4,7-Diiodo-2,1,3-benzothiadiazole and 7,7'-diiodo-4,4'-bi(2,1,3-benzothiadiazole)

In the crystal structures of the title compounds, C₆H₂I₂N₂S, (I), and C₁₂H₄I₂N₄S₂, (II), respectively, a large number of short inter-heteroatom contacts, such as S...N, I...I and N...I, are observed. In (II), which is non-centrosymmetric, two halves of the mol­ecule are related by a crystallographic twofold axis.

S1. Comment

Compounds containing a 2,1,3-benzothiadiazole ring have received much interest, due to their potential use as fungicides, herbicides, fluorescent materials (Mataka et al., 1982) and organic conductors (Yamashita et al., 1996). We have recently synthesized 4,7-diiodo-2,1,3-benzothiadiazole, (I), and 7,7'-diiodo-4,4'-bis(2,1,3-benzothiadiazole), (II), as important synthetic intermediates for functional materials with 2,1,3-benzothiadiazole rings. From the viewpoint of crystal engineering, the peripheral S, N and I atoms of (I) and (II) are expected to form short interheteroatom contacts, which can result in unique molecular networks (Yamashita & Tomura, 1998). However, only two examples (Mikhno et al., 1973; Ono et al., 1994) of structures containing a 4-halogeno-2,1,3-benzothiadiazole unit are known in the Cambridge Structural Database (CSD, Version 5.22; Allen & Kennard, 1993). Therefore, we have carried out X-ray analyses of (I) and (II) and report here their molecular and crystal structures. \sch

The noncentrosymmetric space group of (II) is interesting from the standpoint of nonlinear optical properties. The molecular structures of (I) and (II) are shown in Figs. 1 and 2, and selected geometric parameters are given in Tables 1 and 3, respectively.

The planar 2,1,3-benzothiadiazole rings of (I) and (II) have almost similar geometries. The geometric parameters of the 1,2,5-thiadiazole rings in (I) and (II) are almost same as those of 3,4-diphenyl-1,2,5-thiadiazole (Mellini & Merlino, 1976). Considerable shortening of the C1—C6 and C4—C5 bonds in (I) and (II) is observed. Such double-bond fixation suggests the quinonoid character of the 2,1,3-benzothiadiazole ring in (I) and (II). The angle between the planes for the two 2,1,3-benzothiadiazole rings of (II) is 48.4 (1)°.

Fig. 3 shows the packing diagram for (I) viewed along the c axis. The molecules stack along the c axis. Short S···N interheteroatom contacts (Table 2) are found between the two 1,2,5-thiadiazole rings. The S···N distance is 7.7% shorter than the sum of the corresponding van der Waals radii (Pauling, 1960). Short I···I contacts within the sum of the van der Waals radii are also observed, as shown in Table 2. Four I atoms [I1, I2ⁱⁱ, I2ⁱⁱⁱ and I1^iv in Fig. 3; symmetry codes: (ii) 3/2 - x, y + 1/2, 1 - z; (iii) x + 1/2, 3/2 - y, z + 1; (iv) 2 - x, 2 - y, 2 - z] form a planar I₄ square cluster with short I···I contacts.

Fig. 4 shows the packing diagram for (II) viewed along the c axis. The molecules form uni-stacks along the c axis, and the interstack distance and the intermolecular I···I distance within the stack are 3.596 (5) and 3.942 (3) Å, respectively. In contrast with (I), short N···I contacts are observed [3.333 (8) Å] and are nearly linear [174.2 (4)°], as shown in Fig. 4. Although slightly longer than the typical N···I distance, the N···I contacts may control the crystal packing of (II) (Desiraju & Harlow, 1989; Xu et al., 1994; Walsh et al., 2001).

Studies on the construction of new molecular architectures using compounds (I) and (II) are now in progress.

S2. Experimental

The title compounds were synthesized according to the literature method of Suzuki (1994) for (I) and Fukushima et al. (1999) for (II). Pale-yellow crystals of (I) and (II) suitable for X-ray analysis were grown from an ethyl acetate and a dichloromethane solution, respectively.

S3. Refinement

All H atoms of (I) and (II) were placed in geometrically calculated positions, with C—H = 0.93 Å, and refined using a riding model.

Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988) for (I); CrystalClear (Molecular Structure Corporation & Rigaku Corporation, 2001) for (II). Cell refinement: MSC/AFC Diffractometer Control Software for (I); CrystalClear for (II). For both compounds, data reduction: TEXSAN (Molecular Structure Corporation & Rigaku Corporation, 2000). Program(s) used to solve structure: SHELXS97 (Sheldrick, 1997) for (I); SIR97 (Altomare et al., 1999) for (II). For both compounds, program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-III (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of the molecular structure of (I) with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. A view of the molecular structure of (II) with the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii [symmetry code: (i) 1/2 - x, 1/2 - y, z].
	Fig. 3. The packing diagram for (I) viewed along the c axis. Dotted lines show the short S···N and I···I contacts [symmetry codes: (ii) 3/2 - x, y + 1/2, 1 - z; (iii) x + 1/2, 3/2 - y, z + 1; (iv) 2 - x, 2 - y, 2 - z].
	Fig. 4. The packing diagram for (II) viewed along the c axis. Dotted lines show the short N···I contacts [3.333 (8) Å for N2···I1^v, 174.2 (4)° for N2···I1^v—C1^v; symmetry code: (v) 1/4 - x, y + 1/4, z + 1/4].

(I) 4,7-diiodo-2,1,3-benzothiadiazole

Crystal data

C6H2I2N2S	F(000) = 696
Mr = 387.96	Dx = 2.948 Mg m^−3
Monoclinic, P21/a	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2yab	Cell parameters from 25 reflections
a = 11.0515 (17) Å	θ = 14.7–15.0°
b = 18.2104 (12) Å	µ = 7.37 mm^−1
c = 4.3441 (11) Å	T = 296 K
β = 90.47 (2)°	Plate, pale yellow
V = 874.2 (3) Å^3	0.5 × 0.3 × 0.1 mm
Z = 4

Data collection

Rigaku AFC-7R diffractometer	1763 reflections with I > 2σ(I)
Radiation source: Rigaku rotating anode	Rint = 0.018
Graphite monochromator	θmax = 27.5°, θmin = 2.2°
ω/2θ scans	h = 0→14
Absorption correction: ψ scan (North et al., 1968)	k = 0→23
Tmin = 0.109, Tmax = 0.479	l = −5→5
2110 measured reflections	3 standard reflections every 150 reflections
2014 independent reflections	intensity decay: 0.2%

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.019	H-atom parameters constrained
wR(F^2) = 0.055	w = 1/[σ^2(Fo^2) + (0.027P)^2 + 2.4993P] where P = (Fo^2 + 2Fc^2)/3
S = 0.96	(Δ/σ)max = 0.001
2014 reflections	Δρmax = 0.51 e Å^−3
101 parameters	Δρmin = −0.50 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00185 (18)

Special details

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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

6.4475 (0.0074) x + 1.4243 (0.0197) y - 3.5325 (0.0026) z = 3.7930 (0.0179)

* 0.0053 (0.0019) S1 * 0.0003 (0.0026) N1 * 0.0021 (0.0025) N2 * -0.0079 (0.0028) C1 * -0.0011 (0.0030) C2 * -0.0049 (0.0031) C3 * -0.0086 (0.0029) C4 * 0.0084 (0.0030) C5 * 0.0064 (0.0030) C6 - 0.0394 (0.0044) I1 - 0.0664 (0.0043) I2

Rms deviation of fitted atoms = 0.0058

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 (Ų)

	x	y	z	Uiso*/Ueq
I1	0.92875 (3)	0.86097 (1)	0.97967 (6)	0.04361 (10)
I2	0.70115 (2)	0.52629 (1)	0.43698 (6)	0.04253 (10)
S1	1.05020 (9)	0.60054 (5)	1.0837 (3)	0.0431 (2)
N1	1.0228 (3)	0.68765 (16)	1.0701 (8)	0.0372 (7)
N2	0.9411 (3)	0.56889 (17)	0.8728 (8)	0.0363 (7)
C1	0.8637 (3)	0.76214 (18)	0.8123 (8)	0.0302 (7)
C2	0.9233 (3)	0.69599 (19)	0.8924 (8)	0.0291 (7)
C3	0.8763 (3)	0.62727 (19)	0.7799 (8)	0.0294 (7)
C4	0.7709 (3)	0.6262 (2)	0.5881 (8)	0.0327 (7)
C5	0.7181 (3)	0.6910 (2)	0.5131 (9)	0.0371 (8)
H5	0.6502	0.6911	0.3854	0.045*
C6	0.7642 (3)	0.7589 (2)	0.6253 (9)	0.0360 (8)
H6	0.7254	0.8022	0.5695	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.05485 (18)	0.02726 (14)	0.04851 (16)	−0.00099 (10)	−0.01303 (12)	−0.00163 (10)
I2	0.04839 (16)	0.03278 (14)	0.04626 (16)	−0.00796 (10)	−0.00983 (11)	−0.00278 (10)
S1	0.0381 (5)	0.0333 (5)	0.0577 (6)	0.0041 (4)	−0.0156 (4)	0.0038 (4)
N1	0.0369 (16)	0.0250 (14)	0.0496 (18)	0.0003 (12)	−0.0107 (13)	0.0003 (13)
N2	0.0356 (16)	0.0291 (15)	0.0442 (17)	−0.0006 (12)	−0.0053 (13)	0.0028 (13)
C1	0.0338 (17)	0.0211 (15)	0.0357 (17)	−0.0016 (12)	−0.0021 (13)	0.0000 (13)
C2	0.0303 (16)	0.0245 (15)	0.0325 (16)	−0.0003 (13)	−0.0018 (13)	0.0021 (13)
C3	0.0285 (16)	0.0279 (16)	0.0318 (16)	0.0004 (13)	−0.0005 (13)	0.0027 (13)
C4	0.0354 (18)	0.0312 (17)	0.0316 (16)	−0.0066 (14)	−0.0026 (14)	0.0019 (14)
C5	0.0324 (18)	0.0381 (19)	0.0406 (19)	−0.0043 (15)	−0.0127 (15)	0.0021 (16)
C6	0.0372 (18)	0.0269 (17)	0.0437 (19)	0.0023 (14)	−0.0069 (15)	0.0046 (15)

Geometric parameters (Å, º)

I1—C1	2.068 (3)	C1—C2	1.415 (5)
I2—C4	2.080 (4)	C2—C3	1.439 (5)
S1—N1	1.616 (3)	C3—C4	1.427 (5)
S1—N2	1.615 (3)	C4—C5	1.355 (5)
N1—C2	1.347 (4)	C5—C6	1.421 (5)
N2—C3	1.342 (4)	C5—H5	0.9300
C1—C6	1.363 (5)	C6—H6	0.9300
S1···N2^i	3.093 (3)	I1···I2^iii	4.138 (1)
N2···S1^i	3.093 (3)	I1···I2^iv	4.196 (1)
I1···I2^ii	3.789 (1)
N1—S1—N2	101.00 (16)	C4—C3—C2	120.1 (3)
C2—N1—S1	106.5 (2)	C5—C4—C3	118.4 (3)
C3—N2—S1	106.4 (2)	C5—C4—I2	121.9 (3)
C6—C1—C2	118.7 (3)	C3—C4—I2	119.7 (3)
C6—C1—I1	121.6 (3)	C4—C5—C6	121.5 (3)
C2—C1—I1	119.7 (2)	C4—C5—H5	119.3
N1—C2—C1	127.8 (3)	C6—C5—H5	119.3
N1—C2—C3	112.8 (3)	C1—C6—C5	121.9 (3)
C1—C2—C3	119.4 (3)	C1—C6—H6	119.1
N2—C3—C4	126.6 (3)	C5—C6—H6	119.1
N2—C3—C2	113.3 (3)
N2—S1—N1—C2	−0.1 (3)	N1—C2—C3—C4	179.9 (3)
N1—S1—N2—C3	−0.1 (3)	C1—C2—C3—C4	0.3 (5)
S1—N1—C2—C1	179.9 (3)	N2—C3—C4—C5	−178.8 (4)
S1—N1—C2—C3	0.3 (4)	C2—C3—C4—C5	0.8 (5)
C6—C1—C2—N1	179.3 (4)	N2—C3—C4—I2	2.0 (5)
I1—C1—C2—N1	−0.7 (5)	C2—C3—C4—I2	−178.3 (2)
C6—C1—C2—C3	−1.2 (5)	C3—C4—C5—C6	−1.1 (6)
I1—C1—C2—C3	178.8 (2)	I2—C4—C5—C6	178.0 (3)
S1—N2—C3—C4	179.9 (3)	C2—C1—C6—C5	0.9 (6)
S1—N2—C3—C2	0.3 (4)	I1—C1—C6—C5	−179.1 (3)
N1—C2—C3—N2	−0.4 (4)	C4—C5—C6—C1	0.2 (6)
C1—C2—C3—N2	−180.0 (3)

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

(II) 7,7'-diiodo-4,4'-bis(2,1,3-benzothiadiazole)

Crystal data

C12H4I2N4S2	Dx = 2.523 Mg m^−3
Mr = 522.11	Melting point: 311 K
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: F 2 -2d	Cell parameters from 3274 reflections
a = 20.892 (14) Å	θ = 3.1–27.5°
b = 33.38 (2) Å	µ = 4.87 mm^−1
c = 3.942 (3) Å	T = 296 K
V = 2749 (3) Å^3	Needle, pale yellow
Z = 8	0.60 × 0.04 × 0.04 mm
F(000) = 1936

Data collection

Rigaku Mercury CCD area-detector diffractometer	1438 independent reflections
Radiation source: Rigaku rotating anode	1394 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.054
Detector resolution: 14.62 pixels mm^-1	θmax = 27.5°, θmin = 3.1°
ϕ and ω scans	h = −26→22
Absorption correction: multi-scan (Jacobson, 1998)	k = −36→42
Tmin = 0.132, Tmax = 0.829	l = −5→4
6500 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.055	w = 1/[σ^2(Fo^2) + (0.0648P)^2 + 102.9652P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.152	(Δ/σ)max < 0.001
S = 1.21	Δρmax = 0.98 e Å^−3
1438 reflections	Δρmin = −1.07 e Å^−3
92 parameters	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
1 restraint	Extinction coefficient: 0.0012 (2)
Primary atom site location: structure-invariant direct methods	Absolute structure: Flack (1983); 538 Friedel pairs Query
Secondary atom site location: difference Fourier map	Absolute structure parameter: −0.01 (8)

Special details

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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

8.3358 (0.0495) x - 3.1514 (0.1294) y + 3.5956 (0.0045) z = 3.7555 (0.0296)

* -0.0094 (0.0065) S1 * 0.0071 (0.0098) N1 * -0.0043 (0.0087) N2 * -0.0081 (0.0104) C1 * 0.0150 (0.0103) C2 * -0.0022 (0.0103) C3 * 0.0104 (0.0093) C4 * -0.0045 (0.0089) C5 * -0.0040 (0.0102) C6 0.0277 (0.0151) I1

Rms deviation of fitted atoms = 0.0082

- 8.3358 (0.0493) x + 3.1514 (0.1289) y + 3.5956 (0.0045) z = 1.1633 (0.0484)

Angle to previous plane (with approximate e.s.d.) = 48.41 (0.14)

* -0.0094 (0.0065) S1_$1 * 0.0071 (0.0098) N1_$1 * -0.0043 (0.0087) N2_$1 * -0.0081 (0.0104) C1_$1 * 0.0150 (0.0102) C2_$1 * -0.0022 (0.0103) C3_$1 * 0.0104 (0.0093) C4_$1 * -0.0045 (0.0089) C5_$1 * -0.0040 (0.0102) C6_$1 0.0277 (0.0151) I1_$1

Rms deviation of fitted atoms = 0.0082

Operators for generating equivalent atoms: $1 - x + 1/2, -y + 1/2, z

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 (Ų)

	x	y	z	Uiso*/Ueq
I1	0.17133 (4)	0.08701 (2)	0.7312 (2)	0.0485 (4)
S1	0.07266 (13)	0.21576 (9)	1.0625 (9)	0.0386 (9)
N1	0.0992 (4)	0.1722 (3)	0.967 (4)	0.034 (2)
N2	0.1327 (4)	0.2431 (2)	0.949 (3)	0.0285 (19)
C1	0.1995 (5)	0.1463 (3)	0.708 (3)	0.025 (2)
C2	0.1575 (5)	0.1771 (3)	0.839 (3)	0.025 (2)
C3	0.1774 (5)	0.2185 (3)	0.824 (3)	0.025 (2)
C4	0.2387 (4)	0.2293 (3)	0.695 (3)	0.025 (2)
C5	0.2763 (5)	0.1985 (3)	0.577 (3)	0.026 (2)
H5	0.3163	0.2044	0.4862	0.031*
C6	0.2561 (6)	0.1580 (3)	0.588 (4)	0.039 (4)
H6	0.2840	0.1384	0.5073	0.047*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I1	0.0454 (5)	0.0290 (4)	0.0710 (7)	−0.0053 (3)	0.0004 (5)	−0.0047 (4)
S1	0.0267 (13)	0.0337 (14)	0.055 (3)	−0.0008 (10)	0.0127 (13)	−0.0007 (13)
N1	0.032 (4)	0.029 (4)	0.041 (6)	−0.003 (3)	0.015 (5)	−0.006 (6)
N2	0.025 (4)	0.022 (4)	0.038 (5)	−0.004 (3)	0.004 (4)	−0.007 (4)
C1	0.030 (5)	0.020 (4)	0.027 (6)	0.002 (3)	0.001 (4)	−0.003 (4)
C2	0.017 (4)	0.020 (4)	0.038 (7)	−0.001 (3)	−0.003 (4)	−0.002 (4)
C3	0.025 (5)	0.015 (4)	0.035 (7)	0.002 (3)	0.009 (4)	0.001 (4)
C4	0.018 (4)	0.022 (5)	0.036 (6)	−0.002 (3)	−0.009 (4)	−0.006 (5)
C5	0.026 (5)	0.027 (5)	0.025 (6)	0.000 (4)	0.007 (4)	−0.002 (4)
C6	0.026 (5)	0.019 (5)	0.073 (11)	0.000 (4)	−0.004 (5)	−0.011 (5)

Geometric parameters (Å, º)

I1—C1	2.065 (9)	C2—C3	1.445 (13)
S1—N1	1.599 (9)	C3—C4	1.423 (13)
S1—N2	1.616 (9)	C4—C5	1.376 (14)
N1—C2	1.331 (13)	C4—C4^i	1.462 (18)
N2—C3	1.337 (13)	C5—C6	1.417 (15)
C1—C6	1.332 (16)	C5—H5	0.9300
C1—C2	1.446 (14)	C6—H6	0.9300
N1—S1—N2	100.3 (4)	C2—C3—C4	121.0 (9)
C2—N1—S1	107.3 (7)	C5—C4—C3	116.4 (9)
C3—N2—S1	107.2 (7)	C5—C4—C4^i	121.5 (10)
C6—C1—C2	117.1 (9)	C3—C4—C4^i	122.1 (10)
C6—C1—I1	123.4 (8)	C4—C5—C6	122.2 (10)
C2—C1—I1	119.5 (7)	C4—C5—H5	118.9
N1—C2—C3	113.2 (9)	C6—C5—H5	118.9
N1—C2—C1	127.3 (9)	C1—C6—C5	123.8 (10)
C3—C2—C1	119.5 (9)	C1—C6—H6	118.1
N2—C3—C2	111.9 (9)	C5—C6—H6	118.1
N2—C3—C4	127.1 (9)
N2—S1—N1—C2	−0.1 (11)	N1—C2—C3—C4	179.7 (12)
N1—S1—N2—C3	0.6 (11)	C1—C2—C3—C4	−2.4 (17)
S1—N1—C2—C3	−0.4 (14)	N2—C3—C4—C5	−179.3 (11)
S1—N1—C2—C1	−178.1 (11)	C2—C3—C4—C5	2.0 (17)
C6—C1—C2—N1	179.5 (13)	N2—C3—C4—C4^i	2.1 (17)
I1—C1—C2—N1	−2.8 (18)	C2—C3—C4—C4^i	−176.5 (8)
C6—C1—C2—C3	2.0 (17)	C3—C4—C5—C6	−1.3 (17)
I1—C1—C2—C3	179.6 (8)	C4^i—C4—C5—C6	177.3 (9)
S1—N2—C3—C2	−0.9 (13)	C2—C1—C6—C5	−1 (2)
S1—N2—C3—C4	−179.6 (10)	I1—C1—C6—C5	−178.8 (10)
N1—C2—C3—N2	0.8 (15)	C4—C5—C6—C1	1 (2)
C1—C2—C3—N2	178.7 (11)

Symmetry code: (i) −x+1/2, −y+1/2, z.