Hexa­aqua­manganese(II) bis­[hydrogen (4-amino­phen­yl)arsonate] tetra­hydrate

Smith, G.; Wermuth, U.D.

doi:10.1107/S2414314616019854

metal-organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 1| Part 12| December 2016| x161985

https://doi.org/10.1107/S2414314616019854

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Hexaaquamanganese(II) bis[hydrogen (4-aminophenyl)arsonate] tetrahydrate

Graham Smith ^a ^* and Urs D. Wermuth ^b

^aScience and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Qld 4001, Australia, and ^bSchool of Natural Sciences, Griffith University, Nathan, Qld 4111, Australia
^*Correspondence e-mail: g.smith@qut.edu.au

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 12 December 2016; accepted 12 December 2016; online 16 December 2016)

In the structure of the complex salt formed from the reaction of manganese(II) acetate with (4-aminophenyl)arsonic acid (p-arsanilic acid), [Mn(H₂O)₆](C₆H₇AsNO₃)₂·4H₂O, the centrosymmetric Mn(H₂O)₆ coordination polyhedron has slightly distorted octahedral stereochemistry, with the two hydrogen (4-aminophenyl)arsonate anions and the four water molecules of solvation related by inversion. Extensive O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonds link all species, giving an overall three-dimensional supramolecular structure, which also has weak π–π ring interactions [minimum ring-centroid separation = 3.7304 (15) Å]. The structure is isotypic with that of the Mg salt.

Keywords: crystal structure; p-arsanilic acid; manganese(II) salts; hydrogen bonding.

CCDC reference: 1522310

Structure description

The arsenical (4-aminophenyl)arsonic acid (p-arsanilic acid) has biological significance as an anti-helminth in veterinary applications (Steverding, 2010 ) and its crystal structure (Shimada, 1961 ; Nuttall & Hunter, 1996 ) has shown that it exists as a zwitterion. The hydrated monosodium salt had early usage as an anti-syphilitic (atoxyl) (Ehrlich & Bertheim, 1907 ). We have reported the crystal structure of this salt (a dihydrate) and the NH₄⁺ salt (Smith & Wermuth, 2014 ), together with the structures of the K, Rb and Cs salts (Smith & Wermuth, 2017a ), as well as the alkaline-earth metal salts Mg, Ca, Sr and Ba (Smith & Wermuth, 2017b ). Other single-metal complex structures are known, e.g. with Ag, Pb, Cd, Zn (Lesikar-Parrish et al., 2013 ), but no structures of single-metal first transition series compounds of hydrogen p-arsanilic acid have been reported. Our reaction of this acid with manganese(II) acetate in aqueous ethanol gave the title complex salt, [Mn(H₂O)₆](C₆H₇AsNO₃)₂·4H₂O, and the structure is reported herein.

In the structure (Fig. 1), the cations exist as the common centrosymmetric octahedral [Mn(H₂O)₆]²⁺ species with the hydrogen p-arsanilate counter-anions and the water molecules of solvation (O4W, (O4Wⁱ, and O5W, O5Wⁱ) inversion related [symmetry code (i): −x + 1, −y + 1, −z + 1]. The Mn—O bond length range is 2.170 (2)–2.180 (2) Å. Structures having the [Mn(H₂O)₆]²⁺ cation are quite common, but no examples involving arsonate anions are known and phosphonate examples are few, e.g. hexaaquamanganese(II) bis(hydrogen t-butylphosphonate)·6H₂O (Wang et al., 2009 ). The structure of the title compound is isotypic with that of the Mg hydrogen p-arsanilate complex, [Mg(H₂O)₆](C₆H₇AsNO₃)2·4H₂O (Smith & Wermuth, 2017b), with cell data: a = 15.1693 (6), b = 6.7367 (2), c = 12.9532 (4) Å, β = 108.033 (4), V = 1258.63 (7)°, Z = 4, space group P2₁/c.

Figure 1
The molecular configuration and atom-numbering scheme for the centrosymmetric complex cation, the hydrogen p-arsanilate anion and the water molecules of solvation (O4W and O5W) in the asymmetric unit of the title compound. [Symmetry code: (i) −x + 1, −y + 1, −z + 1.] Non-H atoms are shown as 40% probability displacement ellipsoids and hydrogen-bonding interactions are shown as dashed lines

In the crystal, extensive inter-species O—H⋯O, O—H⋯N and N—H⋯O hydrogen-bonding interactions (Table 1) are present with the p-arsanilate anions linking the hydrogen-bonded layers of associated cations and water molecules across [010], generating a three-dimensional supramolecular structure (Fig. 2). Weak π–π associations are also present between inversion-related anions [minimum ring-centroid separation = 3.7304 (15) Å].

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O13—H13⋯N4ⁱ	0.84 (2)	1.90 (2)	2.734 (3)	174 (4)
N4—H41⋯O4Wⁱⁱ	0.87 (2)	2.09 (3)	2.911 (3)	158 (3)
N4—H42⋯O12ⁱⁱ	0.87 (3)	2.13 (3)	2.982 (3)	169 (3)
O1W—H11W⋯O5W	0.82 (2)	1.90 (2)	2.715 (3)	173 (3)
O1W—H12W⋯O12	0.84 (2)	1.79 (2)	2.626 (3)	176 (4)
O2W—H21W⋯O13	0.83 (3)	1.99 (3)	2.811 (3)	175 (4)
O2W—H22W⋯O11ⁱⁱⁱ	0.85 (2)	1.88 (2)	2.704 (3)	164 (3)
O3W—H31W⋯O5W^iv	0.84 (3)	1.96 (3)	2.791 (3)	171 (3)
O3W—H32W⋯O4W	0.86 (3)	1.91 (3)	2.773 (3)	174 (3)
O4W—H41W⋯O12^iv	0.84 (3)	1.88 (3)	2.725 (3)	177 (3)
O4W—H42W⋯O11ⁱⁱⁱ	0.85 (2)	1.90 (2)	2.720 (3)	164 (3)
O5W—H51W⋯O11^v	0.86 (3)	1.90 (3)	2.749 (3)	170 (4)
O5W—H52W⋯O1W^vi	0.85 (2)	2.07 (2)	2.895 (3)	164 (3)
Symmetry codes: (i) -x, -y+2, -z+1; (ii) -x, -y+1, -z+1; (iii) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (iv) $[x, -y+{\script{1\over 2}}, z-{\script{1\over 2}}]$ ; (v) $[-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (vi) $[-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ .

Figure 2
The packing in the unit cell, viewed along the c-axis direction, showing the associated [Mn(H₂O)₆]²⁺ cation layers linked peripherally across a by hydrogen bonds involving the anions and the water molecules of solvation. Hydrogen-bonding interactions are shown as dashed lines and aromatic H atoms have been omitted.

Synthesis and crystallization

The title compound was synthesized by heating together for 5 min, 1 mmol quantities of (4-aminophenyl)arsonic acid and manganese(II) acetate in 20 ml of 50% ethanol/water. Room temperature evaporation of the solution gave thin colourless crystal blocks suitable for the X-ray analysis.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2.

Table 2
Experimental details

Crystal data
Chemical formula	[Mn(H₂O)₆](C₆H₇AsNO₃)₂·4H₂O
M_r	667.19
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	200
a, b, c (Å)	15.2040 (9), 6.7388 (3), 13.0699 (8)
β (°)	107.951 (7)
V (Å³)	1273.91 (13)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	3.17
Crystal size (mm)	0.35 × 0.26 × 0.18

Data collection
Diffractometer	Oxford Diffraction Gemini-S CCD detector
Absorption correction	Multi-scan (CrysAlis PRO; Rigaku OD, 2015 $[Rigaku OD (2015). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, England.]$ )
T_min, T_max	0.662, 0.980
No. of measured, independent and observed [I > 2σ(I)] reflections	5155, 2496, 2128
R_int	0.025
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.027, 0.068, 1.02
No. of reflections	2496
No. of parameters	190
No. of restraints	13
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.32, −0.46
Computer programs: CrysAlis PRO (Rigaku OD, 2015 $[Rigaku OD (2015). CrysAlis PRO. Rigaku Oxford Diffraction Ltd, Yarnton, England.]$ ), SHELXS97 (Sheldrick, 2008 ), SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 1522310

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S2414314616019854/bt4034sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314616019854/bt4034Isup2.hkl

checkCIF report

Computing details top

Data collection: CrysAlis PRO (Rigaku OD, 2015); cell refinement: CrysAlis PRO (Rigaku OD, 2015); data reduction: CrysAlis PRO (Rigaku OD, 2015); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 2012); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Hexaaquamanganese(II) bis[hydrogen (4-aminophenyl)arsonate] tetrahydrate top

Crystal data top

[Mn(H₂O)₆](C₆H₇AsNO₃)₂·4H₂O	F(000) = 678
M_r = 667.19	D_x = 1.739 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1801 reflections
a = 15.2040 (9) Å	θ = 3.9–29.2°
b = 6.7388 (3) Å	µ = 3.17 mm⁻¹
c = 13.0699 (8) Å	T = 200 K
β = 107.951 (7)°	Block, colourless
V = 1273.91 (13) Å³	0.35 × 0.26 × 0.18 mm
Z = 2

Data collection top

Oxford Diffraction Gemini-S CCD-detector diffractometer	2496 independent reflections
Radiation source: Enhance (Mo) X-ray source	2128 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.025
Detector resolution: 16.077 pixels mm^-1	θ_max = 26.0°, θ_min = 3.3°
ω scans	h = −18→11
Absorption correction: multi-scan (CrysAlis PRO; Rigaku OD, 2015)	k = −8→8
T_min = 0.662, T_max = 0.980	l = −12→16
5155 measured reflections

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)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.068	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ²(F_o²) + (0.0288P)² + 0.7443P] where P = (F_o² + 2F_c²)/3
2496 reflections	(Δ/σ)_max = 0.001
190 parameters	Δρ_max = 0.32 e Å⁻³
13 restraints	Δρ_min = −0.46 e Å⁻³

Special details top

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell esds are taken into account in the estimation of distances, angles and torsion angles

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
As1	0.22953 (2)	0.74539 (4)	0.59945 (2)	0.0134 (1)
O11	0.29612 (12)	0.8896 (3)	0.69561 (14)	0.0193 (6)
O12	0.26527 (12)	0.5118 (3)	0.60584 (15)	0.0193 (5)
O13	0.23649 (13)	0.8281 (3)	0.47601 (15)	0.0200 (6)
N4	−0.17885 (16)	0.7872 (3)	0.5635 (2)	0.0196 (7)
C1	0.10328 (18)	0.7644 (3)	0.5914 (2)	0.0157 (8)
C2	0.07608 (19)	0.7936 (4)	0.6825 (2)	0.0228 (8)
C3	−0.01696 (19)	0.7990 (4)	0.6739 (2)	0.0229 (9)
C4	−0.08400 (18)	0.7749 (4)	0.5742 (2)	0.0170 (8)
C5	−0.05619 (19)	0.7490 (4)	0.4827 (2)	0.0184 (8)
C6	0.03656 (18)	0.7431 (3)	0.4914 (2)	0.0167 (8)
Mn1	0.50000	0.50000	0.50000	0.0164 (2)
O1W	0.44009 (13)	0.4411 (3)	0.62823 (15)	0.0203 (6)
O2W	0.38051 (15)	0.6723 (3)	0.40765 (16)	0.0293 (7)
O3W	0.43599 (15)	0.2291 (3)	0.42193 (18)	0.0281 (7)
O4W	0.26434 (15)	0.2457 (3)	0.26621 (17)	0.0244 (7)
O5W	0.54204 (13)	0.5174 (3)	0.83471 (16)	0.0228 (6)
H2	0.12130	0.80990	0.75080	0.0270*
H3	−0.03530	0.81930	0.73630	0.0280*
H5	−0.10130	0.73540	0.41410	0.0220*
H6	0.05500	0.72450	0.42890	0.0200*
H13	0.223 (2)	0.948 (3)	0.465 (3)	0.0300*
H41	−0.190 (2)	0.764 (4)	0.6237 (18)	0.0230*
H42	−0.2109 (19)	0.704 (4)	0.516 (2)	0.0230*
H11W	0.470 (2)	0.474 (5)	0.6899 (16)	0.0300*
H12W	0.3851 (13)	0.467 (4)	0.624 (3)	0.0300*
H21W	0.340 (2)	0.724 (5)	0.429 (3)	0.0440*
H22W	0.359 (2)	0.674 (5)	0.3397 (15)	0.0440*
H31W	0.469 (2)	0.147 (4)	0.402 (3)	0.0420*
H32W	0.3817 (16)	0.226 (5)	0.375 (2)	0.0420*
H41W	0.266 (2)	0.164 (4)	0.218 (2)	0.0370*
H42W	0.263 (2)	0.359 (3)	0.238 (2)	0.0370*
H51W	0.5943 (15)	0.473 (4)	0.833 (3)	0.0340*
H52W	0.546 (2)	0.636 (3)	0.858 (3)	0.0340*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
As1	0.0117 (2)	0.0153 (2)	0.0139 (2)	0.0010 (1)	0.0052 (1)	0.0003 (1)
O11	0.0173 (10)	0.0222 (10)	0.0176 (9)	−0.0039 (8)	0.0041 (8)	−0.0026 (8)
O12	0.0162 (9)	0.0169 (9)	0.0253 (10)	0.0029 (7)	0.0073 (8)	0.0013 (8)
O13	0.0234 (10)	0.0224 (10)	0.0179 (10)	0.0081 (8)	0.0117 (8)	0.0048 (9)
N4	0.0141 (12)	0.0240 (12)	0.0221 (13)	−0.0006 (9)	0.0077 (10)	−0.0002 (11)
C1	0.0134 (13)	0.0163 (13)	0.0185 (14)	0.0010 (10)	0.0064 (11)	0.0004 (11)
C2	0.0191 (14)	0.0349 (16)	0.0136 (13)	0.0012 (12)	0.0041 (11)	−0.0003 (12)
C3	0.0209 (15)	0.0351 (16)	0.0148 (14)	0.0037 (12)	0.0085 (12)	0.0026 (12)
C4	0.0153 (13)	0.0149 (13)	0.0230 (14)	0.0012 (10)	0.0091 (11)	0.0019 (11)
C5	0.0172 (14)	0.0201 (14)	0.0163 (13)	0.0005 (10)	0.0028 (11)	0.0003 (11)
C6	0.0174 (13)	0.0196 (14)	0.0159 (13)	0.0013 (10)	0.0091 (11)	−0.0014 (11)
Mn1	0.0156 (3)	0.0203 (3)	0.0145 (3)	0.0014 (2)	0.0065 (2)	−0.0006 (2)
O1W	0.0139 (10)	0.0322 (11)	0.0164 (9)	0.0032 (8)	0.0070 (8)	−0.0001 (9)
O2W	0.0256 (12)	0.0448 (13)	0.0170 (10)	0.0168 (10)	0.0057 (9)	−0.0006 (10)
O3W	0.0240 (12)	0.0276 (12)	0.0313 (12)	0.0008 (9)	0.0064 (10)	−0.0085 (10)
O4W	0.0312 (12)	0.0238 (11)	0.0212 (11)	−0.0031 (9)	0.0126 (9)	−0.0018 (9)
O5W	0.0203 (10)	0.0216 (10)	0.0269 (11)	0.0001 (9)	0.0079 (9)	−0.0045 (9)

Geometric parameters (Å, º) top

Mn1—O1W	2.177 (2)	O4W—H41W	0.84 (3)
Mn1—O1Wⁱ	2.177 (2)	O4W—H42W	0.85 (2)
Mn1—O2W	2.180 (2)	O5W—H51W	0.86 (3)
Mn1—O2Wⁱ	2.180 (2)	O5W—H52W	0.85 (2)
Mn1—O3W	2.170 (2)	N4—C4	1.408 (4)
Mn1—O3Wⁱ	2.170 (2)	N4—H41	0.87 (2)
As1—O11	1.6627 (19)	N4—H42	0.87 (3)
As1—O12	1.659 (2)	C1—C6	1.393 (4)
As1—O13	1.7407 (19)	C1—C2	1.390 (4)
As1—C1	1.894 (3)	C2—C3	1.385 (4)
O13—H13	0.84 (2)	C3—C4	1.395 (4)
O1W—H12W	0.84 (2)	C4—C5	1.397 (4)
O1W—H11W	0.82 (2)	C5—C6	1.380 (4)
O2W—H21W	0.83 (3)	C2—H2	0.9500
O2W—H22W	0.847 (19)	C3—H3	0.9500
O3W—H32W	0.86 (3)	C5—H5	0.9500
O3W—H31W	0.84 (3)	C6—H6	0.9500

O11—As1—O12	113.76 (10)	H21W—O2W—H22W	105 (3)
O11—As1—O13	108.46 (9)	Mn1—O3W—H32W	123 (2)
O11—As1—C1	111.90 (10)	H31W—O3W—H32W	107 (3)
O12—As1—O13	103.77 (9)	Mn1—O3W—H31W	118 (2)
O12—As1—C1	112.19 (9)	H41W—O4W—H42W	105 (2)
O13—As1—C1	106.08 (10)	H51W—O5W—H52W	112 (3)
O1Wⁱ—Mn1—O3W	91.42 (8)	C4—N4—H41	112 (2)
O2Wⁱ—Mn1—O3W	89.35 (8)	H41—N4—H42	108 (3)
O3W—Mn1—O3Wⁱ	180.00	C4—N4—H42	112 (2)
O1Wⁱ—Mn1—O2Wⁱ	92.77 (8)	C2—C1—C6	119.7 (3)
O1Wⁱ—Mn1—O3Wⁱ	88.58 (8)	As1—C1—C6	118.5 (2)
O2Wⁱ—Mn1—O3Wⁱ	90.65 (8)	As1—C1—C2	121.7 (2)
O1Wⁱ—Mn1—O2W	87.23 (8)	C1—C2—C3	120.0 (2)
O1W—Mn1—O2W	92.77 (8)	C2—C3—C4	120.5 (2)
O1W—Mn1—O3W	88.58 (8)	N4—C4—C3	121.2 (2)
O1W—Mn1—O1Wⁱ	180.00	C3—C4—C5	119.2 (3)
O1W—Mn1—O2Wⁱ	87.23 (8)	N4—C4—C5	119.6 (2)
O1W—Mn1—O3Wⁱ	91.42 (8)	C4—C5—C6	120.3 (2)
O2W—Mn1—O3W	90.65 (8)	C1—C6—C5	120.3 (2)
O2W—Mn1—O2Wⁱ	180.00	C3—C2—H2	120.00
O2W—Mn1—O3Wⁱ	89.35 (8)	C1—C2—H2	120.00
As1—O13—H13	113 (3)	C2—C3—H3	120.00
Mn1—O1W—H11W	118 (2)	C4—C3—H3	120.00
H11W—O1W—H12W	104 (3)	C6—C5—H5	120.00
Mn1—O1W—H12W	124 (2)	C4—C5—H5	120.00
Mn1—O2W—H21W	128 (3)	C1—C6—H6	120.00
Mn1—O2W—H22W	125 (2)	C5—C6—H6	120.00

O11—As1—C1—C2	−34.0 (2)	As1—C1—C6—C5	177.71 (18)
O11—As1—C1—C6	147.69 (16)	C2—C1—C6—C5	−0.6 (3)
O12—As1—C1—C2	95.2 (2)	C1—C2—C3—C4	0.1 (4)
O12—As1—C1—C6	−83.06 (18)	C2—C3—C4—N4	−177.7 (2)
O13—As1—C1—C2	−152.12 (19)	C2—C3—C4—C5	−1.2 (4)
O13—As1—C1—C6	29.59 (19)	N4—C4—C5—C6	177.9 (2)
As1—C1—C2—C3	−177.48 (19)	C3—C4—C5—C6	1.4 (4)
C6—C1—C2—C3	0.8 (4)	C4—C5—C6—C1	−0.5 (4)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O13—H13···N4ⁱⁱ	0.84 (2)	1.90 (2)	2.734 (3)	174 (4)
N4—H41···O4Wⁱⁱⁱ	0.87 (2)	2.09 (3)	2.911 (3)	158 (3)
N4—H42···O12ⁱⁱⁱ	0.87 (3)	2.13 (3)	2.982 (3)	169 (3)
O1W—H11W···O5W	0.82 (2)	1.90 (2)	2.715 (3)	173 (3)
O1W—H12W···O12	0.84 (2)	1.79 (2)	2.626 (3)	176 (4)
O2W—H21W···O13	0.83 (3)	1.99 (3)	2.811 (3)	175 (4)
O2W—H22W···O11^iv	0.85 (2)	1.88 (2)	2.704 (3)	164 (3)
O3W—H31W···O5W^v	0.84 (3)	1.96 (3)	2.791 (3)	171 (3)
O3W—H32W···O4W	0.86 (3)	1.91 (3)	2.773 (3)	174 (3)
O4W—H41W···O12^v	0.84 (3)	1.88 (3)	2.725 (3)	177 (3)
O4W—H42W···O11^iv	0.85 (2)	1.90 (2)	2.720 (3)	164 (3)
O5W—H51W···O11^vi	0.86 (3)	1.90 (3)	2.749 (3)	170 (4)
O5W—H52W···O1W^vii	0.85 (2)	2.07 (2)	2.895 (3)	164 (3)

Symmetry codes: (ii) −x, −y+2, −z+1; (iii) −x, −y+1, −z+1; (iv) x, −y+3/2, z−1/2; (v) x, −y+1/2, z−1/2; (vi) −x+1, y−1/2, −z+3/2; (vii) −x+1, y+1/2, −z+3/2.

Acknowledgements

The authors acknowledge support from the Science and Engineering Faculty, Queensland University of Technology and Griffith University.

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