(1E,1′E)-4,4′-[1,1′-(Hydrazine-1,2-diyl­idene)bis­(ethan-1-yl-1-yl­idene)]diphenol dihydrate

The asymmetric unit of the title compound, C₁₆H₁₆N₂O₂·2H₂O, contains one half-mol­ecule of diphenol and one water mol­ecule. The complete diphenol mol­ecule is generated by a crystallographic inversion centre. In the mol­ecule, the central C_meth­yl—C=N—N=C—C_meth­yl plane makes a dihedral angle of 8.88 (6)° with its adjacent benzene ring. In the crystal, the components are linked by O—H...N and O—H...O hydrogen bonds into a three-dimensional network. The crystal structure is further stabilized by a weak C—H...π inter­action.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.046
• wR factor = 0.125
• Data-to-parameter ratio = 21.1

checkCIF/PLATON results

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Alert level C
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          3
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          8

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT380_ALERT_4_G Check Incorrectly? Oriented X(sp2)-Methyl Moiety         C8
PLAT720_ALERT_4_G Number of Unusual/Non-Standard Labels ..........          1

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   2 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   3 ALERT level G = General information/check it is not something unexpected

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
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   1 ALERT type 5 Informative message, check

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S1. Comment

Hydrazones have been reported to possess fluorescence properties (Qin et al., 2009) and various biological activities such as to be used as insecticides, antitumor agents and antioxidants (Kitaev et al., 1970), as well as antimicrobial (Ramamohan et al., 1995) and antiviral properties (El-Tabl et al., 2008; Rollas & Küçükgüzel, 2007) and tyrosinase inhibitory activity (Bendre et al., 1998). With our on-going research on structural studies and properties of hydrazones (Chantrapromma et al., 2010; Fun et al., 2010; Jansrisewangwong et al., 2010), the title compound (I) was synthesized. Our results show that (I) was inactive for tyrosinase inhibitory activity. Herein we report the synthesis and crystal structure of the title compound (I).

The asymmetric unit of (I) (Fig. 1), C₁₆H₁₆N₂O₂.2H₂O, contains one half-molecule of diphenol and the complete molecule is generated by a crystallographic inversion centre 1 - x, 1 - y, 1 - z. The molecule of (I) exists in an E,E configuration with respect to the two C═N double bonds [1.2985 (13) Å] and the torsion angle N1A–N1–C7–C1 = 177.76 (10)°. The diethylidenehydrazine moiety (C7/C8/N1/N1A/C7A/C8A) is planar with an r.m.s deviation of 0.0084 (1) Å. This C/C/N/N/C/C plane makes a dihedral angle of 8.88 (6)° with its both adjacent benzene rings. Each hydroxy group is co-planarly attached with the benzene ring with the r.m.s. of 0.0056 (1) Å for the seven non H atoms. The bond distances are of normal values (Allen et al., 1987) and are comparable with related structures (Chantrapromma et al., 2010; Fun et al., 2010; Jansrisewangwong et al., 2010).

In the crystal structure (Fig. 2), the molecules are linked into three dimensional network by O—H···N and O—H···O hydrogen bonds (Table 1). C—H···π interaction was also also observed (Table 1).

Related literature

For bond-length data, see: Allen et al. (1987). For related structures, see: Chantrapromma et al. (2010); Fun et al. (2010); Jansrisewangwong et al. (2010). For background to and the biological activity of hydrozones, see: Bendre et al. (1998); El-Tabl et al. (2008); Kitaev et al. (1970); Qin et al. (2009); Ramamohan et al. (1995); Rollas & Küçükgüzel (2007). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

S2. Experimental

The title compound was synthesized by mixing a solution (1:2 molar ratio) of hydrazine hydrate (0.10 ml, 2 mmol) and 4-hydroxyacetophenone (0.54 g, 4 mmol) in ethanol (20 ml). The resulting solution was refluxed for 6 h, yielding the yellow solid. The resultant solid was filtered off and washed with methanol. Yellow block-shaped single crystals of the title compound suitable for x-ray structure determination were recrystalized from acetone by slow evaporation of the solvent at room temperature over several days, m.p. 377–379 K.

S3. Refinement

The water hydrogen atoms were restrained to the ideal positions. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(O—H) = 0.86 Å, and d(C—H) = 0.93 Å for aromatic and 0.96 Å for CH₃ atoms. The U_iso values were constrained to be 1.5U_eq of the carrier atom for methyl H atoms and 1.2U_eq for the remaining H atoms. A rotating group model was used for the methyl groups. The highest residual electron density peak is located at 0.40 Å from H1W and the deepest hole is located at 0.35 Å from H1W.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme. Atoms with suffix A were generated by symmetry code 1 - x, 1 - y, 1 - z.
	Fig. 2. The crystal packing of the title compound viewed approximately along the b axis, showing three dimensional network.

4-[(1E)-1-[(E)-2-[1-(4-hydroxyphenyl)ethylidene]hydrazin- 1-ylidene]ethyl]phenol

Crystal data

C16H16N2O2·2H2O	F(000) = 324
Mr = 304.34	Dx = 1.376 Mg m^−3
Monoclinic, P21/c	Melting point = 377–379 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 7.8522 (1) Å	Cell parameters from 2129 reflections
b = 5.5151 (1) Å	θ = 2.4–30.0°
c = 17.8918 (3) Å	µ = 0.10 mm^−1
β = 108.536 (1)°	T = 100 K
V = 734.62 (2) Å^3	Block, yellow
Z = 2	0.35 × 0.26 × 0.22 mm

Data collection

Bruker APEXII CCD area-detector diffractometer	2129 independent reflections
Radiation source: sealed tube	1903 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
ϕ and ω scans	θmax = 30.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −10→11
Tmin = 0.966, Tmax = 0.979	k = −7→7
8010 measured reflections	l = −24→24

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.125	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.061P)^2 + 0.4114P] where P = (Fo^2 + 2Fc^2)/3
2129 reflections	(Δ/σ)max = 0.001
101 parameters	Δρmax = 0.39 e Å^−3
0 restraints	Δρmin = −0.34 e Å^−3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 120.0 (1) K.

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
O1	0.97567 (10)	0.63439 (15)	0.90238 (4)	0.01443 (19)
H1O1	1.0145	0.4971	0.9166	0.022*
N1	0.55899 (11)	0.49760 (17)	0.53887 (5)	0.0144 (2)
C1	0.64270 (13)	0.65293 (19)	0.66844 (6)	0.0106 (2)
C2	0.63628 (14)	0.83658 (19)	0.72163 (6)	0.0131 (2)
H2A	0.5566	0.9650	0.7045	0.016*
C3	0.74735 (14)	0.82980 (19)	0.79977 (6)	0.0137 (2)
H3A	0.7421	0.9534	0.8343	0.016*
C4	0.86615 (13)	0.63756 (19)	0.82596 (6)	0.0111 (2)
C5	0.87307 (13)	0.45094 (19)	0.77420 (6)	0.0126 (2)
H5A	0.9515	0.3215	0.7918	0.015*
C6	0.76265 (13)	0.45958 (19)	0.69653 (6)	0.0123 (2)
H6A	0.7680	0.3350	0.6623	0.015*
C7	0.52532 (13)	0.65863 (19)	0.58524 (6)	0.0113 (2)
C8	0.37991 (14)	0.8466 (2)	0.56043 (6)	0.0160 (2)
H8A	0.4326	1.0054	0.5696	0.024*
H8B	0.2989	0.8269	0.5904	0.024*
H8C	0.3152	0.8278	0.5054	0.024*
O1W	0.07930 (12)	0.31062 (17)	0.45773 (6)	0.0252 (2)
H1W	0.0793	0.3113	0.5058	0.038*
H2W	0.1722	0.3860	0.4541	0.038*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0167 (4)	0.0153 (4)	0.0088 (3)	0.0003 (3)	0.0007 (3)	0.0002 (3)
N1	0.0136 (4)	0.0180 (5)	0.0093 (4)	0.0038 (3)	0.0002 (3)	−0.0019 (3)
C1	0.0106 (4)	0.0118 (5)	0.0093 (4)	−0.0001 (3)	0.0029 (3)	−0.0004 (3)
C2	0.0145 (4)	0.0122 (5)	0.0121 (4)	0.0025 (4)	0.0034 (4)	−0.0005 (3)
C3	0.0163 (5)	0.0125 (5)	0.0120 (4)	0.0007 (4)	0.0041 (4)	−0.0025 (3)
C4	0.0114 (4)	0.0131 (5)	0.0087 (4)	−0.0023 (3)	0.0030 (3)	−0.0001 (3)
C5	0.0132 (4)	0.0125 (5)	0.0116 (4)	0.0026 (3)	0.0033 (3)	0.0004 (3)
C6	0.0141 (4)	0.0121 (5)	0.0106 (4)	0.0013 (3)	0.0039 (3)	−0.0017 (3)
C7	0.0103 (4)	0.0131 (5)	0.0102 (4)	0.0005 (3)	0.0028 (3)	0.0006 (3)
C8	0.0164 (5)	0.0166 (5)	0.0128 (5)	0.0059 (4)	0.0016 (4)	−0.0010 (4)
O1W	0.0194 (4)	0.0227 (5)	0.0337 (5)	−0.0016 (3)	0.0089 (4)	0.0060 (4)

Geometric parameters (Å, º)

O1—C4	1.3644 (11)	C4—C5	1.3971 (14)
O1—H1O1	0.8256	C5—C6	1.3854 (13)
N1—C7	1.2985 (13)	C5—H5A	0.9300
N1—N1^i	1.4050 (16)	C6—H6A	0.9300
C1—C2	1.4016 (14)	C7—C8	1.5010 (14)
C1—C6	1.4056 (14)	C8—H8A	0.9600
C1—C7	1.4814 (13)	C8—H8B	0.9600
C2—C3	1.3934 (13)	C8—H8C	0.9600
C2—H2A	0.9300	O1W—H1W	0.8598
C3—C4	1.3913 (14)	O1W—H2W	0.8601
C3—H3A	0.9300
C4—O1—H1O1	111.9	C6—C5—H5A	120.1
C7—N1—N1^i	114.55 (10)	C4—C5—H5A	120.1
C2—C1—C6	118.04 (9)	C5—C6—C1	121.28 (9)
C2—C1—C7	121.45 (9)	C5—C6—H6A	119.4
C6—C1—C7	120.50 (9)	C1—C6—H6A	119.4
C3—C2—C1	121.04 (9)	N1—C7—C1	116.07 (9)
C3—C2—H2A	119.5	N1—C7—C8	125.01 (9)
C1—C2—H2A	119.5	C1—C7—C8	118.92 (9)
C4—C3—C2	119.82 (9)	C7—C8—H8A	109.5
C4—C3—H3A	120.1	C7—C8—H8B	109.5
C2—C3—H3A	120.1	H8A—C8—H8B	109.5
O1—C4—C3	119.26 (9)	C7—C8—H8C	109.5
O1—C4—C5	120.65 (9)	H8A—C8—H8C	109.5
C3—C4—C5	120.09 (9)	H8B—C8—H8C	109.5
C6—C5—C4	119.72 (9)	H1W—O1W—H2W	110.1
C6—C1—C2—C3	0.95 (16)	C2—C1—C6—C5	−0.70 (15)
C7—C1—C2—C3	−179.93 (9)	C7—C1—C6—C5	−179.83 (9)
C1—C2—C3—C4	−0.37 (16)	N1^i—N1—C7—C1	177.76 (10)
C2—C3—C4—O1	179.26 (9)	N1^i—N1—C7—C8	−2.78 (17)
C2—C3—C4—C5	−0.48 (16)	C2—C1—C7—N1	171.18 (10)
O1—C4—C5—C6	−179.01 (9)	C6—C1—C7—N1	−9.72 (14)
C3—C4—C5—C6	0.72 (15)	C2—C1—C7—C8	−8.31 (15)
C4—C5—C6—C1	−0.12 (16)	C6—C1—C7—C8	170.78 (10)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

Cg1 is the centroid of the C1–C6 ring.

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1O1···O1W^ii	0.83	1.86	2.6747 (12)	171
O1W—H1W···O1^iii	0.86	2.07	2.8429 (12)	149
O1W—H2W···N1^i	0.86	2.17	3.0132 (14)	166
C5—H5A···Cg1^iv	0.93	2.80	3.5046 (12)	134

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