5-Bromo­phthalazine hemihydrate

The title compound, C₈H₅BrN₂·0.5H₂O, is a phthalazine derivative synthesized from 3-bromo­benzene-1,2-dicarbaldehyde and hydrazine. The mol­ecule is essentially planar, the deviation from the mean plane of the phthalazine ring being 0.015 (3) Å. The O atom of the solvent water mol­ecule is situated on a twofold rotation axis. In the crystal, O—H...N hydrogen bonds and short N...Br [2.980 (3) Å] contacts lead to the formation of a two-dimensional network parallel to (101).

Key indicators

• Single-crystal X-ray study
• T = 113 K
• Mean [sigma](C-C) = 0.004 Å
Some non-H atoms missing
• R factor = 0.029
• wR factor = 0.074
• Data-to-parameter ratio = 16.7

checkCIF/PLATON results

No syntax errors found



Alert level A
ABSMU01_ALERT_1_A  The ratio of given/expected absorption coefficient lies
               outside the range 0.90 <> 1.10
            Calculated value of mu =     5.978
            Value of mu given      =     5.314
CHEMW03_ALERT_2_A ALERT: The ratio of given/expected molecular weight as
            calculated from the _atom_site* data lies outside
            the range 0.90 <> 1.10
           From the CIF: _cell_formula_units_Z                   18
           From the CIF: _chemical_formula_weight           218.06
           TEST: Calculate formula weight from _atom_site_*
           atom     mass    num     sum
           C        12.01    7.11   85.41
           H         1.01    5.33    5.38
           N        14.01    1.78   24.90
           O        16.00    0.44    7.11
           Br       79.90    0.89   71.03
           Calculated formula weight              193.83
DENSD01_ALERT_1_A  The ratio of the submitted crystal density and that
            calculated from the formula is outside the range 0.90 <> 1.10
            Crystal density given    =      1.895
            Calculated crystal density =      2.132
PLAT043_ALERT_1_A Check Reported Molecular Weight ................     218.06
PLAT046_ALERT_1_A Reported Z, MW and D(calc) are Inconsistent ....      2.132

Alert level C
PLAT041_ALERT_1_C Calc. and Reported SumFormula    Strings  Differ          ?
PLAT042_ALERT_1_C Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       0.44 Ratio

Alert level G
FORMU01_ALERT_2_G  There is a discrepancy between the atom counts in the
            _chemical_formula_sum and the formula from the _atom_site* data.
            Atom count from _chemical_formula_sum:C8 H6 Br1 N2 O0.5
            Atom count from the _atom_site data:  C7.111111 H5.333333 Br0.888888
CELLZ01_ALERT_1_G Difference between formula and atom_site contents detected.
CELLZ01_ALERT_1_G ALERT: Large difference may be due to a
            symmetry error - see SYMMG tests
           From the CIF: _cell_formula_units_Z   18
           From the CIF: _chemical_formula_sum  C8 H6 Br1 N2 O0.5
           TEST: Compare cell contents of formula and atom_site data

           atom    Z*formula  cif sites diff
           C        144.00    128.00   16.00
           H        108.00     96.00   12.00
           Br        18.00     16.00    2.00
           N         36.00     32.00    4.00
           O          9.00      8.00    1.00
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.84
           From the CIF: _reflns_number_total               1819
           Count of symmetry unique reflns          980
           Completeness (_total/calc)            185.61%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       839
           Fraction of Friedel pairs measured     0.856
           Are heavy atom types Z>Si present        yes
PLAT002_ALERT_2_G Number of Distance or Angle Restraints on AtSite          2
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT158_ALERT_4_G The Input Unitcell is NOT Standard/Reduced .....          ?
PLAT431_ALERT_2_G Short Inter HL..A  Contact  Br1    ..  N2      .       2.98 Ang.
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          2

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

   9 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 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
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Phthalazine derivatives have played an important role in the development of corrosion science as they can inhibit the corrosion of mild steel (Musa et al., 2012). Moreover, they are of particular interest owing to their biological activity and optical properties (Caira, et al., 2011).

In this paper, the title new phthalazine derivative derived from the condensation of 3-bromo-benzene-1,2-dicarboxaldehyde with hydrazine is reported. The molecular structure of the title compound (Fig.1) is essentially planar with a deviation from the mean plane of the phthalazine ring of 0.0115 (3) Å. All bond lengths have normal values.The oxygen atom of the solvent water molecule is situated on a twofold rotation axis. In the crystal, O—H···N hydrogen bonds and short N···Br contacts lead to the formation of a two dimensional network structure (Fig.2).

Related literature

For general background on applications of phthalazines, see: Caira et al. (2011); Musa et al. (2012).

S2. Experimental

A solution of 0.1 mol of 3-bromo-benzene-1,2-dicarboxaldehyde is dissolved in 100 ml of ethanol and added dropwise with constant stirring, under a blanket of nitrogen, to an ice-cooled solution of 0.3 mol of hydrazine hydrate in 100 ml of ethanol. The light yellowish reaction mixture is kept with constant stirring for an additional three hours. Ethanol and excess hydrazine are removed under reduced pressure. The remaining yellowish solid may be purified by recrystallization from diethyl ether to yield the yellowish title compound (yield 48%). Finally, the title compound was dissolved in a small amount of methanol and the solution was kept for 10 days at ambient temperature to give rise to white flake crystals due to slow evaporation of the solvent.

S3. Refinement

The H atom of the solvent water was located in a difference fourier map and refined as a riding atom with U_iso(H) = 1.2U_eq(O). Remaining H atoms were positioned geometrically with C—H = 0.93–0.98 Å and constrained to ride on their parent atoms with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku/MSC, 2002); cell refinement: CrystalClear (Rigaku/MSC, 2002); data reduction: CrystalClear (Rigaku/MSC, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Crystal Impact, 2009); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2006).

Figures

	Fig. 1. Molecular structure of the title compound showing 30% probability displacement ellipsoids.
	Fig. 2. Molecular packing of the title compound with hydrogen bonds and N···Br contacts shown as dashed lines.

5-Bromophthalazine hemihydrate

Crystal data

C8H5BrN2·0.5H2O	F(000) = 1712
Mr = 218.06	Dx = 1.895 Mg m^−3
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 2874 reflections
a = 13.5000 (18) Å	θ = 1.4–28.0°
b = 29.964 (5) Å	µ = 5.31 mm^−1
c = 7.5565 (5) Å	T = 113 K
V = 3056.7 (7) Å^3	Prism, colorless
Z = 16	0.30 × 0.22 × 0.18 mm

Data collection

Rigaku Saturn724 CCD diffractometer	1819 independent reflections
Radiation source: rotating anode	1781 reflections with I > 2σ(I)
Multilayer monochromator	Rint = 0.064
Detector resolution: 14.22 pixels mm^-1	θmax = 27.8°, θmin = 2.7°
ω and φ scans	h = −17→17
Absorption correction: multi-scan (CrystalClear; Rigaku/MSC, 2002)	k = −37→39
Tmin = 0.299, Tmax = 0.448	l = −9→9
7799 measured reflections

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)] = 0.029	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.074	w = 1/[σ^2(Fo^2) + (0.0496P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
1819 reflections	Δρmax = 0.74 e Å^−3
109 parameters	Δρmin = −0.77 e Å^−3
2 restraints	Absolute structure: Flack (1983), 839 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.002 (10)

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
Br1	0.655288 (19)	0.300585 (8)	0.53761 (6)	0.02108 (10)
N1	0.65121 (19)	0.45112 (8)	0.5432 (5)	0.0234 (5)
N2	0.71705 (19)	0.47790 (9)	0.6304 (4)	0.0256 (6)
C1	0.6599 (2)	0.40781 (10)	0.5487 (6)	0.0204 (6)
H1	0.6127	0.3904	0.4862	0.024*
C2	0.7360 (2)	0.38513 (10)	0.6426 (4)	0.0176 (5)
C3	0.7467 (2)	0.33818 (10)	0.6536 (4)	0.0184 (6)
C4	0.8227 (2)	0.32011 (10)	0.7484 (4)	0.0220 (6)
H4	0.8286	0.2886	0.7578	0.026*
C5	0.8923 (2)	0.34786 (12)	0.8323 (4)	0.0245 (7)
H5	0.9461	0.3348	0.8946	0.029*
C6	0.8843 (2)	0.39313 (11)	0.8259 (4)	0.0228 (7)
H6	0.9313	0.4115	0.8846	0.027*
C7	0.8049 (2)	0.41233 (10)	0.7306 (4)	0.0189 (6)
C8	0.7888 (2)	0.45888 (11)	0.7189 (5)	0.0255 (7)
H8	0.8337	0.4778	0.7801	0.031*
O1	0.5000	0.5000	0.3550 (5)	0.0295 (8)
H1A	0.543 (2)	0.4874 (15)	0.413 (5)	0.045 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.02422 (15)	0.01764 (14)	0.02139 (15)	−0.00117 (9)	−0.00086 (12)	−0.00143 (13)
N1	0.0232 (12)	0.0237 (12)	0.0231 (13)	0.0039 (8)	0.0011 (11)	0.0018 (14)
N2	0.0291 (14)	0.0195 (12)	0.0281 (15)	0.0028 (10)	0.0021 (12)	−0.0008 (12)
C1	0.0179 (12)	0.0221 (13)	0.0211 (15)	0.0007 (10)	0.0008 (12)	−0.0016 (16)
C2	0.0202 (14)	0.0169 (13)	0.0157 (14)	0.0005 (11)	0.0021 (11)	−0.0001 (12)
C3	0.0226 (13)	0.0184 (14)	0.0141 (12)	−0.0010 (10)	0.0015 (11)	−0.0028 (11)
C4	0.0273 (14)	0.0201 (14)	0.0185 (15)	0.0043 (12)	0.0017 (12)	0.0000 (12)
C5	0.0232 (15)	0.0290 (16)	0.0214 (17)	0.0063 (13)	0.0003 (11)	0.0005 (12)
C6	0.0212 (14)	0.0255 (14)	0.0215 (18)	−0.0005 (12)	−0.0004 (11)	−0.0018 (12)
C7	0.0193 (13)	0.0220 (14)	0.0154 (13)	0.0011 (11)	0.0036 (10)	−0.0018 (11)
C8	0.0265 (16)	0.0216 (14)	0.0284 (16)	−0.0023 (11)	0.0020 (13)	−0.0067 (13)
O1	0.0263 (18)	0.0323 (18)	0.0298 (18)	0.0044 (14)	0.000	0.000

Geometric parameters (Å, º)

Br1—C3	1.887 (3)	C4—C5	1.406 (5)
N1—C1	1.304 (4)	C4—H4	0.9500
N1—N2	1.367 (4)	C5—C6	1.362 (5)
N2—C8	1.308 (4)	C5—H5	0.9500
C1—C2	1.421 (4)	C6—C7	1.413 (4)
C1—H1	0.9500	C6—H6	0.9500
C2—C7	1.405 (4)	C7—C8	1.414 (4)
C2—C3	1.417 (4)	C8—H8	0.9500
C3—C4	1.363 (4)	O1—H1A	0.82 (2)
C1—N1—N2	120.7 (3)	C5—C4—H4	119.8
C8—N2—N1	118.2 (3)	C6—C5—C4	121.3 (3)
N1—C1—C2	123.9 (3)	C6—C5—H5	119.3
N1—C1—H1	118.1	C4—C5—H5	119.3
C2—C1—H1	118.1	C5—C6—C7	118.9 (3)
C7—C2—C3	118.7 (3)	C5—C6—H6	120.5
C7—C2—C1	115.9 (3)	C7—C6—H6	120.5
C3—C2—C1	125.3 (3)	C2—C7—C6	120.5 (3)
C4—C3—C2	120.2 (3)	C2—C7—C8	116.2 (3)
C4—C3—Br1	119.9 (2)	C6—C7—C8	123.3 (3)
C2—C3—Br1	119.9 (2)	N2—C8—C7	125.1 (3)
C3—C4—C5	120.3 (3)	N2—C8—H8	117.4
C3—C4—H4	119.8	C7—C8—H8	117.4
C1—N1—N2—C8	0.1 (5)	C4—C5—C6—C7	−1.0 (5)
N2—N1—C1—C2	0.0 (6)	C3—C2—C7—C6	1.0 (4)
N1—C1—C2—C7	−0.9 (5)	C1—C2—C7—C6	−179.1 (3)
N1—C1—C2—C3	178.9 (4)	C3—C2—C7—C8	−178.3 (3)
C7—C2—C3—C4	0.1 (4)	C1—C2—C7—C8	1.6 (4)
C1—C2—C3—C4	−179.8 (3)	C5—C6—C7—C2	−0.6 (4)
C7—C2—C3—Br1	179.8 (2)	C5—C6—C7—C8	178.7 (3)
C1—C2—C3—Br1	0.0 (4)	N1—N2—C8—C7	0.7 (5)
C2—C3—C4—C5	−1.6 (5)	C2—C7—C8—N2	−1.6 (5)
Br1—C3—C4—C5	178.7 (2)	C6—C7—C8—N2	179.1 (3)
C3—C4—C5—C6	2.0 (5)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···N1	0.82 (2)	2.07 (3)	2.887 (3)	175 (5)