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The asymmetric unit of the title polymeric complex, [HgBr(C6H4NO2)]n or HgBr(nic), contains mercury coordinated via two Br atoms [Hg—Br = 2.6528 (9) and 2.6468 (9) Å], two carboxyl­ate O atoms, which form a characteristic four-membered chelate ring [Hg—O = 2.353 (6) and 2.478 (7) Å], and an N atom [Hg—N = 2.265 (5) Å], in the form of a very irregular (3+2)-coordination polyhedron. The pronounced irregularity of the effective Hg (3+2)-coordination is a result of the rigid stereochemistry of the nicotinate ligand. According to the covalent and van der Waals radii criteria, the strongest bonds are Hg—Br and Hg—N. These covalent interactions form a two-dimensional poly­mer. The puckered planes are connected by van der Waals interactions, and there are only two intermolecular C—H...O hydrogen bonds [3.428 (10) and 3.170 (10) Å].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103005705/av1131sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270103005705/av1131Isup2.hkl
Contains datablock I

CCDC reference: 214140

Comment top

Recently, we started to investigate mercury(II) coordination chemistry with ligands containing N– and O-donor atoms, such as mono- and disubstituted pyridine carboxylic acids, which form polymeric complexes of the HgX(L) and HgX(L)(LH) type (L is deprotonated pyridine carboxylic acid, LH is neutral pyridine carboxylic acid) (Popović et al., 1999; Matković-Čalogović et al., 2001; Matković-Čalogović et al., 2002).

Interestingly, in all of these complexes, the replacement of one halide atom occurred. Moreover, different kinds of coordination modes of mercury are obtained, i.e. with COOH or COO groups as well as the pyridine N-donor atom. The COOH and COO groups can act as monodentate, chelating and/or bridging, while the pyridine N-donor atom acts monodentately. The tendency of the Hg atom to achieve effective coordination (Grdenić, 1981), which includes covalent bonds as well as van der Waals interactions (Pauling, 1960, Bondi, 1964, Grdenić, 1965, Nyburg, S·C. & Faerman, C·H., 1985, Matković-Čalogović, 1994), along with the spatial arrangement of donor atoms (i.e. the type of pyridine carboxylic acid used) leads to various, mostly irregular, coordination polyhedra of mercury.

No structural data on mercury(II) complexes with nicotinic acid or the nicotinate ion are reported in the Cambridge Structure Database (Version 5.24, November 2002; Allen & Kennard, 1993; Allen, 2002). NicH (pyridine-3-carboxylic acid or nicotinic acid) and nic (nicotinate ion) exhibit various coordination modes in metal complexes. The polymerization can occur by the formation of covalent bonds or by extensive hydrogen-bond networks. Catena-(bis(trans-bis(µ2-thiocyanato)-bis(nicotinic acid)-cadmium(II) bis(nicotinic acid) chlatrate is the only known complex of the 12. group metals with nicH as a ligand (Yang et al., 2001). NicH is coordinated by the Cd atom through the pyridine N atom, while the COOH group does not take ?part? in coordination. There are a few other examples of nicH complexes with Cu (Goher & Mak, 1987; Aakeröy et al., 2000; Naumov et al., 2001), or Pd (Qin et al., 1999) where coordination also occurs via the N atom. There is only one complex with a different coordination mode of nicH through the keto O atom of the carboxyl group, viz. the Cr trinuclear complex where the structure was solved from powder X-ray data (Mullica et al., 1986).

In the case of the deprotonated nic ligand, coordination can be obtained via the pyridine N atom, as in the structures of trans-tetra-aqua-bis(pyridine-3-carboxylate-N)-chromium(II), (Cooper et al., 1984, Broderick et al., 1986, Marsh & Spek, 2001), trans-tetra-aqua-bis(nicotinate-N)-zinc(II), (Broderick et al., 1986) and trans-tetra-aqua-bis(pyridine-3-carboxylate-N)nickel(II), (Batten & Harris, 2001) or trans-tetra-aqua-bis(pyridine-3-carboxylate-N)copper(II) (Kenar et al., 1999). On the other hand, the nicotinate ion can act bidentately through carboxylate O,O donor atoms, as in the structure of trans-dichloro-bis(N-methylpyridinium-3-carboxylato)-copper(II), (Nakagawa et al., 1999), or through the N,O donor set, as in the structure of the polymeric catena-ammonium bis(pyridine-3-carboxylato-O,N,N')silver(I) complex (Smith et al., 1994).

In the title polymeric complex, HgBr(nic), (I), the irregular five-coordination of mercury is strongly dictated by the rigid geometry of the nic ligand (Fig. 1). The Hg atom is surrounded by two carboxylic O atoms from the deprotonated nic ligand in the form of a characteristic four-membered chelate ring [Hg—O1 = 2.353 (6) and Hg—O2 = 2.478 (7) Å; remarkably longer than the tetrahedral Hg—O covalent bond of 2.14 Å; Grdenić, 1965; Pauling, 1960], two symmetry-related bridging Br atoms [Hg—Br = 2.6528 (9) and Hg—Bri = 2.6468 (9) Å, i=1/2 − x,1/2 + y,1/2 − z; slightly longer than 2.62 Å for the Hg(tetrahedral)—Br covalent bond) (Grdenić, 1965; Pauling, 1960) and the pyridine N atom [Hg—Nii = 2.265 (5) Å, ii=1/2 + x,1/2 + y,z; slightly longer than 2.23 Å for the tetrahedral Hg—N covalent bond) (Grdenić, 1965; Pauling, 1960). Bond angles range from 53.7 (2)° for the O1—Hg—O2 angle to 140.9 (2)° for the O1—Hg—Ni angle. The largest bond-angle value of 140.9 (2)° is accompanied by the stronger Hg—O1 bond of 2.353 (6) Å [compared with the Hg—O2 bond of 2.478 (7) Å]. The O1—Hg—Ni bond-angle value is the consequence of the constraints of ligand geometry rather than an indication of a strong Hg—O bond. It is obvious that the strongest bonds are towards N and Br atoms, although the bond angles' values exhibit significant irregularity [Br—Hg—Ni = 98.65 (16)°, Brii—Hg—Ni = 106.38 (15)° and Br—Hg—Brii = 124.27 (2)°; Table 1) and therefore lead to a deformed 3 + 2 mercury coordination. The geometry of nic is normal (Allen et al., 1987). The crystal structure of nicH is known [refcodes NICOAC (Wright & King, 1953), NICOAC01 (Gupta & Kumar, 1975) and NICOAC02 (Kutoglu & Scheringer, 1983)]. The molecules of nicH are linked through O—H···N intermolecular hydrogen bonds parallel to the b axis. The endocyclic C—N bonds within the pyridine ring in (I) are comparable to those in the structure of nicotinic acid itself [N—C3 and N—C4 of 1.334 (8) and 1.343 (9) Å, respectively, in (I) versus N—C1 and N—C5 of 1.348 (4) and 1.342 (4) Å in the acid; Kutoglu & Scheringer, 1983]. The deprotonation of the carboxyl group implies changes in the C—O bond lengths, being 1.226 (11) and 1.259 (10) Å for bonds O1—C1 and O2—C1, respectively, in (I) compared with O1—C6 and O2—C6 of 1.308 (4) and 1.211 (4) Å in nicH (Kutoglu & Scheringer, 1983). The two-dimensional polymeric structure of (I) is formed by the covalent interactions of Br and nic ions with Hg atoms. The planes are connected by van der Waals contacts of the pyridine rings. There are only two weak intermolecular hydrogen bonds of the C—H···O type (Table 2).

Experimental top

An aqueous solution of HgBr2 (0.3 g; 0.83 mmol) and nicH (0.1 g; 0.82 mmol) was mixed and left to stand for a few days. Colourless crystals (0.17 g; yield 50.73%) were filtered off and dried. The compound is soluble in DMSO, DMF, γ-picoline and py. Analysis; calculated for HgBr(nic): C 17.90, H 1.00, N 3.48, Hg 49.82%. Found: C 18.02, H 1.21, N 3.51, Hg 49.87%. IR spectral data supported the presence of the deprotonated nicotinate ion, which displaced one Br ion from HgBr2. Absorption bands typical for intermolecular O—H···O hydrogen bonds of free pyridine acids around 2600 cm−1 and 1900 cm−1 were not observed in the IR spectrum of HgBr(nic). The shift of carbonyl stretching band from 1655 cm−1 in the free nicH towards 1631 cm−1 in HgBr(nic) was observed. The pyridine ring N-atom coordination to Hg in the 1600–1400 cm−1 spectrum area is indicated by the spliting of Cδb C and Cδb N vibration bands.

Refinement top

H atoms bonded to C atoms were introduced at calculated positions and refined by applying the riding model [Uiso (H) = 1.2 Ueq (C) and C—H = 0.93 Å. ?The applied absorption correction was semi-empirical because of the irregular shape of the crystal block and was calculated with X-RED? (Stoe & Cie, 1995b). Four reflections were used for the psi-scan absorption correction (−5 − 1 5, −5 − 1 6, −9 − 1 12 and 9 1 − 12). The value µ . R was taken to be 2.533.

Computing details top

Data collection: STADI4 (Stoe & Cie, 1995); cell refinement: STADI4; data reduction: X-RED (Stoe & Cie, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON98 (Spek, 1998); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1]
[Figure 2]
Fig.1. The structure of HgBr(nic) with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. Fig.2. The PLATON view of the crystal structure of (I).
catena-(di-µ-bromo(pyridine-3-carboxylato-O,O',N))mercury(II) top
Crystal data top
[HgBr(C6H4NO2)]F(000) = 1424
Mr = 402.60Dx = 3.502 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 14.2021 (12) ÅCell parameters from 55 reflections
b = 7.2102 (16) Åθ = 10.0–18.0°
c = 15.368 (3) ŵ = 25.33 mm1
β = 103.945 (9)°T = 293 K
V = 1527.3 (5) Å3Irregular block, colourless
Z = 80.13 × 0.09 × 0.08 mm
Data collection top
Philips PW1100 updated by STOE
diffractometer
1426 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.024
Graphite monochromatorθmax = 30.0°, θmin = 3.2°
ω–scanh = 1919
Absorption correction: ψ scan
X-RED (Stoe & Cie, 1995b)
k = 210
Tmin = 0.019, Tmax = 0.065l = 121
5692 measured reflections4 standard reflections every 90 min
2216 independent reflections intensity decay: 3.1%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.032Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.084H-atom parameters constrained
S = 0.97 w = 1/[σ2(Fo2) + (0.0482P)2]
where P = (Fo2 + 2Fc2)/3
2216 reflections(Δ/σ)max = 0.001
100 parametersΔρmax = 0.98 e Å3
0 restraintsΔρmin = 2.02 e Å3
Crystal data top
[HgBr(C6H4NO2)]V = 1527.3 (5) Å3
Mr = 402.60Z = 8
Monoclinic, C2/cMo Kα radiation
a = 14.2021 (12) ŵ = 25.33 mm1
b = 7.2102 (16) ÅT = 293 K
c = 15.368 (3) Å0.13 × 0.09 × 0.08 mm
β = 103.945 (9)°
Data collection top
Philips PW1100 updated by STOE
diffractometer
1426 reflections with I > 2σ(I)
Absorption correction: ψ scan
X-RED (Stoe & Cie, 1995b)
Rint = 0.024
Tmin = 0.019, Tmax = 0.0654 standard reflections every 90 min
5692 measured reflections intensity decay: 3.1%
2216 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0320 restraints
wR(F2) = 0.084H-atom parameters constrained
S = 0.97Δρmax = 0.98 e Å3
2216 reflectionsΔρmin = 2.02 e Å3
100 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Hg0.268279 (17)0.14614 (4)0.32713 (2)0.04019 (11)
Br0.33117 (5)0.04035 (12)0.20344 (6)0.04460 (19)
O10.1321 (4)0.0441 (10)0.3206 (5)0.0572 (16)
O20.2229 (4)0.0051 (9)0.4559 (5)0.0619 (18)
N0.0863 (4)0.2817 (8)0.4192 (4)0.0310 (12)
C10.1481 (5)0.0665 (11)0.4020 (7)0.0440 (19)
C20.0742 (4)0.1631 (9)0.4409 (5)0.0299 (14)
C30.0155 (5)0.2103 (10)0.3863 (5)0.0336 (14)
H30.02650.19140.32480.040*
C40.0706 (5)0.3119 (9)0.5078 (5)0.0337 (15)
H40.12050.36210.53000.040*
C50.0156 (5)0.2721 (10)0.5666 (5)0.0384 (16)
H50.02440.29380.62770.046*
C60.0902 (5)0.1977 (10)0.5324 (6)0.0399 (18)
H60.15020.17150.57060.048*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg0.03165 (12)0.04011 (16)0.04848 (18)0.00845 (12)0.00901 (11)0.00105 (17)
Br0.0488 (3)0.0431 (4)0.0463 (4)0.0095 (3)0.0200 (3)0.0086 (4)
O10.054 (3)0.053 (4)0.073 (4)0.010 (3)0.032 (3)0.006 (4)
O20.037 (2)0.062 (4)0.087 (5)0.023 (3)0.015 (3)0.009 (4)
N0.033 (2)0.023 (3)0.036 (3)0.008 (2)0.006 (2)0.001 (3)
C10.033 (3)0.033 (4)0.072 (6)0.004 (3)0.024 (4)0.004 (4)
C20.029 (2)0.018 (3)0.045 (4)0.005 (2)0.012 (3)0.009 (3)
C30.038 (3)0.029 (3)0.035 (4)0.004 (3)0.013 (3)0.002 (3)
C40.033 (3)0.032 (4)0.039 (4)0.005 (2)0.014 (3)0.002 (3)
C50.045 (3)0.033 (4)0.033 (4)0.003 (3)0.003 (3)0.005 (4)
C60.029 (3)0.038 (4)0.050 (4)0.005 (3)0.003 (3)0.006 (4)
Geometric parameters (Å, º) top
Hg—Ni2.265 (5)C1—C21.498 (9)
Hg—O12.353 (6)C2—C31.388 (9)
Hg—O22.478 (7)C2—C61.391 (11)
Hg—Brii2.6468 (9)C3—H30.9300
Hg—Br2.6528 (9)C4—C51.365 (9)
Hg—C12.745 (7)C4—H40.9300
O1—C11.226 (11)C5—C61.399 (10)
O2—C11.259 (10)C5—H50.9300
N—C31.334 (8)C6—H60.9300
N—C41.343 (9)
Ni—Hg—O1140.9 (2)O1—C1—Hg58.7 (4)
Ni—Hg—O288.6 (2)O2—C1—Hg64.5 (4)
O1—Hg—O253.7 (2)C2—C1—Hg173.1 (5)
Ni—Hg—Brii106.38 (15)C3—C2—C6118.0 (6)
O1—Hg—Brii95.30 (17)C3—C2—C1120.1 (7)
O2—Hg—Brii106.69 (15)C6—C2—C1121.8 (6)
Ni—Hg—Br98.65 (16)N—C3—C2122.1 (7)
O1—Hg—Br95.13 (17)N—C3—H3118.9
O2—Hg—Br123.15 (15)C2—C3—H3118.9
Brii—Hg—Br124.27 (2)N—C4—C5122.7 (6)
Hgiii—Br—Hg107.62 (3)N—C4—H4118.7
C1—O1—Hg94.9 (5)C5—C4—H4118.7
C1—O2—Hg88.2 (6)C4—C5—C6118.1 (7)
C3—N—C4119.4 (6)C4—C5—H5120.9
C3—N—Hgiv120.6 (5)C6—C5—H5120.9
C4—N—Hgiv120.0 (4)C2—C6—C5119.7 (6)
O1—C1—O2123.0 (7)C2—C6—H6120.2
O1—C1—C2119.5 (7)C5—C6—H6120.2
O2—C1—C2117.5 (8)
Ni—Hg—Br—Hgiii131.85 (15)Hgiv—N—C3—C2179.5 (5)
O1—Hg—Br—Hgiii11.49 (17)C6—C2—C3—N1.9 (10)
O2—Hg—Br—Hgiii37.85 (15)C1—C2—C3—N174.1 (7)
Brii—Hg—Br—Hgiii111.47 (5)C3—N—C4—C50.1 (11)
O1—C1—C2—C36.3 (11)Hgiv—N—C4—C5179.7 (5)
O2—C1—C2—C3170.8 (7)N—C4—C5—C60.3 (11)
O1—C1—C2—C6177.8 (8)C3—C2—C6—C52.1 (10)
O2—C1—C2—C65.1 (11)C1—C2—C6—C5173.9 (6)
C4—N—C3—C21.0 (10)C4—C5—C6—C21.3 (11)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x+1/2, y+1/2, z+1/2; (iii) x+1/2, y1/2, z+1/2; (iv) x1/2, y1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3···O1v0.932.603.428 (10)149
C4—H4···O2iv0.932.473.170 (10)132
Symmetry codes: (iv) x1/2, y1/2, z; (v) x, y, z+1/2.

Experimental details

Crystal data
Chemical formula[HgBr(C6H4NO2)]
Mr402.60
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)14.2021 (12), 7.2102 (16), 15.368 (3)
β (°) 103.945 (9)
V3)1527.3 (5)
Z8
Radiation typeMo Kα
µ (mm1)25.33
Crystal size (mm)0.13 × 0.09 × 0.08
Data collection
DiffractometerPhilips PW1100 updated by STOE
diffractometer
Absorption correctionψ scan
X-RED (Stoe & Cie, 1995b)
Tmin, Tmax0.019, 0.065
No. of measured, independent and
observed [I > 2σ(I)] reflections
5692, 2216, 1426
Rint0.024
(sin θ/λ)max1)0.703
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.032, 0.084, 0.97
No. of reflections2216
No. of parameters100
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.98, 2.02

Computer programs: STADI4 (Stoe & Cie, 1995), STADI4, X-RED (Stoe & Cie, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), PLATON98 (Spek, 1998), SHELXL97.

Selected geometric parameters (Å, º) top
Hg—Ni2.265 (5)O1—C11.226 (11)
Hg—O12.353 (6)O2—C11.259 (10)
Hg—O22.478 (7)N—C31.334 (8)
Hg—Brii2.6468 (9)N—C41.343 (9)
Hg—Br2.6528 (9)
Ni—Hg—O1140.9 (2)O2—Hg—Brii106.69 (15)
Ni—Hg—O288.6 (2)Ni—Hg—Br98.65 (16)
O1—Hg—O253.7 (2)O1—Hg—Br95.13 (17)
Ni—Hg—Brii106.38 (15)O2—Hg—Br123.15 (15)
O1—Hg—Brii95.30 (17)Brii—Hg—Br124.27 (2)
Symmetry codes: (i) x+1/2, y+1/2, z; (ii) x+1/2, y+1/2, z+1/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3···O1iii0.932.603.428 (10)149
C4—H4···O2iv0.932.473.170 (10)132
Symmetry codes: (iii) x, y, z+1/2; (iv) x1/2, y1/2, z.
 

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