Piperazinium bis­(pyridine-2,6-dicarboxyl­ato)mercurate(II) hexa­hydrate

The reaction of mercury(II) nitrate with the proton-transfer compound (pipzH₂)(pydc), where pipz is piperazine and pydcH₂ is pyridine-2,6-dicarboxylic acid, in aqueous solution leads to the formation of the title compound, (pipzH₂)[Hg(pydc)₂]·6H₂O or (C₄H₁₂N₂)[Hg(C₇H₃NO₄)₂]·6H₂O. The structure features six-coordinate Hg²⁺ (site symmetry 2) with a distorted octa­hedral geometry. Extensive inter­molecular O—H...O, N—H...O and C—H...O hydrogen bonding involving the (pydc)²⁻ ligand, (pipzH₂)²⁺ (site symmetry 2) as a counter-ion and uncoordinated water mol­ecules forms a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 120 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.024
• wR factor = 0.062
• Data-to-parameter ratio = 16.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.24
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C6     ...       1.53 Ang.
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........         12
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          3
              H2 O
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          4
              H2 O

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

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

---

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT-Plus (Bruker, 1998); program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Piperazinium bis(pyridine-2,6-dicarboxylato)mercurate(II) hexahydrate

Crystal data

(C4H12N2)[Hg(C7H3NO4)2]·6H2O	F(000) = 1432
Mr = 727.05	Dx = 1.905 Mg m^−3
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 999 reflections
a = 13.444 (7) Å	θ = 3–27°
b = 8.377 (4) Å	µ = 6.15 mm^−1
c = 22.512 (13) Å	T = 120 K
V = 2535 (2) Å^3	Prism, colourless
Z = 4	0.19 × 0.16 × 0.14 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	2731 independent reflections
Radiation source: fine-focus sealed tube	1739 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
φ and ω scans	θmax = 27.0°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 1998)	h = −17→14
Tmin = 0.303, Tmax = 0.427	k = −10→10
16680 measured reflections	l = −28→28

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)] = 0.024	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.062	H-atom parameters constrained
S = 0.97	w = 1/[σ^2(Fo^2) + (0.0328P)^2] where P = (Fo^2 + 2Fc^2)/3
2731 reflections	(Δ/σ)max < 0.001
168 parameters	Δρmax = 2.66 e Å^−3
0 restraints	Δρmin = −1.19 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
Hg1	0.5000	0.72351 (2)	0.2500	0.02021 (8)
O1	0.34504 (19)	0.4607 (3)	0.39279 (11)	0.0265 (6)
O2	0.4688 (2)	0.5437 (3)	0.33497 (12)	0.0296 (7)
O3	0.4172 (2)	0.9091 (3)	0.18068 (12)	0.0309 (7)
O4	0.2664 (2)	0.9466 (3)	0.14124 (11)	0.0310 (7)
N1	0.3387 (3)	0.7123 (4)	0.26561 (14)	0.0202 (7)
C1	0.3031 (3)	0.6258 (4)	0.31094 (15)	0.0205 (8)
C2	0.2013 (3)	0.6166 (5)	0.32082 (16)	0.0245 (8)
H2A	0.1763	0.5583	0.3538	0.029*
C3	0.1367 (3)	0.6925 (5)	0.28248 (17)	0.0276 (9)
H3A	0.0669	0.6849	0.2881	0.033*
C4	0.1760 (3)	0.7809 (5)	0.23513 (18)	0.0269 (10)
H4A	0.1328	0.8339	0.2082	0.032*
C5	0.2770 (3)	0.7904 (4)	0.22783 (17)	0.0215 (9)
C6	0.3786 (3)	0.5369 (5)	0.34932 (16)	0.0253 (9)
C7	0.3248 (3)	0.8894 (4)	0.17902 (16)	0.0253 (9)
N1S	0.4947 (2)	0.6331 (3)	0.53959 (12)	0.0200 (6)
H1SC	0.5441	0.6072	0.5661	0.024*
H1SD	0.4670	0.7283	0.5514	0.024*
C1S	0.4169 (3)	0.5063 (4)	0.54052 (17)	0.0239 (8)
H1SE	0.3617	0.5362	0.5136	0.029*
H1SF	0.3896	0.4957	0.5812	0.029*
C2S	0.5387 (3)	0.6523 (5)	0.47921 (16)	0.0244 (8)
H2SC	0.5911	0.7353	0.4801	0.029*
H2SD	0.4866	0.6863	0.4508	0.029*
O1S	0.2943 (2)	1.1970 (3)	0.06515 (12)	0.0361 (7)
H1SB	0.2697	1.2685	0.0853	0.043*
H1SA	0.2935	1.1143	0.0846	0.043*
O2S	0.3325 (2)	1.1386 (3)	−0.05314 (12)	0.0400 (8)
H2SB	0.3320	1.1593	−0.0175	0.048*
H2SA	0.2824	1.1028	−0.0690	0.048*
O3S	0.4956 (2)	0.9449 (3)	−0.07949 (13)	0.0357 (7)
H3SB	0.5095	0.9881	−0.1111	0.043*
H3SA	0.4491	1.0019	−0.0692	0.043*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Hg1	0.01594 (11)	0.02334 (11)	0.02136 (11)	0.000	0.00087 (10)	0.000
O1	0.0228 (15)	0.0294 (15)	0.0272 (14)	−0.0016 (12)	−0.0030 (12)	0.0073 (12)
O2	0.0217 (15)	0.0362 (17)	0.0308 (15)	0.0016 (12)	0.0005 (12)	0.0096 (13)
O3	0.0217 (17)	0.0386 (17)	0.0323 (15)	0.0015 (13)	0.0010 (13)	0.0114 (13)
O4	0.0342 (18)	0.0293 (16)	0.0296 (14)	−0.0020 (13)	−0.0100 (13)	0.0096 (12)
N1	0.0142 (17)	0.0179 (16)	0.0285 (17)	−0.0003 (13)	0.0006 (13)	−0.0030 (11)
C1	0.022 (2)	0.0195 (19)	0.0204 (17)	0.0005 (16)	0.0013 (16)	−0.0019 (14)
C2	0.023 (2)	0.027 (2)	0.0234 (18)	−0.0018 (17)	−0.0002 (17)	0.0011 (16)
C3	0.021 (2)	0.034 (2)	0.028 (2)	0.0016 (18)	0.0018 (18)	−0.0040 (18)
C4	0.025 (2)	0.021 (2)	0.035 (2)	0.0030 (17)	−0.0086 (18)	−0.0003 (15)
C5	0.023 (2)	0.019 (2)	0.0231 (16)	0.0012 (16)	−0.0010 (17)	−0.0026 (15)
C6	0.028 (2)	0.025 (2)	0.0229 (19)	−0.0024 (17)	−0.0026 (18)	−0.0026 (16)
C7	0.032 (2)	0.0189 (19)	0.0255 (19)	0.0026 (18)	0.0002 (19)	−0.0031 (15)
N1S	0.0232 (17)	0.0166 (15)	0.0204 (13)	0.0052 (16)	−0.0032 (15)	−0.0022 (10)
C1S	0.019 (2)	0.028 (2)	0.0243 (18)	0.0005 (17)	0.0022 (17)	0.0008 (15)
C2S	0.026 (2)	0.022 (2)	0.0253 (19)	−0.0023 (17)	0.0020 (17)	0.0010 (16)
O1S	0.050 (2)	0.0247 (16)	0.0337 (15)	0.0008 (14)	0.0086 (15)	0.0020 (12)
O2S	0.0261 (17)	0.055 (2)	0.0385 (16)	−0.0048 (15)	−0.0005 (14)	−0.0135 (15)
O3S	0.0412 (19)	0.0246 (14)	0.0412 (16)	0.0086 (15)	0.0106 (15)	0.0110 (12)

Geometric parameters (Å, º)

Hg1—N1	2.198 (4)	C4—H4A	0.9500
Hg1—N1^i	2.198 (4)	C5—C7	1.519 (5)
Hg1—O3^i	2.468 (3)	N1S—C1S	1.491 (4)
Hg1—O2	2.471 (3)	N1S—C2S	1.491 (5)
Hg1—O3	2.468 (3)	N1S—H1SC	0.9200
Hg1—O2^i	2.471 (3)	N1S—H1SD	0.9200
O1—C6	1.252 (4)	C1S—C2S^ii	1.523 (5)
O2—C6	1.257 (5)	C1S—H1SE	0.9900
O3—C7	1.254 (5)	C1S—H1SF	0.9900
O4—C7	1.253 (4)	C2S—C1S^ii	1.523 (5)
N1—C1	1.340 (4)	C2S—H2SC	0.9900
N1—C5	1.356 (5)	C2S—H2SD	0.9900
C1—C2	1.388 (5)	O1S—H1SB	0.8201
C1—C6	1.527 (5)	O1S—H1SA	0.8198
C2—C3	1.380 (5)	O2S—H2SB	0.8199
C2—H2A	0.9500	O2S—H2SA	0.8200
C3—C4	1.401 (6)	O3S—H3SB	0.8200
C3—H3A	0.9500	O3S—H3SA	0.8200
C4—C5	1.370 (6)
N1—Hg1—N1^i	175.08 (16)	C3—C4—H4A	120.1
N1—Hg1—O3^i	111.75 (10)	N1—C5—C4	120.2 (4)
N1^i—Hg1—O3^i	71.55 (10)	N1—C5—C7	117.3 (4)
N1—Hg1—O3	71.55 (10)	C4—C5—C7	122.5 (4)
N1^i—Hg1—O3	111.75 (10)	O1—C6—O2	124.9 (4)
O3^i—Hg1—O3	101.90 (14)	O1—C6—C1	116.8 (4)
N1—Hg1—O2	71.51 (10)	O2—C6—C1	118.3 (3)
N1^i—Hg1—O2	105.36 (10)	O4—C7—O3	126.2 (4)
O3^i—Hg1—O2	88.33 (10)	O4—C7—C5	115.8 (4)
O3—Hg1—O2	142.87 (9)	O3—C7—C5	118.0 (3)
N1—Hg1—O2^i	105.36 (10)	C1S—N1S—C2S	111.6 (3)
N1^i—Hg1—O2^i	71.51 (10)	C1S—N1S—H1SC	109.3
O3^i—Hg1—O2^i	142.87 (9)	C2S—N1S—H1SC	109.3
O3—Hg1—O2^i	88.33 (10)	C1S—N1S—H1SD	109.3
O2—Hg1—O2^i	104.86 (14)	C2S—N1S—H1SD	109.3
C6—O2—Hg1	113.0 (2)	H1SC—N1S—H1SD	108.0
C7—O3—Hg1	112.5 (2)	N1S—C1S—C2S^ii	110.0 (3)
C1—N1—C5	121.3 (4)	N1S—C1S—H1SE	109.7
C1—N1—Hg1	119.8 (3)	C2S^ii—C1S—H1SE	109.7
C5—N1—Hg1	118.8 (3)	N1S—C1S—H1SF	109.7
N1—C1—C2	120.3 (3)	C2S^ii—C1S—H1SF	109.7
N1—C1—C6	117.2 (3)	H1SE—C1S—H1SF	108.2
C2—C1—C6	122.5 (3)	N1S—C2S—C1S^ii	109.1 (3)
C3—C2—C1	119.6 (4)	N1S—C2S—H2SC	109.9
C3—C2—H2A	120.2	C1S^ii—C2S—H2SC	109.9
C1—C2—H2A	120.2	N1S—C2S—H2SD	109.9
C2—C3—C4	118.8 (4)	C1S^ii—C2S—H2SD	109.9
C2—C3—H3A	120.6	H2SC—C2S—H2SD	108.3
C4—C3—H3A	120.6	H1SB—O1S—H1SA	108.5
C5—C4—C3	119.7 (4)	H2SB—O2S—H2SA	119.7
C5—C4—H4A	120.1	H3SB—O3S—H3SA	99.4
N1—Hg1—O2—C6	−3.7 (3)	C6—C1—C2—C3	−176.3 (3)
N1^i—Hg1—O2—C6	−179.8 (3)	C1—C2—C3—C4	−1.6 (6)
O3^i—Hg1—O2—C6	109.9 (3)	C2—C3—C4—C5	−0.1 (6)
O3—Hg1—O2—C6	2.2 (3)	C1—N1—C5—C4	−0.6 (6)
O2^i—Hg1—O2—C6	−105.3 (3)	Hg1—N1—C5—C4	177.6 (3)
N1—Hg1—O3—C7	−12.1 (3)	C1—N1—C5—C7	178.1 (3)
N1^i—Hg1—O3—C7	164.0 (3)	Hg1—N1—C5—C7	−3.6 (4)
O3^i—Hg1—O3—C7	−121.3 (3)	C3—C4—C5—N1	1.2 (6)
O2—Hg1—O3—C7	−18.0 (3)	C3—C4—C5—C7	−177.5 (3)
O2^i—Hg1—O3—C7	94.7 (3)	Hg1—O2—C6—O1	−176.1 (3)
O3^i—Hg1—N1—C1	−78.2 (3)	Hg1—O2—C6—C1	4.7 (4)
O3—Hg1—N1—C1	−174.0 (3)	N1—C1—C6—O1	177.7 (3)
O2—Hg1—N1—C1	2.2 (2)	C2—C1—C6—O1	−3.8 (5)
O2^i—Hg1—N1—C1	103.1 (3)	N1—C1—C6—O2	−3.0 (5)
O3^i—Hg1—N1—C5	103.5 (3)	C2—C1—C6—O2	175.5 (4)
O3—Hg1—N1—C5	7.7 (3)	Hg1—O3—C7—O4	−167.1 (3)
O2—Hg1—N1—C5	−176.1 (3)	Hg1—O3—C7—C5	14.4 (4)
O2^i—Hg1—N1—C5	−75.2 (3)	N1—C5—C7—O4	172.9 (3)
C5—N1—C1—C2	−1.1 (5)	C4—C5—C7—O4	−8.4 (5)
Hg1—N1—C1—C2	−179.3 (3)	N1—C5—C7—O3	−8.5 (5)
C5—N1—C1—C6	177.5 (3)	C4—C5—C7—O3	170.3 (4)
Hg1—N1—C1—C6	−0.8 (4)	C2S—N1S—C1S—C2S^ii	58.7 (4)
N1—C1—C2—C3	2.2 (6)	C1S—N1S—C2S—C1S^ii	−58.2 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1S—H1SC···O1^ii	0.92	1.84	2.753 (4)	169
N1S—H1SD···O3S^i	0.92	1.99	2.765 (4)	141
O1S—H1SB···O4^iii	0.82	2.01	2.823 (4)	170
O1S—H1SA···O4	0.82	1.93	2.734 (4)	166
O2S—H2SB···O1S	0.82	1.95	2.756 (4)	165
O2S—H2SA···O1^iv	0.82	1.99	2.805 (4)	174
O3S—H3SB···O3^v	0.82	2.04	2.839 (4)	164
O3S—H3SA···O2S	0.82	1.97	2.792 (4)	174

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