Bis(acetato-κO)bis­(4,5-dimethyl­benzene-1,2-diamine-κN)zinc

Abstract

The structure of the title compound, [Zn(CH₃COO)₂(C₈H₁₂N₂)₂], has one half molecule in the asymmetric unit. The Zn^II atom is situated on a twofold rotation axis and is tetrahedrally coordinated by two N and two O atoms. The crystal packing displays inter­molecular N—H⋯O hydrogen bonds and intra­molecular N—H⋯O and N—H⋯N hydrogen bonding.

Related literature  

For the role of complexes in biochemical systems with zinc in tetrahedral coordination, see: Parkin (2004 ▶); Maret & Li (2009 ▶). For the structure of the corresponding 1,2-diamino­benzene complex, see: Mei et al. (2009 ▶). For an example of a structurally characterized tetramine complex with zinc in tetrahedral coordination, see: Xu et al. (1998 ▶). For an example carboxyl­ate coordination in a similar complex, see: Harding (2001 ▶).

Experimental  

Crystal data  

• [Zn(C₂H₃O₂)₂(C₈H₁₂N₂)₂]

• M _r = 455.85

• Monoclinic,

• a = 18.432 (3) Å

• b = 4.7414 (6) Å

• c = 25.740 (4) Å

• β = 92.284 (4)°

• V = 2247.8 (5) ų

• Z = 4

• Mo Kα radiation

• μ = 1.12 mm⁻¹

• T = 200 K

• 0.80 × 0.30 × 0.20 mm

Data collection  

• Bruker SMART X2S benchtop diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 2008b ▶) T _min = 0.467, T _max = 0.806

• 11403 measured reflections

• 1986 independent reflections

• 1905 reflections with I > 2σ(I)

• R _int = 0.046

Refinement  

• R[F ² > 2σ(F ²)] = 0.036

• wR(F ²) = 0.094

• S = 1.12

• 1986 reflections

• 151 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.67 e Å⁻³

• Δρ_min = −0.37 e Å⁻³

Data collection: APEX2 (Bruker, 2010 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008a ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008a ▶); molecular graphics: XSHELL (Bruker, 2004 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Supplementary material file. DOI: 10.1107/S160053681203036X/bv2208Isup2.cdx

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1A⋯O1i	0.84 (4)	2.10 (4)	2.897 (3)	158 (3)
N2—H2A⋯O2	0.88 (3)	2.15 (3)	3.013 (3)	168 (3)
N2—H2B⋯N2ii	0.81 (4)	2.26 (4)	3.076 (3)	179 (3)

Symmetry codes: (i) ; (ii) .

supplementary crystallographic information

Comment

Tetrahedrally coordinated zinc complexes play important structural (e.g., zinc fingers) and catalytic (e.g., carbonic anydrase) roles in biochemical systems (Parkin 2004, Maret & Li 2009). Although coordination via three amino acid residues (Zn—N coordination) and a water or hydroxide ligand is the most common coordination motif, carboxylate coordination is also known (Harding 2001). The title compound exhibits tetrahedral coordination involving two phenylenediamine ligands and two acetate ligands all coordinated in a monodentate fashion (see figure 1). The Zn atom sits on a twofold rotation axis resulting in a one-half molecule asymmetric unit. The complex exhibits intramolecular hydrogen bonding involving the uncoordinated amine nitrogen, N2, and the uncoordinated acetate oxygen, O2 (see figure 2). In addition, one of the H atoms of the coordinated amine is involved in two weak intramolecular hydrogen bonding intractions with the uncoordinated acetate oxygen atom (N1—H1B^···O2 = 2.77 (3) Å, 114 (3)°) and the coordinated amine (N1—H1B^···N2 = 2.57 (3) Å, 99 (3)°). An intermolecular hydrogen bonding network involving N2—H^···N2 and N1—H^···O1 interactions results in planes of molecules perpindicular to the c axis (see figure 3).

Experimental

The title compound was prepared by the reaction of two equivalents of 4,5-dimethyl-1,2-diaminobenzene with zinc(II) acetate dihydrate in refluxing ethanol. Slow evaporation of the solvent resulted in large, well formed crystals. The sample used for analysis was cut from a larger crystal. ¹H NMR spectrum (CDCl₃, 400 MHz, p.p.m.): 6.15 (4H, s), 3.89 (8H, b), 2.05 (12H, s), 1.92 (6H, s).

Refinement

The structure was originally solved in the non-centrosymmetric space group Cc because the mean |E*E-1| statistic was 0.745. The structure refined to R₁ = 0.051. However, many atoms displayed disc-shaped thermal ellipsoids and one of the nitrogen atoms coordinated to the zinc became nonpositive definite. Inverting the structure gave no improvement. Using TWIN resulted in a refined BASF of 0.49 with no significant improvement in the R₁ value (0.048) or thermal parameters (the nitrogen remained nonpositive definite). The structure was subsequently solved and successfully refined in the centrosymmetric space group C2/c, which resulted in a lower R₁ (0.0363)and much improved behavior of the thermal parameters. All H atoms atoms were found in difference fourier maps. Hydrogen atoms bonded to carbon atoms were refined using a riding model (AFIX 43 for aromatic C—H and AFIX 137 for methyl groups). The atomic coordinates and isotropic thermal parameters of all amine hydrogen atoms were refined.

Figures

Fig. 1.

Perspective view of the title compound with displacement ellipsoids of non-hydrogen atoms drawn at the 50% probability level.

Fig. 2.

Perspective view of the title compound displaying the intramolecular hydrogen bonding.

Fig. 3.

View of the unit cell of the title compound down the b axis displaying the intermolecular hydrogen bonding network.

Crystal data

[Zn(C2H3O2)2(C8H12N2)2]	F(000) = 960
Mr = 455.85	Dx = 1.347 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C2yc	Cell parameters from 5876 reflections
a = 18.432 (3) Å	θ = 2.7–25.0°
b = 4.7414 (6) Å	µ = 1.12 mm−1
c = 25.740 (4) Å	T = 200 K
β = 92.284 (4)°	Plate, colourless
V = 2247.8 (5) Å3	0.80 × 0.30 × 0.20 mm
Z = 4

Data collection

Bruker SMART X2S benchtop diffractometer	1986 independent reflections
Radiation source: fine-focus sealed tube	1905 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.046
ω scans	θmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 2008b)	h = −21→21
Tmin = 0.467, Tmax = 0.806	k = −5→5
11403 measured reflections	l = −28→30

Refinement

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.094	H atoms treated by a mixture of independent and constrained refinement
S = 1.12	w = 1/[σ2(Fo2) + (0.0434P)2 + 4.1592P] where P = (Fo2 + 2Fc2)/3
1986 reflections	(Δ/σ)max < 0.001
151 parameters	Δρmax = 0.67 e Å−3
0 restraints	Δρmin = −0.37 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
Zn1	0.5000	0.21781 (8)	0.2500	0.02608 (16)
O1	0.53194 (10)	0.4948 (4)	0.30352 (6)	0.0343 (4)
O2	0.60458 (11)	0.1492 (4)	0.33024 (7)	0.0421 (5)
N1	0.56934 (12)	−0.0427 (5)	0.21196 (8)	0.0281 (5)
N2	0.69849 (13)	0.2531 (6)	0.23902 (9)	0.0360 (6)
C1	0.60972 (12)	0.0974 (5)	0.17273 (9)	0.0262 (5)
C2	0.67121 (13)	0.2524 (5)	0.18723 (10)	0.0279 (6)
C3	0.70681 (14)	0.3968 (6)	0.14856 (10)	0.0344 (6)
H3	0.7496	0.4999	0.1579	0.041*
C4	0.68215 (14)	0.3954 (7)	0.09706 (10)	0.0364 (6)
C5	0.61975 (15)	0.2423 (7)	0.08302 (10)	0.0383 (7)
C6	0.58503 (14)	0.0931 (7)	0.12132 (10)	0.0351 (6)
H6	0.5431	−0.0149	0.1119	0.042*
C7	0.5892 (2)	0.2368 (9)	0.02749 (12)	0.0659 (12)
H7A	0.5444	0.1254	0.0258	0.099*
H7B	0.6248	0.1515	0.0049	0.099*
H7C	0.5787	0.4298	0.0159	0.099*
C8	0.72326 (19)	0.5613 (8)	0.05768 (12)	0.0553 (9)
H8A	0.7708	0.6160	0.0729	0.083*
H8B	0.6957	0.7310	0.0478	0.083*
H8C	0.7300	0.4446	0.0268	0.083*
C9	0.57583 (14)	0.3768 (6)	0.33792 (9)	0.0308 (6)
C10	0.58890 (18)	0.5363 (7)	0.38778 (11)	0.0488 (8)
H10A	0.6249	0.4360	0.4099	0.073*
H10B	0.5433	0.5516	0.4059	0.073*
H10C	0.6070	0.7256	0.3801	0.073*
H1A	0.5413 (19)	−0.167 (7)	0.1990 (12)	0.045 (9)*
H1B	0.5973 (17)	−0.120 (7)	0.2345 (12)	0.039 (8)*
H2A	0.6658 (18)	0.234 (6)	0.2628 (12)	0.039 (9)*
H2B	0.7263 (18)	0.383 (8)	0.2448 (12)	0.042 (9)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Zn1	0.0257 (2)	0.0218 (2)	0.0310 (2)	0.000	0.00465 (15)	0.000
O1	0.0391 (10)	0.0294 (10)	0.0338 (9)	0.0044 (8)	−0.0066 (7)	−0.0022 (8)
O2	0.0462 (12)	0.0404 (13)	0.0398 (10)	0.0137 (10)	0.0034 (8)	0.0026 (9)
N1	0.0235 (10)	0.0279 (13)	0.0330 (11)	−0.0022 (10)	0.0030 (9)	0.0003 (9)
N2	0.0251 (11)	0.0492 (17)	0.0336 (12)	−0.0046 (11)	−0.0011 (10)	0.0021 (10)
C1	0.0210 (11)	0.0258 (13)	0.0323 (12)	0.0021 (10)	0.0053 (9)	−0.0003 (10)
C2	0.0213 (12)	0.0306 (15)	0.0319 (12)	0.0030 (10)	0.0022 (9)	−0.0002 (10)
C3	0.0232 (12)	0.0393 (16)	0.0410 (14)	−0.0057 (12)	0.0055 (10)	−0.0013 (12)
C4	0.0315 (14)	0.0424 (17)	0.0360 (13)	0.0002 (13)	0.0101 (11)	0.0045 (12)
C5	0.0327 (14)	0.0525 (19)	0.0297 (13)	−0.0007 (13)	0.0026 (11)	0.0009 (12)
C6	0.0260 (13)	0.0440 (17)	0.0355 (13)	−0.0073 (12)	0.0033 (10)	−0.0067 (12)
C7	0.053 (2)	0.110 (4)	0.0338 (16)	−0.014 (2)	−0.0010 (14)	0.0017 (18)
C8	0.0550 (19)	0.066 (2)	0.0455 (17)	−0.0125 (18)	0.0163 (14)	0.0110 (16)
C9	0.0298 (13)	0.0311 (15)	0.0314 (12)	−0.0015 (11)	0.0017 (10)	0.0037 (11)
C10	0.066 (2)	0.0427 (19)	0.0368 (15)	0.0084 (16)	−0.0131 (14)	−0.0038 (13)

Geometric parameters (Å, º)

Zn1—O1	1.9759 (18)	C3—H3	0.9500
Zn1—O1i	1.9759 (18)	C4—C5	1.395 (4)
Zn1—N1	2.054 (2)	C4—C8	1.511 (4)
Zn1—N1i	2.054 (2)	C5—C6	1.390 (4)
O1—C9	1.302 (3)	C5—C7	1.516 (4)
O2—C9	1.222 (3)	C6—H6	0.9500
N1—C1	1.441 (3)	C7—H7A	0.9800
N1—H1A	0.84 (4)	C7—H7B	0.9800
N1—H1B	0.84 (3)	C7—H7C	0.9800
N2—C2	1.406 (3)	C8—H8A	0.9800
N2—H2A	0.88 (3)	C8—H8B	0.9800
N2—H2B	0.81 (4)	C8—H8C	0.9800
C1—C6	1.382 (3)	C9—C10	1.501 (4)
C1—C2	1.389 (4)	C10—H10A	0.9800
C2—C3	1.394 (4)	C10—H10B	0.9800
C3—C4	1.384 (4)	C10—H10C	0.9800
O1—Zn1—O1i	96.70 (10)	C6—C5—C4	118.6 (2)
O1—Zn1—N1	123.94 (8)	C6—C5—C7	119.7 (3)
O1i—Zn1—N1	103.95 (8)	C4—C5—C7	121.7 (3)
O1—Zn1—N1i	103.95 (8)	C1—C6—C5	121.9 (2)
O1i—Zn1—N1i	123.94 (8)	C1—C6—H6	119.1
N1—Zn1—N1i	106.06 (13)	C5—C6—H6	119.1
C9—O1—Zn1	110.40 (17)	C5—C7—H7A	109.5
C1—N1—Zn1	113.93 (17)	C5—C7—H7B	109.5
C1—N1—H1A	112 (2)	H7A—C7—H7B	109.5
Zn1—N1—H1A	103 (2)	C5—C7—H7C	109.5
C1—N1—H1B	111 (2)	H7A—C7—H7C	109.5
Zn1—N1—H1B	108 (2)	H7B—C7—H7C	109.5
H1A—N1—H1B	109 (3)	C4—C8—H8A	109.5
C2—N2—H2A	115 (2)	C4—C8—H8B	109.5
C2—N2—H2B	112 (2)	H8A—C8—H8B	109.5
H2A—N2—H2B	113 (3)	C4—C8—H8C	109.5
C6—C1—C2	119.9 (2)	H8A—C8—H8C	109.5
C6—C1—N1	120.3 (2)	H8B—C8—H8C	109.5
C2—C1—N1	119.6 (2)	O2—C9—O1	122.1 (2)
C1—C2—C3	118.1 (2)	O2—C9—C10	121.8 (2)
C1—C2—N2	120.9 (2)	O1—C9—C10	116.1 (2)
C3—C2—N2	121.0 (2)	C9—C10—H10A	109.5
C4—C3—C2	122.4 (2)	C9—C10—H10B	109.5
C4—C3—H3	118.8	H10A—C10—H10B	109.5
C2—C3—H3	118.8	C9—C10—H10C	109.5
C3—C4—C5	119.1 (2)	H10A—C10—H10C	109.5
C3—C4—C8	119.1 (3)	H10B—C10—H10C	109.5
C5—C4—C8	121.8 (3)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1ii	0.84 (4)	2.10 (4)	2.897 (3)	158 (3)
N2—H2A···O2	0.88 (3)	2.15 (3)	3.013 (3)	168 (3)
N2—H2B···N2iii	0.81 (4)	2.26 (4)	3.076 (3)	179 (3)

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