Dihydroxido­bis(melamine-κN)zinc(II) monohydrate

In the title compound, dihydroxido­bis­(2,4,6-triamino-1,3,5-triazine-κN)­zinc(II) monohydrate, [Zn(OH)₂(C₃N₆H₆)₂]·H₂O, Zn^II is tetra­hedrally coordinated by two melamine and two hydr­oxy groups; there is also a solvent water mol­ecule. The dihedral angle between the two melamine rings is 86.3 (9)°. Intra­molecular N—H...O and N—H...N hydrogen bonds help to stabilize the mol­ecular conformation. Numerous inter­molecular hydrogen bonds between water, hydr­oxy and melamine groups link the mol­ecules into a three-dimensional supra­molecular network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](N-C) = 0.010 Å
• R factor = 0.053
• wR factor = 0.143
• Data-to-parameter ratio = 9.3

checkCIF/PLATON results

No syntax errors found



Alert level G
REFLT03_ALERT_4_G  WARNING: Large fraction of Friedel related reflns may
                     be needed to determine absolute structure
           From the CIF: _diffrn_reflns_theta_max           25.05
           From the CIF: _reflns_number_total               1843
           Count of symmetry unique reflns         1230
           Completeness (_total/calc)            149.84%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       613
           Fraction of Friedel pairs measured     0.498
           Are heavy atom types Z>Si present        yes
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Zn1         (2)       1.71
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

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

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

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S1. Comment

The transition metal complexes are potential photo-luminescent, paramagnetic and radioactive materials due to their attractive photochemical and photophysical properties(Ford et al., 1999). Low dimensional metal organic complexes have received great attention in recent years for their potential applications in optics, electronics, magnetics, biology, catalyst and medicine (Tandon et al., 1994). The ligand, melamine, has both acceptor and donnor atoms suitable for hydrogen bonding and is analogous to nucleobases that may lead to some interesting new chemotherapeutic possibilities (Zhu et al., 1999).

In the complex I, the zinc cation is coordinated by two melamine and two hydroxyl ligands, forming a distorted tetrahedral geometry, while intramolecular N—H···O and N—H···H hydrogen bonds help to stabilize the molecular conformation (Fig. 1). The two melamine rings make a dihedral angle of 86.3 (9) °. All of the bond lengths and angles are within normal ranges (Allen et al., 1987). The Zn—N bond lengths (2.021 Å and 2.024 Å) in the title compound are slightly shorter than that (2.039 Å) in the compound [Zn(C₃N₆H₆)(H₂O)_0.5Cl₂](C₃N₆H₆)(H₂O) (Yu et al., 2004). The Zn—O bond lengths (2.018 Å and 2.041 Å) are slightly longer than that (1.984 Å) in the compound [Zn(C₃N₆H₆)(H₂O)_0.5Cl₂](C₃N₆H₆)(H₂O) (Yu et al., 2004).

As can be seen from the packing diagram (Fig. 2), intermolecular N—H···O, N—H···N, O—H..O and O—H···N hydrogen bonds(Table 1) link the molecules into a three-dimensional network, which may be effective in the stabilization of the crystal structure.

Related literature

For general background, see: Ford et al. (1999); Tandon et al. (1994); Zhu et al. (1999). For a related structure, see: Yu et al. (2004). For bond-length data, see: Allen et al. (1987).

S2. Experimental

A mixture of zinc chloride (0.136 g, 1 mmol), melamine (0.252 g, 2 mmol), and distilled water(8 ml) was heated at 180°C for 4 days in hydrothermal tube. After being cooled to room temperature, colourless block crystals were obtained. Elemental analysis calcd for compound(I): C 19.58%, H 4.40%, N 45.60%; Found: C 19.51%, H 4.35%, N 45.53%.

S3. Refinement

H atoms attached to NH₂ and hydroxyl groups were positioned geometrically (O—H = 0.84 and N—H = 0.86 Å) and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(N,O). H atoms from water were located in a difference map and refined with distance restraints of O—H = 0.84 \%A and Uĩso~(H) = 1.5U~eq~(O).

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2000); software used to prepare material for publication: SHELXTL (Bruker, 2000).

Figures

	Fig. 1. A view of the molecular structure of (I) showing the atom-numbering scheme and 30% displacement ellipsoids (arbitrary spheres for the H atoms). Intramolecular hydrogen bonds are shown as double dashed lines.
	Fig. 2. A packing diagram of complex(I). Hydrogen bonds are shown as dashed lines.

Dihydroxidobis(melamine-κN)zinc(II) monohydrate

Crystal data

[Zn(OH)2(C3N6H6)2]·H2O	F(000) = 760
Mr = 369.70	Dx = 1.865 Mg m^−3
Orthorhombic, Pna21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2n	Cell parameters from 25 reflections
a = 17.531 (4) Å	θ = 9–13°
b = 6.6251 (13) Å	µ = 1.91 mm^−1
c = 11.335 (2) Å	T = 293 K
V = 1316.5 (5) Å^3	Block, colourless
Z = 4	0.40 × 0.40 × 0.22 mm

Data collection

Enraf–Nonius CAD-4 diffractometer	1682 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.037
Graphite monochromator	θmax = 25.1°, θmin = 2.3°
ω/2θ scans	h = −11→20
Absorption correction: ψ scan (North et al., 1968)	k = −7→7
Tmin = 0.508, Tmax = 0.657	l = −13→11
3467 measured reflections	3 standard reflections every 200 reflections
1843 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.053	H-atom parameters constrained
wR(F^2) = 0.143	w = 1/[σ^2(Fo^2) + (0.0759P)^2 + 5.1018P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
1843 reflections	Δρmax = 0.23 e Å^−3
199 parameters	Δρmin = −0.38 e Å^−3
1 restraint	Absolute structure: Flack (1983), 636 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.06 (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	1.0926 (4)	0.8133 (12)	0.2026 (8)	0.0288 (18)
C2	1.2208 (4)	0.9046 (10)	0.1426 (11)	0.0301 (16)
C3	1.1128 (4)	1.1158 (13)	0.0982 (8)	0.032 (2)
C4	0.9359 (4)	0.7899 (13)	−0.0664 (9)	0.0327 (19)
C5	0.8131 (5)	0.6933 (14)	−0.1435 (9)	0.035 (2)
C6	0.8286 (4)	0.9887 (13)	−0.0226 (9)	0.0306 (18)
N1	1.0653 (3)	0.9865 (9)	0.1520 (9)	0.0303 (18)
N2	1.0510 (3)	0.6883 (9)	0.2514 (6)	0.0264 (16)
H2A	1.0026	0.7081	0.2547	0.032*
H2B	1.0705	0.5814	0.2821	0.032*
N3	1.1697 (3)	0.7769 (10)	0.1947 (7)	0.0313 (16)
N4	1.2893 (2)	0.8706 (8)	0.1433 (8)	0.0246 (13)
H4A	1.3205	0.9558	0.1124	0.030*
H4B	1.3064	0.7614	0.1747	0.030*
N5	1.1901 (4)	1.0702 (10)	0.0957 (7)	0.0319 (17)
N6	1.0884 (4)	1.2648 (11)	0.0488 (7)	0.039 (2)
H6A	1.0402	1.2885	0.0479	0.046*
H6B	1.1193	1.3467	0.0145	0.046*
N7	0.9038 (4)	0.9458 (10)	−0.0072 (7)	0.0242 (17)
N8	1.0043 (3)	0.7584 (11)	−0.0641 (8)	0.041 (2)
H8A	1.0338	0.8362	−0.0240	0.050*
H8B	1.0232	0.6582	−0.1025	0.050*
N9	0.8892 (4)	0.6602 (11)	−0.1310 (7)	0.0329 (17)
N10	0.7718 (4)	0.5743 (10)	−0.1966 (7)	0.0318 (17)
H10A	0.7239	0.5988	−0.2035	0.038*
H10B	0.7909	0.4665	−0.2269	0.038*
N11	0.7853 (4)	0.8644 (11)	−0.0947 (7)	0.0338 (16)
N12	0.7985 (3)	1.1327 (10)	0.0259 (7)	0.0333 (18)
H12A	0.8250	1.2100	0.0711	0.040*
H12B	0.7509	1.1568	0.0149	0.040*
O1	0.9360 (3)	1.3630 (9)	0.1356 (11)	0.0580 (17)
H1	0.9357	1.4061	0.2053	0.087*
O2	0.8931 (5)	0.9344 (13)	0.2726 (9)	0.051 (3)
H2	0.9153	0.9581	0.3368	0.077*
O3	0.8689 (4)	0.4538 (10)	0.3936 (8)	0.053 (2)
H3A	0.8521	0.3534	0.4307	0.080*
H3B	0.8286	0.4959	0.3620	0.080*
Zn1	0.95397 (4)	1.06209 (11)	0.13850 (11)	0.0287 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.026 (4)	0.027 (4)	0.033 (5)	0.005 (3)	−0.001 (3)	−0.006 (4)
C2	0.029 (3)	0.030 (4)	0.031 (4)	−0.006 (3)	−0.012 (5)	0.002 (5)
C3	0.026 (4)	0.037 (4)	0.032 (5)	−0.001 (3)	0.005 (3)	−0.003 (4)
C4	0.028 (4)	0.033 (4)	0.037 (5)	0.003 (3)	0.001 (4)	−0.005 (4)
C5	0.036 (4)	0.032 (5)	0.038 (5)	0.004 (4)	0.001 (4)	−0.0041 (4)
C6	0.025 (4)	0.035 (4)	0.033 (5)	0.005 (3)	−0.008 (3)	0.000 (4)
N1	0.020 (2)	0.029 (3)	0.042 (5)	−0.004 (2)	−0.002 (4)	0.009 (4)
N2	0.015 (3)	0.021 (3)	0.043 (4)	0.002 (3)	0.007 (3)	0.018 (3)
N3	0.022 (3)	0.027 (3)	0.045 (4)	−0.002 (3)	0.003 (3)	0.009 (3)
N4	0.009 (2)	0.019 (3)	0.047 (4)	0.0011 (18)	0.008 (4)	0.004 (4)
N5	0.026 (3)	0.034 (4)	0.036 (4)	−0.001 (3)	0.002 (3)	0.010 (3)
N6	0.018 (3)	0.025 (4)	0.043 (5)	0.004 (3)	0.011 (3)	0.018 (4)
N7	0.020 (3)	0.028 (4)	0.025 (5)	0.002 (3)	−0.003 (3)	−0.008 (3)
N8	0.020 (3)	0.040 (4)	0.064 (6)	0.008 (3)	−0.004 (3)	−0.036 (4)
N9	0.028 (3)	0.035 (4)	0.035 (4)	0.003 (3)	−0.001 (3)	−0.012 (4)
N10	0.021 (3)	0.029 (3)	0.045 (5)	0.000 (3)	−0.008 (3)	−0.022 (3)
N11	0.028 (3)	0.033 (4)	0.040 (4)	0.004 (3)	0.002 (3)	−0.010 (4)
N12	0.021 (3)	0.034 (4)	0.054 (5)	0.010 (3)	−0.009 (3)	−0.031 (4)
O1	0.057 (3)	0.046 (3)	0.071 (5)	0.007 (3)	0.000 (6)	0.009 (6)
O2	0.055 (5)	0.047 (6)	0.062 (7)	−0.011 (4)	0.005 (4)	0.002 (5)
O3	0.032 (3)	0.058 (4)	0.069 (5)	0.005 (3)	−0.008 (3)	−0.021 (4)
Zn1	0.0224 (4)	0.0304 (5)	0.0334 (5)	0.0006 (3)	−0.0005 (5)	−0.0012 (6)

Geometric parameters (Å, º)

C1—N2	1.234 (10)	N2—H2A	0.8600
C1—N1	1.369 (11)	N2—H2B	0.8600
C1—N3	1.377 (10)	N4—H4A	0.8600
C2—N4	1.222 (8)	N4—H4B	0.8600
C2—N5	1.334 (10)	N6—H6A	0.8600
C2—N3	1.366 (10)	N6—H6B	0.8600
C3—N6	1.213 (11)	N7—Zn1	2.024 (8)
C3—N1	1.341 (11)	N8—H8A	0.8600
C3—N5	1.389 (10)	N8—H8B	0.8600
C4—N8	1.217 (10)	N10—H10A	0.8600
C4—N7	1.354 (11)	N10—H10B	0.8600
C4—N9	1.395 (11)	N12—H12A	0.8600
C5—N10	1.227 (11)	N12—H12B	0.8600
C5—N11	1.353 (12)	O1—Zn1	2.018 (6)
C5—N9	1.359 (11)	O1—H1	0.8396
C6—N12	1.221 (11)	O2—Zn1	2.041 (10)
C6—N7	1.360 (11)	O2—H2	0.8400
C6—N11	1.387 (11)	O3—H3A	0.8396
N1—Zn1	2.021 (6)	O3—H3B	0.8399
N2—C1—N1	122.9 (7)	C2—N5—C3	124.4 (7)
N2—C1—N3	119.5 (7)	C3—N6—H6A	120.0
N1—C1—N3	117.6 (7)	C3—N6—H6B	120.0
N4—C2—N5	123.5 (8)	H6A—N6—H6B	120.0
N4—C2—N3	121.9 (7)	C4—N7—C6	119.9 (8)
N5—C2—N3	114.6 (6)	C4—N7—Zn1	121.0 (6)
N6—C3—N1	120.8 (7)	C6—N7—Zn1	116.5 (6)
N6—C3—N5	120.7 (8)	C4—N8—H8A	120.0
N1—C3—N5	118.4 (8)	C4—N8—H8B	120.0
N8—C4—N7	122.0 (8)	H8A—N8—H8B	120.0
N8—C4—N9	119.0 (8)	C5—N9—C4	122.2 (7)
N7—C4—N9	119.0 (7)	C5—N10—H10A	120.0
N10—C5—N11	121.8 (8)	C5—N10—H10B	120.0
N10—C5—N9	121.8 (8)	H10A—N10—H10B	120.0
N11—C5—N9	116.5 (9)	C5—N11—C6	122.8 (7)
N12—C6—N7	121.7 (8)	C6—N12—H12A	120.0
N12—C6—N11	119.5 (7)	C6—N12—H12B	120.0
N7—C6—N11	118.9 (8)	H12A—N12—H12B	120.0
C3—N1—C1	120.6 (6)	Zn1—O1—H1	108.8
C3—N1—Zn1	114.0 (5)	Zn1—O2—H2	109.0
C1—N1—Zn1	125.2 (5)	H3A—O3—H3B	100.5
C1—N2—H2A	120.0	O1—Zn1—N1	113.4 (3)
C1—N2—H2B	120.0	O1—Zn1—N7	107.2 (4)
H2A—N2—H2B	120.0	N1—Zn1—N7	112.8 (3)
C2—N3—C1	124.3 (7)	O1—Zn1—O2	109.8 (4)
C2—N4—H4A	120.0	N1—Zn1—O2	110.2 (4)
C2—N4—H4B	120.0	N7—Zn1—O2	102.9 (3)
H4A—N4—H4B	120.0
N6—C3—N1—C1	176.7 (9)	N12—C6—N7—Zn1	21.0 (12)
N5—C3—N1—C1	−0.4 (14)	N11—C6—N7—Zn1	−158.6 (7)
N6—C3—N1—Zn1	1.3 (12)	N10—C5—N9—C4	−177.1 (9)
N5—C3—N1—Zn1	−175.8 (6)	N11—C5—N9—C4	3.0 (13)
N2—C1—N1—C3	−178.8 (9)	N8—C4—N9—C5	−175.8 (9)
N3—C1—N1—C3	−0.8 (14)	N7—C4—N9—C5	4.9 (13)
N2—C1—N1—Zn1	−3.9 (13)	N10—C5—N11—C6	172.1 (9)
N3—C1—N1—Zn1	174.1 (6)	N9—C5—N11—C6	−8.0 (13)
N4—C2—N3—C1	176.1 (10)	N12—C6—N11—C5	−174.5 (9)
N5—C2—N3—C1	−1.6 (15)	N7—C6—N11—C5	5.1 (14)
N2—C1—N3—C2	180.0 (9)	C3—N1—Zn1—O1	−33.1 (9)
N1—C1—N3—C2	1.8 (14)	C1—N1—Zn1—O1	151.7 (8)
N4—C2—N5—C3	−177.3 (10)	C3—N1—Zn1—N7	88.9 (7)
N3—C2—N5—C3	0.4 (15)	C1—N1—Zn1—N7	−86.3 (9)
N6—C3—N5—C2	−176.5 (10)	C3—N1—Zn1—O2	−156.7 (7)
N1—C3—N5—C2	0.5 (14)	C1—N1—Zn1—O2	28.1 (9)
N8—C4—N7—C6	172.8 (10)	C4—N7—Zn1—O1	143.5 (7)
N9—C4—N7—C6	−8.0 (13)	C6—N7—Zn1—O1	−54.9 (7)
N8—C4—N7—Zn1	−26.2 (13)	C4—N7—Zn1—N1	18.0 (8)
N9—C4—N7—Zn1	153.0 (7)	C6—N7—Zn1—N1	179.6 (6)
N12—C6—N7—C4	−177.2 (9)	C4—N7—Zn1—O2	−100.7 (7)
N11—C6—N7—C4	3.2 (13)	C6—N7—Zn1—O2	60.9 (7)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O2	0.86	2.44	3.221 (11)	151
N2—H2B···N9^i	0.86	2.01	2.865 (9)	174
N4—H4A···O1^ii	0.86	2.37	3.120 (8)	146
N4—H4B···O2^iii	0.86	2.29	3.089 (11)	156
N6—H6A···O1	0.86	2.14	2.921 (10)	151
N6—H6B···O3^iv	0.86	1.91	2.670 (9)	146
N8—H8A···N1	0.86	2.30	3.070 (12)	150
N8—H8B···O3^v	0.86	2.03	2.674 (9)	131
N10—H10A···O2^vi	0.86	2.34	3.057 (11)	141
N10—H10B···N3^v	0.86	1.97	2.826 (9)	176
N12—H12A···O1	0.86	2.31	3.111 (10)	155
N12—H12B···N5^vii	0.86	2.29	2.849 (9)	123
O1—H1···O3^viii	0.84	2.46	3.209 (14)	150
O2—H2···N8^ix	0.84	2.60	3.288 (10)	139
O3—H3A···N11^x	0.84	2.43	2.770 (9)	105
O3—H3B···N11^x	0.84	2.23	2.770 (9)	122

Symmetry codes: (i) −x+2, −y+1, z+1/2; (ii) x+1/2, −y+5/2, z; (iii) x+1/2, −y+3/2, z; (iv) −x+2, −y+2, z−1/2; (v) −x+2, −y+1, z−1/2; (vi) −x+3/2, y−1/2, z−1/2; (vii) x−1/2, −y+5/2, z; (viii) x, y+1, z; (ix) −x+2, −y+2, z+1/2; (x) −x+3/2, y−1/2, z+1/2.