1,2-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)­oxy]ethane

Nikolayenko, V.I.; Akerman, M.P.; Grimmer, C.D.; Reddy, D.

doi:10.1107/S1600536812030292

organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 68| Part 8| August 2012| Pages o2384-o2385

https://doi.org/10.1107/S1600536812030292

Open

access

1,2-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)oxy]ethane

Varvara I. Nikolayenko,^a ^* Matthew P. Akerman,^a Craig D. Grimmer ^a and Desigan Reddy ^a

^aSchool of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, Pietermaritzburg, South Africa
^*Correspondence e-mail: 207513620@stu.ukzn.ac.za

(Received 26 June 2012; accepted 3 July 2012; online 7 July 2012)

The title compound, C₃₂H₂₄N₆O₂, has an inversion centre located at the mid-point of the central C—C bond of the diether bridging unit. The terminal pyridine rings are canted relative to the central pyridine ring, with dihedral angles of 12.98 (6) and 26.80 (6)°. The maximum deviation from the eight-atom mean plane, defined by the two bridging O and C atoms and the central pyridine ring, is 0.0383 (10)° for the N atom.

Related literature

For the structure of the un-substituted 2,2′:6′,2′′-terpyridine compound, see: Bessel et al. (1992 ). For the structure of the precursor to the title compound, 4′-chloro-2,2′:6′,2′′-terpyridine, see: Beves et al. (2006 ). For the structure of 1,4-bis[(2,2′:6′,2′′-terpyridin-4′-yl)oxy]butane, see: Akerman et al. (2011 ). For the structure of 1,6-bis[(2,2′:6′,2′′-terpyridin-4′-yl)oxy]hexane, see: Nikolayenko et al. (2012 ). For a full review of functionalized 2,2′:6′,2′′-terpyridine complexes, see: Fallahpour (2003 ); Heller & Schubert (2003 ). For a comprehensive summary of platinum(II) terpyridines, see: Newkome et al. (2008 ). For the structure of bis(2,2′:6′,2′′-terpyridyl) ether, see: Constable et al. (1995 ). For the syntheses and structures of related bis(terpyridine) structures linked by an alkoxy spacer, see: Constable et al. (2006 ). For the syntheses of diol-bridged terpyridines, see: Constable et al. (2005 ); Van der Schilden (2006 ).

Experimental

Crystal data

C₃₂H₂₄N₆O₂
M_r = 524.58
Triclinic, $[P \overline 1]$
a = 6.2576 (6) Å
b = 10.0851 (9) Å
c = 10.2388 (9) Å
α = 93.850 (6)°
β = 98.760 (6)°
γ = 102.468 (5)°
V = 620.20 (10) Å³
Z = 1
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 100 K
0.20 × 0.10 × 0.05 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2010 ) T_min = 0.982, T_max = 0.996
8371 measured reflections
4459 independent reflections
3364 reflections with I > 2σ(I)
R_int = 0.041

Refinement

R[F² > 2σ(F²)] = 0.062
wR(F²) = 0.182
S = 1.04
4459 reflections
181 parameters
H-atom parameters constrained
Δρ_max = 0.77 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT-Plus (Bruker, 2010); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXL97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: WinGX (Farrugia, 1999 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536812030292/fj2578sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812030292/fj2578Isup2.hkl

Supporting information file. DOI: https://doi.org/10.1107/S1600536812030292/fj2578Isup3.cml

checkCIF report

Comment top

The title compound is the last in a series of ligands developed in an effort to boost multifunctional activity. Coordination of these ligands to platinum(II) should enable covalent binding of DNA through both metal centres, thus increasing the number of adducts formed. Furthermore the presence of the flexible diol derived linkage will provide the complex with the potential to engage in long range interactions with DNA.

The ligand crystallized in the triclinic space group P1, with a half molecule in the asymmetric unit and Z = 1. Crystallographically imposed inversion symmetry relates the two halves of the ligand to one another. The inversion centre is located at the mid-point of the diol linkage unit. The three pyridine rings adopt a trans, trans conformation. The same configuration is observed in the other ligands of this series with butyl and hexyl diol linkages (Akerman et al., 2011; Nikolayenko et al., 2012). The parent compound 4'-chloro-2,2':6',2''-terpyridine (Beves et al. 2006), and uncoordinated terpyridine ligands in general show the same configuration.

The central pyridine ring of the terpyridine moeity is in the same plane as the bridging diol chain. The terminal pyridine rings of the terpyridine ligand are, however, canted relative to the central pyridine ring. The C7—C6—C5—N1 torsion angle is 25.9 (2)° while the C9—C10—C11—N3 torsion angle is 11.9 (2)° (refer to Fig. 1 for the atom numbering scheme). The large torsion angle of the pyridine ring containing N1 is seemingly to allow for hydrogen bonding between the pyridine nitrogen atom N1 and the pyridine hydrogen atom H3 of an adjacent molecule. This hydrogen bond links the molecules into an infinite, one-dimensional chain (Fig. 2). The hydrogen bonded chain is co-linear with the a-axis. The hydrogen bond lengths and bond angles are summarized in Table 1. Although the hydrogen bond length does not necessarily correlate linearly with bond strength, due to packing constraints, the interaction is relatively long and it is therefore likely to be a weak interaction. There is no indication of meaningful π–π or C—H···π interactions in the lattice, which are often observed in terpyridine structures (Beves et al. 2006).

Related literature top

For the structure of the un-substituted 2,2':6',2''-terpyridine compound, see: Bessel et al. (1992). For the structure of the precursor to the title compound, 4'-chloro-2,2':6',2''-terpyridine, see: Beves et al. (2006). For the structure of the 1,4-bis[(2,2':6',2''-terpyridin-4'-yl)oxy]-butane, see: Akerman et al. (2011). For the structure of 1,6-bis[(2,2':6',2''-terpyridin-4'-yl)oxy]-hexane, see: Nikolayenko et al. (2012). For a full review of functionalized 2,2':6',2''-terpyridine complexes, see: Fallahpour (2003); Heller & Schubert (2003). For a comprehensive summary of platinum(II) terpyridines, see: Newkome et al. (2008). For the structure of bis(2,2':6',2''-terpyridyl)ether, see: Constable et al. (1995). For the syntheses and structures of related bis(terpyridine) structures linked by an alkoxy spacer, see: Constable et al. (2006). For the syntheses of diol-bridged terpyridines, see: Constable et al. (2005); Van der Schilden (2006).

Experimental top

The title compound was prepared by an adaptation of a previously described method (Van der Schilden, 2006; Constable et al., 2005). Ethanediol (1.13 mmol) was added to a suspension of ground potassium hydroxide (6.69 mmol) in DMSO (30 ml). The solution was heated to reflux for 1 h after which 4'-chloro-2,2':6'2''-terpyridine (2.23 mmol) was added. The mixture was again brought to reflux for an additional 24 h. After cooling to room temperature, the brown mixture was added to cold water (100 ml). The resulting off-white precipitate was collected, rinsed with cold ethanol and air dried. Single crystals were grown by slow liquid diffusion of n-hexane into a chloroform solution of the compound.

Structure description top

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT-Plus (Bruker, 2010); data reduction: SAINT-Plus (Bruker, 2010); program(s) used to solve structure: SHELXL97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: WinGX (Farrugia, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

	Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at 50% probability level.
	Fig. 2. A view of packing of the title compound.

1,2-Bis[(2,2':6',2''-terpyridin-4'-yl)oxy]ethane top

Crystal data top

C₃₂H₂₄N₆O₂	Z = 1
M_r = 524.58	F(000) = 274
Triclinic, P1	D_x = 1.405 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.2576 (6) Å	Cell parameters from 3364 reflections
b = 10.0851 (9) Å	θ = 2.0–32.8°
c = 10.2388 (9) Å	µ = 0.09 mm⁻¹
α = 93.850 (6)°	T = 100 K
β = 98.760 (6)°	Needle, colourless
γ = 102.468 (5)°	0.20 × 0.10 × 0.05 mm
V = 620.20 (10) Å³

Data collection top

Bruker APEXII CCD diffractometer	4459 independent reflections
Radiation source: fine-focus sealed tube	3364 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.041
ω and φ scans	θ_max = 32.8°, θ_min = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2010)	h = −9→8
T_min = 0.982, T_max = 0.996	k = −15→15
8371 measured reflections	l = −15→15

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)] = 0.062	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.182	H-atom parameters constrained
S = 1.04	w = 1/[σ²(F_o²) + (0.1018P)² + 0.0609P] where P = (F_o² + 2F_c²)/3
4459 reflections	(Δ/σ)_max = 0.001
181 parameters	Δρ_max = 0.77 e Å⁻³
0 restraints	Δρ_min = −0.27 e Å⁻³

Crystal data top

C₃₂H₂₄N₆O₂	γ = 102.468 (5)°
M_r = 524.58	V = 620.20 (10) Å³
Triclinic, P1	Z = 1
a = 6.2576 (6) Å	Mo Kα radiation
b = 10.0851 (9) Å	µ = 0.09 mm⁻¹
c = 10.2388 (9) Å	T = 100 K
α = 93.850 (6)°	0.20 × 0.10 × 0.05 mm
β = 98.760 (6)°

Data collection top

Bruker APEXII CCD diffractometer	4459 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2010)	3364 reflections with I > 2σ(I)
T_min = 0.982, T_max = 0.996	R_int = 0.041
8371 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.062	0 restraints
wR(F²) = 0.182	H-atom parameters constrained
S = 1.04	Δρ_max = 0.77 e Å⁻³
4459 reflections	Δρ_min = −0.27 e Å⁻³
181 parameters

Special details top

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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
C1	0.8540 (2)	0.33313 (15)	0.60520 (14)	0.0283 (3)
H1	0.7963	0.3499	0.6837	0.034*
C2	1.0660 (2)	0.30976 (14)	0.61813 (14)	0.0269 (3)
H2	1.1508	0.3100	0.7034	0.032*
C3	1.1514 (2)	0.28615 (14)	0.50440 (14)	0.0250 (3)
H3	1.2977	0.2721	0.5101	0.030*
C4	1.0195 (2)	0.28323 (13)	0.38123 (13)	0.0208 (3)
H4	1.0724	0.2648	0.3013	0.025*
C5	0.80907 (19)	0.30792 (12)	0.37783 (12)	0.0166 (2)
C6	0.66344 (19)	0.30803 (12)	0.24834 (11)	0.0162 (2)
C7	0.5019 (2)	0.38379 (12)	0.24126 (12)	0.0174 (2)
H7	0.4845	0.4371	0.3173	0.021*
C8	0.36599 (19)	0.37913 (11)	0.11862 (12)	0.0164 (2)
C9	0.3930 (2)	0.29829 (12)	0.01032 (12)	0.0175 (2)
H9	0.2993	0.2913	−0.0733	0.021*
C10	0.56189 (19)	0.22744 (11)	0.02768 (12)	0.0163 (2)
C11	0.5964 (2)	0.14184 (12)	−0.08808 (12)	0.0176 (2)
C12	0.7865 (2)	0.09098 (13)	−0.08388 (13)	0.0216 (3)
H12	0.8959	0.1077	−0.0057	0.026*
C13	0.8136 (2)	0.01537 (14)	−0.19586 (14)	0.0263 (3)
H13	0.9440	−0.0183	−0.1966	0.032*
C14	0.6474 (3)	−0.01030 (14)	−0.30669 (14)	0.0286 (3)
H14	0.6605	−0.0627	−0.3845	0.034*
C15	0.4620 (3)	0.04248 (14)	−0.30107 (14)	0.0277 (3)
H15	0.3471	0.0234	−0.3765	0.033*
C16	0.07750 (19)	0.45488 (12)	−0.01226 (11)	0.0167 (2)
H16A	−0.0069	0.3610	−0.0461	0.020*
H16B	0.1703	0.4909	−0.0778	0.020*
N1	0.72577 (19)	0.33330 (12)	0.48743 (11)	0.0235 (2)
N2	0.69872 (17)	0.23327 (10)	0.14323 (10)	0.0170 (2)
N3	0.4356 (2)	0.11876 (11)	−0.19559 (11)	0.0231 (2)
O1	0.21257 (15)	0.45611 (9)	0.11416 (8)	0.0196 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
C1	0.0317 (7)	0.0380 (7)	0.0155 (6)	0.0149 (6)	−0.0030 (5)	−0.0009 (5)
C2	0.0312 (7)	0.0294 (6)	0.0178 (6)	0.0113 (5)	−0.0085 (5)	0.0004 (5)
C3	0.0227 (6)	0.0284 (6)	0.0231 (6)	0.0116 (5)	−0.0060 (5)	0.0004 (5)
C4	0.0200 (5)	0.0256 (6)	0.0177 (6)	0.0111 (4)	−0.0015 (4)	0.0004 (4)
C5	0.0185 (5)	0.0175 (5)	0.0138 (5)	0.0074 (4)	−0.0016 (4)	0.0011 (4)
C6	0.0174 (5)	0.0184 (5)	0.0135 (5)	0.0077 (4)	−0.0004 (4)	0.0020 (4)
C7	0.0195 (5)	0.0191 (5)	0.0145 (5)	0.0095 (4)	−0.0006 (4)	0.0007 (4)
C8	0.0170 (5)	0.0170 (5)	0.0164 (5)	0.0085 (4)	−0.0004 (4)	0.0025 (4)
C9	0.0199 (5)	0.0192 (5)	0.0141 (5)	0.0092 (4)	−0.0015 (4)	0.0012 (4)
C10	0.0181 (5)	0.0166 (5)	0.0148 (5)	0.0075 (4)	−0.0001 (4)	0.0007 (4)
C11	0.0218 (5)	0.0166 (5)	0.0150 (5)	0.0080 (4)	0.0003 (4)	0.0005 (4)
C12	0.0251 (6)	0.0205 (5)	0.0201 (6)	0.0110 (4)	−0.0005 (4)	−0.0003 (4)
C13	0.0348 (7)	0.0236 (6)	0.0247 (7)	0.0154 (5)	0.0060 (5)	0.0007 (5)
C14	0.0449 (8)	0.0234 (6)	0.0188 (6)	0.0127 (6)	0.0046 (5)	−0.0028 (5)
C15	0.0399 (8)	0.0247 (6)	0.0162 (6)	0.0103 (5)	−0.0044 (5)	−0.0037 (5)
C16	0.0175 (5)	0.0184 (5)	0.0148 (5)	0.0089 (4)	−0.0022 (4)	0.0015 (4)
N1	0.0245 (5)	0.0319 (6)	0.0155 (5)	0.0141 (4)	−0.0016 (4)	−0.0004 (4)
N2	0.0190 (5)	0.0179 (4)	0.0146 (5)	0.0081 (4)	−0.0007 (3)	0.0007 (3)
N3	0.0292 (6)	0.0233 (5)	0.0158 (5)	0.0103 (4)	−0.0034 (4)	−0.0019 (4)
O1	0.0219 (4)	0.0248 (4)	0.0145 (4)	0.0155 (3)	−0.0033 (3)	−0.0008 (3)

Geometric parameters (Å, º) top

C1—N1	1.3431 (16)	C9—H9	0.9500
C1—C2	1.385 (2)	C10—N2	1.3404 (14)
C1—H1	0.9500	C10—C11	1.4891 (16)
C2—C3	1.381 (2)	C11—N3	1.3437 (14)
C2—H2	0.9500	C11—C12	1.3895 (17)
C3—C4	1.3928 (16)	C12—C13	1.3865 (18)
C3—H3	0.9500	C12—H12	0.9500
C4—C5	1.3879 (16)	C13—C14	1.3859 (19)
C4—H4	0.9500	C13—H13	0.9500
C5—N1	1.3393 (17)	C14—C15	1.384 (2)
C5—C6	1.4902 (15)	C14—H14	0.9500
C6—N2	1.3457 (15)	C15—N3	1.3354 (17)
C6—C7	1.3889 (15)	C15—H15	0.9500
C7—C8	1.3972 (15)	C16—O1	1.4318 (13)
C7—H7	0.9500	C16—C16ⁱ	1.502 (2)
C8—O1	1.3564 (13)	C16—H16A	0.9900
C8—C9	1.3849 (16)	C16—H16B	0.9900
C9—C10	1.3945 (15)

N1—C1—C2	123.44 (13)	N2—C10—C11	117.52 (10)
N1—C1—H1	118.3	C9—C10—C11	118.88 (10)
C2—C1—H1	118.3	N3—C11—C12	122.67 (11)
C3—C2—C1	118.57 (11)	N3—C11—C10	116.21 (10)
C3—C2—H2	120.7	C12—C11—C10	121.12 (10)
C1—C2—H2	120.7	C13—C12—C11	118.78 (11)
C2—C3—C4	118.90 (12)	C13—C12—H12	120.6
C2—C3—H3	120.6	C11—C12—H12	120.6
C4—C3—H3	120.6	C14—C13—C12	118.95 (12)
C5—C4—C3	118.52 (12)	C14—C13—H13	120.5
C5—C4—H4	120.7	C12—C13—H13	120.5
C3—C4—H4	120.7	C15—C14—C13	118.25 (12)
N1—C5—C4	123.13 (10)	C15—C14—H14	120.9
N1—C5—C6	116.44 (10)	C13—C14—H14	120.9
C4—C5—C6	120.42 (11)	N3—C15—C14	123.72 (12)
N2—C6—C7	123.58 (10)	N3—C15—H15	118.1
N2—C6—C5	116.82 (9)	C14—C15—H15	118.1
C7—C6—C5	119.60 (10)	O1—C16—C16ⁱ	105.29 (11)
C6—C7—C8	117.85 (10)	O1—C16—H16A	110.7
C6—C7—H7	121.1	C16ⁱ—C16—H16A	110.7
C8—C7—H7	121.1	O1—C16—H16B	110.7
O1—C8—C9	123.90 (10)	C16ⁱ—C16—H16B	110.7
O1—C8—C7	116.52 (10)	H16A—C16—H16B	108.8
C9—C8—C7	119.58 (10)	C5—N1—C1	117.40 (11)
C8—C9—C10	118.00 (10)	C10—N2—C6	117.30 (9)
C8—C9—H9	121.0	C15—N3—C11	117.59 (11)
C10—C9—H9	121.0	C8—O1—C16	116.69 (9)
N2—C10—C9	123.59 (10)

N1—C1—C2—C3	0.4 (2)	C9—C10—C11—C12	167.31 (12)
C1—C2—C3—C4	−1.6 (2)	N3—C11—C12—C13	1.2 (2)
C2—C3—C4—C5	1.72 (19)	C10—C11—C12—C13	−178.02 (12)
C3—C4—C5—N1	−0.60 (19)	C11—C12—C13—C14	−1.9 (2)
C3—C4—C5—C6	179.03 (11)	C12—C13—C14—C15	0.8 (2)
N1—C5—C6—N2	−154.39 (12)	C13—C14—C15—N3	1.2 (2)
C4—C5—C6—N2	25.96 (17)	C4—C5—N1—C1	−0.62 (19)
N1—C5—C6—C7	25.91 (17)	C6—C5—N1—C1	179.74 (12)
C4—C5—C6—C7	−153.74 (12)	C2—C1—N1—C5	0.7 (2)
N2—C6—C7—C8	1.52 (19)	C9—C10—N2—C6	2.55 (18)
C5—C6—C7—C8	−178.80 (11)	C11—C10—N2—C6	−178.40 (11)
C6—C7—C8—O1	−178.82 (11)	C7—C6—N2—C10	−3.38 (18)
C6—C7—C8—C9	1.27 (18)	C5—C6—N2—C10	176.93 (10)
O1—C8—C9—C10	178.08 (11)	C14—C15—N3—C11	−1.9 (2)
C7—C8—C9—C10	−2.02 (18)	C12—C11—N3—C15	0.7 (2)
C8—C9—C10—N2	0.09 (19)	C10—C11—N3—C15	179.90 (13)
C8—C9—C10—C11	−178.94 (11)	C9—C8—O1—C16	−1.95 (18)
N2—C10—C11—N3	168.96 (11)	C7—C8—O1—C16	178.14 (10)
C9—C10—C11—N3	−11.94 (18)	C16ⁱ—C16—O1—C8	178.97 (12)
N2—C10—C11—C12	−11.79 (18)

Symmetry code: (i) −x, −y+1, −z.

Experimental details

Crystal data
Chemical formula	C₃₂H₂₄N₆O₂
M_r	524.58
Crystal system, space group	Triclinic, P1
Temperature (K)	100
a, b, c (Å)	6.2576 (6), 10.0851 (9), 10.2388 (9)
α, β, γ (°)	93.850 (6), 98.760 (6), 102.468 (5)
V (Å³)	620.20 (10)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.20 × 0.10 × 0.05

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2010)
T_min, T_max	0.982, 0.996
No. of measured, independent and observed [I > 2σ(I)] reflections	8371, 4459, 3364
R_int	0.041
(sin θ/λ)_max (Å⁻¹)	0.761

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.062, 0.182, 1.04
No. of reflections	4459
No. of parameters	181
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.77, −0.27

Computer programs: APEX2 (Bruker, 2010), SAINT-Plus (Bruker, 2010), SHELXL97 (Sheldrick, 2008), WinGX (Farrugia, 1999), publCIF (Westrip, 2010).

Acknowledgements

The authors thank the Univeristy of Kwazulu-Natal for supporting this research by providing both funding and facilities.

References

Akerman, M. P., Grimmer, C. D., Nikolayenko, V. I. & Reddy, D. (2011). Acta Cryst. E67, o3478–o3479. Web of Science CSD CrossRef IUCr Journals Google Scholar
Bessel, C. A., See, R. F., Jameson, D. L., Churchill, M. R. & Takeuchi, K. J. (1992). J. Chem. Soc. Dalton Trans. pp. 3223–3228. CSD CrossRef Web of Science Google Scholar
Beves, J. E., Constable, E. C., Housecroft, C. E., Neuburger, M. & Schaffner, S. (2006). Acta Cryst. E62, o2497–o2498. Web of Science CSD CrossRef IUCr Journals Google Scholar
Bruker (2010). APEX2, SAINT and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Constable, E. C., Chow, H. S., Housecroft, C. E., Neuburger, M. & Schaffner, S. (2006). Polyhedron, 25, 1831–1843. Google Scholar
Constable, E. C., Housecroft, C. E., Neuburger, M., Schaffner, S. & Smith, C. B. (2005). Dalton Trans. pp. 2259–2267. Web of Science CSD CrossRef Google Scholar
Constable, E. C., Thompson, A. M., Harveson, P., Macko, L. & Zehnder, M. (1995). Chem. Eur. J. 1, 360–367. CrossRef CAS Web of Science Google Scholar
Fallahpour, R. A. (2003). Synthesis, 2, 155–184. Web of Science CrossRef Google Scholar
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837–838. CrossRef CAS IUCr Journals Google Scholar
Heller, M. & Schubert, U. S. (2003). Eur. J. Org. Chem. 6, 947–961. CrossRef Google Scholar
Newkome, G. R., Eryazici, I. & Moorefield, C. N. (2008). Chem. Rev. 108, 1834–1895. Web of Science PubMed Google Scholar
Nikolayenko, V. I., Akerman, M. P., Grimmer, C. D. & Reddy, D. (2012). Acta Cryst. E68, o2272–o2273. CSD CrossRef IUCr Journals Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Van der Schilden, K. (2006). PhD Thesis, Leiden University, The Netherlands. Google Scholar
Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925. Web of Science CrossRef CAS IUCr Journals Google Scholar