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Di-2-pyridyl ketone reacts with CdBr2 in water to form the title centrosymmetric dinuclear complex, [Cd2Br4(C11H10­N2O2)2]·3H2O, in which each metal atom is coordinated by an N,O,N′-chelated di-2-pyridyl­methanediol ligand, two bridging bromo ligands and one terminal bromo ligand in a distorted octahedral geometry.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010000754X/da1134sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827010000754X/da1134Isup2.hkl
Contains datablock I

CCDC reference: 150327

Comment top

Reactions of di-2-pyridyl ketone (DPK), a versatile polydentate ligand, with metal ions have attracted considerable attention for many years. A number of nucleophiles, including water and alcohols, have been shown to add to the carbonyl group upon coordination of the pyridyl groups to metal ions such as AgI, CuII, SbIII, CoIII, NiII, BiIII, CrIII, PdII, PtII and AuIII (Tong et al., 1998, 1999; Yang et al., 1998, 1999), although exceptions have also been observed. In AgI—DPK complexes, for instance, the ligand exists in its ketone form without hydration, even though these complexes were obtained from aqueous solution (Sommerer et al., 1994; Yang, et al., 1999). The coordination of DPK to cadmium(II) has been reported only once (Tong et al., 1999) and in this case the complex is mononuclear. We present here the crystal structure of the title dinuclear CdII—DPK complex, (I). \sch

The structure of (I) consists of discrete neutral [Cd2(di-2-pyridylmethanediol)22-Br)2Br2] molecules and interstitial water molecules. A view of the dinuclear molecule is shown in Fig. 1. Each molecule contains a di-µ2-bromo bridge between the two metal atoms, and each metal atom is also bonded to a non-bridging bromo ligand and is capped by the organic ligand which functions in an N,N',O-tridentate mode, resulting in a distorted octahedral coordination environment. The most distorted angle in the octahedron [N2—Cd1—O1, 64.54 (15)°] is due to the chelating coordination of the organic ligand. The two terminal bromo ligands are trans oriented with respect to the bridge plane.

The Cd—O bond distance [2.601 (4) Å] is slightly longer than the Cd—N distances [2.355 (5) and 2.396 (5) Å]. These Cd—N bond lengths fall in the range expected for Cd—Namine bonds (Benecini et al., 1989; Cannas et al., 1980; Tan et al., 1993).

The Cd—Brbridge bond distances [2.7072 (9) and 2.8556 (9) Å] are longer than the Cd—Brterminal distance [2.5889 (10) Å]. The assymetric bridging mode of atom Br1 may be attributed to the trans effect, since Br1 is trans to the stronger donor, the N atom, while Br1i is trans to a weaker donor, the O atom [symmetry code: (i) 1/2 − x, 1/2 − y, 1 − z].

It is also noteworthy that the coordination of atom O1 results in a longer C6—O1 bond [1.432 (6) Å] compared with that of C6—O2 [1.395 (7) Å]. Similar structures have been observed in [Cd2([9]aneN3)22-Cl)2Cl2] and [Cd2([11]aneN3)22Cl)2Br2] (define ligands; Zompa et al., 1995), where the capping organic ligands are cyclotriamines. The distance between the two metal atoms in the title complex is 3.9345 (11) Å, indicating no significant metal-metal interaction.

The structure of (I) is supported by hydrogen bonding involving each hydroxyl group, the lattice water molecules and the terminal Br ligand. The disordered lattice water molecule (O2W) forms weak hydrogen bonds with the other water molecule and with the bromo ligand.

Experimental top

CdBr2 (0.344 g, 1 mmol) was added to an aqueous solution of DPK (0.184 g, 1 mmol). The mixture was stirred until all the solids were totally dissolved and a colourless solution was obtained. The pH of the solution was then adjusted to 4 by HNO3. After filtration, the filtrate was removed by slow evaporation in a desiccator to give colourless crystals of (I) in 3 d.

Refinement top

The H atoms of the interstitial water molecules were located in difference maps and included with Uiso fixed, but were not refined. All other H atoms were generated geometrically. One of the water molecules (O2W) is disordered about a twofold axis.

Computing details top

Data collection: R3m Software (Siemens, 1990); cell refinement: R3m Software; data reduction: R3m Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1995); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. A view of the dinuclear complex (I) showing the atom-numbering scheme [symmetry code: (i) 1/2 − x, 1/2 − y, 1 − z]. H atoms are drawn as spheres of arbitrary radii. Prob level?
Di-µ-bromo-bis[bromo(di-2-pyridylmethanediol-N,O,N')cadmium(II)] trihydrate top
Crystal data top
[Cd2(C11H10N2O2)2Br4]·3H2OF(000) = 1912
Mr = 1002.91Dx = 2.207 Mg m3
Monoclinic, C2/cMo Kα radiation, λ = 0.71073 Å
a = 8.114 (2) ÅCell parameters from 25 reflections
b = 22.474 (4) Åθ = 7.5–15.0°
c = 16.642 (3) ŵ = 6.75 mm1
β = 96.08 (2)°T = 293 K
V = 3017.7 (11) Å3Block, colourless
Z = 40.3 × 0.2 × 0.2 mm
Data collection top
Siemens R3m
diffractometer
1997 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.011
Graphite monochromatorθmax = 25.1°, θmin = 1.8°
ω scanh = 09
Absorption correction: ψ-scan (north et al., 1968)
?
k = 026
Tmin = 0.152, Tmax = 0.259l = 1919
4305 measured reflections2 standard reflections every 150 reflections
2675 independent reflections intensity decay: 1.1%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.040Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.080H atoms treated by a mixture of independent and constrained refinement
S = 1.07Calculated w = 1/[σ2(Fo2) + (0.0295P)2 + 13.965P]
where P = (Fo2 + 2Fc2)/3
2675 reflections(Δ/σ)max = 0.002
181 parametersΔρmax = 0.77 e Å3
0 restraintsΔρmin = 0.61 e Å3
Crystal data top
[Cd2(C11H10N2O2)2Br4]·3H2OV = 3017.7 (11) Å3
Mr = 1002.91Z = 4
Monoclinic, C2/cMo Kα radiation
a = 8.114 (2) ŵ = 6.75 mm1
b = 22.474 (4) ÅT = 293 K
c = 16.642 (3) Å0.3 × 0.2 × 0.2 mm
β = 96.08 (2)°
Data collection top
Siemens R3m
diffractometer
1997 reflections with I > 2σ(I)
Absorption correction: ψ-scan (north et al., 1968)
?
Rint = 0.011
Tmin = 0.152, Tmax = 0.2592 standard reflections every 150 reflections
4305 measured reflections intensity decay: 1.1%
2675 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0400 restraints
wR(F2) = 0.080H atoms treated by a mixture of independent and constrained refinement
S = 1.07Δρmax = 0.77 e Å3
2675 reflectionsΔρmin = 0.61 e Å3
181 parameters
Special details top

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 (Å2) top
xyzUiso*/UeqOcc. (<1)
Cd10.20017 (6)0.335665 (19)0.50005 (3)0.03658 (15)
Br10.06370 (9)0.23007 (3)0.56177 (4)0.04215 (19)
Br20.32990 (11)0.37054 (3)0.64101 (4)0.0583 (2)
O10.0123 (5)0.42203 (17)0.5036 (2)0.0355 (10)
H1B0.11330.40900.52470.080*
O20.1620 (5)0.47928 (18)0.4036 (3)0.0408 (11)
H2H0.13690.51780.42830.080*
N10.0213 (6)0.3299 (2)0.3967 (3)0.0354 (12)
N20.2579 (6)0.4226 (2)0.4246 (3)0.0369 (12)
C10.0655 (9)0.2788 (3)0.3574 (4)0.0438 (17)
H1A0.00930.24230.37520.080*
C20.1855 (9)0.2764 (3)0.2936 (4)0.0484 (18)
H2A0.21700.23880.26790.080*
C30.2623 (9)0.3287 (3)0.2671 (4)0.0462 (17)
H3A0.34510.32870.22050.080*
C40.2187 (8)0.3817 (3)0.3077 (4)0.0367 (15)
H4A0.27140.41890.29020.080*
C50.0990 (8)0.3803 (3)0.3725 (3)0.0310 (14)
C60.0398 (8)0.4360 (3)0.4193 (3)0.0313 (14)
C70.1293 (8)0.4558 (3)0.3954 (3)0.0294 (14)
C80.1442 (8)0.5042 (3)0.3461 (4)0.0372 (15)
H8A0.04710.52650.32440.080*
C90.3008 (9)0.5203 (3)0.3284 (4)0.0471 (18)
H9A0.31490.55440.29410.080*
C100.4364 (9)0.4879 (3)0.3595 (4)0.0491 (18)
H10A0.54760.49860.34840.080*
C110.4090 (8)0.4394 (3)0.4071 (4)0.0453 (17)
H11A0.50370.41620.42930.080*
O1W0.2632 (8)0.3605 (3)0.5555 (4)0.087 (2)
H1WA0.24760.35920.61400.100*
H1WB0.26570.32240.52940.100*
O2W0.057 (2)0.3530 (7)0.7154 (10)0.147 (7)0.50
H2WA0.04870.35710.69590.150*0.50
H2WB0.07090.38430.75240.150*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.0427 (3)0.0276 (2)0.0375 (2)0.0013 (2)0.0048 (2)0.0022 (2)
Br10.0468 (4)0.0357 (4)0.0444 (4)0.0026 (3)0.0070 (3)0.0060 (3)
Br20.0814 (6)0.0411 (4)0.0472 (4)0.0026 (4)0.0182 (4)0.0086 (3)
O10.041 (3)0.035 (2)0.030 (2)0.004 (2)0.002 (2)0.0065 (18)
O20.039 (3)0.028 (2)0.053 (3)0.007 (2)0.004 (2)0.0046 (19)
N10.038 (3)0.030 (3)0.036 (3)0.003 (3)0.001 (2)0.002 (2)
N20.029 (3)0.036 (3)0.045 (3)0.001 (3)0.001 (3)0.004 (2)
C10.055 (5)0.030 (4)0.046 (4)0.005 (3)0.006 (4)0.001 (3)
C20.058 (5)0.036 (4)0.050 (4)0.004 (4)0.002 (4)0.010 (3)
C30.044 (4)0.052 (4)0.042 (4)0.017 (4)0.005 (3)0.014 (3)
C40.033 (4)0.036 (4)0.039 (3)0.003 (3)0.005 (3)0.003 (3)
C50.032 (4)0.031 (3)0.030 (3)0.004 (3)0.003 (3)0.002 (2)
C60.034 (4)0.026 (3)0.033 (3)0.001 (3)0.003 (3)0.003 (2)
C70.034 (4)0.028 (3)0.027 (3)0.000 (3)0.002 (3)0.006 (2)
C80.040 (4)0.032 (3)0.040 (4)0.003 (3)0.003 (3)0.002 (3)
C90.061 (5)0.034 (4)0.047 (4)0.005 (4)0.012 (4)0.001 (3)
C100.042 (4)0.038 (4)0.069 (5)0.008 (4)0.015 (4)0.001 (4)
C110.033 (4)0.044 (4)0.059 (4)0.006 (3)0.002 (3)0.002 (3)
O1W0.105 (5)0.069 (4)0.094 (4)0.035 (4)0.046 (4)0.017 (3)
O2W0.15 (2)0.161 (15)0.131 (17)0.006 (13)0.034 (13)0.003 (11)
Geometric parameters (Å, º) top
Cd1—N12.355 (5)N2—C111.344 (8)
Cd1—N22.396 (5)C1—C21.364 (9)
Cd1—Br22.5889 (10)C2—C31.382 (9)
Cd1—O12.601 (4)C3—C41.395 (8)
Cd1—Br1i2.7072 (9)C4—C51.373 (8)
Cd1—Br12.8556 (9)C5—C61.525 (8)
Cd1—Cd1i3.9345 (11)C6—C71.534 (8)
Br1—Cd1i2.7072 (9)C7—C81.378 (8)
O1—C61.432 (6)C8—C91.382 (9)
O2—C61.395 (7)C9—C101.374 (9)
N1—C51.338 (7)C10—C111.379 (9)
N1—C11.349 (8)O2W—O2Wii1.40 (3)
N2—C71.331 (7)
N1—Cd1—N280.74 (17)C1—N1—Cd1122.9 (4)
N1—Cd1—Br2152.11 (13)C7—N2—C11117.5 (5)
N2—Cd1—Br298.30 (12)C7—N2—Cd1117.3 (4)
N1—Cd1—O166.54 (15)C11—N2—Cd1125.2 (4)
N2—Cd1—O164.54 (15)N1—C1—C2122.9 (6)
Br2—Cd1—O187.72 (8)C1—C2—C3118.3 (6)
N1—Cd1—Br1i102.01 (13)C2—C3—C4119.2 (6)
N2—Cd1—Br1i93.47 (12)C5—C4—C3118.9 (6)
Br2—Cd1—Br1i105.86 (3)N1—C5—C4121.8 (5)
O1—Cd1—Br1i155.99 (9)N1—C5—C6115.4 (5)
N1—Cd1—Br185.51 (12)C4—C5—C6122.8 (5)
N2—Cd1—Br1166.23 (13)O2—C6—O1111.8 (4)
Br2—Cd1—Br193.53 (3)O2—C6—C5107.3 (5)
O1—Cd1—Br1109.19 (9)O1—C6—C5109.2 (4)
Br1i—Cd1—Br190.01 (3)O2—C6—C7112.7 (5)
N1—Cd1—Cd1i94.95 (12)O1—C6—C7105.5 (5)
N2—Cd1—Cd1i138.30 (12)C5—C6—C7110.3 (5)
Br2—Cd1—Cd1i103.46 (3)N2—C7—C8123.0 (6)
O1—Cd1—Cd1i150.12 (9)N2—C7—C6115.6 (5)
Br1i—Cd1—Cd1i46.533 (18)C8—C7—C6121.4 (6)
Br1—Cd1—Cd1i43.478 (19)C7—C8—C9118.3 (6)
Cd1i—Br1—Cd189.99 (3)C10—C9—C8119.9 (6)
C6—O1—Cd1100.1 (3)C9—C10—C11117.6 (7)
C5—N1—C1118.8 (5)N2—C11—C10123.6 (7)
C5—N1—Cd1118.1 (4)
Symmetry codes: (i) x+1/2, y+1/2, z+1; (ii) x, y, z+3/2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1B···O1W0.971.752.678 (7)159
O2—H2H···O1iii0.972.072.973 (6)154
O2—H2H···Br2iii0.973.113.686 (4)119
O1W—H1WA···O2W0.972.172.996 (17)142
O1W—H1WB···Br1iv0.962.963.590 (6)124
O2W—H2WA···Br20.952.563.51 (2)179
Symmetry codes: (iii) x, y+1, z+1; (iv) x1/2, y+1/2, z+1.

Experimental details

Crystal data
Chemical formula[Cd2(C11H10N2O2)2Br4]·3H2O
Mr1002.91
Crystal system, space groupMonoclinic, C2/c
Temperature (K)293
a, b, c (Å)8.114 (2), 22.474 (4), 16.642 (3)
β (°) 96.08 (2)
V3)3017.7 (11)
Z4
Radiation typeMo Kα
µ (mm1)6.75
Crystal size (mm)0.3 × 0.2 × 0.2
Data collection
DiffractometerSiemens R3m
diffractometer
Absorption correctionψ-scan (North et al., 1968)
Tmin, Tmax0.152, 0.259
No. of measured, independent and
observed [I > 2σ(I)] reflections
4305, 2675, 1997
Rint0.011
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.040, 0.080, 1.07
No. of reflections2675
No. of parameters181
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Calculated w = 1/[σ2(Fo2) + (0.0295P)2 + 13.965P]
where P = (Fo2 + 2Fc2)/3
Δρmax, Δρmin (e Å3)0.77, 0.61

Computer programs: R3m Software (Siemens, 1990), R3m Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Sheldrick, 1995), SHELXL97.

Selected geometric parameters (Å, º) top
Cd1—N12.355 (5)Cd1—O12.601 (4)
Cd1—N22.396 (5)Cd1—Br1i2.7072 (9)
Cd1—Br22.5889 (10)Cd1—Br12.8556 (9)
N1—Cd1—N280.74 (17)N1—Cd1—Br185.51 (12)
N1—Cd1—Br2152.11 (13)N2—Cd1—Br1166.23 (13)
N2—Cd1—Br298.30 (12)Br2—Cd1—Br193.53 (3)
N1—Cd1—O166.54 (15)O1—Cd1—Br1109.19 (9)
N2—Cd1—O164.54 (15)O1—Cd1—Cd1i150.12 (9)
Br2—Cd1—O187.72 (8)C6—O1—Cd1100.1 (3)
N1—Cd1—Br1i102.01 (13)C5—N1—Cd1118.1 (4)
N2—Cd1—Br1i93.47 (12)C1—N1—Cd1122.9 (4)
Br2—Cd1—Br1i105.86 (3)C7—N2—Cd1117.3 (4)
O1—Cd1—Br1i155.99 (9)C11—N2—Cd1125.2 (4)
Symmetry code: (i) x+1/2, y+1/2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1—H1B···O1W0.971.752.678 (7)159.1
O2—H2H···O1ii0.972.072.973 (6)153.9
O2—H2H···Br2ii0.973.113.686 (4)119.2
O1W—H1WA···O2W0.972.172.996 (17)142.1
O1W—H1WB···Br1iii0.962.963.590 (6)124.4
O2W—H2WA···Br20.952.563.51 (2)178.5
Symmetry codes: (ii) x, y+1, z+1; (iii) x1/2, y+1/2, z+1.
 

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