Bis{5-meth­oxy-2-[(1H-pyrrol-2-yl)methyl­imino­meth­yl]phenolato}zinc(II)

The title compound, [Zn(C₁₃H₁₃N₂O₂)₂], contains a Zn(II) centre, located on a twofold rotation axis, that is coordinated by two O atoms and two N atoms from two salicylal Schiff base mol­ecules. The crystal structure is stabilized by inter­molecular C—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.058
• wR factor = 0.154
• Data-to-parameter ratio = 18.0

checkCIF/PLATON results

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Alert level C
PLAT230_ALERT_2_C Hirshfeld Test Diff for    N2     --  C10     ..       6.09 su
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C11    --  C12     ..       6.64 su
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for        C11
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for        C13
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N2
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds (x 1000) Ang ..          7
PLAT420_ALERT_2_C D-H Without Acceptor       N2     -   H2     ...          ?
PLAT731_ALERT_1_C Bond    Calc    1.307(7), Rep    1.308(3) ......       2.33 su-Ra
              C1   -O1      1.555   1.555

Alert level G
PLAT063_ALERT_4_G Crystal Size Likely too Large for Beam Size ....       0.30 mm

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   8 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   6 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Zinc derivatives are particularly interesting owing to their essential importance in several biological processes (Xiao et al., 2008; Xiao & Xiao, 2008; Xiao et al., 2007; Chen et al., 2007). We have reported the structures of a few zinc(II) complexes (You & Zhu, 2006; Qiu et al., 2004; Zhu et al., 2004). As an extension of our work on the structural characterization of zinc compounds, we report the crystal structure of the title compound, (I), which has been determined in an attempt to understand the structural behaviour of nitrogen containing ligands.

The present X-ray single-crystal diffraction study reveals that compound (I), Bis(4-methoxysalicylidene(1H-pyrrol-2-yl)methanaminato)zinc(II), consists of a Zn(II) atom and two bidentate salicylal Schiff base ligands. As shown in Fig. 1, The central Zn atom exhibits 4-coordination by two N atoms from imine moieties and two O-anions from salicylal groups, forming a slightly distorted tetrahedron. The distortion arises from the difference between O—Zn and Zn—N (Table 1). The O1—C1 distance (1.308 (3) Å) and C2—C8 (1.425 (4) Å) are shorter than classical single C—O and C—C bonds, respectively. This suggests that electron significantly delocalized over the O1—C1—C2—C8—N1 group and the same to the O1A—C1A—C2A—C8A—N1A group. Zn1, N1, C8 and O1 almost stand in the plane of ring C1 to C6, and makes dihedral angle of 85.569 (45) ° with corresponding plane of the other half molecules.

The hydrogen-bonding interactions occur between the C—H in the CH₂ group as donors and O in the salicylal moiety as acceptors (Table 1). These intermolecular hydrogen bonds construct an infinite ribbon. Interactions between the ribbons are van der Waals forces.

Related literature

For the importance of zinc derivatives in biological processes, see: Chen et al. (2007); Xiao & Xiao (2008); Xiao et al. (2007, 2008). For related structures, see: You & Zhu (2006); Zhu et al. (2004); Qiu et al. (2004).

S2. Experimental

0.5 mmol of zinc oxide, 1 mmol of 4-methoxysalicylaldehyde and 1 mmol of (1H-pyrrol-2-yl)methanamine were dissolved in 10 ml methanol. After 3 ml ammonia was added, the result solution was then heated to 423 K for 12 h. The reactor was cooled to room temperature at a rate of 10 K h^-1. The mixture was filtered and held at room temperature for 12 d. Colorless block crystals were isolated in 41% yield.

S3. Refinement

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms. U_iso(H) values were set at 1.2 times U_eq(C, N) for aromatic C and N in pyrrole ring groups and 1.5 times U_eq(C) for CH₃ groups.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. The independent components of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.

Bis{5-methoxy-2-[(1H-pyrrol-2-yl)methyliminomethyl]phenolato}zinc(II)

Crystal data

[Zn(C13H13N2O2)2]	F(000) = 1088
Mr = 523.88	Dx = 1.480 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2301 reflections
a = 27.210 (4) Å	θ = 2.5–26.1°
b = 5.2239 (9) Å	µ = 1.09 mm^−1
c = 24.335 (3) Å	T = 298 K
β = 137.179 (9)°	Block, colorless
V = 2351.1 (6) Å^3	0.30 × 0.30 × 0.20 mm
Z = 4

Data collection

Bruker SMART APEX area-detector diffractometer	2881 independent reflections
Radiation source: fine-focus sealed tube	2429 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
ϕ and ω scans	θmax = 28.3°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −36→35
Tmin = 0.736, Tmax = 0.812	k = −6→6
8100 measured reflections	l = −26→32

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)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.154	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0814P)^2 + 2.3252P] where P = (Fo^2 + 2Fc^2)/3
2881 reflections	(Δ/σ)max < 0.001
160 parameters	Δρmax = 0.72 e Å^−3
0 restraints	Δρmin = −0.57 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
C1	0.93603 (16)	0.2495 (6)	0.29548 (18)	0.0401 (6)
C2	0.87592 (16)	0.4163 (6)	0.24129 (18)	0.0398 (6)
C3	0.81985 (18)	0.3941 (7)	0.2349 (2)	0.0503 (8)
H3	0.7802	0.5026	0.1996	0.060*
C4	0.82168 (18)	0.2211 (7)	0.2782 (2)	0.0550 (8)
H4	0.7838	0.2105	0.2720	0.066*
C5	0.8813 (2)	0.0602 (7)	0.3317 (2)	0.0490 (8)
C6	0.93736 (19)	0.0707 (6)	0.3401 (2)	0.0462 (7)
H6	0.9763	−0.0409	0.3754	0.055*
C7	0.9380 (2)	−0.2809 (8)	0.4279 (2)	0.0673 (10)
H7A	0.9385	−0.3953	0.3973	0.101*
H7B	0.9317	−0.3774	0.4559	0.101*
H7C	0.9830	−0.1896	0.4663	0.101*
C8	0.86588 (16)	0.6031 (6)	0.19107 (18)	0.0418 (7)
H8	0.8240	0.7009	0.1592	0.050*
C9	0.88198 (18)	0.8391 (7)	0.1226 (2)	0.0507 (8)
H9A	0.9208	0.9554	0.1449	0.061*
H9B	0.8430	0.9389	0.1065	0.061*
C10	0.85569 (18)	0.7069 (7)	0.0508 (2)	0.0523 (8)
C11	0.8621 (2)	0.7591 (13)	0.0026 (3)	0.0938 (18)
H11	0.8869	0.8941	0.0066	0.113*
C12	0.8210 (3)	0.5539 (14)	−0.0582 (3)	0.103 (2)
H12	0.8155	0.5318	−0.1004	0.123*
C13	0.7934 (3)	0.4069 (13)	−0.0421 (3)	0.103 (2)
H13	0.7646	0.2637	−0.0717	0.124*
N1	0.90797 (13)	0.6538 (5)	0.18427 (15)	0.0398 (5)
N2	0.81349 (18)	0.4967 (6)	0.02362 (19)	0.0571 (8)
H2	0.8016	0.4320	0.0451	0.069*
O1	0.99094 (12)	0.2514 (5)	0.30668 (15)	0.0552 (6)
O2	0.88016 (16)	−0.1038 (6)	0.37455 (17)	0.0663 (7)
Zn1	1.0000	0.46424 (10)	0.2500	0.0430 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0412 (15)	0.0449 (16)	0.0473 (16)	−0.0004 (12)	0.0366 (14)	−0.0027 (13)
C2	0.0376 (14)	0.0469 (17)	0.0450 (16)	−0.0015 (12)	0.0334 (14)	−0.0038 (13)
C3	0.0426 (16)	0.065 (2)	0.0567 (19)	0.0051 (15)	0.0406 (16)	0.0019 (16)
C4	0.0501 (18)	0.073 (2)	0.065 (2)	−0.0037 (17)	0.0497 (18)	−0.0036 (18)
C5	0.058 (2)	0.0520 (18)	0.0553 (19)	−0.0101 (15)	0.0475 (18)	−0.0071 (15)
C6	0.0513 (18)	0.0469 (17)	0.0528 (18)	0.0015 (14)	0.0421 (16)	0.0016 (14)
C7	0.086 (3)	0.060 (2)	0.067 (2)	−0.011 (2)	0.059 (2)	0.0029 (19)
C8	0.0363 (14)	0.0465 (16)	0.0448 (16)	0.0037 (12)	0.0304 (14)	−0.0004 (13)
C9	0.0515 (18)	0.0459 (18)	0.060 (2)	−0.0014 (14)	0.0424 (17)	0.0043 (15)
C10	0.0449 (17)	0.067 (2)	0.0499 (18)	0.0130 (15)	0.0363 (16)	0.0157 (16)
C11	0.067 (3)	0.156 (5)	0.081 (3)	0.038 (3)	0.061 (3)	0.049 (3)
C12	0.081 (4)	0.168 (6)	0.059 (3)	0.047 (4)	0.051 (3)	0.013 (3)
C13	0.091 (4)	0.114 (5)	0.060 (3)	0.025 (3)	0.042 (3)	−0.013 (3)
N1	0.0355 (12)	0.0458 (13)	0.0423 (13)	−0.0016 (10)	0.0298 (11)	−0.0022 (11)
N2	0.0605 (19)	0.0552 (18)	0.0486 (16)	−0.0063 (13)	0.0378 (16)	−0.0074 (13)
O1	0.0481 (12)	0.0674 (15)	0.0712 (15)	0.0150 (11)	0.0504 (13)	0.0210 (12)
O2	0.0821 (18)	0.0695 (17)	0.0832 (19)	−0.0025 (15)	0.0719 (17)	0.0089 (15)
Zn1	0.0374 (3)	0.0513 (3)	0.0530 (3)	0.000	0.0372 (3)	0.000

Geometric parameters (Å, º)

C1—O1	1.308 (3)	C9—N1	1.460 (4)
C1—C6	1.412 (4)	C9—C10	1.487 (5)
C1—C2	1.417 (4)	C9—H9A	0.9700
C2—C3	1.421 (4)	C9—H9B	0.9700
C2—C8	1.425 (4)	C10—C11	1.333 (5)
C3—C4	1.360 (5)	C10—N2	1.359 (5)
C3—H3	0.9300	C11—C12	1.471 (8)
C4—C5	1.391 (5)	C11—H11	0.9300
C4—H4	0.9300	C12—C13	1.318 (9)
C5—O2	1.367 (4)	C12—H12	0.9300
C5—C6	1.384 (5)	C13—N2	1.340 (6)
C6—H6	0.9300	C13—H13	0.9300
C7—O2	1.422 (5)	N1—Zn1	1.983 (2)
C7—H7A	0.9600	N2—H2	0.8600
C7—H7B	0.9600	O1—Zn1	1.923 (2)
C7—H7C	0.9600	Zn1—O1^i	1.923 (2)
C8—N1	1.299 (4)	Zn1—N1^i	1.983 (2)
C8—H8	0.9300
O1—C1—C6	117.6 (3)	N1—C9—H9B	109.5
O1—C1—C2	123.5 (3)	C10—C9—H9B	109.5
C6—C1—C2	118.9 (3)	H9A—C9—H9B	108.1
C1—C2—C3	117.7 (3)	C11—C10—N2	110.3 (4)
C1—C2—C8	125.7 (3)	C11—C10—C9	132.7 (4)
C3—C2—C8	116.6 (3)	N2—C10—C9	116.9 (3)
C4—C3—C2	122.9 (3)	C10—C11—C12	104.0 (5)
C4—C3—H3	118.6	C10—C11—H11	128.0
C2—C3—H3	118.6	C12—C11—H11	128.0
C3—C4—C5	118.8 (3)	C13—C12—C11	107.7 (5)
C3—C4—H4	120.6	C13—C12—H12	126.1
C5—C4—H4	120.6	C11—C12—H12	126.1
O2—C5—C6	123.5 (3)	C12—C13—N2	109.2 (6)
O2—C5—C4	115.5 (3)	C12—C13—H13	125.4
C6—C5—C4	121.1 (3)	N2—C13—H13	125.4
C5—C6—C1	120.6 (3)	C8—N1—C9	117.3 (3)
C5—C6—H6	119.7	C8—N1—Zn1	120.3 (2)
C1—C6—H6	119.7	C9—N1—Zn1	122.2 (2)
O2—C7—H7A	109.5	C13—N2—C10	108.8 (5)
O2—C7—H7B	109.5	C13—N2—H2	125.6
H7A—C7—H7B	109.5	C10—N2—H2	125.6
O2—C7—H7C	109.5	C1—O1—Zn1	125.7 (2)
H7A—C7—H7C	109.5	C5—O2—C7	118.3 (3)
H7B—C7—H7C	109.5	O1—Zn1—O1^i	109.36 (15)
N1—C8—C2	128.1 (3)	O1—Zn1—N1^i	117.41 (10)
N1—C8—H8	116.0	O1^i—Zn1—N1^i	96.71 (10)
C2—C8—H8	116.0	O1—Zn1—N1	96.71 (10)
N1—C9—C10	110.7 (3)	O1^i—Zn1—N1	117.41 (10)
N1—C9—H9A	109.5	N1^i—Zn1—N1	120.10 (15)
C10—C9—H9A	109.5
O1—C1—C2—C3	−180.0 (3)	C2—C8—N1—C9	174.4 (3)
C6—C1—C2—C3	0.1 (4)	C2—C8—N1—Zn1	−1.1 (4)
O1—C1—C2—C8	1.2 (5)	C10—C9—N1—C8	−102.9 (3)
C6—C1—C2—C8	−178.8 (3)	C10—C9—N1—Zn1	72.5 (3)
C1—C2—C3—C4	−0.1 (5)	C12—C13—N2—C10	−0.4 (6)
C8—C2—C3—C4	178.8 (3)	C11—C10—N2—C13	1.4 (5)
C2—C3—C4—C5	0.7 (5)	C9—C10—N2—C13	178.5 (4)
C3—C4—C5—O2	178.3 (3)	C6—C1—O1—Zn1	177.0 (2)
C3—C4—C5—C6	−1.3 (5)	C2—C1—O1—Zn1	−3.0 (5)
O2—C5—C6—C1	−178.3 (3)	C6—C5—O2—C7	−3.0 (5)
C4—C5—C6—C1	1.3 (5)	C4—C5—O2—C7	177.4 (3)
O1—C1—C6—C5	179.4 (3)	C1—O1—Zn1—O1^i	−119.8 (3)
C2—C1—C6—C5	−0.7 (5)	C1—O1—Zn1—N1^i	131.4 (3)
C1—C2—C8—N1	1.1 (5)	C1—O1—Zn1—N1	2.4 (3)
C3—C2—C8—N1	−177.8 (3)	C8—N1—Zn1—O1	−0.4 (3)
N1—C9—C10—C11	−139.4 (4)	C9—N1—Zn1—O1	−175.6 (2)
N1—C9—C10—N2	44.4 (4)	C8—N1—Zn1—O1^i	115.5 (2)
N2—C10—C11—C12	−1.7 (4)	C9—N1—Zn1—O1^i	−59.7 (3)
C9—C10—C11—C12	−178.1 (4)	C8—N1—Zn1—N1^i	−127.6 (3)
C10—C11—C12—C13	1.4 (6)	C9—N1—Zn1—N1^i	57.2 (2)
C11—C12—C13—N2	−0.6 (6)

Symmetry code: (i) −x+2, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C9—H9A···O1^ii	0.97	2.32	3.291 (4)	177

Symmetry code: (ii) −x+2, y+1, −z+1/2.