectra of poly-
crystalline samples of 5 and 6 yield a gav value of 2.08 and
2.07 at room temperature, respectively.
Molecular Structure of [Cu(phen)(dmpp)(CH3OH)]2 ·
2CH3OH (5). Compound 5 is a dimeric copper phosphate
where each copper ion is bound to two bridging phosphate
oxygen atoms, one chelating phen ligand, and a solvent
methanol molecule (Figure 4). Whereas the central unit 1 is
a distorted cubane resembling D4R building units of zeolites,
the nonplanar eight-membered ring in compound 5 resembles
the S4R (single-four-ring) SBU of zeolites. Thus, the
syntheses of both 1 and 5 demonstrate that either a D4R or
S4R building block can be obtained by choosing either a
monodentate ligand of appropriate size or a chelating
bidentate ligand, respectively.
188 Inorganic Chemistry, Vol. 48, No. 1, 2009

Copper(II) Mono-organophosphates
Figure 6. Molecular structure (cationic part) of 8 (lattice methanol and
perchlorate ions and hydrogen atoms have been omitted for clarity). Selected
bond distances [Å]: Cu(1)-N(1) 2.006(3), Cu(1)-N(2) 2.022(3), Cu(1)-O(1)
1.930(2), Cu(1)-O(5) 1.922(2), Cu(1)-O(9) 2.230(2), Cu(2)-N(3) 2.020(3),
Cu(2)-N(4) 2.006(3), Cu(2)-O(2) 1.920(2), Cu(2)-O(6) 1.957(2),
Cu(2)-O(10) 2.264(2), Cu(3)-O(3) 1.935(2), Cu(3)-O(7) 1.913(2),
Cu(3)-O(11) 2.364(3), Cu(3) · · ·O(12) 2.845(2). Bond angles [°]: N(1)-
Cu(1)-N(2) 80.0(1), N(1)-Cu(1)-O(9) 91.3(1), N(2)-Cu(1)-O(9) 97.4(1),
O(1)-Cu(1)-N(1) 92.1(1), O(1)-Cu(1)-N(2) 162.9(1), O(1)-Cu(1)-O(9)
97.90(9),O(5)-Cu(1)-N(1)168.8(1),O(5)-Cu(1)-N(2)89.8(1),O(5)-Cu(1)-O(1)
96.57(9), O(5)-Cu(1)-O(9) 94.47(9), N(3)-Cu(2)-O(10) 104.4(1),
N(4)-Cu(2)-N(3) 79.8(1), N(4)-Cu(2)-O(10) 88.9(1), O(2)-Cu(2)-N(3)
93.3(1), O(2)-Cu(2)-N(4) 172.9(1), O(2)-Cu(2)-O(6) 92.46(9), O(2)-
Cu(2)-O(10) 94.36(9), O(6)-Cu(2)-N(3) 161.1(1), O(6)-Cu(2)-N(4)
93.7(1), O(6)-Cu(2)-O(10) 93.06(9), N(5)-Cu(3)-N(6) 80.5(1), N(5)-
Cu(3)-O(11) 88.3(1), N(6)-Cu(3)-O(11) 96.0(1), O(3)-Cu(3)-N(5)
91.5(1), O(3)-Cu(3)-N(6) 166.4(1), O(3)-Cu(3)-O(11) 94.7(1), O(7)-
Cu(3)-N(5) 170.6(1), O(7)-Cu(3)-N(6) 90.3(1), O(7)-Cu(3)-O(3)
97.26(9), O(7)-Cu(3)-O(11) 94.36(9), P(1)-O(1)-Cu(1) 129.2(1),
P(1)-O(2)-Cu(2) 127.0(1), P(1)-O(3)-Cu(3) 158.0(2) P(2)-O(5)-Cu(1)
150.5(2), P(2)-O(6)-Cu(2) 119.5(1), P(2)-O(7)-Cu(3) 132.3(1).
Figure 5. Molecular structure of 6 (lattice methanol molecules and
hydrogen atoms have been omitted for clarity). Selected bond distances
[Å]: Cu(1)-N(1) 2.024(2), Cu(1)-N(2) 2.028(2), Cu(1)-O(1) 1.924(2),
Cu(1)-O(3)#1 1.921(2), Cu(1)-O(5) 2.409(2), P(1)-O(1) 1.520(2),
P(1)-O(2) 1.506(2), P(1)-O(3) 1.516(2), P(1)-O(4) 1.636(2). Bond angles
[°]: N(1)-Cu(1)-N(2) 81.35(8), O(1)-Cu(1)-N(1) 168.89(8), O(3)#1-
Cu(1)-N(1) 90.09(7), N(1)-Cu(1)-O(5) 96.01(7), O(3)#1-Cu(1)-O(1)
98.65(6), O(3)#1-Cu(1)-N(2) 171.16(7), O(1)-Cu(1)-N(2) 89.60(7),
O(3)#1-Cu(1)-O(5) 92.22(6), O(1)-Cu(1)-O(5) 90.54(6), N(2)-
Cu(1)-O(5) 90.87(7), P(1)-O(1)-Cu(1) 130.35(9), P(1)-O(3)-Cu(1)#1
135.40(10).
In the molecular structure of 5, because of the presence
of a bidentate phen ligand occupying two of the coordination
sites around the metal, the phosphoryl oxygen PdO (O2)
remains uncoordinated, and, hence, the ligand exhibits a
[2.110] mode of coordination. The five-coordinated copper
centers adopt square-pyramidal geometry, in which the
equatorial plane is occupied by the two nitrogen atoms of
phen (Cu-N ) 2.012(2) Å) and two phosphate oxygen
atoms (Cu-O distances 1.913(2) and 1.918(2) Å), while the
axial position is occupied by a coordinated methanol
molecule (Cu-O distance 2.383(2) Å). The metric param-
eters are comparable with those of known copper phosphate
compounds. The separation between the metal centers is
4.977 Å, whereas the corresponding P · · · P distance is 3.828
Å. The observed average Cu · · · P distance within the eight-
membered ring (3.140 Å) is slightly longer than that observed
in the eight-membered rings of 1 (3.073 Å). The lattice
methanol molecules play a vital role in intermolecular
interactions through extensive hydrogen-bonding interactions
(see Supporting Information).
Synthesis and Characterization of [Cu3(bpy)3(dm-
pp)2(CH3OH)3] · 2ClO4 · 2CH3OH (7) and [Cu3(bpy)3-
(dipp)2(CH3OH)3] · 2ClO4 · 2CH3OH (8). After varying the
substituents on phosphate esters and pyrazole ligands and
also after studying the role of monodentate versus bidentate
N-donor auxiliary ligand in the synthesis of molecular copper
phosphates, the possibility of synthesizing complexes of other
nuclearity has been investigated by changing the copper(II)
ion source. The precursor complex [Cu2(bpy)2(OAc)-
(H2O)] ·2ClO4 that already incorporates a chelating N-donor
bidentate ligand has been chosen as the starting material.
Stirring a methanol solution of this precursor complex and
dmppH2/dippH2 at room temperature, followed by slow
evaporation of the solvent, leads to the isolation of trinuclear
copper complexes [Cu3(bpy)3(dmpp)2(CH3OH)3] · 2ClO4 ·
2CH3OH 7 and [Cu3(bpy)3(dipp)2(CH3OH)3] · 2ClO4 · 2CH3-
OH 8, respectively. The crystalline products obtained were
found to be analytically pure. The IR spectra of both 7 and
-
Molecular Structure of [Cu(phen)(dipp)(CH3OH)]2 ·
2CH3OH (6). Compound 6 is isostructural to 5, although
they do not belong to the same space group (Figure 5). Since
the overall structure, ring conformation, and the bond
distances and angles of 6 are similar to those of 5, a detailed
description of the structure of 6 is not presented here. The
separation between metal centers in 6 is 5.006 Å, whereas
the corresponding P · · · P distance is 3.848 Å. The average
distance between Cu · · · P is 3.157 Å. The intermolecular
hydrogen-bonding interactions involved in 6 are described
in the Supporting Information.
8 contain strong absorptions due to both M-O-P and ClO4
moieties in the region of 1000-1100 cm-1. The UV-vis
spectrum of 7 in methanol exhibits three strong absorptions
in the UV region (211, 244, and 302 nm) due to the ligand-
centered transitions. The broad, weak absorption appearing
at 672 nm (ꢀ ) 80 L · mol-1 · cm-1) is due to the spin-
forbidden d-d transition of the d9 Cu2+ ion. Compound 8
also displays similar absorption spectral characteristics. The
EPR spectra of both compounds recorded for polycrystalline
samples at 298 and 77 K yield a gav value of 2.08 and 2.09,
respectively.
Inorganic Chemistry, Vol. 48, No. 1, 2009 189

Murugavel et al.
Figure 7. Molecular siloxanes and phosphates exhibiting 4)1 SBU of zeolites.
This SBU is essentially made up of a S4R A2O4B2 SBU that
has been capped by another AO2 or BO2 fragment. The five-
coordinated (Cu(1)) copper centers in the molecule adopt a
square-pyramidal geometry. The equatorial coordination sites
are occupied by two nitrogen atoms of bpy (Cu-N )
2.006(3) and 2.022(3) Å) and two oxygen atoms of the
phosphate ligand (Cu-O ) 1.922(2) and 1.930(2) Å).
Oxygen of a coordinated methanol molecule (Cu-O )
2.230(2) Å) fills up the fifth axial site on each Cu2+ ion.
Interestingly, around the Cu(3) ion, a second methanol shows
a very weak interaction to the metal (Cu(3)-O12 ) 2.845(2)
Å) diagonally opposite to the other methanol oxygen (O(11))
that is firmly bound to the metal.
Conclusion
It has been shown in this contribution that a number of
structurally diverse oligomeric copper arylphosphate com-
plexes, whose core resembles the secondary building units
of zeolites, can be synthesized by varying (a) the aryl
substituent on the phosphate ester, (b) the ancillary ligand,
(c) the organic substituents on the auxiliary ligands, and (d)
the source of the metal ion. The change of substituent on
the auxiliary pyrazole ligand from tert-butyl to methyl group
changes the nuclearity of the cluster from four to six
(complexes 1 and 2), whereas the change of substituent from
dmpp to dipp leads to large differences in the reactivity and
the isolation of only organic acid-base phosphate complexes
(3 and 4). Changing monodentate to chelating bidentate 1,10-
phenanthroline results in the blocking of coordination sites
on the metal, which impedes the oligomeric growth and leads
to the eventual isolation of the dimeric phosphates 5 and 6.
Use of a precursor complex in place of simple copper acetate
resulted in the isolation of trinuclear complexes 7 and 8. The
dimeric, tetrameric, and trimeric copper phosphates reported
in this study serve as useful, suitable model compounds for
the S4R, D4R, and 4)1 SBUs of zeolites, respectively, that
incorporate transition metals. The presence of square-planar
copper corners in complex 1 reveals the extent of distortion
a D4R cubane would undergo when tetrahedral atoms are
substituted with metal ions in other coordination environ-
ments. Isolation of the hexanuclear copper phosphate 2
unravels a new structural form for copper clusters and is
also significant in terms of the hydrolysis of an unactivated
phosphate ester during its formation. Clearly, there is further
scope for the isolation of newer structural types of copper
phosphates through attendant changes in the phosphate ligand
and by changing the auxiliary N-donor ligand. We are
currently investigating these possibilities.
Figure 8. Denticity and Harris notation21 of ligands in complexes 1, 2,
and 5-8.
Molecular Structure of [Cu3(bpy)3(dipp)2(CH3OH)3] ·
2ClO4 · 2CH3OH (8). The molecular structure of 8 consists
of a trimeric core of [Cu3(bpy)3(dipp)2(CH3OH)3]2+ cationic
-
part, uncoordinated ClO4 anions, and lattice methanol
molecules (Figure 6). The three copper ions in the cationic
part of complex 8 are held together by the two dipp ligands,
each of which acts as a triply bridging ligand, displaying a
[3.111] mode of Harris notation (Figure 8). The Cu3O6P2
core is similar to bicyclic, eight-membered-ring systems that
have been recently unravelled in tin(IV) siloxane and main
group metal (Al and Zn) phosphate chemistries (Figure
7).9c,22,23 The most interesting aspect of this arrangement is
that the structural unit has been identified as an important
secondary building unit of zeolites, namely 4)1, which has
been found in zeolites such as thomsonite and edingtonite.24
(22) Voigt, A.; Murugavel, R.; Roesky, H. W. Organometallics 1996, 15,
5101.
(23) Lin, Z.-E.; Yao, Y.-W.; Zhang, J.; Yang, G.-Y. Dalton Trans. 2003,
3160.
(24) Baerlocher, Ch.; Meier, W. M.; Olson, D. H. Atlas of Zeolite
Framework Types, 5th ed.; Elsevier: Amsterdam, 2001.
190 Inorganic Chemistry, Vol. 48, No. 1, 2009

Copper(II) Mono-organophosphates
obtained from the reaction mixture after 3 to 4 days. Mp: 205-210
°C. Yield: 350 mg (66%, based on dmppH2). Anal. Calcd for
C75H108N18O22Cu6P4 (Mr ) 2118.97): C, 42.51; H, 5.14; N, 11.90.
Found: C, 42.28; H, 5.24; N, 11.50. IR (KBr, cm-1): 3434(br),
3196(w), 3136(w), 3032(w), 2928(w), 2868(w), 1580(s), 1474(m),
1423(m), 1380(w), 1314(m), 1266(w), 1198(m), 1146(s), 1092(vs),
1042(m), 986(vs), 901(s), 778(s). UV-vis (CH3OH, nm): 214 (ꢀ
) 19 795 L ·mol-1 ·cm-1), 254 (ꢀ ) 5039 L ·mol-1 ·cm-1), 742 (ꢀ
) 67 L ·mol-1 ·cm-1). DRUV-vis (nm): 217, 354, 612. EPR
(polycrystalline sample): gav ) 2.052 (RT), 2.054 (LNT). ꢀMTobs
(cm3 ·K·M-1) ) 2.60, ꢀMTcalcd (cm3 ·K·M-1) ) 2.25.
Experimental Section
Instruments and Methods. Solvents were purified by employing
conventional procedures and were distilled prior to their use.26
Commercially available starting materials such as 2,2′-bipyridine
(Aldrich), 1,10-phenanthroline (Aldrich), and Cu(OAc)2 ·H2O (Flu-
ka) were used as received. Compounds [Cu2(bpy)2(OAc)(OH)-
(H2O)]·2ClO4,25 3,5-dimethylpyrazole (dmpz),26 3,5-di-tert-bu-
tylpyrazole (dbpz),26 2,6-diisopropylphenyl phosphate (dippH2),27
and 2,6-dimethylphenyl phosphate (dmppH2)27 were synthesized
according to previously described literature methods. Infrared
spectra were obtained on a PerkinElmer Spectrum One FT-IR
spectrometer using KBr diluted discs. The melting points were
measured in glass capillaries and are reported uncorrected. Mi-
croanalyses were performed on a Thermo Finnigan (FLASH EA
1112) microanalyzer. Thermogravimetric analysis was carried out
on a PerkinElmer Pyris thermal analysis system under a stream of
nitrogen gas with the heating rate of 10 °C/min. Magnetic
susceptibility was measured on a PAR vibrating sample magne-
tometer. The EPR measurements were made with a Varian model
109C E-line X-band spectrometer, and the spectra were calibrated
using tetracyanoethylene. UV-vis spectra were obtained on a
Shimadzu UV-260 spectrophotometer, and the fluorescence mea-
surements were carried out on a PerkinElmer LS-55 luminescence
spectrometer. X-ray powder diffraction data were obtained on a
Philips X’Pert Pro X-ray diffraction system using monochromated
Cu KR1 radiation (λ ) 1.5406 Å).
Synthesis of [Cu(dmpp)(dbpz)]4 (1). A solution of 3,5-di-tert-
butyl pyrazole (180 mg, 1 mmol) in methanol (10 mL) was added
to a hot solution of Cu(OAc)2 ·H2O (198 mg, 1 mmol) in MeOH
(30 mL). The resulting mixture was stirred to obtain a clear solution,
and then solid dmppH2 (202 mg, 1 mmol) was added. The reaction
mixture was stirred for 4 h at room temperature, and 1,4-dioxane
(5 mL) was added. The reaction mixture was subsequently filtered,
and the filtrate was kept for crystallization at room temperature.
Blue single crystals of 1 were obtained from this solution after one
week. Mp: 202-204 °C. Yield: 340 mg (77%, based on dmppH2).
Anal. Calcd for C76H116N8O16P4Cu4 (Mr ) 1775.88): C, 51.40; H,
6.58; N, 6.30. Found: C, 51.65; H, 6.99; N, 6.08. IR (KBr, cm-1):
3188(br), 3110(w), 3018(w), 2963(s), 2869(w), 1583(m), 1472(s),
1364(m), 1303(w), 1253(m), 1201(m), 1170(w), 1150(vs), 1122(w),
1055(m), 1033(m), 1003(w), 980(vs), 925(s), 875(w), 778(m).
UV-vis (CH3OH, nm): 211 (ꢀ ) 17632 L ·mol-1 ·cm-1), 252 (ꢀ
) 5141 L ·mol-1 ·cm-1), 766 (ꢀ ) 53 L ·mol-1 ·cm-1). Diffuse
reflectance UV-vis (nm): 210, 261, 355, 770. TGA: temp range
°C (% weight loss): 87-163 (7.1), 163-296 (30.8), 296-480 (25).
DSC (°C): 129 (endo), 221 (endo). EPR (polycrystalline sample):
gav ) 2.134 (RT), 2.196 (LNT). ꢀMTobs (cm3 ·K·M-1) ) 1.16,
ꢀMTcalcd (cm3 ·K·M-1) ) 1.51.
Synthesis of [Cu(phen)(dmpp)(CH3OH)]2 ·2CH3OH (5). [Cu-
(OAc)2 ·H2O] (198 mg, 1 mmol), 1,10-phenanthroline (199 mg, 1
mmol), and dmppH2 (202 mg, 1 mmol) were mixed in methanol
(30 mL) and stirred to obtain a clear solution. The solvent was
subsequently removed under reduced pressure, and the residue was
dissolved in methanol (10 mL). The insoluble components were
filtered, and the filtrate was kept at 5 °C for crystallization. Blue
crystals of 5 were obtained after 7 days. Mp: >275 °C. Yield: 320
mg (63%, based on dmppH2). Anal. Calcd for C44H50N4O12P2Cu2
(Mr ) 1015.94): C, 52.02; H, 4.96; N, 5.52. Found: C, 50.40; H,
4.32; N, 5.90. IR (KBr, cm-1): 3451(br), 3076(m), 3006(m),
2922(m), 2854(w), 1690(m), 1627(w), 1585(m), 1512(m), 1470(m),
1215(s), 1168(vs), 1095(vs), 980(s), 856(s), 781(s), 761(m), 725(s).
UV-vis (CH3OH, nm): 214 (ꢀ ) 17 970 L ·mol-1 ·cm-1), 271 (ꢀ
) 14 003 L ·mol-1 ·cm-1), 673 (ꢀ ) 92 L ·mol-1 ·cm-1). DRUV-vis
(nm): 311, 404, 646. EPR (polycrystalline sample): gav ) 2.08 (RT).
ꢀMTobs (cm3 ·K·M-1) ) 0.96, ꢀMTcalcd (cm3 ·K·M-1) ) 0.75.
Synthesis of [Cu(phen)(dipp)(CH3OH)]2 ·2CH3OH (6). This
compound has been synthesized by essentially following the
procedure used for the preparation of 5. Mp: >275 °C. Yield: 300
mg (53%, based on dippH2). Anal. Calcd for C52H66N4O12P22Cu2
(Mr ) 1128.2): C, 55.36; H, 5.90; N, 4.97. Found: C, 56.70; H,
5.72; N, 3.77. IR (KBr, cm-1): 3436(br), 3063(w), 2966(s), 2929(w),
2867(w), 2382(br), 1630(w), 1589(w), 1519(m), 1441(m), 1330(w),
1291(w), 1211(w), 1201(m), 1175(vs), 1142(w), 1105(w), 1073(s),
978(m), 935(s), 910(vs), 848(w), 769(s). DRUV-vis (nm): 262,
304, 351, 639. EPR (polycrystalline sample): gav ) 2.07 (RT).
ꢀMTobs (cm3 ·K·M-1) ) 0.58, ꢀMTcalcd (cm3 ·K·M-1) ) 0.75.
Synthesis of [Cu3(bpy)3(dmpp)2(CH3OH)3]·2ClO4 ·2CH3-
OH (7). Solid dmppH2 (101 mg, 0.5 mmol) was added to a
methanolic solution (35 mL) of [Cu2(bpy)2(OAc)(OH)(H2O)]·2ClO4
(366 mg, 0.5 mmol) and stirred for 1 h, then filtered. The filtrate
was kept at room temperature. Blue crystals of 7 were obtained
from the reaction mixture after 3 to 4 days. Mp: >275 °C. Yield:
230 mg (65%, based on dmppH2). Anal. Calcd for
C51H62P2O21N6Cl2Cu3 (Mr ) 1418.6): C, 43.18; H, 4.41; N, 5.92.
Found: C, 42.12; H, 3.75; N, 6.27. IR (KBr, cm-1): 3439(br),
3115(w), 3068(w), 2957(w), 2923(w), 1603(s), 1569(w), 1474(s),
1447(s), 1314(m), 1253(w), 1180(s), 1120(w), 1096(vs), 1060(w),
1031(m), 1021(m), 1001(w), 897(s), 768(s). UV-vis (CH3OH, nm):
211 (ꢀ ) 13 612 L ·mol-1 ·cm-1), 244 (ꢀ ) 5232 L ·mol-1 ·cm-1),
302 (ꢀ ) 11 061 L ·mol-1 ·cm-1), 672 (ꢀ ) 80 L ·mol-1 ·cm-1).
DRUV-vis (nm): 215, 360, 605. EPR (polycrystalline sample):
gav ) 2.08 (RT, LNT). ꢀMTobs (cm3 ·K·M-1) ) 1.02, ꢀMTcalcd
(cm3 ·K·M-1) ) 1.12.
Synthesis of [Cu6(PO4)(dmpp)3(OAc)3(dmpz)9] (2). A solution
of 3,5-dimethyl pyrazole (dmpz) (192 mg, 2 mmol) in methanol
(10 mL) was added to Cu(OAc)2 ·H2O (198 mg, 1 mmol) in
methanol (30 mL). Immediately, the solution color changed from
sky blue to dark blue. A solution of dmppH2 (202 mg, 1 mmol) in
methanol (10 mL) was added to the above solution, and the mixture
was stirred for 1 h, filtered, and the clear solution was kept at room
temperature for crystallization. Blue color single crystals of 2 were
Synthesis of [Cu3(bpy)3(dipp)2(CH3OH)3]·2ClO4 ·2CH3OH
(8). This compound has been synthesized by essentially following
the procedure used for the preparation of 7. Mp: >275 °C. Yield:
310 mg (81%, based on dippH2). Anal. Calcd for C59H78-
P2O21N6Cl2Cu3 (Mr ) 1530.8): C, 46.29; H, 5.14; N, 5.49. Found:
C, 44.86; H, 4.55; N, 5.96. IR (KBr, cm-1): 3420(br), 3115(w),
3082(w), 2964(m), 2868(w), 1603(s), 1575(w), 1496(w), 1472(m),
(25) Synthesis of [Cu2(bpy)2(OAc)(OH)(H2O)]·2ClO4: Christou, G.; Per-
lepes, S. P.; Libby, E.; Folting, K.; Huffman, J. C.; Webb, R. J.;
Hendrickson, D. N. Inorg. Chem. 1990, 29, 3657.
(26) Vogel, A. I. Vogel’s Textbook of Practical Organic Chemistry, 5th
ed.; Langman Group: Essex, Harlow, U.K., 1989.
(27) Kosolapoff, G. M.; Arpke, C. K.; Lamb, R. W.; Reich, H. J. Chem.
Soc. C 1968, 7, 815.
Inorganic Chemistry, Vol. 48, No. 1, 2009 191

Murugavel et al.
Table 1. Crystal Data and Structure Refinement Details for Compounds 1, 4, 5, 6, and 8
compound
1
4
5
6
8
identification code
formula
fw
temp [K]
crystal system
space group
a [Å]
mur111
rm166a
C22H35N4O4P
450.51
293(2)
triclinic
newrm137
C46H58Cu2N4O14P2
1079.98
150(2)
monoclinic
C2/c
22.0352(13)
10.5235(6)
22.1141(13)
90
108.522(5)
90
newrm136
C54H74Cu2N4O14P2
1192.19
150(2)
monoclinic
P21/n
12.1723(5)
18.5865(5)
13.3937(6)
90
108.113(4)
90
newrm119
C59H78Cl2Cu3N6O21P2
1530.73
150(2)
monoclinic
P21/n
13.4608(3)
13.8104(4)
35.7174(9)
90
92.906(3)
90
6631.3(3)
4
1.533
C84H132Cu4N8O20P4
1952.02
100(2)
orthorhombic
Aba2
17.8321(21)
26.9021(18)
19.4751(13)
90
P1
9.5984(19)
11.7585(11)
12.3069(10)
68.357(7)
84.115(10)
75.241(10)
1248.4(3)
2
1.198
0.143
0.30 × 0.25 × 0.25
1.78 to 24.97
4674
b [Å]
c [Å]
R [°]
ꢁ [°]
90
90
γ [°]
V [Å3]
9342.6(11)
4
1.388
4862.4(5)
4
1.475
2880.04(19)
2
1.375
Z
Dcalcd [g/cm3]
µ [mm-1
]
1.037
1.010
0.860
1.161
cryst size [mm3]
θ range [°]
0.27 × 0.23 × 0.22
2.74 to 25.00
4236
4236
1.065
0.34 × 0.28 × 0.22
3.11 to 25.00
15873
4285
1.084
0.22 × 0.17 × 0.13
2.93 to 25.00
15618
5045
1.045
0.38 × 0.34 × 0.26
3.03 to 25.00
39764
11643
1.036
no. of reflns collected
no. of obsd reflns (I0 > 2σ(I0)
GOF
4387
1.013
R1(I0 > 2σ(I0)
0.0291
0.0782
-0.542, 1.117
0.0499
0.1397
-0.302, 0.196
0.0321
0.0860
-0.473, 0.526
0.0317
0.0909
-0.262, 0.875
0.0420
0.0894
-0.476, 0.411
wR2 (all data)
largest hole and peak [e ·Å-3
]
1446(s), 1383(w), 1336(w), 1313(w), 1254(m), 1165(s), 1119(vs),
1107(vs), 1059(s), 1031(m), 1021(m), 1000(m), 911(m), 881(w),
suffer from persistent twinning problems. The data obtained with
one such crystal yielded the molecular structure of 2, with a twin
component that could not be resolved or modeled. Hence, only the
gross structural features are described herein. If successful, the fully
refined structure will be reported in a crystallographic journal in
the future. The crystal data for 1, 4-6, and 8 are presented in Table
1.
808(w), 770(s). UV-vis (CH3OH, nm): 302 (ꢀ
) 9973
L·mol-1 ·cm-1), 667 (ꢀ ) 310 L ·mol-1 ·cm-1). DRUV-vis (nm):
216, 262, 317, 635. EPR (polycrystalline sample): gav ) 2.09 (RT,
LNT). ꢀMTobs (cm3 ·K·M-1) ) 1.10, ꢀMTcalcd (cm3 ·K·M-1) ) 1.12.
Single-Crystal X-ray Diffraction Studies. Intensity data were
collected for 1 on a Siemens STOE AED2 four-circle diffractrom-
eter, for 4 on a Bruker AXS, and for 2, 5, 6, and 8 on an Oxford
Xcalibur CCD diffractometer. All calculations were carried out
using the programs in WinGX module.28 The structure was solved
in each case by direct methods (SIR-92).29 The final refinement of
the structure was carried out using full least-squares methods on
F2 using SHELXL-97.30 Several crystals of 2 were examined for
the diffraction experiments. The crystals were, however, found to
Acknowledgment. This work was supported by DST,
New Delhi. M.P.S. thanks UGC, New Delhi, for a research
fellowship. We thank the DST funded National Single
Crystal Diffraction Facility at IIT-Bombay for the diffraction
data, and SAIF, IIT-Bombay, for the spectral data.
Supporting Information Available: Details of X-ray structure
investigations and the details of synthesis, spectral characterization,
solution studies, and crystal structure details of 3 and 4, and packing
diagrams for 5 and 6. This material is available free of charge via
the Internet at http://pubs.acs.org.
(28) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837. WinGX, version
1.64.05.
(29) Altomare, A.; Cascarano, G.; Giacovazzo, C.; Gualardi, A. J. Appl.
Crystallogr. 1993, 26, 343.
(30) Sheldrick, G. M. SHELXL-97, Program for Structure Refinement;
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
IC801532Y
192 Inorganic Chemistry, Vol. 48, No. 1, 2009