Di­aqua­bis­(di­methyl sulfoxide)­bis(3,5-di­nitro­benzoato)­zinc(II) and the synthesis of the Cu, Ni and Co analogs

In order to model processes of chemisorption in organic salts formed between di­nitro­benzoic acids (DNBH) and secondary amines (R₂NH), a series of compounds of composition [M^II(3,5-DNB)₂(DMSO)₂(H₂O)₂] (where M^II is Zn, Cu, Ni or Co, 3,5-DNB is the 3,5-di­nitro­benzoate ion, and DMSO is di­methyl sulfoxide) have been prepared. In di­aqua­bis­(di­methyl sulf­oxide)­bis(3,5-DNB)­zinc(II), [Zn(C₇H₃N₂O₆)₂(C₂H₆OS)₂(H₂O)₂], the 3,5-DNB ions and mol­ecules of DMSO are monodentate ligands that are coordinated to the Zn atom through their O atoms. These ligands, together with two mol­ecules of water, form a slightly distorted octahedral coordination environment for the Zn atom, which lies on a center of symmetry.

S1. Comment

The complexes of Co, Ni, Cu and Zn obtained by the reaction of dialkylammonium 3,5-dinitrobenzoates with hydrated metal sulfates in dimethyl sulfoxide (DMSO) have the same stoichiometry, with two molecules of both water and DMSO accompanying each metal bis(3,5-dinitrobenzoate) entity. Both the 3,5-dinitrobenzoate ion (3,5-DNB) and DMSO ligands are known to be versatile reagents that, in the complexes of such ligands with metals, can interact with the metal cation or remain as counteranions (Hundal et al.,1996) or lattice 'solvents', and thus play significant roles in the hydrogen bonding in crystals. When involved in coordination processes, benzoates exhibit a wide range of coordination modes. The carboxylate group of benzoates can coordinate the metal ions in a monodentate, bidentate or bridging fashion. A typical example of monodentate coordination of 3,5-DNB is in the structure of tetraaquabis(3,5-DNB)cobalt(II) tetrahydrate (Tahir et al., 1996), where 3,5-DNB ions are involved in the coordination sphere of the Co atom in trans positions. The benzoate ions act as bidentate ligands in complexes such as bipyridine-bis-(p-nitrobenzoato)copper(II) (Usubaliev et al., 1981) and tetrakis(benzoato)bis(pyridine)dicopper(II) (Speier et al., 1989), where Cu atoms are octahedrally coordinated by four O atoms from two carboxyl groups and two N atoms from ??each of?? the two pyridines in a trans configuration. The [Cu₃(3,5-DNB)₆(CH₃OH)₂]_n complex is a linear polymeric chain, in which the 3,5-DNB ions form all bridges (Hökelek et al.,1998). The DMSO molecule can have different modes of coordination, or pack in the crystals as crystalline solvent molecules. The reaction of benzylamine with palladium chloride in the presence of DMSO forms the compound [PdCl₂(C₇H₉N)₂]·2Me₂SO (Decken et al., 2000). In the crystal, these molecules are packed in such way that each DMSO molecule bridges two palladium complex molecules through long-range intermolecular interactions (H···Cl and H···O), thus forming infinite chains. In the complexes of platinum with 2-methoxypyridine, with composition [PtCl₂(C₆H₇NO)(C₂H₆OS)] (Arvanitis et al., 2000), and in [RuCl₂(C₇H₇NO)(C₂H₆OS)₂] (Pal & Pal, 2002), the DMSO is coordinated by the metal atoms through the S atom. The same type of coordination is observed in heteroligand complex compounds of ruthenium(II) (Coe et al., 1993) and vanadium(III) (Magill et al., 1993). In the trinuclear nickel complex [Ni₃(C₁₇H₁₆N₂O₂)₂(C₂H₃O₂)₂{(C₂H₆OS)}₂] with salicylidene-1,3-propanediaminate ligands (Ülkü et al., 1997), the coordination octahedron of the terminal Ni atoms comprises two O and two N atoms of the aromatic ligand in the equatorial plane and O atoms of acetate and DMSO molecules in axial positions. It has been recently reported that [Ru(tpy)(bpy)(DMSO)](CF₃SO₃)₂ demonstrates intermolecular phototriggered linkage isomerism in the solid state (Rack et al., 2001).

In the title compound, Zn(3,5-DNB)₂(DMSO)₂(H₂O)₂, (I), Zn is shown to lie on a crystallographic center of symmetry with the ligands bonded to Zn in an all-trans fashion (Fig.1). The coordination polyhedron around the Zn atom is a slightly distorted octahedron (Table 2) that involves the O atoms of the dimethyl sulfoxide groups in axial positions. Bond angles O—Zn—O around the Zn atom lie in the range 86.53 (3)–93.47 (3)° (Table 2). The Zn—O_(DMSO) bond lengths of 2.1475 (8) Å are slightly longer than other examples in the literature [e.g. 2.122 Å (Lalioti et al., 1998); 2.10 (1) and 2.12 (1) Å (Persson, 1982)]. ??The Zn–O_(3,5-DNB) distance of 2.0747 (7) Å falls within the range of typical Zn—O_{(carboxylate)} bond distances [2.047 (1)–2.180 (2) Å], and the Zn—O_(water) distance of 2.0857 (7) Å is also comparable to literature values [2.052 (1)–2.195 (3) Å; Arranz-Mascaros et al., 2000; Lalioti et al., 1998; Nefedov et al., 1991; Persson, 1982; Sequeira et al., 1992; Tahir et al., 1997].?? The other ligand geometries correspond to normal values and are in good agreement with other literature data (Shvelashvili et al., 2001). The conformation of the molecule is described by the dihedral and torsion angles. The angle between the the carboxylate groups and the equatorial plane ?? formed by water atom O1, the Zn atom and carboxyl atom O71 ?? is 13.7 (1)°; the angle between the equatorial plane and the plane of the benzene ring is 23.2 (1)°. The nitro- and carboxylate groups of the 3,5-DNB molecules are planar and are approximately coplanar with the benzene ring; the dihedral angles between the benzene ring and the planes formed by O71—C7—O72, O31—N3—O32 and O51—N5—O52 are 10.1 (1), 5.1 (2) and 8.2 (1)°, respectively. The coordinated water molecules are bonded to the uncoordinated carboxylate O atoms with particularly strong intramolecular hydrogen bonds [O1···O72' = 2.629 (1) Å]. The orientation of the DMSO fragment in the molecule may be described by the dihedral angle between the planes O1—Zn—O11 and Zn—O11—S1 [14.7 (1)°], where one of the methyl groups (atom C11) lies almost in the plane Zn—O11—S1. The torsion angle C11—S1—O11—Zn is 176.49 (5)° and C12—S1—O11—Zn is −80.86 (6)°. The crystal packing of (I) consists of columns parallel to the b axis (Fig. 2), where ??molecules in neighboring columns are linked by weak hydrogen bonds (Table 3) that comprise the shortest intermolecular interaction.??

The 3,5-DNB ion and DMSO are monodentate ligands that are coordinated to the metal through their O atoms. ??This conformation?? models the processes of their chemisorption and confirms that dinitrobenzoates may act as corrosion inhibitors. The monodentate carboxylate O binding implies that the rest of the ligand should project from the metal surface, thus inhibiting the approach of further molecules to the metal.

S2. Experimental

Solutions of ZnSO₄·7H₂O (1.43 g, 0.005 mol) in DMSO (15 ml) and piperidinium 3,5-dinitrobenzoate (2.86 g, 0.010 mol) in DMSO (15 ml) were mixed and filtered, after which the filtrate was allowed stand at room temperature for 24 h as colorless crystals were slowly deposited. The crystals were collected, washed with diethyl ether and dried at room temperature (Table 1). The same technique was used for the synthesis of analogous compounds with Cu, Ni, and Co. All the complexes obtained in this way showed low solubility in water. 2,4-dinitrobenzoates could be obtained with similar ease.

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular structure of Zn(3,5-DNB)2(DMSO)2(H2O)2, showing the atom-numbering scheme and displacement ellipsoids at the 50% probability level.
	Fig. 2. Perspective packing diagram of the structure, showing the intermolecular hydrogen bonds (dashed lines); [101] projection.

Bisaquabis(dimethylsulfoxide)bis(3,5-dinitrobenzoato)zinc(II)

Crystal data

[Zn(C7H3N2O6)2(C2H6OS)2(H2O)2]	F(000) = 696
Mr = 679.89	Dx = 1.795 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 8192 reflections
a = 10.479 (2) Å	θ = 16.4–37.5°
b = 5.296 (1) Å	µ = 1.23 mm^−1
c = 22.686 (5) Å	T = 153 K
β = 91.96 (3)°	Prism, colourless
V = 1258.3 (4) Å^3	0.20 × 0.20 × 0.14 mm
Z = 2

Data collection

Bruker AXS CCD diffractometer	6588 independent reflections
Radiation source: sealed tube	5319 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ω scans	θmax = 37.6°, θmin = 1.8°
Absorption correction: multi-scan SADABS (Sheldrick, 1996)	h = −17→17
Tmin = 0.791, Tmax = 0.847	k = −9→8
24698 measured reflections	l = −38→38

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.071	H atoms treated by a mixture of independent and constrained refinement
S = 1.01	w = 1/[σ^2(Fo^2) + (0.040P)^2] where P = (Fo^2 + 2Fc^2)/3
6588 reflections	(Δ/σ)max = 0.002
195 parameters	Δρmax = 0.61 e Å^−3
1 restraint	Δρmin = −0.31 e Å^−3

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.

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
Zn	0.5000	0.0000	0.5000	0.01240 (4)
O1	0.64347 (6)	0.25613 (13)	0.52442 (3)	0.01705 (12)
H11	0.6213 (14)	0.407 (2)	0.5176 (6)	0.026*
H12	0.6494 (13)	0.239 (3)	0.5614 (5)	0.026*
S1	0.22983 (2)	0.22182 (4)	0.55149 (1)	0.01554 (4)
O11	0.36863 (6)	0.26491 (13)	0.53611 (3)	0.01907 (12)
C11	0.18375 (10)	0.51519 (18)	0.58341 (4)	0.02024 (16)
H111	0.2231	0.5307	0.6230	0.030*
H112	0.0906	0.5208	0.5859	0.030*
H113	0.2122	0.6549	0.5588	0.030*
C12	0.13934 (10)	0.2475 (2)	0.48368 (5)	0.02529 (19)
H121	0.1632	0.1105	0.4572	0.038*
H122	0.1570	0.4104	0.4652	0.038*
H123	0.0481	0.2355	0.4914	0.038*
C1	0.44135 (8)	0.27625 (16)	0.31966 (4)	0.01396 (13)
C2	0.51852 (8)	0.49026 (16)	0.32320 (4)	0.01410 (13)
H2	0.5480	0.5544	0.3603	0.017*
C3	0.55142 (8)	0.60771 (16)	0.27100 (4)	0.01471 (14)
C4	0.51101 (9)	0.52213 (16)	0.21568 (4)	0.01612 (14)
H4	0.5357	0.6038	0.1806	0.019*
C5	0.43285 (8)	0.31166 (17)	0.21429 (4)	0.01552 (14)
C6	0.39598 (8)	0.18808 (17)	0.26499 (4)	0.01494 (14)
H6	0.3408	0.0459	0.2624	0.018*
N3	0.63765 (7)	0.82680 (14)	0.27396 (3)	0.01637 (13)
O31	0.65944 (7)	0.93682 (15)	0.22748 (3)	0.02264 (14)
O32	0.68274 (7)	0.89065 (14)	0.32211 (3)	0.02226 (14)
N5	0.39748 (8)	0.20151 (16)	0.15650 (3)	0.01838 (14)
O51	0.33914 (9)	0.00120 (14)	0.15544 (4)	0.02762 (16)
O52	0.43256 (7)	0.31244 (15)	0.11216 (3)	0.02419 (14)
C7	0.41593 (8)	0.12382 (16)	0.37472 (3)	0.01449 (14)
O71	0.47296 (7)	0.19759 (13)	0.42160 (3)	0.01891 (12)
O72	0.34514 (7)	−0.06513 (14)	0.36855 (3)	0.02152 (13)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn	0.01478 (6)	0.01118 (6)	0.01120 (6)	−0.00050 (4)	−0.00013 (4)	0.00130 (4)
O1	0.0191 (3)	0.0141 (3)	0.0178 (3)	−0.0024 (2)	−0.0006 (2)	0.0037 (2)
S1	0.01647 (9)	0.01366 (9)	0.01647 (9)	−0.00092 (7)	0.00037 (7)	0.00164 (7)
O11	0.0159 (3)	0.0181 (3)	0.0234 (3)	−0.0001 (2)	0.0030 (2)	−0.0043 (2)
C11	0.0210 (4)	0.0209 (4)	0.0190 (4)	0.0032 (3)	0.0041 (3)	−0.0019 (3)
C12	0.0262 (4)	0.0275 (5)	0.0217 (4)	−0.0014 (4)	−0.0070 (3)	−0.0028 (4)
C1	0.0150 (3)	0.0152 (3)	0.0117 (3)	0.0005 (3)	0.0006 (2)	0.0017 (2)
C2	0.0156 (3)	0.0150 (3)	0.0117 (3)	0.0009 (3)	0.0011 (2)	0.0017 (2)
C3	0.0158 (3)	0.0140 (3)	0.0143 (3)	0.0007 (3)	0.0013 (3)	0.0026 (3)
C4	0.0183 (3)	0.0178 (4)	0.0123 (3)	0.0031 (3)	0.0017 (3)	0.0040 (3)
C5	0.0177 (3)	0.0180 (4)	0.0108 (3)	0.0031 (3)	−0.0005 (3)	0.0003 (3)
C6	0.0161 (3)	0.0160 (3)	0.0127 (3)	0.0003 (3)	−0.0003 (3)	0.0013 (3)
N3	0.0173 (3)	0.0148 (3)	0.0172 (3)	0.0008 (2)	0.0031 (2)	0.0034 (2)
O31	0.0262 (3)	0.0219 (3)	0.0201 (3)	−0.0029 (3)	0.0050 (3)	0.0083 (3)
O32	0.0272 (3)	0.0205 (3)	0.0190 (3)	−0.0049 (3)	−0.0014 (2)	0.0010 (2)
N5	0.0207 (3)	0.0216 (4)	0.0127 (3)	0.0053 (3)	−0.0017 (3)	−0.0001 (3)
O51	0.0389 (4)	0.0241 (4)	0.0194 (3)	−0.0036 (3)	−0.0044 (3)	−0.0034 (3)
O52	0.0287 (4)	0.0326 (4)	0.0113 (3)	0.0047 (3)	0.0011 (2)	0.0031 (3)
C7	0.0165 (3)	0.0155 (3)	0.0115 (3)	−0.0003 (3)	0.0010 (3)	0.0020 (2)
O71	0.0269 (3)	0.0179 (3)	0.0117 (2)	−0.0054 (2)	−0.0025 (2)	0.0033 (2)
O72	0.0268 (3)	0.0215 (3)	0.0161 (3)	−0.0101 (3)	−0.0016 (2)	0.0031 (2)

Geometric parameters (Å, º)

Zn—O1	2.0857 (7)	C1—C6	1.3935 (12)
Zn—O1^i	2.0857 (7)	C1—C7	1.5185 (12)
Zn—O11	2.1475 (8)	C2—C3	1.3914 (12)
Zn—O11^i	2.1475 (8)	C2—H2	0.9500
Zn—O71	2.0747 (7)	C3—C4	1.3868 (13)
Zn—O71^i	2.0747 (7)	C3—N3	1.4707 (12)
O1—H11	0.844 (10)	C4—C5	1.3829 (13)
O1—H12	0.844 (10)	C4—H4	0.9500
S1—O11	1.5245 (8)	C5—C6	1.3895 (12)
S1—C11	1.7875 (10)	C5—N5	1.4709 (12)
S1—C12	1.7846 (11)	C6—H6	0.9500
C11—H111	0.9800	N3—O32	1.2230 (11)
C11—H112	0.9800	N3—O31	1.2329 (10)
C11—H113	0.9800	N5—O51	1.2242 (11)
C12—H121	0.9800	N5—O52	1.2318 (11)
C12—H122	0.9800	C7—O72	1.2506 (11)
C12—H123	0.9800	C7—O71	1.2639 (11)
C1—C2	1.3930 (12)
O1—Zn—O11	86.53 (3)	S1—C12—H123	109.5
O1^i—Zn—O11	93.47 (3)	H121—C12—H123	109.5
O11^i—Zn—O11	180.00 (3)	H122—C12—H123	109.5
O11—Zn—O71	85.81 (3)	C2—C1—C6	120.24 (8)
O11—Zn—O71^i	94.19 (3)	C2—C1—C7	120.19 (8)
O71—Zn—O71^i	180.0	C6—C1—C7	119.33 (8)
O71—Zn—O1	88.61 (3)	C3—C2—C1	118.35 (8)
O71^i—Zn—O1	91.39 (3)	C3—C2—H2	120.8
O71—Zn—O1^i	91.39 (3)	C1—C2—H2	120.8
O71^i—Zn—O1^i	88.61 (3)	C4—C3—C2	123.17 (8)
O1—Zn—O1^i	180.00 (3)	C4—C3—N3	117.86 (7)
O71—Zn—O11^i	94.19 (3)	C2—C3—N3	118.92 (8)
O71^i—Zn—O11^i	85.81 (3)	C5—C4—C3	116.50 (8)
O1—Zn—O11^i	93.47 (3)	C5—C4—H4	121.7
O1^i—Zn—O11^i	86.53 (3)	C3—C4—H4	121.7
Zn—O1—H11	112.0 (10)	C4—C5—C6	122.83 (8)
Zn—O1—H12	102.7 (10)	C4—C5—N5	118.09 (8)
H11—O1—H12	107.2 (13)	C6—C5—N5	118.83 (8)
O11—S1—C11	103.63 (5)	C5—C6—C1	118.86 (8)
O11—S1—C12	105.92 (5)	C5—C6—H6	120.6
C12—S1—C11	98.05 (5)	C1—C6—H6	120.6
S1—O11—Zn	128.21 (4)	O32—N3—O31	123.79 (8)
S1—C11—H111	109.5	O32—N3—C3	118.48 (7)
S1—C11—H112	109.5	O31—N3—C3	117.73 (8)
H111—C11—H112	109.5	O51—N5—O52	124.05 (8)
S1—C11—H113	109.5	O51—N5—C5	118.14 (8)
H111—C11—H113	109.5	O52—N5—C5	117.75 (8)
H112—C11—H113	109.5	O72—C7—O71	127.09 (8)
S1—C12—H121	109.5	O72—C7—C1	116.96 (8)
S1—C12—H122	109.5	O71—C7—C1	115.89 (8)
H121—C12—H122	109.5	C7—O71—Zn	127.75 (6)
O1—Zn—O11—S1	−165.32 (6)	C2—C3—N3—O31	−175.81 (8)
O71—Zn—O11—S1	105.82 (6)	C2—C3—N3—O32	3.64 (12)
C11—S1—O11—Zn	176.49 (5)	C4—C3—N3—O31	6.78 (12)
C12—S1—O11—Zn	−80.86 (6)	C4—C3—N3—O32	−173.77 (8)
C6—C1—C2—C3	−1.75 (12)	C4—C5—N5—O51	172.80 (8)
C7—C1—C2—C3	172.71 (8)	C4—C5—N5—O52	−4.65 (12)
C1—C2—C3—C4	0.06 (13)	C6—C5—N5—O51	−1.63 (12)
C1—C2—C3—N3	−177.20 (7)	C6—C5—N5—O52	−179.09 (8)
C2—C3—C4—C5	0.98 (13)	C2—C1—C7—O71	−2.99 (12)
N3—C3—C4—C5	178.27 (7)	C2—C1—C7—O72	179.52 (8)
C3—C4—C5—C6	−0.37 (13)	C6—C1—C7—O71	171.51 (8)
C3—C4—C5—N5	−174.57 (8)	C6—C1—C7—O72	−5.98 (12)
C2—C1—C6—C5	2.32 (13)	O11—Zn—O71—C7	−110.55 (8)
C7—C1—C6—C5	−172.18 (8)	O1—Zn—O71—C7	162.83 (8)
C4—C5—C6—C1	−1.26 (13)	C1—C7—O71—Zn	−163.89 (6)
N5—C5—C6—C1	172.90 (8)	O72—C7—O71—Zn	13.30 (14)

Symmetry code: (i) −x+1, −y, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···O11^ii	0.84 (1)	2.13 (1)	2.8851 (11)	149 (1)
O1—H12···O72^i	0.84 (1)	1.84 (1)	2.6292 (11)	156 (1)
C11—H111···O31^iii	0.98	2.49	3.2968 (14)	140
C11—H112···O52^iv	0.98	2.51	3.2376 (14)	131
C11—H113···O1^ii	0.98	2.50	3.3214 (15)	141
C12—H121···O52^v	0.98	2.42	3.2389 (14)	141

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