Hydroxonium triaqua­bis(biuret-κ²O,O′)dichloridolanthanum(III) dichloride dihydrate

In the title compound, (H₃O)[LaCl₂(C₂H₅N₃O₂)₂(H₂O)₃]Cl₂·2H₂O, the La atom is bonded to seven O atoms (arising from two O,O′-bidentate biuret mol­ecules and three water mol­ecules) and two chloride ions in an irregular arrangement. A network of N—H...O, N—H...Cl, O—H...O and O—H...Cl hydrogen bonds helps to establish the packing, leading to a three-dimensional network. The La atom, one Cl atom and four O atoms lie on a crystallographic mirror plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](N-C) = 0.003 Å
• R factor = 0.017
• wR factor = 0.042
• Data-to-parameter ratio = 31.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        La1
PLAT313_ALERT_2_C Oxygen with three covalent bonds (rare) ........         O6
PLAT323_ALERT_2_C Check Hybridisation of  O6     in Solvent/Ion             ?
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H1     ...          ?
PLAT420_ALERT_2_C D-H Without Acceptor       N1     -   H2     ...          ?
PLAT480_ALERT_4_C Long H...A H-Bond Reported H1     ..  CL2     ..       2.94 Ang.

Alert level G
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           32.49
           From the CIF: _reflns_number_total               3793
           Count of symmetry unique reflns         1988
           Completeness (_total/calc)            190.79%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured      1805
           Fraction of Friedel pairs measured     0.908
           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
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
   7 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

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

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S1. Comment

No complexes of lanthanum(III) with biuret (biur), H₂N—CO—NH—CO—NH₂ (or C₂H₅N₃O₂) have been structurally characterized. The structures of two samarium-biuret complexes, Sm(biur)₄.(NO₃)₃ (Haddad, 1987) and Sm(biur)₄.(ClO₄)₃ (Haddad, 1988) have been described. In both cases, an SmO₈ square antiprismatic coordination arises for the metal ion. Based on X-ray photographs, it was suggested that all the Ln(biur)₄.(NO₃)₃ and Ln(biur)₄.(ClO₄)₃ compounds are isostructural with their samarium prototypes. In this paper, we describe the synthesis and structure of the title compound, (I), in which three different ligands are bonded to the trivalent cation.

Compound (I) is an ionic salt containing a new [La(biur)₂(H₂O)₅Cl₂]⁺ complex ion. The complete cation is generated by crystallographic mirror symmetry, with La and the three water O atoms lying on the reflecting plane. A hydroxonium cation (with its O6 atom with site symmetry m), an uncoordinated chloride ion (Cl2) and an uncoordinated water molecule (O7) complete the structure (Fig. 1) of (I).

The resulting LaO₇Cl₂ polyhedral geometry in (I) (Table 1) can only be described as irregular. The Brese & O'Keeffe (1991) bond-valence sum for La1 in (I) of 3.29 is significantly larger than the expected value of 3.00. A local LaO₇Cl₂ grouping has been seen in various other compounds, including [LaCl₂(H₂O)(C₁₂H₂₄O₆)]⁺.Cl^- (Rogers et al., 1993) and [La(H₂O)₄Cl(C₃H₇O₃]²⁺.2Cl^-.H₂O (Su et al., 2006), but otherwise these phases have no similarity to (I).

The O,O-bidenate coordination of the biuret molecule to the lanthanum ion in (I) results in a six-membered chelate ring that is non-planar. As noted previously (Carugo et al., 1992), the biuret molecule can be regarded as two planar amide fragments linked by the NH bridge. Here, the dihedral angle betwen the N1/C1/O1/N2 and N2/C2/O2/N3 units is 5.06 (10)°. The lanthanum cation deviates from the N1/C1/O1/N2 and N2/C2/O2/N3 mean planes by 0.894 (4)Å and 0.606 (4) Å, respectively.

The component species in (I) are linked by a dense array of N—H···O, N—H···Cl, O—H···Cl and O—H···O hydrogen bonds (Table 2) resulting in a three-dimensional network. Of note are the [001] chains resulting from the O—H···O hydrogen bonds involving the complex cation, H₃O6 and H₂O7 (Fig. 2).

The structure of (I) is different to those of the recently reported (Harrison, 2008a,b) M(biur)₂(H₂)₄.Cl₃ (M = Gd, Y) phases, perhaps because the larger La³⁺ cation can accommodate nine atoms in its coordination sphere.

Related literature

For related structures, see: Carugo et al. (1992); Rogers et al. (1993); Su et al. (2006); Haddad (1987, 1988); Harrison (2008a,b)

For related literature, see: Brese & O'Keeffe (1991).

S2. Experimental

0.1 M Aqueous solutions of LaCl₃ (10 ml) and biuret (10 ml) were mixed and a small quantity of dilute hydrochloric acid was added, to result in a colourless solution. Colourless blocks of (I) grew over several days as the water slowly evaporated.

S3. Refinement

The N-bound hydrogen atoms were geometrically placed (N—H = 0.88 Å) and refined as riding with U_iso(H) = 1.2U_eq(N). The water and hydroxonium H atoms were located in difference maps and refined as riding in their as-found relative positions with U_iso(H) = 1.2U_eq(O). Although a plausible hydrogen bonding scheme results, some of the peaks were barely above the noise level of the data, and thus the positions of the O-bonded H atoms should be regarded as less certain.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

	Fig. 1. View of the molecular structure of (I) showing 50% displacement ellipsoids (arbitrary spheres for the H atoms). Symmetry code: (i) -x, y, z.
	Fig. 2. Fragment of the packing for (I) displaying the hydrogen bonds (shows an double dashed lines) leading to chains arising from the complex cation, the hydroxonium ion and the uncoordinated water molecule. Symmetry code: (i) 1/2 - x, 1/2 + y, z.

Hydroxonium triaquabis(biuret-κ²O,O')dichloridolanthanum(III) dichloride dihydrate

Crystal data

(H3O)[LaCl2(C2H5N3O2)2(H2O)3]Cl2·2H2O	F(000) = 1176
Mr = 596.00	Dx = 1.913 Mg m^−3
Orthorhombic, Cmc21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C 2c -2	Cell parameters from 4771 reflections
a = 17.6252 (7) Å	θ = 2.3–32.5°
b = 6.8868 (3) Å	µ = 2.63 mm^−1
c = 17.0447 (7) Å	T = 293 K
V = 2068.91 (15) Å^3	Block, colourless
Z = 4	0.30 × 0.23 × 0.17 mm

Data collection

Bruker SMART1000 CCD diffractometer	3793 independent reflections
Radiation source: fine-focus sealed tube	3716 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.018
ω scans	θmax = 32.5°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 1999)	h = −26→26
Tmin = 0.486, Tmax = 0.636	k = −10→9
11912 measured reflections	l = −24→25

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)] = 0.016	H-atom parameters constrained
wR(F^2) = 0.042	w = 1/[σ^2(Fo^2) + (0.0242P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
3793 reflections	Δρmax = 0.70 e Å^−3
121 parameters	Δρmin = −0.67 e Å^−3
1 restraint	Absolute structure: Flack (1983), 1805 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.001 (9)

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
La1	0.0000	0.234447 (14)	0.341713 (14)	0.01947 (3)
Cl1	0.10789 (2)	−0.09170 (6)	0.32281 (3)	0.03634 (12)
C1	0.18755 (10)	0.3315 (3)	0.40149 (12)	0.0293 (4)
C2	0.17044 (10)	0.4278 (3)	0.26382 (12)	0.0290 (3)
N1	0.24102 (12)	0.2964 (3)	0.45518 (14)	0.0459 (5)
H1	0.2283	0.2650	0.5022	0.055*
H2	0.2882	0.3052	0.4427	0.055*
N2	0.21433 (7)	0.3826 (2)	0.32868 (11)	0.0344 (4)
H3	0.2628	0.3870	0.3229	0.041*
N3	0.20884 (11)	0.4877 (3)	0.20138 (13)	0.0445 (4)
H4	0.1851	0.5181	0.1591	0.053*
H5	0.2575	0.4963	0.2032	0.053*
O1	0.11900 (8)	0.3202 (3)	0.41736 (8)	0.0333 (3)
O2	0.10047 (7)	0.41314 (19)	0.26393 (8)	0.0298 (3)
O3	0.0000	0.0881 (4)	0.47616 (14)	0.0488 (7)
H6	0.0406	0.0729	0.5026	0.059*
O4	0.0000	0.1452 (4)	0.19698 (13)	0.0384 (5)
H7	0.0377	0.0935	0.1750	0.046*
O5	0.0000	0.5850 (3)	0.39200 (13)	0.0388 (5)
H8	−0.0323	0.6527	0.3843	0.047*
Cl2	0.36579 (3)	0.51610 (15)	0.08766 (5)	0.04627 (14)
O6	0.5000	0.1924 (5)	0.17243 (18)	0.0617 (7)
H9	0.4686	0.1472	0.2081	0.074*
H10	0.5000	0.1363	0.1273	0.074*
O7	0.39583 (14)	−0.0187 (4)	0.06811 (12)	0.0695 (6)
H11	0.3960	−0.1404	0.0560	0.083*
H12	0.3976	0.0476	0.0265	0.083*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
La1	0.01375 (4)	0.02565 (5)	0.01902 (5)	0.000	0.000	0.00102 (8)
Cl1	0.01972 (15)	0.03484 (19)	0.0545 (3)	0.00363 (13)	0.00053 (17)	−0.00126 (18)
C1	0.0219 (8)	0.0309 (9)	0.0351 (9)	−0.0001 (6)	−0.0063 (7)	−0.0041 (7)
C2	0.0240 (7)	0.0303 (8)	0.0325 (9)	−0.0042 (6)	0.0059 (7)	−0.0006 (7)
N1	0.0305 (9)	0.0593 (11)	0.0479 (11)	0.0024 (8)	−0.0163 (9)	0.0009 (10)
N2	0.0164 (5)	0.0455 (7)	0.0412 (11)	−0.0021 (5)	0.0022 (6)	0.0039 (7)
N3	0.0322 (9)	0.0584 (11)	0.0430 (10)	−0.0067 (8)	0.0141 (8)	0.0071 (9)
O1	0.0228 (6)	0.0510 (8)	0.0260 (6)	−0.0028 (6)	−0.0025 (5)	−0.0012 (6)
O2	0.0211 (6)	0.0395 (7)	0.0288 (6)	−0.0032 (5)	0.0006 (5)	0.0062 (6)
O3	0.0248 (10)	0.086 (2)	0.0352 (13)	0.000	0.000	0.0282 (12)
O4	0.0265 (10)	0.0609 (15)	0.0279 (10)	0.000	0.000	−0.0113 (10)
O5	0.0301 (10)	0.0299 (9)	0.0564 (14)	0.000	0.000	−0.0004 (9)
Cl2	0.03018 (19)	0.0726 (4)	0.0360 (2)	0.0037 (3)	−0.0008 (3)	−0.0124 (2)
O6	0.076 (2)	0.0640 (16)	0.0453 (16)	0.000	0.000	0.0068 (14)
O7	0.0972 (16)	0.0730 (12)	0.0384 (10)	0.0050 (13)	−0.0051 (10)	0.0115 (10)

Geometric parameters (Å, º)

La1—O3	2.503 (2)	C2—N2	1.385 (3)
La1—O2	2.5313 (13)	N1—H1	0.8600
La1—O2^i	2.5313 (12)	N1—H2	0.8600
La1—O1	2.5318 (14)	N2—H3	0.8600
La1—O1^i	2.5318 (14)	N3—H4	0.8600
La1—O4	2.542 (2)	N3—H5	0.8600
La1—O5	2.562 (2)	O3—H6	0.8522
La1—Cl1^i	2.9606 (4)	O4—H7	0.8418
La1—Cl1	2.9606 (4)	O5—H8	0.7477
C1—O1	1.241 (2)	O6—H9	0.8786
C1—N1	1.336 (3)	O6—H10	0.8615
C1—N2	1.374 (3)	O7—H11	0.8631
C2—O2	1.237 (2)	O7—H12	0.8446
C2—N3	1.327 (3)
O3—La1—O2	132.46 (4)	O2—La1—Cl1	82.10 (3)
O3—La1—O2^i	132.46 (4)	O2^i—La1—Cl1	139.57 (4)
O2—La1—O2^i	88.78 (6)	O1—La1—Cl1	72.56 (4)
O3—La1—O1	68.14 (5)	O1^i—La1—Cl1	139.86 (4)
O2—La1—O1	64.78 (4)	O4—La1—Cl1	73.20 (5)
O2^i—La1—O1	137.12 (5)	O5—La1—Cl1	138.709 (15)
O3—La1—O1^i	68.14 (5)	Cl1^i—La1—Cl1	79.930 (17)
O2—La1—O1^i	137.12 (5)	O1—C1—N1	121.8 (2)
O2^i—La1—O1^i	64.78 (4)	O1—C1—N2	123.21 (16)
O1—La1—O1^i	111.87 (7)	N1—C1—N2	115.01 (18)
O3—La1—O4	142.27 (9)	O2—C2—N3	122.33 (19)
O2—La1—O4	67.01 (5)	O2—C2—N2	122.51 (17)
O2^i—La1—O4	67.01 (5)	N3—C2—N2	115.16 (17)
O1—La1—O4	123.41 (3)	C1—N1—H1	120.0
O1^i—La1—O4	123.41 (3)	C1—N1—H2	120.0
O3—La1—O5	94.19 (9)	H1—N1—H2	120.0
O2—La1—O5	73.56 (5)	C1—N2—C2	125.93 (14)
O2^i—La1—O5	73.56 (5)	C1—N2—H3	117.0
O1—La1—O5	67.03 (4)	C2—N2—H3	117.0
O1^i—La1—O5	67.03 (4)	C2—N3—H4	120.0
O4—La1—O5	123.54 (8)	C2—N3—H5	120.0
O3—La1—Cl1^i	78.13 (5)	H4—N3—H5	120.0
O2—La1—Cl1^i	139.57 (4)	C1—O1—La1	135.26 (12)
O2^i—La1—Cl1^i	82.10 (3)	C2—O2—La1	137.53 (12)
O1—La1—Cl1^i	139.86 (4)	La1—O3—H6	122.3
O1^i—La1—Cl1^i	72.56 (4)	La1—O4—H7	122.3
O4—La1—Cl1^i	73.20 (5)	La1—O5—H8	121.9
O5—La1—Cl1^i	138.709 (15)	H9—O6—H10	117.3
O3—La1—Cl1	78.13 (5)	H11—O7—H12	108.9
O1—C1—N2—C2	−0.1 (3)	Cl1^i—La1—O1—C1	103.6 (2)
N1—C1—N2—C2	−179.32 (19)	Cl1—La1—O1—C1	54.6 (2)
O2—C2—N2—C1	−5.1 (3)	N3—C2—O2—La1	159.25 (15)
N3—C2—N2—C1	174.93 (19)	N2—C2—O2—La1	−20.7 (3)
N1—C1—O1—La1	−149.81 (17)	O3—La1—O2—C2	21.4 (2)
N2—C1—O1—La1	31.0 (3)	O2^i—La1—O2—C2	175.02 (16)
O3—La1—O1—C1	138.5 (2)	O1—La1—O2—C2	29.91 (18)
O2—La1—O1—C1	−34.7 (2)	O1^i—La1—O2—C2	125.52 (18)
O2^i—La1—O1—C1	−91.9 (2)	O4—La1—O2—C2	−119.5 (2)
O1^i—La1—O1—C1	−167.88 (17)	O5—La1—O2—C2	101.81 (19)
O4—La1—O1—C1	−0.6 (2)	Cl1^i—La1—O2—C2	−108.69 (18)
O5—La1—O1—C1	−116.7 (2)	Cl1—La1—O2—C2	−44.48 (18)

Symmetry code: (i) −x, y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···Cl2^ii	0.86	2.94	3.643 (3)	141
N1—H2···Cl1^iii	0.86	2.83	3.574 (3)	145
N2—H3···Cl1^iii	0.86	2.28	3.1399 (14)	173
N3—H4···O7^iii	0.86	2.12	2.927 (3)	156
N3—H5···Cl2	0.86	2.75	3.3835 (18)	132
O3—H6···Cl2^ii	0.85	2.28	3.1181 (16)	168
O4—H7···Cl2^iv	0.84	2.32	3.1396 (17)	164
O5—H8···Cl1^v	0.75	2.44	3.1566 (17)	160
O6—H9···O2^iv	0.88	2.23	3.044 (3)	153
O6—H10···O7	0.86	2.35	2.941 (3)	126
O6—H10···O7^vi	0.86	2.35	2.941 (3)	126
O7—H11···Cl2^vii	0.86	2.48	3.264 (3)	151
O7—H12···O1^viii	0.84	2.09	2.922 (2)	168

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