Novel Cui ethylene complexes with 6,6′-diphenyl-4, 4′-bipyrimidine three-dimensionally self-assembled by an intermodular π-π stacking interaction and a C. - H...N contact

Article abstract of DOI:10.1002/ejic.200900533

Four novel Cu^IPh₂bpm/C₂H₄ adducts [Cu(Ph₂bpm)(C₂H₄)]X [X = BF₄ (1a, 1b), ClO₄ (2) and. PF₆ (3); Ph₂bpm = 6,6′-diphenyl-4,4′-bipyrlmidi

Full text of DOI:10.1002/ejic.200900533

FULL PAPER
DOI: 10.1002/ejic.200900533
Novel CuI Ethylene Complexes with 6,6Ј-Diphenyl-4,4Ј-bipyrimidine Three-
Dimensionally Self-Assembled by an Intermolecular π-π Stacking Interaction
and a C–H···N Contact
Masahiko Maekawa,*[a] Toshi Tominaga,[b] Takashi Okubo,[b] Takayoshi Kuroda-Sowa,[b]
and Megumu Munakata[b]
Keywords: Copper(I) complexes / Ethylene adducts / N ligands / Nitrogen heterocycles / Polymers / Stacking interactions
Four novel CuI–Ph2bpm/C2H4 adducts [Cu(Ph2bpm)(C2H4)]X
[X = BF4 (1a, 1b), ClO4 (2) and PF6 (3); Ph2bpm = 6,6Ј-di-
phenyl-4,4Ј-bipyrimidine] were prepared and they have
been characterized by X-ray, 1H NMR, IR and TG-DTA
analyses. The molecular structures of CuI–Ph2bpm/C2H4
complexes 1a, 1b, 2 and 3 are essentially similar: the Cu atom
is coordinated by two N atoms in the chelate site of Ph2bpm
and the C=C bond of C2H4 in the trigonal-planar geometry.
Interestingly, their crystal packing structures are much dif-
ferent from the connection manners of an intermolecular π–
π stacking interaction and a C–H···N contact, resulting in the
self-assembly of CuI–C2H4 adducts with a unique three-di-
mensional network structure. The X-ray, 1H NMR, IR data
support the assumption that the contribution of the larger
CuIǞC2H4 π back-donation bonding is induced by the elec-
tron-releasing phenyl group.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
By the way, 4,4Ј-bipyrimidine (bpm) and derivatives
thereof are attractive nitrogen ligands with a bidentate site
for chelation and two exo-N-donor sites for bridging since
they can be thought of as a combination of 2,2Ј- and 4,4Ј-
bipyridine. It is expected to produce both finite metallamac-
rocyclic and infinite polymeric compounds with square/
rectangle motifs. However, only a few preliminary reports
on coordination polymers of CuI,[20,21] AgI [21,22] and
Introduction
Adducts of transition metals with alkenes have attracted
a great amount of attention because of their potential appli-
cations in biochemistry, separation and catalysis, etc. Re-
cently, structurally characterized coinage metal {CuI, AgI,
AuI}–C2H4 adducts were reviewed by Dias et al.[1] They
have described that isolable and thermally stable coinage
metal–C2H4 adducts are still limited and get increasingly
sparse as one descends the group 11 triad towards gold.
Coinage metal–C2H4 adducts with more than one C2H4
molecule at a metal center are rare. In particular, CuI–C2H4
adducts play an important role both in biochemistry and
modern organic chemistry in relation to the copper receptor
site ETR 1 of plant hormone[2] and CuI-based catalytic re-
action.[3] Nevertheless, structurally CuI–C2H4 complexes
are poorly characterized due to the extremely labile nature
of the CuI–C2H4 interaction.[4–19] Most of CuI–C2H4 ad-
ducts are mononuclear complexes supported by bidentate
or tridentate nitrogen ligands such as 2,2Ј-bipyridine and
tris(pyrazolyl)borate.[1] Preparative and structural reports
on polynuclear and polymeric CuI–C2H4 complexes are still
scarce.[7,9,16,18]
RhIII [23] together with mononuclear complexes of NiII,[21]
,
RuII [24–28] and ReI,[29] dinuclear complexes of RuII [30] and
AgI,[31] and trinuclear complex of RuII [32] can be found in
the literature. In this study, we describe the preparation of
new CuI–C2H4 adducts starting from complexes with 6,6Ј-
diphenyl-4,4Ј-bipyrimidine (Ph2bpm) as ligand. Four novel
CuI–Ph2bpm/C2H4 adducts that turned out to be three-di-
mensionally self-assembled by an intermolecular π–π stack-
ing interaction and a C–H···N contact were isolated and
1
characterized by X-ray, H NMR, IR and TG-DTA analy-
ses. There is growing interest in the relevance of weak sup-
ramolecular interactions, such as C–H···O and C–H···N hy-
drogen bonds[33–36] and π–π interactions,[37–40] for molecu-
lar packing and coordination in the context of supramolec-
ular crystal engineering. It was found that these weak inter-
actions can drive the crystallization process and select a
particular molecular structure. However, little is still known
about inorganic coordination complexes in contrast to or-
ganic and organometallic compounds. This study is ex-
pected to contribute to the field of design and architecture
of CuI coordination polymers.
[a] Research Institute for Science and Technology, Kinki Univer-
sity,
3-4-1, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan
Fax: +81-6-6730-5896
E-mail: maekawa@rist.kindai.ac.jp
[b] Department of Chemistry, Kinki University,
Kowakae, Higashi-Osaka, Osaka 577-8502, Japan
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M. Maekawa et al.
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Table 1. Selected bond lengths [Å] and bond angles [°] of CuI–
Ph2bpm/C2H4 complexes 1–3.
Results and Discussion
Crystal Structures of CuI–Ph2bpm/C2H4 Complexes
(a) [Cu(Ph2bpm)(C2H4)]BF4 (1a)
Cu(1)–N(2)
Cu(1)–C(1)
C(1)–C(2)
1.988(2)
2.017(2)
1.382(3)
82.52(8)
Cu(1)–N(4)
Cu(1)–C(2)
1.990(2)
1.990(2)
[Cu(Ph2bpm)(C2H4)]BF4 (1a, 1b)
The reaction of [Cu(MeCN)4]BF4 with Ph2bpm in
MeOH under C2H4 affords two kinds of products, small
amounts of brick-shaped crystals (1a) and predominantly
needle-like crystals (1b). The molecular structures of com-
plexes 1a and 1b are shown in parts (a) and (b) of Figure 1.
The Cu atom is coordinated by two N atoms in the chelate
site of Ph2bpm and the C=C bond of C2H4 in the trigonal-
planar geometry in both complexes. Therefore, two terminal
exo-bridging sites of Ph2bpm are coordinatively unsatu-
rated. In contrast to complex 1a, it is interesting that the
N(2)–Cu(1)–N(4)
N(2)–Cu(1)–C(1)
N(4)–Cu(1)–C(1)
C(1)–Cu(1)–C(2)
Cu(1)–N(2)–C(4)
Cu(1)–N(4)–C(8)
Cu(1)–C(2)–C(1)
123.21(9)
154.02(9)
40.35(10)
114.14(15)
114.18(15)
70.89(14)
N(2)–Cu(1)–C(2) 163.53(8)
N(4)–Cu(1)–C(2) 113.83(9)
Cu(1)–N(2)–C(3) 129.35(17)
Cu(1)–N(4)–C(7) 128.73(17)
Cu(1)–C(1)–C(2)
68.76(14)
(b) [Cu(Ph2bpm)(C2H4)]BF4 (1b)
Cu(1)–N(2)
Cu(1)–C(1)
C(1)–C(2)
1.9945(14) Cu(1)–N(4)
1.9979(18) Cu(1)–C(2)
1.374(2)
82.69(5)
1.9921(14)
2.0148(18)
N(2)–Cu(1)–N(4)
N(2)–Cu(1)–C(1)
N(4)–Cu(1)–C(1)
C(1)–Cu(1)–C(2)
Cu(1)–N(2)–C(4)
Cu(1)–N(4)–C(8)
Cu(1)–C(2)–C(1)
116.65(6)
160.66(7)
40.05(7)
113.63(11)
113.46(11)
69.31(10)
–
BF4 anion lies between two phenyl groups in complex 1b.
N(2)–Cu(1)–C(2) 156.36(7)
N(4)–Cu(1)–C(2) 120.65(7)
Cu(1)–N(2)–C(3) 129.39(12)
Cu(1)–N(4)–C(7) 130.00(11)
The dihedral angles between the planes defined by {C(1),
C(2) and Cu(1)} and {N(2), N(4) and Cu(1)} atoms are
3.40 and 5.09° for complexes 1a and 1b, respectively. The
average Cu–N and Cu–C distances are {1.989(2) and
2.004(2) Å} for 1a and {1.9933(14) and 2.0064(14) Å} for
1b. In the coordinated C2H4, the C=C distances of 1.382(3)
Cu(1)–C(1)–C(2)
70.64(11)
(c) [Cu(Ph2bpm)(C2H4)]ClO4 (2)
Cu(1)–N(2)
Cu(1)–C(1)
C(1)–C(2)
1.996(5)
1.993(6)
1.370(9)
82.4(2)
Cu(1)–N(4)
Cu(1)–C(2)
1.983(5)
1.998(6)
(1a) and 1.374(2) Å (1b) are longer than that [1.313 (exp.)
[41,42]
and 1.333 (calcd.) Å] of metal-free C2H4
and those
N(2)–Cu(1)–N(4)
N(2)–Cu(1)–C(1)
N(4)–Cu(1)–C(1)
C(1)–Cu(1)–C(2)
Cu(1)–N(2)–C(4)
Cu(1)–N(4)–C(8)
Cu(1)–C(2)–C(1)
116.5(2)
161.1(2)
40.1(2)
113.6(4)
114.5(3)
69.7(3)
[1.30(1)–1.366(6) Å] in the reported trigonal-planar CuI–
C2H4 complexes,[5–11,18] indicative of the larger CuIǞC2H4
π back-donation bonding.[1] The selected bond lengths and
bond angles of 1a and 1b are listed in Table 1.
N(2)–Cu(1)–C(2) 156.4(2)
N(4)–Cu(1)–C(2) 121.0(2)
Cu(1)–N(2)–C(3) 129.1(4)
Cu(1)–N(4)–C(7) 129.5(4)
Cu(1)–C(1)–C(2)
70.2(3)
(d) [Cu(Ph2bpm)(C2H4)]PF6 (3)
Cu(1)–N(2)
Cu(1)–C(1)
C(1)–C(2)
1.982(3)
2.006(4)
1.371(7)
82.86(16)
Cu(1)–N(4)
Cu(1)–C(2)
1.989(4)
2.000(4)
N(2)–Cu(1)–N(4)
N(2)–Cu(1)–C(1)
N(4)–Cu(1)–C(1)
C(1)–Cu(1)–C(2)
Cu(1)–N(2)–C(4)
Cu(1)–N(4)–C(8)
Cu(1)–C(2)–C(1)
119.18(18)
157.73(18)
40.0(2)
113.4(3)
113.6(3)
70.3(2)
N(2)–Cu(1)–C(2) 159.15(19)
N(4)–Cu(1)–C(2) 117.99(19)
Cu(1)–N(2)–C(3) 129.6(3)
Cu(1)–N(4)–C(7) 129.8(3)
Cu(1)–C(1)–C(2)
69.7(2)
of an intermolecular π–π stacking interaction and a C–
H···N contact. In complex 1a, each [Cu(Ph2bpm)(C2H4)]+
cation moiety is contacted along the b-axis to form a copla-
nar 1D-chain structure through the C–H···N contact [N(3)···
C(14Ј) 3.522 Å] at the N(3) atom in the terminal exo-bridg-
ing site and the H atom with the C(14Ј) atom in the neigh-
boring phenyl group. Additionally, there are two kinds of
(i) the intermolecular π–π stacking interaction between two
symmetric pyrimidine rings with the N(3) and N(3ЈЈ) atoms
[centroid···centroid distance and interplanar angle between
two rings are 3.597 Å and 0°; nearest C(8)···C(10ЈЈ)
3.317 Å], and (ii) the intermolecular π–π stacking interac-
tion between two symmetric phenyl rings with the C(12)
and C(13ЈЈЈ) atoms [centroid···centroid distance and in-
Figure 1. The molecular structures of [Cu(Ph2bpm)(C2H4)]BF4. (a)
brick-shaped crystals 1a and (b) needle-like crystals of 1b.
The crystal packing structures of 1a and 1b are shown in terplanar angle between two rings are 3.763 Å and 0°; near-
Figures 2 and 3, respectively. Despite their similar molecu- est C(12)···C(13ЈЈЈ) 3.376 Å]. In consequent, the four 1D
lar structures, it is to be noted that their crystal packing CuI–Ph2bpm/C2H4 chains are in parallel multi-layered
structures are much different from the connection manners along the c-axis, through the intermolecular π–π stacking
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Novel Cu(I) Ethylene Complexes
interactions between the pyrimidine ring with the N(3)
On the other hand, the [Cu(Ph2bpm)(C2H4)]+ cation
atom
and
phenyl
ring
with
C(11ЈЈЈЈ)
atom moieties in complex 1b are properly oriented to each other
[centroid···centroid distance and interplanar angle between to adopt the face-to-face configuration. There are two kinds
two rings are 3.651 Å and 1.53°; nearest C(10)···C(11ЈЈЈЈ) of (i) intermolecular π–π stacking interactions between two
3.384 Å and C(8)···C(13ЈЈЈЈ) 3.339 Å]. The intermolecular symmetric pyrimidine rings with the N(1) and N(1Ј) atoms
π–π–π–π stacking interactions in the basic unit of [centroid···centroid distance and interplanar angle between
{pyrimidine ring}–{pyrimidine ring}–{phenyl ring}– two rings are 3.623 Å and 0°; nearest C(4)···C(6Ј) 3.239 Å],
{phenyl ring} are repeated along the c-axis.
and (ii) intermolecular π–π stacking interactions between
two symmetric pyrimidine rings with the N(3) and N(3ЈЈ)
atoms [centroid···centroid distance and interplanar angle
between two rings are 3.557 Å and 0°; nearest C(8)···C(10ЈЈ)
3.271 Å]. The intermolecular π–π–π stacking interactions in
the basic unit of {pyrimidine ring}–{pyrimidine ring}–
{pyrimidine ring} are formed along the a-axis (Figure 3).
Consequently, two columns of multi-stacking CuI–Ph2bpm/
C2H4 molecules are correlated through the C–H···N contact
[N(3)···C(19ЈЈЈ) = 3.268 Å] at the N(3) atom in the terminal
exo-bridging site and the H atom with the C(19ЈЈЈ) atom in
the neighboring phenyl group. The zigzag chain structures
of [Cu(Ph2bpm)(C2H4)]+ cation moiety are constructed
along the b-axis.
[Cu(Ph2bpm)(C2H4)]ClO4 (2)
The molecular structure of complex 2 resembles to that
of complex 1b. The Cu atom is coordinated by two N atoms
in the chelate site of Ph2bpm and the C=C bond of the
C2H4 molecule in the trigonal-planar geometry, with the
dihedral angle of 3.89° between the planes defined by {C(1),
Figure 2. The crystal packing structures of [Cu(Ph2bpm)(C2H4)]-
BF4 (1a). (a) partial and (b) extended structures. The BF4 anions
were omitted for clearly.
–
–
C(2) and Cu(1)} and {N(2), N(4) and Cu(1)}. The ClO4
anion is located between two phenyl groups. The average
Cu–N and Cu–C distances are 1.989(5) and 1.995(6) Å,
respectively. The coordinated C=C distance of 1.370(9) Å is
longer than that [1.313 (exptl.) and 1.333 (calcd.) Å] of
metal-free C2H4[41,42] and the C=C distance is close to those
[1.382(3), 1.374(2) Å] of complexes 1a and 1b. The selected
bond lengths and bond angles of complex 2 are listed in
Table 1.
The crystal packing structure of complex 2 is also similar
to that of complex 1b. There are (i) intermolecular π–π
stacking interactions between two symmetric pyrimidine
rings with the N(1) and N(1Ј) atoms [centroid···centroid dis-
tance and interplanar angle between two rings are 3.638 Å
and 0°; nearest C(4)···C(6Ј) 3.305 Å], and (ii) intermolecular
π–π stacking interactions between two symmetric pyrimid-
ine rings with the N(3) and N(3ЈЈ) atoms
[centroid···centroid distance and interplanar angle between
two rings are 3.525 Å and 0°; nearest C(8)···C(10ЈЈ)
3.271 Å]. Furthermore, each of CuI–Ph2bpm/C2H4 mole-
cule is correlated through the C–H···N contact [N(3)···
C(19ЈЈЈ) 3.280 Å]. As
a result, the 3D network of
[Cu(Ph2bpm)(C2H4)]+ cation moieties is formed by the
intermolecular π–π–π stacking interactions along the a-axis
and the C–H···N contacts along the b-axis.
[Cu(Ph2bpm)(C2H4)]PF6 (3)
The molecular structure of complex 3 is similar to those
of complex 1b and 2. The PF6 anion lies between two
phenyl groups. The average Cu–N and Cu–C distances are
Figure 3. The crystal packing structures of [Cu(Ph2bpm)(C2H4)]-
BF4 (1b). (a) partial and (b) extended structures. The BF4 anions
were omitted for clearly.
–
–
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M. Maekawa et al.
FULL PAPER
1.985(4) and 2.003(4) Å, respectively. As well as complexes δmetal-free) of 0.01–0.12, except for the 5-H signal (∆δ =
1
1a, 1b and 2, the coordinated C=C distance of 1.371(7) Å –0.13 ppm). In contrast, one sharp H NMR resonance is
is longer than that [1.313(exptl.) and 1.333(calcd.) Å] of observed for coordinated C2H4 at δ = 4.98, which is shifted
[41,42]
metal-free C2H4
and those [1.30(1)–1.366(6) Å] in the upfield relative to metal-free C2H4 (δ = 5.24 ppm), indica-
reported trigonal-planar CuI–C2H4 complexes.[5–11,18] In a tive of CuIǞC2H4 π back-donation bonding.[1] The chemi-
series of CuI–Ph2bpm/C2H4 complexes, these findings sug- cal shift value is within the range of those reported for tri-
gest that the contribution of the larger π back-donation gonal-planar CuI–C2H4 complexes (δ = 4.48–5.28).[5,9,18,43]
bonding is induced by the electron-releasing phenyl group In comparison with complex 3, adduct 1, dissolved in
in Ph2bpm.[1,43] The selected bond lengths and bond angles CD2Cl2 shows slightly broad 1H NMR signals at 23 °C. The
of complex 3 are listed in Table 1.
1H NMR resonances in the coordinated Ph2bpm ligand are
The crystal packing structure of complex 3 is represented also shifted downfield relative to the metal-free Ph2bpm li-
in Figure 4. It is remarkable that the crystal packing struc- gand, with ∆δ values of 0.07–0.12, except for the 5-H signal
ture of complex 3 is different from those of 1a, 1b and 2. (∆δ = –0.02 ppm). The coordinated C2H4 give rise to one
1
Each [Cu(Ph2bpm)(C2H4)]+ cation moiety is located in the slightly broadened H NMR resonance at δ = 5.08, which
face-to-face configuration. The intermolecular short con- is shifted upfield relative to metal-free C2H4. These results
tact of C(10)···C(20Ј) 3.382 Å [centroid···centroid distance prove that the structures of CuI–Ph2bpm/C2H4 adducts 1
and interplanar angle between two rings are 3.771 Å and and 3 are maintained in solution.
11.49°] is between the C(10) atom of pyrimidine ring with
The νC=C bands of the coordinated ethylene in 1–3 are
the N(3) atom and the C(20Ј) atom of neighboring phenyl observed at 1531, 1529 and 1530 cm–1, respectively. These
ring, resulting in the self-assembly of a unique 1D stair- νC=C bands show a lower frequency shift relative to metal-
shaped structure by the connections of [Cu(Ph2bpm)- free C2H4 (νC=C = 1623 cm–1), and these values are within
(C2H4)]+ cation moieties.
the range of those reported for trigonal-planar CuI–C2H4
complexes (1515–1537 cm–1),[5,8,10,18,43] indicative of
CuIǞC2H4 π back-donation bonding. The IR and 1H
NMR spectroscopic data are consistent with crystallo-
graphic data.
Thermogravimetric analysis (TG-DTA) was carried out
under flowing N2 gas for 1 and 3 (Figure 5). Complex 1
sustained a total mass loss of 5.9% (calcd. 5.7%) with the
relatively gentle curve at 210–275 °C, this corresponds to
loss of one C2H4 molecule. Similarly, complex 3 lost 5.9%
(calcd. 5.1%) of its mass (relatively gentle curve at 80–
265 °C), corresponding to loss of one C2H4 molecule. It is
suggested that CuI–Ph2bpm/C2H4 adducts of type 1 and 3
are thermally stable.
Figure 4. The crystal packing structures of [Cu(Ph2bpm)(C2H4)]-
–
PF6 (3). (a) partial and (b) extended structures. The PF6 anions
were omitted for clearly.
1H NMR, IR Spectra and TG-DTA Curves of CuI–Ph2-
bpm/C2H4 Complexes
We have attempted to determine the structures of 1–3 in
solution by H NMR method. However, these CuI–C2H4
adducts are only poorly soluble in commonly used organic
1
Figure 5. TG-DTA curves of complexes 1 and 3 under flowing N2
gas. (a) solid line for complex 1 and (b) broken line for complex 3.
solvents. Complexes 1 and 3 are slightly soluble in CD2Cl2.
1
Adduct 3, dissolved in CD2Cl2 gave four well-resolved H
NMR resonances at 23 °C without any signals of dissoci-
1
ation species. The H NMR resonances in the coordinated
Ph2bpm ligand are shifted downfield relative to metal-free
Conclusions
Ph2bpm ligand [δ = 9.32(2–H), 8.87(5–H), 8.20(C6H5) and
It is known that planar coordination compounds with
7.50(C6H5)], with the coordination shifts (∆δ = δcomplex
–
aromatic ligands, especially having extended π-systems,
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Novel Cu(I) Ethylene Complexes
[Cu(Ph2bpm)(C2H4)]ClO4 (2): The precursor CuI–C2H4 complex
[Cu(C2H4)n]ClO4 was prepared by reductive reaction of Cu(ClO4)2·
6H2O (74.1 mg, 2.0 mmol) with Cu wire in MeOH (5 mL) under
C2H4. A solution of Ph2bpm (4.8 mg, 1.5 mmol) in 5 mL of MeOH
was added to the above CuI–C2H4 solution. C2H4 gas was bubbled
through the solution for a further 30 min. Then the pale yellow
solution was filtered and the filtrates were sealed in glass tubes
(7 mm inner diameter) under C2H4. The reaction solution was al-
lowed to stand at –5 °C for two weeks; after this time, brown brick-
shaped crystals of complex 2 could be collected. Complex 2 was
show π–π stacking interaction in the solid states. In alkene
or alkyne π-bonded CuI complexes, in-plane coordination
of a C=C or CϵC bond to trigonal planar CuI centers
often leads to planar molecular conformations.[5,6,9,44,45]
For instance, the infinite π–π stacking columns are con-
firmed in 2,2Ј-bipyridine complex [Cu(2,2Ј-bpy)(CH2=
[6]
CH2)]ClO4 and 1,10-phenanthroline complex [Cu(1,10-
[45]
phen)(CHϵCCO2Et)]ClO4
with the nearest carbon-to-
carbon distances of 3.31 and 3.37 Å, respectively, while di-
mer formation through π–π stacking interaction can be seen dried in a flow of C2H4 gas and then immediately used to measure
IR spectroscopic data. Microanalysis and TG-DTA was not per-
in
ClO4
3.42 Å).
a
CuI–alkyne complex [Cu(1,10-phen)(CHϵCH)]-
(the nearest carbon-to-carbon distances being
[45]
formed since 2 tends to explode when heated (see safety remark
below). Yield 4.0 mg (80%). IR (KBr): ν = 1592 (s), 1529 (s, C H ),
˜
2
4
1513 (s), 1465 (s), 1440 (m), 1430 (m), 1390 (s), 1281 (s), 1262 (m),
1243 (m), 1186 (m), 1105–1060 (s, ClO4), 1012 (s), 794 (m), 959
(m), 927 (m), 899 (m), 798 (m), 749 (s), 690 (s), 676 (m), 647 (m),
637 (s), 621 (s), 541 (m), 409 (m) cm–1.
In contrast, the bpm ligand is a multidentate nitrogen
ligand with a bidentate site for chelation and two exo-N-
donor sites for bridging, as mentioned in the introduction.
In this study, we found that the Ph2bpm ligand with a
phenyl group can produce novel CuI–C2H4 adducts that are
three-dimensionally self-assembled by intermolecular π–π
stacking interactions and C–H···N contacts. It is proved
that the contribution of the larger π back-donation bonding
Caution! Perchlorate salts of metal complexes with organic com-
pounds are potentially explosive! Only small amounts of materials
should be prepared and handled with great care.
[Cu(Ph2bpm)(C2H4)]PF6 (3): [Cu(MeCN)4]PF6 (7.6 mg, 2.0 mmol)
is induced by the electron-releasing phenyl group. These and Ph2bpm (3.2 mg, 1.0 mmol) were reacted in MeOH (10 mL)
under C2H4. The reaction solution was filtered and the filtrates
were sealed in glass tubes (7 mm inner diameter) under C2H4. The
reaction solution was allowed to stand for one week at –5 °C. Col-
orless plate-like crystals of 3 were obtained. After drying in a flow
of C2H4 gas, 3 was immediately used to measure elementary analy-
sis, IR, 1H NMR spectra and TG-DTA. Yield 4.8 mg (88%).
C22H18CuF6N4P (546.92): calcd. C 48.31, H 3.32, N 10.24; found
C 48.41, H 3.93, N 8.88. 1H NMR (400 MHz, CD2Cl2, 23 °C): δ =
9.33 (s, 1 H, 2-H), 8.74 (s, 1 H, 5-H), 8.32 (m, 2 H, C6H5) and 7.60
(m, 3 H, C6H5) for Ph2bpm; 4.98 (s, 1 H) for C2H4 ppm. IR (KBr):
new findings are expected to contribute toward design and
architecture of structurally new CuI–C2H4 adducts.
Experimental Section
General Procedures and Reagents: The precursor CuI complexes
[Cu(MeCN)4]X (X = PF6 and BF4) were prepared according to the
literature.[46] Cu(ClO4)2·6H2O and Cu wire were purchased from
Mitsuwa Chemicals (Japan) and used without further purification.
ν = 1603 (s), 1530 (s, C H ), 1518 (s), 1465 (s), 1444 (m), 1427 (m),
˜
2
4
6,6Ј-Diphenyl-4,4Ј-bipyrimidine (Ph2bpm) was prepared by
a
1393 (s), 1279 (s), 1265 (s), 1240 (m), 1185 (m), 1173 (m), 1104 (m),
1075 (m), 1017 (s), 1007 (m), 889–748 (s, PF6), 749 (s), 689 (s), 677
(m), 648 (m), 638 (m), 557 (s), 409 (m) cm–1.
modified literature method.[47] The pure C2H4 gas (Ͼ99.9%) was
purchased from Sumitomo Seika (Japan). All organic solvents were
dried and distilled by usual methods before use. All procedures
were carried out using standard Schlenk techniques under C2H4.
IR spectra were recorded with a JASCO FT-IR 430 spectrometer
as KBr pellets. 1H NMR spectra were measured by JEOL JNM
AL-400 and JNM ECA-500 NMR spectrometers. Thermogravime-
tric analysis (TG-DTA) was recorded by RIGAKU Thermo Plus
8120 under flowing N2 gas.
X-ray Crystal Structure Determinations: All measurements of CuI–
Ph2bpm/C2H4 complexes 1a, 1b, 2 and 3 were made on a Rigaku
Mercury CCD diffractometer with graphite monochromated Mo-
Kα radiation (λ = 0.71070 Å). The diffraction data were collected
at –165 °C for complexes 1a and 1b, and –155 °C for complexes 2
and 3 by the ω scan mode. Of the 22885, 23101, 23479 and 24603,
reflections which were collected, 4605, 4633, 4891 and 4669 were
unique (Rint = 0.053, 0.036, 0.127 and 0.036) for complexes 1a, 1b,
Preparation of CuI–Ph2bpm/C2H4 Complexes
[Cu(Ph2bpm)(C2H4)]BF4 (1a, 1b): [Cu(MeCN)4]BF4 (31.6 mg, 2 and 3, respectively. Data were collected and processed using Crys-
10.0 mmol) and Ph2bpm (3.2 mg, 1.0 mmol) were reacted in MeOH
(10 mL) under C2H4. The reaction solution was filtered and the
filtrates were sealed in glass tubes (7 mm inner diameter) under
C2H4. The reaction solution was allowed to stand for one week at
–5 °C. A small amount of yellow brick-shaped crystals (1a) was
collected, together with a bulk of yellow needle-like crystals (1b).
After drying in a flow of C2H4 gas the crystals were immediately
tal Clear program (Rigaku). The linear absorption coefficient, µ,
for Mo-Kα radiation is 11.377, 11.305, 12.380 and 11.655 cm–1 for
complexes 1a, 1b, 2 and 3, respectively. The data were corrected for
Lorentz and polarization effects. The structures were solved by di-
rect methods (SIR-97 for complexes 1a, 1b, 2 and 3) and expanded
using Fourier techniques. The non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were included but not refined. The
final cycle of full-matrix least-squares refinement was based on
4605, 4633, 4669 and 4891 observed reflections (all data) for com-
plexes 1a, 1b, 2 and 3, respectively. The unweighted and weighted
subjected
to
characterization.
Yield
4.0 mg
(82%).
C22H18BCuF4N4 (488.76): calcd. C 54.06, H 3.71, N 11.46; found
1
C 53.72, H 4.53, N 11.56. H NMR (500Mz, CD2Cl2, 23 °C): δ =
9.39 (s, 1 H, 2-H), 8.89 (s, 1 H, 5-H), 8.45–8.37 (m, 2 H, C6H5) agreement factors of R were used (see footnote of Table 2). The R,
and 7.71–7.65 (m, 3 H, C6H5) for Ph2bpm; 5.08 (s, 1 H) for C2H4
ppm. IR (KBr): ν = 1593 (s), 1531 (s, C H ), 1515 (s), 1466 (s),
R1 and wR2 values were {0.0599, 0.0482 and 0.0943}, {0.0396,
0.0343 and 0.0800}, {0.1430, 0.0994 and 0.2010} and {0.1101,
˜
2
4
1440 (m), 1431 (m), 1391 (s), 1282 (s), 1262 (m), 1244 (m), 1187 0.0982 and 0.1436} for complexes 1a, 1b, 2 and 3, respectively. All
(m), 1123–960 (s, BF4), 798 (m), 749 (s), 690 (s), 676 (m), 647 (m),
calculations were performed using the Crystal Structure 3.8.2 Crys-
tal Structure Analysis Package (Rigaku and Rigaku Americas).
637 (s), 540 (m), 517 (m), 409 (m) cm–1.
Eur. J. Inorg. Chem. 2009, 4225–4231
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4229

M. Maekawa et al.
FULL PAPER
Table 2. Crystallographic data of CuI–Ph2bpm/C2H4 complexes 1–3.[a]
[Cu(Ph2bpm)(C2H4)]BF4 (1a) [Cu(Ph2bpm)(C2H4)]BF4 (1b) [Cu(Ph2bpm)(C2H4)]ClO4 (2) [Cu(Ph2bpm)(C2H4)]PF6 (3)
Formula
C22H18CuN4BF4
488.76
monoclinic
P21/c
12.597(7)
13.699(6)
13.223(7)
117.908(6)
2016.5(17)
4
1.610
992.0
11.377
108
C22H18CuN4BF4
488.76
monoclinic
P21/c
9.470(4)
16.483(7)
13.012(6)
92.267(5)
2029.4(16)
4
1.610
C22H18CuN4ClO4
501.41
monoclinic
P21/c
9.5216(17)
16.362(2)
13.152(2)
93.459(11)
2045.2(6)
4
1.628
1024.0
C22H18CuN4PF6
546.92
monoclinic
P21/a
10.391(6)
19.422(10)
10.710(6)
97.659(7)
2142.1(20)
4
1.696
1104.0
Formula weight
Crystal system
Space group
a [Å]
b [Å]
c [Å]
β [°]
V [Å3]
Z
Dcalcd. [gcm–3]
F(000)
992.0
11.305
108
µ (Mo-Kα) [cm–1]
Temperature [K]
12.380
118
11.655
118
Total number of refl. 22885
23101
23479
24603
Measured refl.
4605 (unique, Rint = 0.053)
4633 (unique, Rint = 0.036)
4633 (all reflections)
0.0396 (all reflections)
0.0343 [IϾ2σ(I)]
0.0800
4669 (unique, Rint = 0.127)
4669 (all reflections)
0.1430 (all reflections)
0.0994 [IϾ2σ(I)]
0.2010
4891(unique, Rint = 0.036)
4891 (all reflections)
0.1101 (all reflections)
0.0982 [IϾ2σ(I)]
0.1436
Observed refl.
4605 (all reflections)
0.0599 (all reflections)
0.0482 [IϾ2σ(I)]
0.0943
R
R1
wR2
[a] R = Σ||Fo| – |Fc|/Σ|Fo|. R1 = Σ||Fo| – |Fc||/Σ|Fo|. wR2 = [Σw(Fo – Fc ) /Σw(Fo2)2]1/2
.
2
2 2
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