6,12-Dihydro­dipyrido[1,2-a:1′,2′-d]pyrazinium bis­(perchlorate)

Kim, N.-H.; Ha, K.

doi:10.1107/S1600536809032528

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 9| September 2009| Page o2203

doi:10.1107/S1600536809032528

Open

access

6,12-Dihydrodipyrido[1,2-a:1′,2′-d]pyrazinium bis(perchlorate)

Nam-Ho Kim ^a and Kwang Ha ^a ^*

^aSchool of Applied Chemical Engineering, the Research Institute of Catalysis, Chonnam National University, Gwangju 500-757, Republic of Korea
^*Correspondence e-mail: hakwang@chonnam.ac.kr

(Received 13 August 2009; accepted 17 August 2009; online 22 August 2009)

In the title compound, C₁₂H₁₂N₂²⁺·2ClO₄⁻, the dihedral angle between the two outer pyridine rings of the dication is 44.8 (1)°. In the crystal, weak intermolecular C—H⋯O hydrogen bonds occur.

Related literature

For the crystal structure of (C₁₂H₁₂N₂)Br₂, see: Bryce et al. (1985 ). For a MNDO (modified neglect of diatomic overlap) study of dipyridopyrazinium and related cations, see: Eaves et al. (1986 ).

Experimental

Crystal data

C₁₂H₁₂N₂²⁺·2ClO₄⁻
M_r = 383.14
Monoclinic, P 2₁ /c
a = 8.1632 (8) Å
b = 13.9396 (14) Å
c = 13.5903 (13) Å
β = 96.023 (2)°
V = 1537.9 (3) Å³
Z = 4
Mo Kα radiation
μ = 0.47 mm⁻¹
T = 296 K
0.22 × 0.16 × 0.10 mm

Data collection

Bruker SMART 1000 CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ) T_min = 0.646, T_max = 0.954
11269 measured reflections
3809 independent reflections
1871 reflections with I > 2σ(I)
R_int = 0.068

Refinement

R[F² > 2σ(F²)] = 0.058
wR(F²) = 0.163
S = 1.06
3809 reflections
217 parameters
H-atom parameters constrained
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯O1	0.93	2.49	3.358 (6)	156
C2—H2⋯O1ⁱ	0.93	2.57	3.160 (5)	122
C4—H4⋯O6ⁱ	0.93	2.54	3.228 (5)	132
C6—H6B⋯O3ⁱⁱ	0.97	2.56	3.343 (5)	137
C7—H7⋯O6ⁱⁱⁱ	0.93	2.45	3.249 (5)	144
C9—H9⋯O7^iv	0.93	2.44	3.190 (5)	138
Symmetry codes: (i) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (ii) x-1, y, z; (iii) $[-x, y+{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iv) $[x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]$ .

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997 ) and PLATON (Spek, 2009 ); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809032528/om2266sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809032528/om2266Isup2.hkl

checkCIF report

Comment top

The asymmetric unit of the title compound, C₁₂H₁₂N₂²⁺.2ClO₄^-, consists of a 6,12-dihydrodipyrido[1,2-a:1',2'-d]pyrazinium dication and two perchlorate counter-anions (Fig. 1). In the dication, two pyridine rings are linked by two methylene groups and the bridgehead N atoms are disposed on the opposite side of the central six-membered ring which adopts an eclipsed boat conforamtion. The two methylene C atoms (C6 and C12) lie practically on the pyridine ring planes with the largest deviations 0.046 (6) Å (C6) and 0.023 (6) Å (C12) from the respective least-squares planes, and the dihedral angles between these planes is 44.8 (1)°. The geometry of the ClO₄^- anions is nearly tetrahedral with the O—Cl—O bond angles of 107.4 (2)°–112.5 (2)°, and the Cl—O bond distances are almost equal (1.416 (3)–1.426 (3) Å). The compound displays intermolecular C—H···O hydrogen bonds (Table 1 and Fig. 2). There may also be weak intermolecular π-π interactions between adjacent pyridine rings, with a shortest centroid-centroid distance of 5.057 (2) Å.

Related literature top

For the crystal structure of (C₁₂H₁₂N₂)Br₂, see: Bryce et al. (1985). For a MNDO [define MNDO] study of dipyridopyrazinium and related cations, see: Eaves et al. (1986).

Experimental top

Single crystals of the title compound were unexpectedly obtained as a byproduct of an attempted preparation of an Mn(II) complex by reacting 2-(chloromethyl)pyridine hydrochloride (0.99 g, 6.04 mmol), 1,6-diaminohexane (0.17 g, 1.46 mmol), NaOH (for adjustment of pH 7–8) and Mn(ClO₄)₂.6H₂O (0.37 g, 1.02 mmol) in EtOH (10 ml) and H₂O (5 ml) for 2 h at 60 °C. Crystals suitable for X-ray analysis were obtained by slow evaporation from a CH₃CN solution of the orange reaction product.

Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The structure of the title compound, with displacement ellipsoids drawn at the 30% probability level for non-H atoms.
	Fig. 2. View of the unit-cell contents of the title compound. Hydrogen-bond interactions are drawn with dashed lines.

6,12-Dihydrodipyrido[1,2-a:1',2'-d]pyrazinium bis(perchlorate) top

Crystal data top

C₁₂H₁₂N₂²⁺·2ClO₄⁻	F(000) = 784
M_r = 383.14	D_x = 1.655 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2227 reflections
a = 8.1632 (8) Å	θ = 2.5–23.7°
b = 13.9396 (14) Å	µ = 0.47 mm⁻¹
c = 13.5903 (13) Å	T = 296 K
β = 96.023 (2)°	Block, colorless
V = 1537.9 (3) Å³	0.22 × 0.16 × 0.10 mm
Z = 4

Data collection top

Bruker SMART 1000 CCD diffractometer	3809 independent reflections
Radiation source: fine-focus sealed tube	1871 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.068
ϕ and ω scans	θ_max = 28.3°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −10→10
T_min = 0.646, T_max = 0.954	k = −18→16
11269 measured reflections	l = −15→18

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.163	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0561P)² + 0.3329P] where P = (F_o² + 2F_c²)/3
3809 reflections	(Δ/σ)_max < 0.001
217 parameters	Δρ_max = 0.39 e Å⁻³
0 restraints	Δρ_min = −0.48 e Å⁻³

Crystal data top

C₁₂H₁₂N₂²⁺·2ClO₄⁻	V = 1537.9 (3) Å³
M_r = 383.14	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 8.1632 (8) Å	µ = 0.47 mm⁻¹
b = 13.9396 (14) Å	T = 296 K
c = 13.5903 (13) Å	0.22 × 0.16 × 0.10 mm
β = 96.023 (2)°

Data collection top

Bruker SMART 1000 CCD diffractometer	3809 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2000)	1871 reflections with I > 2σ(I)
T_min = 0.646, T_max = 0.954	R_int = 0.068
11269 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.058	0 restraints
wR(F²) = 0.163	H-atom parameters constrained
S = 1.06	Δρ_max = 0.39 e Å⁻³
3809 reflections	Δρ_min = −0.48 e Å⁻³
217 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
N1	0.4245 (4)	0.3340 (2)	0.2124 (2)	0.0413 (8)
N2	0.1643 (4)	0.4419 (2)	0.2709 (2)	0.0424 (8)
C1	0.5777 (5)	0.3093 (3)	0.1934 (3)	0.0512 (11)
H1	0.6517	0.2840	0.2435	0.061*
C2	0.6240 (6)	0.3214 (3)	0.1007 (3)	0.0592 (12)
H2	0.7284	0.3025	0.0867	0.071*
C3	0.5151 (6)	0.3618 (3)	0.0275 (3)	0.0584 (12)
H3	0.5465	0.3718	−0.0356	0.070*
C4	0.3592 (5)	0.3872 (3)	0.0490 (3)	0.0518 (11)
H4	0.2849	0.4144	0.0004	0.062*
C5	0.3140 (4)	0.3723 (2)	0.1422 (3)	0.0360 (8)
C6	0.1484 (5)	0.3943 (3)	0.1727 (3)	0.0486 (10)
H6A	0.0892	0.4359	0.1240	0.058*
H6B	0.0860	0.3353	0.1759	0.058*
C7	0.0714 (5)	0.5186 (3)	0.2886 (3)	0.0528 (11)
H7	−0.0036	0.5428	0.2386	0.063*
C8	0.0869 (6)	0.5607 (3)	0.3796 (3)	0.0607 (12)
H8	0.0235	0.6140	0.3919	0.073*
C9	0.1978 (5)	0.5233 (3)	0.4535 (3)	0.0582 (12)
H9	0.2083	0.5505	0.5163	0.070*
C10	0.2924 (5)	0.4459 (3)	0.4336 (3)	0.0497 (10)
H10	0.3685	0.4211	0.4828	0.060*
C11	0.2753 (4)	0.4047 (2)	0.3413 (2)	0.0334 (8)
C12	0.3709 (5)	0.3198 (3)	0.3127 (3)	0.0444 (10)
H12A	0.4667	0.3107	0.3604	0.053*
H12B	0.3031	0.2627	0.3130	0.053*
Cl1	0.93531 (13)	0.21962 (7)	0.40847 (7)	0.0483 (3)
O1	0.7805 (4)	0.2646 (2)	0.4167 (2)	0.0735 (9)
O2	1.0582 (4)	0.2624 (3)	0.4763 (3)	0.1006 (13)
O3	0.9764 (4)	0.2311 (2)	0.3100 (2)	0.0798 (10)
O4	0.9247 (4)	0.1204 (2)	0.4313 (2)	0.0759 (10)
Cl2	0.38056 (13)	0.06673 (7)	0.22970 (8)	0.0508 (3)
O5	0.5488 (4)	0.0854 (3)	0.2602 (3)	0.0955 (12)
O6	0.2971 (4)	0.0624 (3)	0.3163 (2)	0.0988 (13)
O7	0.3618 (4)	−0.0210 (2)	0.1771 (2)	0.0821 (11)
O8	0.3058 (5)	0.1403 (2)	0.1684 (2)	0.0844 (11)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.047 (2)	0.0404 (18)	0.0363 (17)	−0.0034 (15)	0.0031 (15)	−0.0021 (14)
N2	0.0370 (18)	0.053 (2)	0.0378 (17)	−0.0020 (15)	0.0059 (15)	0.0048 (15)
C1	0.048 (3)	0.052 (3)	0.054 (3)	0.0070 (19)	0.006 (2)	−0.007 (2)
C2	0.054 (3)	0.078 (3)	0.048 (3)	0.002 (2)	0.020 (2)	−0.012 (2)
C3	0.065 (3)	0.068 (3)	0.044 (2)	−0.011 (2)	0.014 (2)	−0.011 (2)
C4	0.063 (3)	0.060 (3)	0.031 (2)	−0.009 (2)	0.000 (2)	0.0016 (19)
C5	0.038 (2)	0.040 (2)	0.0285 (18)	−0.0069 (17)	0.0014 (16)	−0.0012 (15)
C6	0.048 (3)	0.061 (3)	0.036 (2)	−0.006 (2)	−0.0005 (19)	−0.0014 (19)
C7	0.044 (3)	0.062 (3)	0.053 (3)	0.015 (2)	0.010 (2)	0.009 (2)
C8	0.065 (3)	0.059 (3)	0.061 (3)	0.018 (2)	0.021 (3)	−0.003 (2)
C9	0.067 (3)	0.065 (3)	0.044 (2)	−0.001 (2)	0.015 (2)	−0.007 (2)
C10	0.057 (3)	0.057 (3)	0.034 (2)	0.004 (2)	0.0051 (19)	−0.0004 (19)
C11	0.034 (2)	0.0347 (19)	0.0311 (18)	−0.0020 (15)	0.0029 (16)	0.0035 (15)
C12	0.054 (3)	0.044 (2)	0.035 (2)	0.0008 (19)	0.0062 (19)	0.0034 (17)
Cl1	0.0477 (6)	0.0519 (6)	0.0458 (6)	0.0002 (5)	0.0080 (5)	−0.0004 (5)
O1	0.062 (2)	0.088 (2)	0.073 (2)	0.0230 (18)	0.0171 (17)	0.0126 (18)
O2	0.086 (3)	0.098 (3)	0.108 (3)	−0.009 (2)	−0.035 (2)	−0.029 (2)
O3	0.103 (3)	0.083 (2)	0.061 (2)	−0.001 (2)	0.046 (2)	0.0076 (18)
O4	0.106 (3)	0.0527 (19)	0.071 (2)	0.0025 (18)	0.020 (2)	0.0110 (16)
Cl2	0.0563 (7)	0.0471 (6)	0.0472 (6)	0.0066 (5)	−0.0020 (5)	−0.0077 (5)
O5	0.055 (2)	0.120 (3)	0.107 (3)	−0.005 (2)	−0.015 (2)	−0.016 (2)
O6	0.085 (3)	0.166 (4)	0.048 (2)	0.000 (2)	0.0160 (19)	−0.012 (2)
O7	0.117 (3)	0.0503 (19)	0.072 (2)	0.0157 (18)	−0.021 (2)	−0.0168 (16)
O8	0.120 (3)	0.0476 (18)	0.078 (2)	0.0072 (18)	−0.026 (2)	0.0011 (16)

Geometric parameters (Å, º) top

N1—C1	1.348 (5)	C7—H7	0.9300
N1—C5	1.352 (4)	C8—C9	1.382 (6)
N1—C12	1.488 (4)	C8—H8	0.9300
N2—C7	1.346 (5)	C9—C10	1.370 (5)
N2—C11	1.351 (4)	C9—H9	0.9300
N2—C6	1.484 (5)	C10—C11	1.372 (5)
C1—C2	1.364 (6)	C10—H10	0.9300
C1—H1	0.9300	C11—C12	1.492 (5)
C2—C3	1.383 (6)	C12—H12A	0.9700
C2—H2	0.9300	C12—H12B	0.9700
C3—C4	1.382 (6)	Cl1—O2	1.420 (3)
C3—H3	0.9300	Cl1—O4	1.421 (3)
C4—C5	1.371 (5)	Cl1—O3	1.423 (3)
C4—H4	0.9300	Cl1—O1	1.426 (3)
C5—C6	1.487 (5)	Cl2—O5	1.416 (3)
C6—H6A	0.9700	Cl2—O7	1.417 (3)
C6—H6B	0.9700	Cl2—O8	1.418 (3)
C7—C8	1.363 (6)	Cl2—O6	1.421 (3)

C1—N1—C5	122.0 (3)	C7—C8—C9	119.2 (4)
C1—N1—C12	120.6 (3)	C7—C8—H8	120.4
C5—N1—C12	117.4 (3)	C9—C8—H8	120.4
C7—N2—C11	121.7 (3)	C10—C9—C8	119.6 (4)
C7—N2—C6	121.3 (3)	C10—C9—H9	120.2
C11—N2—C6	117.0 (3)	C8—C9—H9	120.2
N1—C1—C2	119.8 (4)	C9—C10—C11	120.3 (4)
N1—C1—H1	120.1	C9—C10—H10	119.9
C2—C1—H1	120.1	C11—C10—H10	119.9
C1—C2—C3	119.7 (4)	N2—C11—C10	118.9 (3)
C1—C2—H2	120.1	N2—C11—C12	116.7 (3)
C3—C2—H2	120.1	C10—C11—C12	124.4 (3)
C4—C3—C2	119.3 (4)	N1—C12—C11	110.2 (3)
C4—C3—H3	120.4	N1—C12—H12A	109.6
C2—C3—H3	120.4	C11—C12—H12A	109.6
C5—C4—C3	120.0 (4)	N1—C12—H12B	109.6
C5—C4—H4	120.0	C11—C12—H12B	109.6
C3—C4—H4	120.0	H12A—C12—H12B	108.1
N1—C5—C4	119.2 (3)	O2—Cl1—O4	108.8 (2)
N1—C5—C6	116.3 (3)	O2—Cl1—O3	110.1 (2)
C4—C5—C6	124.5 (4)	O4—Cl1—O3	109.87 (19)
N2—C6—C5	110.3 (3)	O2—Cl1—O1	109.6 (2)
N2—C6—H6A	109.6	O4—Cl1—O1	109.6 (2)
C5—C6—H6A	109.6	O3—Cl1—O1	108.8 (2)
N2—C6—H6B	109.6	O5—Cl2—O7	110.9 (2)
C5—C6—H6B	109.6	O5—Cl2—O8	112.5 (2)
H6A—C6—H6B	108.1	O7—Cl2—O8	108.15 (19)
N2—C7—C8	120.3 (4)	O5—Cl2—O6	107.4 (2)
N2—C7—H7	119.8	O7—Cl2—O6	110.2 (2)
C8—C7—H7	119.8	O8—Cl2—O6	107.6 (2)

C5—N1—C1—C2	−1.1 (6)	C11—N2—C7—C8	−0.4 (6)
C12—N1—C1—C2	179.0 (3)	C6—N2—C7—C8	179.4 (4)
N1—C1—C2—C3	2.1 (6)	N2—C7—C8—C9	−0.5 (6)
C1—C2—C3—C4	−1.6 (6)	C7—C8—C9—C10	1.2 (6)
C2—C3—C4—C5	0.1 (6)	C8—C9—C10—C11	−1.1 (6)
C1—N1—C5—C4	−0.5 (5)	C7—N2—C11—C10	0.5 (5)
C12—N1—C5—C4	179.5 (3)	C6—N2—C11—C10	−179.2 (3)
C1—N1—C5—C6	178.8 (3)	C7—N2—C11—C12	−179.9 (3)
C12—N1—C5—C6	−1.3 (5)	C6—N2—C11—C12	0.3 (4)
C3—C4—C5—N1	0.9 (6)	C9—C10—C11—N2	0.2 (6)
C3—C4—C5—C6	−178.2 (4)	C9—C10—C11—C12	−179.3 (4)
C7—N2—C6—C5	136.2 (4)	C1—N1—C12—C11	137.8 (3)
C11—N2—C6—C5	−44.1 (4)	C5—N1—C12—C11	−42.2 (4)
N1—C5—C6—N2	44.5 (4)	N2—C11—C12—N1	42.6 (4)
C4—C5—C6—N2	−136.4 (4)	C10—C11—C12—N1	−137.9 (4)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···O1	0.93	2.49	3.358 (6)	156
C2—H2···O1ⁱ	0.93	2.57	3.160 (5)	122
C4—H4···O6ⁱ	0.93	2.54	3.228 (5)	132
C6—H6B···O3ⁱⁱ	0.97	2.56	3.343 (5)	137
C7—H7···O6ⁱⁱⁱ	0.93	2.45	3.249 (5)	144
C9—H9···O7^iv	0.93	2.44	3.190 (5)	138

Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) x−1, y, z; (iii) −x, y+1/2, −z+1/2; (iv) x, −y+1/2, z+1/2.

Experimental details

Crystal data
Chemical formula	C₁₂H₁₂N₂²⁺·2ClO₄⁻
M_r	383.14
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	296
a, b, c (Å)	8.1632 (8), 13.9396 (14), 13.5903 (13)
β (°)	96.023 (2)
V (Å³)	1537.9 (3)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.47
Crystal size (mm)	0.22 × 0.16 × 0.10

Data collection
Diffractometer	Bruker SMART 1000 CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2000)
T_min, T_max	0.646, 0.954
No. of measured, independent and observed [I > 2σ(I)] reflections	11269, 3809, 1871
R_int	0.068
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.058, 0.163, 1.06
No. of reflections	3809
No. of parameters	217
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.39, −0.48

Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···O1	0.93	2.49	3.358 (6)	155.5
C2—H2···O1ⁱ	0.93	2.57	3.160 (5)	121.9
C4—H4···O6ⁱ	0.93	2.54	3.228 (5)	131.6
C6—H6B···O3ⁱⁱ	0.97	2.56	3.343 (5)	137.4
C7—H7···O6ⁱⁱⁱ	0.93	2.45	3.249 (5)	144.2
C9—H9···O7^iv	0.93	2.44	3.190 (5)	138.0

Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) x−1, y, z; (iii) −x, y+1/2, −z+1/2; (iv) x, −y+1/2, z+1/2.

Acknowledgements

This work was supported by the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (KRF-2007–412-J02001).

References

Bruker (2000). SADABS, SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bryce, M. R., Eaves, J. G., Parker, D., Howard, J. A. K. & Johnson, O. (1985). J. Chem. Soc. Perkin Trans. 2, pp. 433–436. CSD CrossRef Google Scholar
Eaves, J. G., Parker, D. & Rudgewick-Brown, N. (1986). Can. J. Chem. 64, 1711–1713. CrossRef CAS Web of Science Google Scholar
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565. CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Spek, A. L. (2009). Acta Cryst. D65, 148–155. Web of Science CrossRef CAS IUCr Journals Google Scholar