4-Bromo-N-(diisopropoxyphosphor­yl)benzamide

Strasser, C.E.; Sheng, X.; Safin, D.A.; Raubenheimer, H.G.; Luckay, R.C.

doi:10.1107/S1600536809044523

organic compounds

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ISSN: 2056-9890

Volume 65| Part 11| November 2009| Page o2926

https://doi.org/10.1107/S1600536809044523

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4-Bromo-N-(diisopropoxyphosphoryl)benzamide

Christoph E. Strasser,^a Xia Sheng,^a Damir A. Safin,^b Helgard G. Raubenheimer ^a and Robert C. Luckay ^a ^*

^aDepartment of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland, 7602, South Africa, and ^bA. M. Butlerov Chemistry Institute, Kazan State University, Kremlevskaya Street 18, 420008 Kazan, Russian Federation
^*Correspondence e-mail: rcluckay@sun.ac.za

(Received 11 October 2009; accepted 26 October 2009; online 31 October 2009)

In the title compound, C₁₃H₁₉BrNO₄P, the crystal structure is stabilized by intermolecular N—H⋯O hydrogen bonds between the phosphoryl O atom and the amide N atom which link the molecules into centrosymmetric dimers. These dimers are further packed into stacks along the c axis by intermolecular C—H⋯O and C—H⋯π interactions.

Related literature

For the synthesis, see: Safin, Sokolov, Baranov et al. (2008 ). For related structures, see: Chekhlov (1990 ); Safin et al. (2009 ); Safin, Sokolov, Nöth et al. (2008 ); Solov'ev et al. (1990 ). For the chemistry of phosphine derivatives of urea and thiourea, see: Birdsall et al. (1999 ). For the use of bidentate organophosphorus ligand systems, see: Crespo et al. (2004 ); Safin et al. (2006 ) and for the transport and extraction of metal ions, see: Luckay et al. (2009a ,b ).

Experimental

Crystal data

C₁₃H₁₉BrNO₄P
M_r = 364.17
Monoclinic, P 2₁ /n
a = 8.611 (1) Å
b = 19.786 (3) Å
c = 9.849 (1) Å
β = 95.357 (2)°
V = 1670.7 (4) Å³
Z = 4
Mo Kα radiation
μ = 2.57 mm⁻¹
T = 100 K
0.32 × 0.07 × 0.05 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2002 ) T_min = 0.494, T_max = 0.893
9035 measured reflections
3405 independent reflections
2604 reflections with I > 2σ(I)
R_int = 0.038

Refinement

R[F² > 2σ(F²)] = 0.044
wR(F²) = 0.120
S = 1.05
3405 reflections
185 parameters
H-atom parameters constrained
Δρ_max = 1.29 e Å⁻³
Δρ_min = −0.65 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱ	0.88	1.96	2.819 (3)	166
C3—H3⋯O4ⁱⁱ	0.95	2.29	3.213 (4)	163
C6—H6⋯O1ⁱ	0.95	2.48	3.241 (3)	137
C16—H16C⋯Cgⁱⁱⁱ	0.98	2.63	3.608 (4)	173
Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) $[x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (iii) x, y, z+1. Cg is the centroid of the C1–C6 benzene ring.

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2003 ); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ; Atwood & Barbour, 2003 ); software used to prepare material for publication: X-SEED.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536809044523/lx2117sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536809044523/lx2117Isup2.hkl

checkCIF report

Comment top

The chemistry of phosphine derivatives of urea and thiourea was first studied during the 1960 s (Birdsall et al., 1999). Subsequently, related bidentate organophosphorus ligand systems were developed to form R¹C(X)NHPR₂ and their derivatives (Safin et al., 2006). Different R¹C(X)NHP(Y)R²R³ (R¹ = RNH or NZ₂ with Z = H, alkyl or aryl; R², R³ = alkyl, aryl, alkoxy or aryloxy; X, Y = O, S, Se) have been reported (Crespo et al., 2004). These types of ligands have recently been used successfully as ionophores for the transport and extraction of a number of metal ions (Luckay et al., 2009a, 2009b). Here we report the crystal structure of the title compound (I) (Fig. 1).

The crystal structure is stabilized by intermolecular N—H···O hydrogen bonds between the phosphoryl O atom and the amide N atom which link the molecules into centrosymmetric dimers (Table 1 and Fig. 2). These dimers are further packed into stacks along the c axis by intermolecular C—H···O and C—H···π interactions; the first between the benzene H atom and the oxygen of the C═O unit, with a C3—H3···O4ⁱⁱ, the second between the benzene H atom and the oxygen of the P═O unit, with a C6—H6···O1ⁱ, the third between the methyl H atom of the isopropyl group and the benzene ring, with a C16—H16C···Cgⁱⁱⁱ (Cg is the centroid of the C1–C6 benzene ring), respectively (Table 1 and Fig. 2).

Related literature top

For the synthesis, see: Safin, Sokolov, Baranov et al. (2008). For related structures, see: Chekhlov (1990); Safin et al. (2009); Safin, Sokolov, Nöth et al. (2008); Solov"ev et al. (1990). For chemistry of phosphine derivatives of urea and thiourea, see: Birdsall et al. (1999). For the use of bidentate organophosphorus ligand systems (Crespo et al., 2004; Safin et al., 2006) for the transport and extraction of metal ions, see: Luckay et al. (2009a,b). Cg is the centroid of the C1–C6 benzene ring.

Experimental top

4-bromo-N-(diisopropoxyphosphoryl)benzthioamide was prepared according to the procedure of Safin et al. (2009). This ligand and one equivalent of copper(I) iodide was dissolved in acetone and heated to 50 °C for 2 hours. The colourless powder obtained was dissolved in a minimal quantity of THF and allowed to slowly evaporate. After 6 days, colourless needles were deposited. The hydrolysis of the thione group group was most likely caused by the presence of moisture in the solvents as well as the presence of the Cu⁺ ion.

Structure description top

For the synthesis, see: Safin, Sokolov, Baranov et al. (2008). For related structures, see: Chekhlov (1990); Safin et al. (2009); Safin, Sokolov, Nöth et al. (2008); Solov"ev et al. (1990). For chemistry of phosphine derivatives of urea and thiourea, see: Birdsall et al. (1999). For the use of bidentate organophosphorus ligand systems (Crespo et al., 2004; Safin et al., 2006) for the transport and extraction of metal ions, see: Luckay et al. (2009a,b). Cg is the centroid of the C1–C6 benzene ring.

Computing details top

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001; Atwood & Barbour, 2003); software used to prepare material for publication: X-SEED (Barbour, 2001; Atwood & Barbour, 2003).

Figures top

	Fig. 1. The molecular structure of the title compound with the atom numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.
	Fig. 2. N—H···O, C—H···O and C—H···π interactions (dotted lines) in the crystal structure of the title compound. Cg denotes the ring centroids. Symmetry codes: (i) - x + 1, - y + 1, - z + 1; (ii) x - 1/2, - y + 1/2, z - 1/2; (iii) x, y, z + 1.

4-Bromo-N-(diisopropoxyphosphoryl)benzamide top

Crystal data top

C₁₃H₁₉BrNO₄P	F(000) = 744
M_r = 364.17	D_x = 1.448 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 2372 reflections
a = 8.611 (1) Å	θ = 2.3–26.3°
b = 19.786 (3) Å	µ = 2.57 mm⁻¹
c = 9.849 (1) Å	T = 100 K
β = 95.357 (2)°	Needle, colourless
V = 1670.7 (4) Å³	0.32 × 0.07 × 0.05 mm
Z = 4

Data collection top

Bruker APEX CCD area-detector diffractometer	3405 independent reflections
Radiation source: fine-focus sealed tube	2604 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.038
ω scans	θ_max = 26.5°, θ_min = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2002)	h = −10→9
T_min = 0.494, T_max = 0.893	k = −24→24
9035 measured reflections	l = −8→12

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)] = 0.044	Hydrogen site location: difference Fourier map
wR(F²) = 0.120	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0687P)²] where P = (F_o² + 2F_c²)/3
3405 reflections	(Δ/σ)_max = 0.001
185 parameters	Δρ_max = 1.29 e Å⁻³
0 restraints	Δρ_min = −0.65 e Å⁻³

Crystal data top

C₁₃H₁₉BrNO₄P	V = 1670.7 (4) Å³
M_r = 364.17	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.611 (1) Å	µ = 2.57 mm⁻¹
b = 19.786 (3) Å	T = 100 K
c = 9.849 (1) Å	0.32 × 0.07 × 0.05 mm
β = 95.357 (2)°

Data collection top

Bruker APEX CCD area-detector diffractometer	3405 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2002)	2604 reflections with I > 2σ(I)
T_min = 0.494, T_max = 0.893	R_int = 0.038
9035 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	0 restraints
wR(F²) = 0.120	H-atom parameters constrained
S = 1.05	Δρ_max = 1.29 e Å⁻³
3405 reflections	Δρ_min = −0.65 e Å⁻³
185 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
Br1	−0.02989 (4)	0.39671 (2)	−0.17708 (4)	0.03600 (16)
P1	0.63994 (9)	0.40142 (4)	0.52752 (8)	0.01485 (19)
O1	0.6535 (2)	0.46798 (10)	0.5943 (2)	0.0195 (5)
O2	0.7917 (2)	0.37315 (10)	0.4748 (2)	0.0174 (5)
O3	0.5980 (2)	0.34095 (10)	0.6189 (2)	0.0190 (5)
O4	0.5279 (3)	0.29938 (10)	0.3200 (2)	0.0260 (5)
N1	0.5031 (3)	0.40726 (12)	0.3964 (2)	0.0161 (5)
H1	0.4524	0.4457	0.3836	0.019*
C1	0.3453 (3)	0.36868 (15)	0.1896 (3)	0.0160 (6)
C2	0.2722 (4)	0.31254 (15)	0.1264 (3)	0.0201 (7)
H2	0.2994	0.2684	0.1583	0.024*
C3	0.1603 (3)	0.32078 (16)	0.0175 (3)	0.0217 (7)
H3	0.1095	0.2827	−0.0254	0.026*
C4	0.1240 (4)	0.38516 (17)	−0.0273 (3)	0.0233 (7)
C5	0.1961 (4)	0.44202 (16)	0.0329 (3)	0.0228 (7)
H5	0.1702	0.4860	−0.0007	0.027*
C6	0.3062 (3)	0.43314 (15)	0.1425 (3)	0.0177 (6)
H6	0.3556	0.4714	0.1860	0.021*
C10	0.4653 (3)	0.35442 (15)	0.3062 (3)	0.0166 (6)
C11	0.8492 (5)	0.4199 (2)	0.2571 (4)	0.0480 (11)
H11C	0.8381	0.3738	0.2210	0.072*
H11B	0.9284	0.4440	0.2107	0.072*
H11A	0.7491	0.4435	0.2414	0.072*
C12	0.8981 (4)	0.41721 (17)	0.4076 (4)	0.0287 (8)
H12	0.8952	0.4638	0.4469	0.034*
C13	1.0587 (4)	0.3875 (2)	0.4397 (4)	0.0439 (11)
H13A	1.0828	0.3848	0.5388	0.066*
H13B	1.1359	0.4162	0.4007	0.066*
H13C	1.0618	0.3420	0.4005	0.066*
C14	0.3657 (4)	0.28522 (19)	0.6749 (4)	0.0366 (9)
H14A	0.3324	0.2823	0.5772	0.055*
H14B	0.2737	0.2884	0.7262	0.055*
H14C	0.4256	0.2447	0.7036	0.055*
C15	0.4659 (4)	0.34681 (17)	0.7022 (3)	0.0246 (7)
H15	0.4038	0.3879	0.6732	0.030*
C16	0.5304 (5)	0.3551 (2)	0.8481 (3)	0.0445 (11)
H16A	0.5854	0.3137	0.8792	0.067*
H16C	0.4449	0.3637	0.9048	0.067*
H16B	0.6033	0.3932	0.8556	0.067*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.0283 (2)	0.0495 (3)	0.0267 (2)	0.00590 (16)	−0.01544 (16)	−0.00825 (16)
P1	0.0128 (4)	0.0175 (4)	0.0137 (4)	0.0027 (3)	−0.0017 (3)	−0.0004 (3)
O1	0.0173 (11)	0.0195 (11)	0.0204 (11)	0.0039 (9)	−0.0046 (9)	−0.0037 (9)
O2	0.0118 (10)	0.0202 (11)	0.0200 (11)	0.0009 (8)	0.0004 (8)	0.0004 (9)
O3	0.0174 (11)	0.0204 (11)	0.0197 (11)	0.0047 (9)	0.0043 (9)	0.0039 (9)
O4	0.0309 (13)	0.0168 (12)	0.0285 (13)	0.0061 (10)	−0.0071 (10)	0.0023 (9)
N1	0.0173 (13)	0.0148 (13)	0.0153 (13)	0.0027 (10)	−0.0040 (10)	−0.0011 (9)
C1	0.0156 (15)	0.0201 (16)	0.0125 (14)	−0.0008 (12)	0.0025 (12)	−0.0010 (12)
C2	0.0213 (16)	0.0184 (16)	0.0209 (16)	−0.0074 (12)	0.0024 (13)	0.0005 (12)
C3	0.0171 (16)	0.0243 (17)	0.0238 (17)	−0.0073 (13)	0.0028 (13)	−0.0050 (13)
C4	0.0150 (16)	0.040 (2)	0.0140 (16)	0.0005 (13)	−0.0025 (12)	−0.0076 (13)
C5	0.0240 (17)	0.0236 (17)	0.0196 (16)	0.0043 (13)	−0.0035 (13)	−0.0005 (13)
C6	0.0188 (16)	0.0163 (15)	0.0172 (15)	−0.0003 (12)	−0.0023 (12)	−0.0023 (12)
C10	0.0192 (15)	0.0174 (16)	0.0133 (15)	−0.0025 (12)	0.0026 (12)	−0.0016 (11)
C11	0.039 (2)	0.062 (3)	0.045 (3)	0.012 (2)	0.0156 (19)	0.027 (2)
C12	0.0242 (18)	0.0203 (17)	0.044 (2)	−0.0065 (14)	0.0148 (16)	−0.0082 (15)
C13	0.0169 (19)	0.077 (3)	0.039 (2)	−0.0014 (18)	0.0074 (17)	−0.010 (2)
C14	0.0266 (19)	0.040 (2)	0.045 (2)	−0.0015 (16)	0.0130 (16)	0.0000 (17)
C15	0.0194 (17)	0.0299 (18)	0.0257 (17)	0.0053 (14)	0.0082 (13)	0.0019 (14)
C16	0.036 (2)	0.077 (3)	0.0219 (19)	−0.011 (2)	0.0110 (16)	−0.0021 (19)

Geometric parameters (Å, º) top

Br1—C4	1.902 (3)	C6—H6	0.9500
P1—O1	1.472 (2)	C11—C12	1.504 (5)
P1—O2	1.555 (2)	C11—H11C	0.9800
P1—O3	1.560 (2)	C11—H11B	0.9800
P1—N1	1.669 (2)	C11—H11A	0.9800
O2—C12	1.466 (4)	C12—C13	1.509 (5)
O3—C15	1.468 (4)	C12—H12	1.0000
O4—C10	1.217 (4)	C13—H13A	0.9800
N1—C10	1.390 (4)	C13—H13B	0.9800
N1—H1	0.8800	C13—H13C	0.9800
C1—C6	1.388 (4)	C14—C15	1.503 (5)
C1—C2	1.394 (4)	C14—H14A	0.9800
C1—C10	1.498 (4)	C14—H14B	0.9800
C2—C3	1.383 (4)	C14—H14C	0.9800
C2—H2	0.9500	C15—C16	1.500 (4)
C3—C4	1.374 (4)	C15—H15	1.0000
C3—H3	0.9500	C16—H16A	0.9800
C4—C5	1.391 (4)	C16—H16C	0.9800
C5—C6	1.380 (4)	C16—H16B	0.9800
C5—H5	0.9500

O1—P1—O2	115.92 (12)	H11C—C11—H11B	109.5
O1—P1—O3	116.21 (12)	C12—C11—H11A	109.5
O2—P1—O3	99.42 (11)	H11C—C11—H11A	109.5
O1—P1—N1	107.74 (12)	H11B—C11—H11A	109.5
O2—P1—N1	108.74 (12)	O2—C12—C11	109.7 (3)
O3—P1—N1	108.36 (12)	O2—C12—C13	105.8 (3)
C12—O2—P1	121.12 (19)	C11—C12—C13	112.8 (3)
C15—O3—P1	119.68 (18)	O2—C12—H12	109.5
C10—N1—P1	123.3 (2)	C11—C12—H12	109.5
C10—N1—H1	118.4	C13—C12—H12	109.5
P1—N1—H1	118.4	C12—C13—H13A	109.5
C6—C1—C2	119.8 (3)	C12—C13—H13B	109.5
C6—C1—C10	123.9 (3)	H13A—C13—H13B	109.5
C2—C1—C10	116.3 (3)	C12—C13—H13C	109.5
C3—C2—C1	120.3 (3)	H13A—C13—H13C	109.5
C3—C2—H2	119.8	H13B—C13—H13C	109.5
C1—C2—H2	119.8	C15—C14—H14A	109.5
C4—C3—C2	118.6 (3)	C15—C14—H14B	109.5
C4—C3—H3	120.7	H14A—C14—H14B	109.5
C2—C3—H3	120.7	C15—C14—H14C	109.5
C3—C4—C5	122.3 (3)	H14A—C14—H14C	109.5
C3—C4—Br1	118.8 (2)	H14B—C14—H14C	109.5
C5—C4—Br1	119.0 (3)	O3—C15—C16	107.9 (3)
C6—C5—C4	118.5 (3)	O3—C15—C14	107.3 (3)
C6—C5—H5	120.7	C16—C15—C14	114.5 (3)
C4—C5—H5	120.7	O3—C15—H15	109.0
C5—C6—C1	120.4 (3)	C16—C15—H15	109.0
C5—C6—H6	119.8	C14—C15—H15	109.0
C1—C6—H6	119.8	C15—C16—H16A	109.5
O4—C10—N1	121.8 (3)	C15—C16—H16C	109.5
O4—C10—C1	121.4 (3)	H16A—C16—H16C	109.5
N1—C10—C1	116.8 (3)	C15—C16—H16B	109.5
C12—C11—H11C	109.5	H16A—C16—H16B	109.5
C12—C11—H11B	109.5	H16C—C16—H16B	109.5

O1—P1—O2—C12	−40.8 (2)	Br1—C4—C5—C6	179.2 (2)
O3—P1—O2—C12	−166.1 (2)	C4—C5—C6—C1	1.0 (5)
N1—P1—O2—C12	80.7 (2)	C2—C1—C6—C5	−0.4 (4)
O1—P1—O3—C15	49.5 (2)	C10—C1—C6—C5	178.9 (3)
O2—P1—O3—C15	174.7 (2)	P1—N1—C10—O4	2.0 (4)
N1—P1—O3—C15	−71.9 (2)	P1—N1—C10—C1	−177.1 (2)
O1—P1—N1—C10	176.7 (2)	C6—C1—C10—O4	−158.7 (3)
O2—P1—N1—C10	50.3 (3)	C2—C1—C10—O4	20.6 (4)
O3—P1—N1—C10	−56.8 (3)	C6—C1—C10—N1	20.4 (4)
C6—C1—C2—C3	−0.4 (4)	C2—C1—C10—N1	−160.3 (3)
C10—C1—C2—C3	−179.7 (3)	P1—O2—C12—C11	−88.3 (3)
C1—C2—C3—C4	0.5 (5)	P1—O2—C12—C13	149.8 (2)
C2—C3—C4—C5	0.1 (5)	P1—O3—C15—C16	−106.3 (3)
C2—C3—C4—Br1	−180.0 (2)	P1—O3—C15—C14	129.8 (2)
C3—C4—C5—C6	−0.9 (5)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.88	1.96	2.819 (3)	166
C3—H3···O4ⁱⁱ	0.95	2.29	3.213 (4)	163
C6—H6···O1ⁱ	0.95	2.48	3.241 (3)	137
C16—H16C···Cgⁱⁱⁱ	0.98	2.63	3.608 (4)	173

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

Experimental details

Crystal data
Chemical formula	C₁₃H₁₉BrNO₄P
M_r	364.17
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	100
a, b, c (Å)	8.611 (1), 19.786 (3), 9.849 (1)
β (°)	95.357 (2)
V (Å³)	1670.7 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	2.57
Crystal size (mm)	0.32 × 0.07 × 0.05

Data collection
Diffractometer	Bruker APEX CCD area-detector
Absorption correction	Multi-scan (SADABS; Bruker, 2002)
T_min, T_max	0.494, 0.893
No. of measured, independent and observed [I > 2σ(I)] reflections	9035, 3405, 2604
R_int	0.038
(sin θ/λ)_max (Å⁻¹)	0.627

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.120, 1.05
No. of reflections	3405
No. of parameters	185
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	1.29, −0.65

Computer programs: SMART (Bruker, 2002), SAINT (Bruker, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001; Atwood & Barbour, 2003).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.88	1.96	2.819 (3)	165.5
C3—H3···O4ⁱⁱ	0.95	2.29	3.213 (4)	163.3
C6—H6···O1ⁱ	0.95	2.48	3.241 (3)	136.8
C16—H16C···Cgⁱⁱⁱ	0.98	2.63	3.608 (4)	172.8

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

Acknowledgements

We would like to thank the National Research Foundation (NRF) of South Africa for financial support.

References

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