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Acta Crystallographica Section E

Structure Reports
OnlineISSN 1600-5368(2,2 -Bipyridine)bis(N-methyl-4,4 -bipyridinium)platinum(II)tetraperchlorate
00

Ken Sakai, Manabu Osada, Yoshimi Yokoyama, Yasushi Tomita and Taro
Tsubomura

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Acta Cryst. (2003). E59, m512–m514

Ken Sakai et al.  [Pt(C10 H8 N2 )(C11 H11 N2 )2 ](ClO4 )4metal-organic papers
Acta Crystallographica Section E

Structure Reports
Online(2,20 -Bipyridine)bis(N-methyl-4,40 -bipyridinium)platinum(II) tetraperchlorate

ISSN 1600-5368

Ken Sakai,a* Manabu Osada,aYoshimi Yokoyama,a Yasushi
Tomitab and Taro Tsubomurab
aDepartment of Applied Chemistry, Faculty ofScience, Tokyo University of Science,
Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601,
Japan, and bDepartment of Applied Chemistry,
Faculty of Engineering, Seikei University, Kichijoji-Kitamachi 3-3-1, Musashino, Tokyo
180-8633, Japan

Correspondence e-mail:ksakai@rs.kagu.tus.ac.jp

Key indicators
Single-crystal X-ray study
T = 293 KÊMean (C±C) = 0.009 A
Disorder in solvent or counterion
R factor = 0.047
wR factor = 0.126
Data-to-parameter ratio = 18.3
For details of how these key indicators wereautomatically derived from the article, see
http://journals.iucr.org/e.

# 2003 International Union of Crystallography
Printed in Great Britain ± all rights reservedm512

In the title compound, [Pt(C10H8N2)(C11H11N2)2](ClO4)4, thesquare-planar PtN4 coordination geometry is slightly
deformed, with the coordinated N atom of one of the NÊ out of themethyl-4,40 -bipyridinium (MQ) ligands 0.262 (8) A
plane de®ned by the rest of the coordinated N atoms and thePt atom. The exceptional behavior of this MQ ligand isinterpreted in terms of the electrostatic interactions between
the positively charged MQ ligands and the perchlorate anions,where the N(MQ)  O(perchlorate) distances are in the range
Ê.
2.932 (12)±3.259 (13) AReceived 28 May 2003
Accepted 19 June 2003
Online 30 June 2003

CommentWe previously reported that amidate-bridge PtII dimers with ageneral formula of [Pt2(NH3)4(-amidate)2]2+ (amidate =acetamidate, -pyrrolidinonate, -pyridonate, etc.) serve as
effective H2-producing catalysts in a well known photosystem
consisting of edta, Ru(bpy)32+ and methylviologen (Sakai etal., 1993) (methylviologen = N,N0 -dimethyl-4,40 -bipyridinium
dichloride). Up to now, a large number of mono- and dinuclear
PtII complexes have been prepared by us, and their catalyticactivity has been evaluated, based on the amount of H2
evolved under visible-light illumination (unpublished results).
Consequently, we recently found that mononuclear PtII
complexes of N-methyl-4,40 -bipyridinium (MQ), such as thetitle compound, (I), exhibit relatively high catalytic activity
compared to the common mononuclear platinum(II)complexes. We report here the crystal structure of one of suchcomplexes prepared in our laboratory.

The asymmetric unit of (I) consists of a mononuclear PtII
complex cation and four perchlorate anions. The stereochemistry of the Pt ion can be described as a distorted squareÊplanar geometry, in which atom N5 is displaced by 0.262 (8) A
from the Pt coordination plane de®ned by the remainder ofthe coordinated N atoms and the Pt atom (the r.m.s. deviationÊ ). This distortion is not only dueof these four atoms is 0.0181 A
to the relatively strong intermolecular ±-stacking interactions achieved between the bpy ligands (see Fig. 2), but also

Ken Sakai et al.  [Pt(C10H8N2)(C11H11N2)2](ClO4)4

DOI: 10.1107/S1600536803013801

electronic reprint

Acta Cryst. (2003). E59, m512±m514

metal-organic papers

Figure 3
Figure 1

The structure of the cation in (I), showing the atom-labeling scheme.
Displacement ellipsoids are drawn at the 50% probability level.

A view nearly parallel to the N1±N3/Pt1 plane, showing the electrostaticinteractions between the MQ ligands and the perchlorate ions. H atoms
have been omitted for clarity.

the two aromatic rings within each MQ is 47.5 (2) for the MQ
involving N3 and N4, and is 42.9 (2) for that involving N5 andN6.
Ê , con®rming theThe shortest Pt  Pt distance is 7.9822 (6) Alack of any Pt  Pt interaction in (I) (see also Table 1). As
shown in Fig. 2, the cations are arranged in a stair-like fashion
to give a sort of one-dimensional -stacked array. An inversion center is located midway between pairs of stacked rings.
The N1/C1±C5 ring is -stacked with a neighbouring ring
through an inversion center, and the average plane-to-planeÊ . The N2/C6±C10 ring isseparation is estimated as 3.469 (6) Asimilarly stacked with a neighbouring ring through an inversion center, with an average plane-to-plane separation ofÊ.
3.574 (17) A

ExperimentalFigure 2

Crystal packing view of (I), showing the ± stacking interactions in the
crystal structure. Perchlorate anions and H atoms have been omitted forclarity.

due to the fact that the positively charged MQ ligands havestrong electrostatic interactions with one of ClO4ÿ ions (Fig.
3). The strong interactions between MQ and the ClO4ÿ ion
can be recognised from the following contacts: O10BÐN6 =Ê , O11AÐN6 = 2.996 (12) A
Ê , O10BÐN4i =2.932 (12) AiÊÊ [symmetry code:
2.998 (12) A and O11AÐN4 = 3.259 (13) A(i) x, y, z ÿ 1]. The two pyridyl units within bpy are twisted by
7.7 (5) relative to each other. The bpy plane is tilted withrespect to the N1±N3/Pt1 plane by an angle of 3.8 (3) , whichis also relevant to the intermolecular associations achieved in
the crystal. On the other hand, the coordinated pyridyl ligands
within the MQ ligands are steeply inclined with respect to theN1±N3/Pt1 plane [75.8 (2) for the ring involving N3 and75.6 (2) for that involving N5]. The dihedral angle between
Acta Cryst. (2003). E59, m512±m514

N-Methyl-4,40 -bipyridinium perchlorate, used in the following
synthesis, was prepared as follows: a solution of N-methyl-4,40 bipyridinium iodide (3.4 mmol; Van Emon et al., 1986) and AgClO4(3.5 mmol) in water (10 ml) was heated in the dark at 333 K for 2 h,followed by hot ®ltration in order to remove the precipitated AgCl.
Leaving the ®ltrate at 278 K overnight afforded the perchlorate saltof MQ as colorless needles, which were collected by ®ltration and airdried (yield: 78%). The purity was satisfactorily con®rmed by 1HNMR.
Compound (I) was prepared as follows: a solution of PtCl2(bpy)(0.10 mmol, 0.042 g; Morgan & Burstall, 1963) and AgClO4(0.20 mmol, 0.042 g) in water (20 ml) was re¯uxed in the dark for 2 h.
To the solution was added N-methyl-4,40 -bipyridinium perchlorate(0.20 mmol, 0.054 g) and the mixture was further re¯uxed for 4 h.
After the precipitated AgCl was removed by ®ltration, the ®ltrate wasevaporated to a total volume of about 5 ml until a small amount ofyellow precipitate started to deposit. To the solution were then added
2±3 drops of a saturated aqueous sodium perchlorate solution.
Leaving the solution overnight afforded (I) as a yellow precipitate.
The product was recrystallized from hot water to give the ®nal
product as yellow plates (yield: 67%). 1H NMR (D2O, 296 K):  4.30(s, 6H), 7.47 (m, 2H), 7.60 (m, 2H), 8.07 (d, 4H, J = 6.80 Hz), 8.26 (d,electronic reprint

Ken Sakai et al.  [Pt(C10H8N2)(C11H11N2)2](ClO4)4m513

metal-organic papers
4H, J = 6.80 Hz), 8.81 (d, 4H, J = 6.80 Hz), 9.22 p.p.m. (d, 4H, J =6.98 Hz).
Crystal data
[Pt(C10H8N2)(C11H11N2)2](ClO4)4
Mr = 1091.51
Monoclinic, P21 =nÊ
a = 10.0690 (9) AÊb = 35.111 (3) AÊc = 11.7298 (10) A= 101.835 (2)Ê3
V = 4058.8 (6) AZ=4Dx = 1.786 Mg mÿ3Mo K radiation
Cell parameters from 6625
re¯ections
 = 2.4±28.2
 = 3.80 mmÿ1
T = 296 (2) K
Plate, pale yellow
0.18  0.05  0.03 mm

Data collection
Bruker SMART APEX CCDdetector diffractometer! scans
Absorption correction: Gaussian(XPREP in SAINT; Bruker,2001)
Tmin = 0.251, Tmax = 0.531
25 018 measured re¯ections

9347 independent re¯ections
7198 re¯ections with I > 2(I)Rint = 0.080
max = 28.3
h = ÿ10 ! 13
k = ÿ45 ! 41
l = ÿ15 ! 14Re®nementRe®nement on F 2
R[F 2 > 2(F 2)] = 0.047
wR(F 2) = 0.126
S = 1.019347 re¯ections
511 parameters

H-atom parameters constrained
w = 1/[ 2(Fo2) + (0.0668P)2]
where P = (Fo2 + 2Fc2)/3(/)max = 0.001
Ê ÿ3max = 2.53 e AÊ ÿ3min = ÿ1.09 e A

Table 1

Ê ,  ).
Selected geometric parameters (APt1ÐN1
Pt1ÐN2
Pt1ÐN3
Pt1ÐN5

1.997 (4)2.009 (4)2.015 (4)2.028 (4)Pt1ÐPt1i
Pt1ÐPt1ii
Pt1ÐPt1iii

7.9822 (6)8.3972 (6)8.5707 (6)N1ÐPt1ÐN2N1ÐPt1ÐN3N2ÐPt1ÐN380.93 (18)177.29 (19)98.04 (19)N1ÐPt1ÐN5N2ÐPt1ÐN5N3ÐPt1ÐN596.22 (17)173.5 (2)85.05 (17)Symmetry codes: (i) 2 ÿ x; ÿy; 1 ÿ z; (ii) 2 ÿ x; ÿy; ÿz; (iii) 1 ÿ x; ÿy; ÿz.

For two of the four ClO4ÿ ions, O atoms (O9±O16) were treated as
disordered over two sites. For each disordered anion, isotropic
displacement parameters of O atoms were de®ned with a commonvalue. In each case, the occupation factors of the two sites werere®ned, showing that they were equal. As a result, their occupation
factors were all ®xed at 50%. In the re®nement of these disorderedÊ and the sixgroups, the ClÐO distances were restrained to 1.43 (3) Am514

Ken Sakai et al.  [Pt(C10H8N2)(C11H11N2)2](ClO4)4O  O distances within each perchlorate ion were restrained as equal.
One of the remaining ClO4ÿ ions was also judged to be partiallydisordered, in which only one of the four O atoms was assumed to bedisordered over two sites (O8A and O8B) with 50% population each.
Since a void problem was suggested by PLATON (Spek, 2003), an O
atom was located and re®ned isotropically, assuming the presence of awater molecule. However, the occupation factor of the atom
converged at 18 (1)%. Moreover, the difference Fourier map, without
inclusion of this atom in the model, did not show suf®cient electron
density in the void so we decided not to locate any atom within theÊ 3. All H atoms werevoid, which has an estimated volume of 41 A
Ê andlocated at their idealized positions (methyl CÐH = 0.96 AÊ ), and included in the re®nement in ridingaromatic CÐH = 0.93 A
motion approximation, with Uiso(H) = 1.5Ueq(C) and 1.2Ueq(C) for
methyl and aromatic H atoms, respectively. In the ®nal differenceÊ ÿ3
Fourier synthesis, six residual peaks in the range 1.17±2.53 e AÊwere observed within 1.08 A from Pt1. The deepest hole was locatedÊ from atom O16B.
0.18 A
Data collection: SMART (Bruker, 2001); cell re®nement: SAINT(Bruker, 2001); data reduction: SAINT; program(s) used to solve
structure: SHELXS97 (Sheldrick, 1997); program(s) used to re®nestructure: SHELXL97 (Sheldrick, 1997); molecular graphics: KENX(Sakai, 2002); software used to prepare material for publication:
SHELXL97, TEXSAN (Molecular Structure Corporation, 2001),
KENX and ORTEPII (Johnson, 1976).

This work was partly supported by a Grant-in-Aid for
Scienti®c Research (No. 14340223) from the Ministry ofEducation, Science, Sports, and Culture of Japan.

References
Bruker (2001). SAINT (Version 6.22) and SMART (Version 5.625). Bruker
AXS Inc., Madison, Wisconsin, USA.
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge NationalLaboratory, Tennessee, USA.
Molecular Structure Corporation (2001). TEXSAN, Version 1.11r1. MSC,9009 New Trails Drive, The Woodlands, TX 77381, USA.
Morgan, G. T. & Burstall, F. H. (1963). J. Chem. Soc. pp. 965±971.
Sakai, K. (2002). KENX. Tokyo University of Science, Japan.
Sakai, K., Kizaki, Y., Tsubomura, T. & Matsumoto, K. (1993). J. Mol. Catal. 74,141±152.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University ofGoÈttingen, Germany.
Spek, A. L. (2003). J. Appl. Cryst. 36, 7±13.
Van Emon, J., Hammock, B. & Seiber, J. N. (1986). Anal. Chem. 58, 1866±1873.

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Acta Cryst. (2003). E59, m512±m514