Utilizing bifurcated halogen-bonding interactions with the uranyl oxo group in the assembly of a UO₂–3-bromo-5-iodo­benzoic acid coordination polymer

The synthesis and crystal structure of a new uranyl coordination polymer featuring 3-bromo-5-iodobenzoic acid is described and the luminescent and vibrational properties of the material have been explored. Compound (1), [UO₂(C₇H₃BrIO₂)₂]_n, features dimeric uranyl units chelated and then linked by 3-bromo-5-iodobenzoic acid ligands to form a one-dimensional coordination polymer that is subsequently assembled via bifurcated halogen-bonding interactions with uranyl oxo atoms to form a supramolecular three-dimensional network. The asymmetric, bifurcated halogen-bonding interaction in (1) is notable as it represents the first observation of this synthon in a uranyl hybrid material. Raman and IR spectroscopy showed that halogen-bonding inter­actions with the uranyl oxo atoms result in small shifts in υ₁ and υ₃ frequencies, whereas luminescence spectra collected at an excitation wavelength of 420 nm reveal partially resolved uranyl emission.

Computing details

Data collection: APEX, Bruker-AXS; cell refinement: SAINT, Bruker-AXS; data reduction: SAINT, Bruker-AXS; program(s) used to solve structure: SHELXS2014 (Sheldrick, 2014); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2014); molecular graphics: WinGX (Farrugia, 2012); software used to prepare material for publication: Crystal Maker (Palmer, 2009).

(I)

Crystal data

C14H6Br2I2O6U	F(000) = 1624
Mr = 921.84	Dx = 3.092 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 9.589 (4) Å	Cell parameters from 35379 reflections
b = 17.193 (8) Å	θ = 5.0–52.5°
c = 12.241 (6) Å	µ = 15.37 mm^−1
β = 101.085 (7)°	T = 293 K
V = 1980.6 (15) Å^3	Plate, yellow
Z = 4	0.27 × 0.20 × 0.16 mm

Data collection

Bruker APEX II CCD diffractometer	3479 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.055
ω scans	θmax = 27.3°, θmin = 2.1°
Absorption correction: empirical (using intensity measurements) TWINABS (Sheldrick, 2008)	h = −12→12
Tmin = 0.318, Tmax = 0.746	k = 0→22
4426 measured reflections	l = 0→15
4426 independent reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.049	H-atom parameters constrained
wR(F^2) = 0.154	w = 1/[σ^2(Fo^2) + (0.0931P)^2 + 9.2033P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max < 0.001
4426 reflections	Δρmax = 3.03 e Å^−3
226 parameters	Δρmin = −2.82 e Å^−3

Special details

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
U1	0.78189 (4)	0.52267 (2)	0.48736 (3)	0.02935 (15)
I2	0.35982 (13)	0.09723 (6)	0.64653 (12)	0.0844 (4)
Br2	0.76471 (18)	0.13343 (9)	0.35288 (13)	0.0644 (4)
O3	1.0293 (7)	0.5713 (4)	0.4637 (7)	0.0369 (17)
O5	0.6402 (8)	0.4169 (4)	0.5011 (8)	0.046 (2)
O1	0.7631 (9)	0.5021 (5)	0.3452 (7)	0.0443 (19)
O2	0.8066 (9)	0.5430 (5)	0.6307 (7)	0.0456 (19)
O6	0.5710 (9)	0.5896 (4)	0.4546 (9)	0.052 (2)
C11	0.6417 (13)	0.1804 (7)	0.4383 (10)	0.043 (3)
C8	0.5348 (11)	0.3784 (5)	0.5180 (9)	0.030 (2)
C4	1.2206 (12)	0.7150 (8)	0.2506 (9)	0.042 (3)
C9	0.5406 (11)	0.2941 (6)	0.5076 (9)	0.032 (2)
C14	0.4576 (12)	0.2475 (7)	0.5628 (11)	0.042 (3)
H14	0.3941	0.2690	0.6030	0.051*
C5	1.1997 (13)	0.7953 (8)	0.2591 (10)	0.049 (3)
H5	1.2524	0.8297	0.2247	0.059*
C2	1.0494 (11)	0.6927 (6)	0.3681 (9)	0.035 (2)
C13	0.4739 (14)	0.1669 (7)	0.5550 (12)	0.053 (3)
C10	0.6319 (12)	0.2606 (7)	0.4470 (9)	0.041 (3)
H10	0.6879	0.2922	0.4114	0.049*
C7	1.0224 (12)	0.7724 (7)	0.3749 (9)	0.040 (3)
H7	0.9558	0.7906	0.4147	0.048*
C3	1.1487 (12)	0.6643 (6)	0.3064 (9)	0.037 (2)
H3	1.1654	0.6112	0.3036	0.044*
C6	1.0995 (13)	0.8243 (6)	0.3194 (10)	0.043 (3)
O4	0.8530 (8)	0.6540 (4)	0.4469 (7)	0.0384 (18)
C1	0.9740 (12)	0.6375 (6)	0.4298 (9)	0.035 (2)
C12	0.5640 (13)	0.1329 (7)	0.4947 (12)	0.049 (3)
H12	0.5725	0.0790	0.4919	0.059*
I1	1.06946 (14)	0.93906 (6)	0.32972 (13)	0.0870 (4)
Br1	1.35979 (14)	0.67742 (9)	0.16544 (11)	0.0541 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
U1	0.0203 (2)	0.0290 (2)	0.0422 (2)	−0.00198 (14)	0.01454 (15)	0.00015 (15)
I2	0.0722 (8)	0.0621 (6)	0.1257 (10)	−0.0101 (5)	0.0360 (7)	0.0352 (6)
Br2	0.0675 (10)	0.0675 (8)	0.0621 (8)	0.0136 (7)	0.0222 (7)	−0.0196 (7)
O3	0.020 (4)	0.030 (3)	0.063 (5)	0.001 (3)	0.014 (3)	0.008 (3)
O5	0.020 (4)	0.031 (4)	0.090 (6)	−0.001 (3)	0.018 (4)	0.013 (4)
O1	0.042 (5)	0.050 (4)	0.044 (4)	−0.003 (4)	0.013 (4)	0.000 (4)
O2	0.044 (5)	0.050 (4)	0.048 (5)	−0.001 (4)	0.021 (4)	0.000 (4)
O6	0.030 (4)	0.032 (4)	0.098 (7)	0.002 (3)	0.024 (5)	0.009 (4)
C11	0.040 (7)	0.041 (6)	0.046 (6)	0.006 (5)	0.000 (5)	−0.005 (5)
C8	0.021 (5)	0.028 (4)	0.039 (5)	0.003 (4)	0.004 (4)	0.002 (4)
C4	0.027 (6)	0.062 (7)	0.036 (6)	−0.009 (5)	0.001 (5)	0.011 (5)
C9	0.019 (5)	0.029 (5)	0.048 (6)	−0.004 (4)	0.005 (4)	0.007 (4)
C14	0.023 (5)	0.040 (6)	0.063 (8)	−0.001 (4)	0.007 (5)	0.010 (5)
C5	0.038 (7)	0.058 (7)	0.053 (7)	−0.011 (6)	0.014 (6)	0.018 (6)
C2	0.023 (5)	0.036 (5)	0.043 (6)	−0.006 (4)	0.003 (4)	0.008 (4)
C13	0.040 (7)	0.037 (6)	0.080 (9)	−0.009 (5)	0.007 (6)	0.017 (6)
C10	0.031 (6)	0.048 (6)	0.040 (6)	−0.006 (5)	−0.003 (5)	0.000 (5)
C7	0.035 (6)	0.046 (6)	0.040 (6)	−0.003 (5)	0.012 (5)	0.008 (5)
C3	0.032 (6)	0.038 (5)	0.041 (6)	−0.001 (5)	0.006 (5)	0.006 (5)
C6	0.039 (7)	0.035 (6)	0.053 (7)	−0.005 (5)	0.002 (5)	0.016 (5)
O4	0.024 (4)	0.027 (3)	0.069 (5)	0.001 (3)	0.022 (4)	0.005 (3)
C1	0.031 (6)	0.032 (5)	0.041 (6)	−0.008 (4)	0.008 (4)	0.000 (4)
C12	0.036 (7)	0.031 (5)	0.076 (9)	−0.002 (5)	0.003 (6)	−0.005 (6)
I1	0.0798 (8)	0.0589 (6)	0.1270 (11)	0.0081 (6)	0.0320 (7)	0.0306 (6)
Br1	0.0452 (7)	0.0790 (9)	0.0437 (6)	0.0059 (6)	0.0229 (5)	0.0128 (6)

Geometric parameters (Å, º)

U1—O2	1.759 (9)	C4—C5	1.401 (19)
U1—O1	1.750 (8)	C4—Br1	1.955 (13)
U1—O6	2.294 (8)	C9—C10	1.378 (16)
U1—O5	2.295 (7)	C9—C14	1.392 (15)
U1—O3^i	2.414 (7)	C14—C13	1.401 (17)
U1—O4	2.438 (7)	C14—H14	0.9300
U1—O3	2.584 (7)	C5—C6	1.411 (19)
U1—C1	2.879 (10)	C5—H5	0.9300
I2—C13	2.088 (13)	C2—C7	1.399 (16)
Br2—C11	1.900 (13)	C2—C3	1.411 (16)
O3—C1	1.290 (13)	C2—C1	1.485 (14)
O3—U1^i	2.414 (7)	C13—C12	1.37 (2)
O5—C8	1.259 (12)	C10—H10	0.9300
O6—C8^ii	1.255 (13)	C7—C6	1.413 (15)
C11—C12	1.377 (18)	C7—H7	0.9300
C11—C10	1.387 (16)	C3—H3	0.9300
C8—O6^ii	1.255 (13)	C6—I1	2.001 (11)
C8—C9	1.457 (14)	O4—C1	1.250 (13)
C4—C3	1.373 (15)	C12—H12	0.9300
O2—U1—O1	178.2 (4)	C3—C4—Br1	121.0 (10)
O2—U1—O6	91.1 (4)	C5—C4—Br1	119.2 (9)
O1—U1—O6	90.5 (4)	C10—C9—C14	120.2 (10)
O2—U1—O5	93.0 (4)	C10—C9—C8	120.1 (9)
O1—U1—O5	87.9 (4)	C14—C9—C8	119.6 (10)
O6—U1—O5	84.0 (3)	C9—C14—C13	117.0 (12)
O2—U1—O3^i	86.3 (3)	C9—C14—H14	121.5
O1—U1—O3^i	92.3 (3)	C13—C14—H14	121.5
O6—U1—O3^i	166.6 (3)	C4—C5—C6	120.6 (10)
O5—U1—O3^i	83.0 (3)	C4—C5—H5	119.7
O2—U1—O4	91.7 (3)	C6—C5—H5	119.7
O1—U1—O4	88.0 (3)	C7—C2—C3	121.4 (10)
O6—U1—O4	76.8 (3)	C7—C2—C1	118.8 (10)
O5—U1—O4	160.3 (3)	C3—C2—C1	119.7 (10)
O3^i—U1—O4	116.4 (2)	C12—C13—C14	123.3 (12)
O2—U1—O3	95.6 (3)	C12—C13—I2	119.6 (9)
O1—U1—O3	82.9 (3)	C14—C13—I2	117.0 (11)
O6—U1—O3	128.0 (2)	C11—C10—C9	121.1 (11)
O5—U1—O3	146.5 (2)	C11—C10—H10	119.4
O3^i—U1—O3	65.4 (3)	C9—C10—H10	119.4
O4—U1—O3	51.6 (2)	C2—C7—C6	118.1 (11)
O2—U1—C1	97.9 (4)	C2—C7—H7	121.0
O1—U1—C1	81.0 (4)	C6—C7—H7	121.0
O6—U1—C1	101.4 (3)	C4—C3—C2	120.1 (11)
O5—U1—C1	167.7 (3)	C4—C3—H3	119.9
O3^i—U1—C1	92.0 (3)	C2—C3—H3	119.9
O4—U1—C1	25.5 (3)	C5—C6—C7	119.9 (11)
O3—U1—C1	26.6 (3)	C5—C6—I1	120.2 (8)
C1—O3—U1^i	155.8 (7)	C7—C6—I1	119.9 (10)
C1—O3—U1	89.5 (6)	C1—O4—U1	97.4 (6)
U1^i—O3—U1	114.6 (3)	O4—C1—O3	119.0 (9)
C8—O5—U1	159.2 (7)	O4—C1—C2	119.8 (10)
C8^ii—O6—U1	154.7 (9)	O3—C1—C2	121.2 (10)
C12—C11—C10	120.0 (12)	O4—C1—U1	57.1 (5)
C12—C11—Br2	118.4 (9)	O3—C1—U1	63.8 (5)
C10—C11—Br2	121.6 (10)	C2—C1—U1	163.8 (7)
O6^ii—C8—O5	121.9 (9)	C13—C12—C11	118.3 (10)
O6^ii—C8—C9	120.4 (9)	C13—C12—H12	120.8
O5—C8—C9	117.7 (9)	C11—C12—H12	120.8
C3—C4—C5	119.7 (11)

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