Coordination polymers of Cd^II and Pb^II with croconate show remarkable differences in coordination patterns: a structural and spectroscopic study

The croconate dianion is a highly versatile ligand with two tautomeric forms making it useful for building large superstructures in the solid state. The single-crystal X-ray structures of Pb^II– and Cd^II–croconate coordination polymers, namely catena-poly[[[di­aqua­lead(II)]-μ-croconato-κ⁴O¹,O²:O³,O⁴] monohydrate], {[Pb(C₅O₅)(H₂O)₂]·H₂O}_n, 1, and catena-poly[[tri­aqua­cadmium(II)]-μ-croconato-κ⁴O¹,O²:O³,O⁴], [Cd(C₅O₅)(H₂O)₃]_n, 2, have been determined. Both polymers form one-dimensional (1D) structures; 1 is a nonplanar 1D zigzag coordination polymer extended along the crystallographic b axis, whereas 2 is a planar 1D ribbon parallel to the [101] direction. In 2, three H₂O mol­ecules are coordinated directly to the metal atom, while in 1, only two H₂O mol­ecules are directly coordinated to the metal atom. A third inter­stitial H₂O mol­ecule is involved in hydrogen bonding with O atoms of the croconate ligands of an adjacent layer and other H₂O mol­ecules, resulting in stacked double layers parallel to the [105] plane. Solid-state FT–IR and solution UV–Vis spectra also substanti­ate the croconate coordination.

Computing details

For both structures, data collection: SAINT (Bruker, 2015); cell refinement: APEX2 (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b). Molecular graphics: OLEX2 (Dolomanov et al., 2009) and CrystalMaker (Palmer, 2014) for rgr545_a_pl; OLEX2 (Dolomanov et al., 2009) and CrystalMaker (Version 9; Palmer, 2014) for rgr560_a. For both structures, software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

catena-Poly[[[diaqualead(II)]-µ-croconato-κ⁴O¹,O²:O³,O⁴] monohydrate] (rgr545_a_pl)

Crystal data

[Pb(C5O5)(H2O)2]·H2O	Z = 2
Mr = 401.29	F(000) = 364
Triclinic, P1	Dx = 3.256 Mg m^−3
a = 6.4360 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.9058 (4) Å	Cell parameters from 6853 reflections
c = 8.3495 (5) Å	θ = 3.2–28.3°
α = 104.055 (1)°	µ = 20.63 mm^−1
β = 90.956 (2)°	T = 296 K
γ = 96.200 (2)°	Needle, yellow
V = 409.30 (4) Å^3	0.13 × 0.04 × 0.03 mm

Data collection

Bruker D8 with PHOTON 100 detector diffractometer	1928 reflections with I > 2σ(I)
Detector resolution: 10.42 pixels mm^-1	Rint = 0.027
φ and ω shutterless scans	θmax = 28.3°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Bruker, 2016)	h = −8→8
Tmin = 0.415, Tmax = 0.746	k = −10→10
8040 measured reflections	l = −11→10
2026 independent reflections

Refinement

Refinement on F^2	4 restraints
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.017	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.042	w = 1/[σ^2(Fo^2) + (0.0217P)^2 + 0.0167P] where P = (Fo^2 + 2Fc^2)/3
S = 1.22	(Δ/σ)max = 0.001
2026 reflections	Δρmax = 0.49 e Å^−3
144 parameters	Δρmin = −1.37 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Data were collected on a Bruker D8 Quest diffractometer with graphite monochromated Mo Kα radiation using the APEX3 suite (Bruker, 2015). Structures were solved by intrinsic phasing method using SHELXT (Sheldrick, 2015a) and were refined using SHELXL (Sheldrick, 2015b) with the Olex2 program (Dolomanov et al., 2009).

Graphics were prepared using CrystalMaker (Palmer, 2014).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Pb1	0.09912 (2)	0.70968 (2)	0.35063 (2)	0.02400 (6)
O1	0.1805 (4)	0.4301 (3)	0.4220 (3)	0.0249 (5)
O2	0.2089 (4)	0.4717 (3)	0.0930 (3)	0.0265 (5)
O3	0.2472 (5)	0.1217 (3)	−0.1318 (3)	0.0318 (6)
O4	0.2391 (5)	−0.1311 (3)	0.0789 (3)	0.0352 (6)
O5	0.2032 (4)	0.0626 (3)	0.4195 (3)	0.0267 (5)
O6	0.4883 (4)	0.7389 (3)	0.3353 (3)	0.0262 (5)
H6A	0.548854	0.801583	0.429182	0.039*
H6B	0.528764	0.800381	0.264501	0.039*
O7	0.2731 (4)	0.8030 (3)	0.6382 (3)	0.0288 (5)
O8	−0.2576 (5)	0.4678 (4)	0.2181 (3)	0.0307 (6)
C1	0.2054 (5)	0.3091 (4)	0.2983 (4)	0.0171 (6)
C2	0.2195 (5)	0.3295 (4)	0.1308 (4)	0.0178 (6)
C3	0.2370 (5)	0.1582 (4)	0.0204 (4)	0.0215 (7)
C4	0.2352 (5)	0.0287 (4)	0.1255 (4)	0.0196 (6)
C5	0.2143 (5)	0.1274 (4)	0.2964 (4)	0.0181 (6)
H7A	0.248 (9)	0.902 (5)	0.706 (6)	0.060 (16)*
H7B	0.274 (7)	0.721 (5)	0.692 (5)	0.043 (13)*
H8A	−0.351 (6)	0.537 (6)	0.254 (6)	0.046 (15)*
H8B	−0.270 (9)	0.467 (8)	0.116 (3)	0.072 (19)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pb1	0.02980 (8)	0.01489 (8)	0.02673 (8)	0.00468 (5)	0.00083 (5)	0.00310 (5)
O1	0.0435 (15)	0.0158 (11)	0.0156 (11)	0.0059 (10)	0.0042 (10)	0.0030 (9)
O2	0.0445 (15)	0.0166 (12)	0.0203 (12)	0.0050 (10)	0.0031 (11)	0.0077 (9)
O3	0.0536 (17)	0.0246 (13)	0.0134 (11)	−0.0008 (12)	0.0083 (11)	−0.0005 (10)
O4	0.0583 (19)	0.0171 (13)	0.0294 (14)	0.0106 (12)	0.0021 (13)	0.0013 (10)
O5	0.0456 (16)	0.0163 (12)	0.0200 (12)	0.0018 (10)	0.0004 (10)	0.0088 (9)
O6	0.0277 (13)	0.0318 (14)	0.0190 (12)	0.0030 (10)	0.0020 (9)	0.0060 (10)
O7	0.0427 (15)	0.0198 (13)	0.0233 (13)	0.0043 (11)	0.0006 (11)	0.0042 (10)
O8	0.0431 (16)	0.0321 (15)	0.0192 (13)	0.0121 (12)	0.0035 (11)	0.0072 (11)
C1	0.0207 (15)	0.0147 (15)	0.0157 (14)	0.0028 (11)	0.0012 (11)	0.0030 (11)
C2	0.0232 (15)	0.0147 (15)	0.0153 (14)	0.0014 (11)	0.0018 (11)	0.0039 (11)
C3	0.0253 (16)	0.0207 (17)	0.0187 (15)	0.0043 (13)	0.0033 (12)	0.0047 (13)
C4	0.0238 (16)	0.0153 (15)	0.0192 (15)	0.0058 (12)	0.0010 (12)	0.0016 (12)
C5	0.0218 (15)	0.0148 (14)	0.0174 (15)	0.0019 (11)	0.0009 (12)	0.0033 (12)

Geometric parameters (Å, º)

Pb1—O1	2.529 (2)	O6—H6B	0.8779
Pb1—O2	2.653 (2)	O7—H7A	0.88 (2)
Pb1—O5^i	2.714 (2)	O7—H7B	0.876 (19)
Pb1—O6	2.499 (2)	O8—H8A	0.864 (19)
Pb1—O7	2.537 (3)	O8—H8B	0.85 (2)
O1—C1	1.251 (4)	C1—C2	1.449 (4)
O2—C2	1.248 (4)	C1—C5	1.440 (4)
O3—C3	1.238 (4)	C2—C3	1.458 (4)
O4—C4	1.231 (4)	C3—C4	1.501 (5)
O5—C5	1.255 (4)	C4—C5	1.467 (4)
O6—H6A	0.8782
O1—Pb1—O2	66.73 (7)	H7A—O7—H7B	110 (5)
O1—Pb1—O5^i	144.36 (8)	H8A—O8—H8B	98 (5)
O1—Pb1—O7	74.06 (8)	O1—C1—C2	124.7 (3)
O2—Pb1—O5^i	127.18 (7)	O1—C1—C5	126.3 (3)
O6—Pb1—O1	79.20 (8)	C5—C1—C2	108.9 (3)
O6—Pb1—O2	70.11 (8)	O2—C2—C1	123.6 (3)
O6—Pb1—O5^i	77.15 (8)	O2—C2—C3	127.8 (3)
O6—Pb1—O7	69.40 (8)	C1—C2—C3	108.6 (3)
O7—Pb1—O2	127.50 (9)	O3—C3—C2	127.7 (3)
O7—Pb1—O5^i	72.84 (8)	O3—C3—C4	125.2 (3)
C1—O1—Pb1	113.6 (2)	C2—C3—C4	107.1 (3)
C2—O2—Pb1	110.12 (19)	O4—C4—C3	127.5 (3)
C5—O5—Pb1^ii	115.4 (2)	O4—C4—C5	125.7 (3)
Pb1—O6—H6A	111.0	C5—C4—C3	106.7 (3)
Pb1—O6—H6B	110.7	O5—C5—C1	126.0 (3)
H6A—O6—H6B	103.2	O5—C5—C4	125.2 (3)
Pb1—O7—H7A	120 (4)	C1—C5—C4	108.7 (3)
Pb1—O7—H7B	116 (3)
Pb1—O1—C1—C2	9.0 (4)	O3—C3—C4—C5	−178.0 (3)
Pb1—O1—C1—C5	−167.6 (3)	O4—C4—C5—O5	2.0 (6)
Pb1—O2—C2—C1	−8.9 (4)	O4—C4—C5—C1	−177.0 (3)
Pb1—O2—C2—C3	168.0 (3)	C1—C2—C3—O3	178.1 (3)
Pb1^ii—O5—C5—C1	160.7 (2)	C1—C2—C3—C4	−0.4 (4)
Pb1^ii—O5—C5—C4	−18.3 (4)	C2—C1—C5—O5	−178.8 (3)
O1—C1—C2—O2	0.4 (5)	C2—C1—C5—C4	0.2 (4)
O1—C1—C2—C3	−177.0 (3)	C2—C3—C4—O4	177.0 (3)
O1—C1—C5—O5	−1.7 (6)	C2—C3—C4—C5	0.6 (4)
O1—C1—C5—C4	177.3 (3)	C3—C4—C5—O5	178.6 (3)
O2—C2—C3—O3	0.9 (6)	C3—C4—C5—C1	−0.5 (4)
O2—C2—C3—C4	−177.7 (3)	C5—C1—C2—O2	177.5 (3)
O3—C3—C4—O4	−1.6 (6)	C5—C1—C2—C3	0.1 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O6—H6A···O5^iii	0.88	2.05	2.868 (4)	155
O6—H6B···O3^iv	0.88	1.97	2.757 (3)	149
O7—H7A···O3^v	0.88 (2)	1.92 (2)	2.795 (4)	169 (5)
O7—H7B···O8^vi	0.88 (2)	1.82 (2)	2.691 (4)	173 (5)
O8—H8A···O6^vii	0.86 (2)	1.98 (2)	2.831 (4)	167 (5)
O8—H8B···O2^viii	0.85 (2)	1.95 (3)	2.769 (4)	159 (6)

Symmetry codes: (iii) −x+1, −y+1, −z+1; (iv) −x+1, −y+1, −z; (v) x, y+1, z+1; (vi) −x, −y+1, −z+1; (vii) x−1, y, z; (viii) −x, −y+1, −z.

catena-Poly[[triaquacadmium(II)]-µ-croconato-κ⁴O¹,O²:O³,O⁴] (rgr560_a)

Crystal data

[Cd(C5O5)(H2O)3]	F(000) = 592
Mr = 306.50	Dx = 2.569 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 6.5123 (3) Å	Cell parameters from 9903 reflections
b = 8.8174 (4) Å	θ = 3.0–28.3°
c = 13.8763 (6) Å	µ = 2.78 mm^−1
β = 96.053 (1)°	T = 298 K
V = 792.36 (6) Å^3	Block, red
Z = 4	0.18 × 0.14 × 0.09 mm

Data collection

Bruker D8 with PHOTON 100 detector diffractometer	1843 reflections with I > 2σ(I)
φ and ω scans	Rint = 0.023
Absorption correction: multi-scan (SADABS; Bruker, 2016)	θmax = 28.3°, θmin = 3.0°
Tmin = 0.688, Tmax = 0.746	h = −8→8
22305 measured reflections	k = −11→11
1970 independent reflections	l = −18→18

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.015	All H-atom parameters refined
wR(F^2) = 0.038	w = 1/[σ^2(Fo^2) + (0.0216P)^2 + 0.2417P] where P = (Fo^2 + 2Fc^2)/3
S = 1.13	(Δ/σ)max = 0.001
1970 reflections	Δρmax = 0.48 e Å^−3
151 parameters	Δρmin = −0.52 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cd1	0.43724 (2)	0.88271 (2)	0.68614 (2)	0.02022 (5)
O1	0.2558 (2)	0.89361 (12)	0.51854 (9)	0.0268 (3)
O2	0.37243 (18)	0.63493 (12)	0.62976 (8)	0.0226 (2)
O3	0.26637 (19)	0.35768 (12)	0.51165 (9)	0.0248 (2)
O4	0.08427 (18)	0.46592 (14)	0.32039 (7)	0.0284 (3)
O5	0.06505 (17)	0.78557 (14)	0.31997 (7)	0.0290 (3)
O6	0.7487 (2)	0.87789 (12)	0.61835 (10)	0.0239 (2)
O7	0.4245 (2)	1.13414 (13)	0.64388 (10)	0.0317 (3)
O8	0.1165 (2)	0.89464 (13)	0.74291 (10)	0.0251 (2)
C1	0.2310 (2)	0.76145 (16)	0.48626 (10)	0.0182 (3)
C2	0.2908 (2)	0.62790 (14)	0.54359 (10)	0.0166 (3)
C3	0.2409 (2)	0.49220 (15)	0.48598 (10)	0.0166 (3)
C4	0.1502 (2)	0.54480 (16)	0.39068 (10)	0.0179 (3)
C5	0.1411 (2)	0.71068 (16)	0.39055 (10)	0.0190 (3)
H6A	0.751 (3)	0.798 (3)	0.5861 (16)	0.039 (6)*
H8A	0.114 (3)	0.970 (3)	0.7824 (18)	0.047 (6)*
H6B	0.745 (3)	0.944 (3)	0.5841 (16)	0.035 (6)*
H8B	0.025 (4)	0.896 (2)	0.7057 (19)	0.040 (7)*
H7A	0.426 (4)	1.198 (4)	0.6907 (19)	0.070 (9)*
H7B	0.353 (4)	1.182 (4)	0.601 (2)	0.076 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.02547 (7)	0.01806 (7)	0.01602 (7)	−0.00052 (4)	−0.00309 (4)	−0.00174 (3)
O1	0.0415 (7)	0.0179 (5)	0.0192 (6)	−0.0015 (4)	−0.0054 (5)	−0.0019 (4)
O2	0.0318 (6)	0.0213 (5)	0.0132 (5)	−0.0028 (4)	−0.0054 (4)	−0.0001 (4)
O3	0.0334 (6)	0.0182 (5)	0.0217 (6)	0.0032 (4)	−0.0027 (5)	0.0024 (4)
O4	0.0419 (7)	0.0225 (6)	0.0178 (5)	0.0003 (5)	−0.0102 (5)	−0.0043 (4)
O5	0.0425 (7)	0.0218 (6)	0.0194 (5)	0.0009 (5)	−0.0119 (5)	0.0034 (4)
O6	0.0298 (6)	0.0156 (5)	0.0256 (6)	0.0008 (4)	0.0006 (5)	0.0006 (4)
O7	0.0514 (8)	0.0207 (6)	0.0207 (6)	0.0074 (5)	−0.0073 (5)	0.0010 (4)
O8	0.0279 (6)	0.0239 (6)	0.0226 (6)	0.0021 (4)	−0.0019 (5)	−0.0032 (4)
C1	0.0216 (7)	0.0175 (6)	0.0149 (6)	−0.0013 (5)	−0.0014 (5)	−0.0004 (5)
C2	0.0167 (6)	0.0186 (6)	0.0140 (6)	−0.0004 (5)	−0.0005 (5)	0.0006 (5)
C3	0.0173 (6)	0.0175 (6)	0.0146 (6)	0.0001 (5)	0.0000 (5)	−0.0002 (5)
C4	0.0195 (6)	0.0183 (7)	0.0152 (6)	−0.0006 (5)	−0.0015 (5)	−0.0008 (5)
C5	0.0219 (7)	0.0189 (7)	0.0154 (6)	−0.0009 (5)	−0.0022 (5)	0.0003 (5)

Geometric parameters (Å, º)

Cd1—O1	2.4971 (12)	O6—H6A	0.83 (2)
Cd1—O2	2.3439 (11)	O6—H6B	0.75 (2)
Cd1—O4^i	2.4067 (11)	O7—H7A	0.86 (3)
Cd1—O5^i	2.4529 (11)	O7—H7B	0.83 (3)
Cd1—O6	2.3244 (13)	O8—H8A	0.86 (3)
Cd1—O7	2.2924 (12)	O8—H8B	0.74 (3)
Cd1—O8	2.3112 (13)	C1—C2	1.4512 (19)
O1—C1	1.2528 (18)	C1—C5	1.464 (2)
O2—C2	1.2578 (18)	C2—C3	1.4565 (18)
O3—C3	1.2445 (17)	C3—C4	1.4657 (18)
O4—C4	1.2373 (17)	C4—C5	1.464 (2)
O5—C5	1.2402 (17)
O2—Cd1—O1	70.98 (4)	Cd1—O6—H6A	107.5 (15)
O2—Cd1—O4^i	144.91 (4)	Cd1—O6—H6B	105.6 (17)
O2—Cd1—O5^i	73.96 (4)	H6A—O6—H6B	109 (2)
O4^i—Cd1—O1	144.11 (4)	Cd1—O7—H7A	116 (2)
O4^i—Cd1—O5^i	70.97 (4)	Cd1—O7—H7B	132 (2)
O5^i—Cd1—O1	144.87 (3)	H7A—O7—H7B	100 (3)
O6—Cd1—O1	88.35 (5)	Cd1—O8—H8A	109.4 (15)
O6—Cd1—O2	88.96 (4)	Cd1—O8—H8B	116.6 (19)
O6—Cd1—O4^i	91.75 (4)	H8A—O8—H8B	111 (2)
O6—Cd1—O5^i	93.12 (4)	O1—C1—C2	122.81 (13)
O7—Cd1—O1	73.96 (4)	O1—C1—C5	129.26 (14)
O7—Cd1—O2	144.65 (4)	C2—C1—C5	107.92 (12)
O7—Cd1—O4^i	70.27 (4)	O2—C2—C1	122.90 (12)
O7—Cd1—O5^i	141.16 (4)	O2—C2—C3	127.57 (12)
O7—Cd1—O6	85.63 (5)	C1—C2—C3	109.53 (12)
O7—Cd1—O8	91.92 (5)	O3—C3—C2	127.63 (13)
O8—Cd1—O1	87.69 (5)	O3—C3—C4	126.06 (13)
O8—Cd1—O2	91.08 (4)	C2—C3—C4	106.30 (11)
O8—Cd1—O4^i	90.63 (4)	O4—C4—C3	127.35 (13)
O8—Cd1—O5^i	90.93 (4)	O4—C4—C5	123.37 (13)
O8—Cd1—O6	175.80 (4)	C5—C4—C3	109.25 (11)
C1—O1—Cd1	109.12 (9)	O5—C5—C1	129.92 (14)
C2—O2—Cd1	113.98 (9)	O5—C5—C4	123.08 (13)
C4—O4—Cd1^ii	112.03 (10)	C4—C5—C1	106.98 (12)
C5—O5—Cd1^ii	110.55 (10)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O6—H6A···O3^iii	0.83 (2)	1.93 (2)	2.746 (2)	167 (2)
O8—H8A···O2^iv	0.86 (3)	1.89 (3)	2.755 (2)	176 (2)
O6—H6B···O1^v	0.75 (2)	2.02 (2)	2.767 (2)	174 (2)
O8—H8B···O6^vi	0.74 (3)	2.07 (3)	2.806 (2)	170 (2)
O7—H7A···O8^iv	0.86 (3)	1.99 (3)	2.811 (2)	158 (3)
O7—H7B···O3^vii	0.83 (3)	2.03 (3)	2.813 (2)	157 (3)

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