The preparation, crystal structure and properties of a mixed-ligand copper(I) complex [CuI(PPh3)(DPPZ)]·DMF

Article abstract of DOI:10.1016/S0022-2860(02)00565-3

The mixed ligand mononuclear copper(I) complex of formula [CuI(PPh₃)(DPPZ)]·DMF (DPPZ = dipyrido[3,2,-a:2′,3′-c]phenazine) has been synthesized and has been characterized by single-crystal X-ray diffraction method, FT-IR spectrum, the electrospray ionization mass spectrum and the thermogravimetric analysis. The pairwise π-π stacking between DPPZ ligands exists through the crystal lattice.

Full text of DOI:10.1016/S0022-2860(02)00565-3

Journal of Molecular Structure 650 (2003) 27–32
www.elsevier.com/locate/molstruc
The preparation, crystal structure and properties of a mixed-ligand
copper(I) complex [CuI(PPh3)(DPPZ)]·DMF
1
Yu-Jun Shi , Shu-Jian Chen, Bin Huang, Xue-Tai Chen, Yong Zhang, Xiao-Zeng You
*
State Key Laboratory of Coordination Chemistry, Coordination Chemistry Institute, Nanjing University, Nanjing 210093,
People’s Republic of China
Received 12 March 2002; revised 18 October 2002; accepted 18 October 2002
Abstract
The mixed ligand mononuclear copper(I) complex of formula [CuI(PPh3)(DPPZ)]·DMF (DPPZ ¼ dipyrido[3,2,-a:20,30-
c]phenazine) has been synthesized and has been characterized by single-crystal X-ray diffraction method, FT-IR spectrum, the
electrospray ionization mass spectrum and the thermogravimetric analysis. The pairwise p–p stacking between DPPZ ligands
exists through the crystal lattice.
q 2002 Published by Elsevier Science B.V.
Keywords: Copper(I) complex; Crystal structure; Electrospray ionization mass spectrum; DPPZ
1. Introduction
the crystal structure of these complexes [15–20].
To the best of our knowledge, no crystal structure of
a copper(I) complex of this ligand has been
reported. In the present paper, we report the
preparation, X-ray crystal structure and properties
of copper(I) complex [CuI(PPh3)(DPPZ)]·DMF.
Metal polypyridyl coordination compounds such
as ruthenium polypyridyl complexes have been
extensively studied in the past few years, as their
unusual binding properties combined with their
general photoactivity, make them suitable candi-
dates as DNA secondary structure probes, photo-
cleavers and antitumor drugs [1]. It is of note that
despite the interesting properties and the large
amount of work that has performed on complexes
with dipyrido[3,2,-a:20,30-c]phenazine (DPPZ)
[2–20], there are relatively few reports on
2. Experimental
2.1. Materials and measurements
All chemicals used were of analytical grade and
used as received. The ligand DPPZ was prepared as
described earlier [21] while 1,10-phenanthroline-5,6-
quinone was prepared according to the literature
method [3]. Elemental analyses were performed
*
Corresponding author. Tel.: þ86-25-3592969; fax: þ86-25-
3314502.
E-mail address: xyz@netra.nju.edu.cn (X.-Z. You).
Permanent address: Department of Chemistry, Nantong
1
with
spectrum was recorded on a Nicolet 170SX FT-IR
a
Perkin–Elmer 240C instrument. IR
Teacher’s College, Nantong 226007, People’s Republic of China.
0022-2860/03/$ - see front matter q 2002 Published by Elsevier Science B.V.
PII: S0022-2860(02)00565-3

28
Y.-J. Shi et al. / Journal of Molecular Structure 650 (2003) 27–32
spectrophotometer (range: 400–4000 cm21) as KBr
pellets. Electrospray ionization mass spectrum (ESI-
MS) was recorded with a Finnigan mat APISSQ 710
mass spectrometer, with MeOH on the mobile
phase, the flow rate of the mobile phase was
0.75 cm3 min21. The spray voltage was 4.5 kV and
the capillary voltage was 38.0 V. The capillary
temperature was 200 8C. Thermogravimetric and
differential analyses were taken on a TA Inst 2100
thermal analyzer under flowing N2 with a heating
rate of 10 8C min21. Luminescence spectra were
recorded on a Hitachi 850 fluorescence spectrometer
at room temperature (25 8C).
Table 1
Crystal data and structure refinement parameters for the title
complex
Empirical formula
Molecular weight
Crystal size (mm)
Crystal system
C39H32CuIN5OP
808.11
0.24 £ 0.23 £ 0.21
Triclinic
P-1
Space group
˚
a (A)
˚
b (A)
12.4424(12)
12.641(2)
13.9553(18)
64.426(11)
65.656(10)
88.860(9)
1770.2(4)
2
˚
c (A)
a (deg)
b (deg)
g(deg)
3
˚
V (A )
Z
2.2. Preparation of [CuI(PPh3)(DPPZ)]·DMF
DCalc (g cm23
)
1.516
m (mm21
F(000)
)
1.573
812
To 20 ml DMF was added 0.190 g (1 mmol)
CuI, 0.520 g (2 mmol) PPh3 and 0.262 g (1 mmol)
DPPZ with stirring, the mixture was then stirred at
room temperature for about 8 h, after which it was
filtered. Orange-red single crystals of the complex
suitable for X-ray diffraction were obtained by
evaporating the filtrate in air for a few days.
The yield of the compound is ca. 60%. Anal.
Found: C, 58.22; H, 3.80; N, 8.57%; Calc. for
C39H32N5CuIPO: C, 57.96; H, 3.99; N, 8.67%. IR
(KBr pellets)/cm21: 1676(vs), 1577(m), 1482(vs),
1431(s), 1409(vs), 1381(m), 1354(s), 1089(s),
1069(vs), 996(m), 818(m), 738(s), 696(vs), 521(s),
498(m).
u Range for data
collection (deg)
Index ranges
1.81–24.96
0 # h # 14, 215 # k # 15,
215 # l # 16
6510, 6194
Reflections collected: total,
independent
Rint
0.0463
Data/restraints/parameters
Goodness-of-fit S on F 2
Final R1, wR2 ½I . 2sðIÞꢀ
All data
6194/8/409
1.109
0.0500, 0.1535
0.0719, 0.1788
1.437, 21.350
23
˚
Largest peak, hole (e A
)
were refined anisotropically whereas the hydrogen
atoms were generated geometrically. In the final
difference map, the residual maxima and minima
´
23
˚
2.3. X-ray crystallography
were 1.437 and 21.350 e A
, respectively.
The goodness of fit on F 2 is 1.080. All calculations
were performed on a PC-586 personal computer
An orange-red block crystal of the new mixed-
ligand
complex,
with
the
dimensions
using
SHELXTL-97
program.
Details
of
0.24 £ 0.23 £ 0.21 mm3, was selected for unit cell
parameters determination and collection of intensity
data at 293 K on an Euraf Nonius CAD4 diffract-
ometer with graphite monochromated Mo Ka radi-
crystal data, collection and refinement are listed in
Table 1.
´
˚
ation (l ¼ 0.7103 A) using a u/2u scan mode. The
3. Results and discussion
data was corrected for Lorenz and polarization
effects during data reduction. An empirical absorp-
tion correction based on c scans was applied. The
structure was solved by the direct methods and
refined by a full-matrix least-squares on F 2 to
R1 ¼ 0.0500 (wR2 ¼ 0.1535) for 6194 reflections
ðI . 2sðIÞÞ of 6510 reflections collected in the
range 1.818 # u # 24.968. All non-hydrogen atoms
3.1. Description of the structure
The atomic coordinates and equivalent isotropic
displacement parameters for the non-hydrogen atoms
are listed in Table 2. Selected bond distances and
angles are listed in Table 3. The structure of the title

Y.-J. Shi et al. / Journal of Molecular Structure 650 (2003) 27–32
29
complex is shown in Fig. 1 and the unit cell is
illustrated in Fig. 2.
Table 2
Atomic coordinates ( £ 104) and equivalent isotropic displacement
The title complex crystallizes in space group P-1
and X-ray analysis shows that it is a mononuclear
copper(I) complex.
3
˚
parameters (A £ 10 ) for the title complex. Ueq is defined as one
third of the trace of the orthogonalized Uij tensor
Atom
x
y
z
Ueq
The four-coordinated copper atom is surrounded
by one iodide, one phosphorous and two nitrogen
atoms to form a distorted tetrahedral geometry.
Cu(1)
I(1)
2820(1)
1131(1)
2754(1)
2484(1)
3684(1)
2487(4)
1548(4)
1155(4)
3114(4)
2722(5)
2578(6)
1816(7)
1154(7)
1273(8)
2062(6)
4960(5)
5249(6)
6200(6)
6928(6)
6661(7)
5674(6)
4272(5)
5442(6)
5850(6)
5075(7)
3924(7)
3514(6)
272(5)
4812(1)
5063(1)
2948(1)
9182(4)
9512(4)
5915(4)
6173(4)
2516(5)
1518(6)
1286(8)
2028(10)
3032(9)
32,829(6)
2569(5)
1772(5)
1538(6)
2079(6)
2864(6)
3114(6)
1800(5)
877(5)
41(1)
46(1)
38(1)
44(1)
41(1)
41(1)
39(1)
42(1)
52(2)
73(2)
85(3)
82(3)
59(2)
39(1)
50(1)
55(2)
59(2)
60(2)
50(2)
38(1)
49(1)
60(2)
60(2)
57(2)
48(1)
37(1)
49(2)
54(2)
50(2)
33(1)
35(1)
37(1)
50(2)
54(2)
49(1)
36(1)
35(1)
42(1)
43(1)
53(2)
57(2)
61(2)
56(2)
99(2)
146(5)
138(5)
164(6)
276(8)
´
˚
The Cu–I distance is 2.5880(8) A, which is
P(1)
2545(1)
26033(4)
25921(4)
22084(4)
21996(4)
´
0.003 A shorter than that of [CuI(PPh3)(2,20-
N(1)
˚
´
N(2)
˚
bipy)] [22]. The Cu–P distance is 2.2146 A,
N(3)
´
˚
which is 0.0164 A longer than that in
´
N(4)
[CuI(PPh3)(2,20-bipy)] [22] and about 0.05 A
˚
C(1)
21106(50
2453(6)
2938(9)
22081(10)
22765(8)
22286(6)
21285(5)
21782(6)
22330(6)
22418(7)
21914(7)
21376(6)
1014(5)
C(2)
shorter than that in {[Cu(PPh3)2]2BH4}ClO4 [23].
´
C(3)
˚
The Cu–N distances are 2.091(5) A for Cu(1)–
C(4)
´
˚
N(3) and 2.094(5) A for Cu(1)–N(4), while in
C(5)
[CuI(PPh3)(2,20-bipy)] [22], the Cu–N distances
C(6)
´
C(7)
˚
are 2.070(3) and 2.082(4) A. In [CuI(PPh3)(-
C(8)
DPPZ)]·DMF, the binding angle of the two
coordinating nitrogens of the DPPZ ligand N(3)–
Cu(1)–N(4) is 79.00(17)8, almost the same as in
[CuI(PPh3)(2,20-bipy)] [22], which are in the range
of the reported values 74.1–82.18 in dppz com-
plexes [15–20].
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
N(5)
1425(6)
2595(6)
46(6)
The DPPZ ligand is essentially planar, similar
to that in [RuO(dppz)(tpy)]2þ [16] and in
[Co(en)2(dppz)](ClO4)3·0.5H2O [18]. The dihedral
angle between the two planes of the ligands is
about 2.18. A pairwise p-stacking interaction
therefore exists throughout the crystal, as shown
in Fig. 3. All previously reported structures
containing the DPPZ ligand have shown crystal
packing that appears to be driven by favorable p–
p interactions of the extended conjugated systems
of the ligands. The distance between the ring
3396(6)
104(6)
3026(6)
1017(60
1870(5)
7568(5)
7409(6)
6518(6)
5794(5)
6804(4)
6965(4)
7904(5)
8051(6)
7273(6)
6348(5)
8497(5)
8673(4)
10,209(5)
1830(6)
24056(5)
24036(6)
23050(6)
22094(6)
23061(4)
23007(5)
23951(5)
23810(6)
22786(6)
21912(6)
25076(5)
25021(5)
26914(5)
26967(5)
27919(6)
28910(6)
28972(6)
28023(6)
5102(8)
2755(5)
2800(6)
157(5)
1190(4)
2251(5)
2347(5)
3354(6)
4203(5)
4058(5)
385(5)
´
˚
planes of the two ligands is about 3.4 A, about
´
1413(5)
665(5)
˚
0.1 A
shorter
than
in
[16]
the
and
case
[Co(en)2(-
of
[RuO(dppz)(tpy)]2þ
2356(5)
775(6)
100,032(5)
11,114(5)
11,820(5)
11,657(6)
10,791(6)
5400(8)
dppz)](ClO4)3·0.5H2O [18], similar to the base-
pair stacking distance in DNA [24] and the
intercalator-base pair stacking distance in crystal
structure of oligonucleotide–intercalator complexes
[25,26]. The same two-ring overlap pattern has
2102(6)
21126(7)
21248(6)
6962(8)
C(38)
C(39)
C(37)
O(1)
4484(14)
5694(13)
5089(16)
5687(18)
6431(13)
8157(11)
6459(15)
8531(17)
5009(13)
4696(13)
6534(12)
3668(17)
been
observed
as
in
the
case
of
[RuO(dppz)(tpy)]2þ [16], while in the case of
[Co(en)2(dppz)](ClO4)3·0.5H2O [18], the DPPZ
ligands of adjacent molecules do not lie directly

30
Y.-J. Shi et al. / Journal of Molecular Structure 650 (2003) 27–32
Table 3
˚
Selected bond distances (A) and bond angles (deg)
Cu(1)–N(3)
Cu(1)–P(1)
P(1)–C(7)
2.091(5)
Cu(1)–N(4)
Cu(1)–I(1)
P(1)–C(1)
2.094(5)
2.5880(8)
1.828(6)
1.323(7)
1.319(7)
1.344(7)
1.332(7)
2.2146(16)
1.826(6)
1.830(6)
1.346(8)
1.359(7)
1.350(7)
1.364(7)
P(1)–C(13)
N(1)–C(32)
N(2)–C(31)
N(3)–C(23)
N(4)–C(24)
N(1)–C(29)
N(2)–C(30)
N(3)–C(22)
N(4)–C(28)
N(3)–Cu(1)–N(4)
N(4)–Cu(1)–P(1)
N(4)–Cu(1)–I(1)
C(7)–P(1)–C(1)
C(1)–P(1)–C(13)
C(1)–P(1)–Cu(1)
79.00(17)
124.83(14)
106.40(13)
103.2(3)
N(3)–Cu(1)–P(1)
N(3)–Cu(1)–I(1)
P(1)–Cu(1)–I(1)
C(7)–P(1)–C(13)
C(7)–P(1)–Cu(1)
C(13)–P(1)–Cu(1)
115.80(14)
110.47(14)
114.97(5)
103.7(3)
102.5(3)
116.08(18)
116.40(19)
113.26(19)
above each other but are displaced along the b-
axis so that there is no overlap of any of the
atoms of the ligands.
assigned to [Cu(PPh3)(DPPZ)]þ. The peak at m/z
376.9 is probably due to [Cu(DPPZ)]þ(CH3OH).
3.3. Luminescent properties
3.2. ESI-MS spectrum
Fig. 5 shows the emission spectrum of the title
complex in solid state at room temperature. A
broad peak at 620 nm was observed when the solid
sample was excited at 350 nm. Barton et al. [14]
reported the emission spectra of Ruthenium dipyr-
idophenazine complex [Ru(phen)2(DPPZ)](PF6)2 in
CH3CN solution, where a maximum emission peak
The structure of the complex in solution was
also studied by ESI-MS [27–29]. Fig. 4 displays a
positive ion ESI mass spectrum of the title complex
in the methanol solution. Three main peaks were
observed. The peak at m/z 868.7 is assigned to
[Cu(PPh3)2(DPPZ)]þ and the peak at m/z 607.1 is
Fig. 1. ORTEP diagram and atomic labeling system of [CuI(PPh3)(DPPZ)]. Hydrogen atoms are omitted for clarity.

Y.-J. Shi et al. / Journal of Molecular Structure 650 (2003) 27–32
31
Fig. 2. Unit cell packing diagram of the title complex. DMF molecule is omitted for clarity.
Fig. 3. Pairwise p–p stacking diagram showing the two-ring overlap pattern in the title complex.
at 618 nm was observed, which was attributed to
the metal-to-ligand charge transfer (MLCT). We
assign the emission peak of 619 nm in the complex
to the MLCT.
3.4. Thermogravimetric analysis
The title complex (4.70 mg) was heated in a
nitrogen atmosphere from 25 to 600 8C at a heating
rate of 10 8C min21. Thermogravimetric analysis
(TGA) shows that the decomposition starts at
110 8C, a significant mass loss at 125 8C correspond-
ing to the loss of one DMF molecule per formula unit
(observed 8.9%, calculated 9.0%). The second step of
decomposition takes place between 213 and 260 8C
Fig. 4. Positive ion ESI mass spectrum of complex in methanol
solution.

32
Y.-J. Shi et al. / Journal of Molecular Structure 650 (2003) 27–32
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ligand (observed 34.8%, calculated 34.9%), and the
last decomposition step is observed between 430 and
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Acknowledgements
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This work was supported by the Major State Basic
Research Development Program (Grant No.
G2000077500) National Science Grant of Jiangsu
Province (BK 99032), and National Natural Science
Foundation of China (No. 20028101). The authors
thank Mr Wang Huaqing (Center of Materials
Analysis, Nanjing University) for the X-ray structure
determination.
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