A new vanadate containing helical chains

The structure of a new vanadium oxide compound, catena-poly[N,N′-bis­(2-ammonio­ethyl)oxamide [dioxidovanadate-μ-oxido-dioxidovanadate-μ-oxido]], {(C₆H₁₆N₄O₂)[V₂O₆]}_n, ex­hibits helical vanadate chains, constructed from corner-sharing VO₄ tetra­hedra. Adjacent chains are packed together by extensive hydrogen bonds involving the inorganic framework and the templating guest cations, which are centrosymmetric and occupy the free space between the stacks of chains.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.029
• wR factor = 0.078
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

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Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       2.00 Ratio
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for          V
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C1     -   C1_c   ...       1.53 Ang.

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for V           (5)       5.20

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   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   3 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
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S1. Comment

Microporous inorganic solids have attracted considerable attention in the past decades due to their structural diversity and potential applications in diverse areas (Cheetham et al., 1999; Hagrman et al., 2001). Among those, vanadium oxide family has proved a particularly rich source of new compounds. This is in part due to the flexible ability of vanadium to adopt tetrahedral, square-pyramidal, trigonal bipyramidal and octahedral coordination geometries, as well as their various oxidation states (III, IV and V). Besides, the utilizaion of hydrothermal technique in combination with cationic organic templates has also resulted in a huge number of new structures (Nazar et al., 1996; Zhang et al., 1996; Chirayil et al., 1998; Hagrman & Zubieta, 2000; Khan et al., 2000; Liu et al., 2002). One may expect that the rational design of crystalline solids with complex architectures may be realised through shrewd choice of organic species. The aim of our work is to explore the construction of such materials, and a new chain-like vanadate (I), has been described here.

As shown in Fig. 1, the asymmetric unit contains only one half of a [(H₂oxen)²⁺ ion. The V^v atom possesses a distorted tetrahedal geometry and is coordinated by two symetry related images of a bridging oxo group (O3) and two terminal unshared oxygen atoms (O1 and O2) with short vanadyl V=O bond distances (Table 1). The VO₄ tetrahedra are linked together through common vertices, leading to the formation of unusual helical –O—V—O—V—O– chains (Fig. 2). Adjacent chains are further stacked in an ABAB sequence along the c axis. The diprotonated templates H₂oxen, adopting the transoid conformation with an inversion centre at the mid-point of the C1—C1ⁱ bond [symmetry code: (i) 1 - x, 2 - y, -z], fill the space of neighboring chains to compensate the negative charges and further extend the structure into 3-D supramolecular framework through hydrogen bonds with N···O distances in the range 2.705 (3)–3.013 (3) Å (Fig. 3).

Related literature

For related literature, see: Cheetham et al. (1999); Chirayil et al. (1998); Hagrman & Zubieta (2000); Hagrman et al. (2001); Khan et al. (2000); Liu et al. (2002); Nazar et al. (1996); Ojima & Nonoyama (1988); Zhang et al. (1996).

S2. Experimental

The Cu(oxen) was prepared according to the method of Ojima & Nonoyama (1988). A mixture of NH₄VO₃ (0.117 g,1.0 mmol), Cu(oxen) (0.118 g,0.5 mmol), H₂C₂O₄.2H₂O (0.0257 g,0.2 mmol) and methanol (8 ml), was sealed in a 25 ml Teflon-lined steel autoclave and heated under autogenous pressure at 353 K for 6 h. Then, the filtrate was kept at room temperature and brown block-like crystals were obtained after a week.

S3. Refinement

All the H atoms were positioned geometrically, with C—H = 0.97 Å and with N—H = 0.86 (NH) or 0.89 (NH₃) Å, and allowed to ride during refinement with U_iso(H) = 1.2U_eq(C,N) for the CH₂ and NH groups or 1.5U_eq(N) for the NH₃ groups.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids. [symmetry codes: (i) 1 - x, 2 - y, -z; (ii) 1.5 - x, -1/2 + y, 1/2 - z. (i) 1 - x, 2 - y, -z;(ii) 1.5 - x, -1/2 + y, 1/2 - z;(iii) 1.5 - x, 1/2 + y, 1/2 - z; (iv) x, -1 + y, z.
	Fig. 2. View of the 1-D helical vanadate chain of 1.
	Fig. 3. Packing diagram of the title compound.

catena-poly[N,N'-bis(2-ammonioethyl)oxamide [dioxidovanadate-µ-oxido-dioxidovanadate-µ-oxido]],

Crystal data

(C6H16N4O2)[V2O6]	F(000) = 380
Mr = 374.11	Dx = 1.869 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 4832 reflections
a = 6.7453 (3) Å	θ = 3.1–26.0°
b = 5.5087 (1) Å	µ = 1.45 mm^−1
c = 18.1775 (2) Å	T = 295 K
β = 100.114 (3)°	Block, brown
V = 664.94 (3) Å^3	0.20 × 0.12 × 0.08 mm
Z = 2

Data collection

Siemems SMART CCD diffractometer	1300 independent reflections
Radiation source: fine-focus sealed tube	1217 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
φ and ω scans	θmax = 26.0°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→8
Tmin = 0.760, Tmax = 0.893	k = −6→6
4832 measured reflections	l = −22→22

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.078	H-atom parameters constrained
S = 1.11	w = 1/[σ^2(Fo^2) + (0.0358P)^2 + 0.6776P] where P = (Fo^2 + 2Fc^2)/3
1300 reflections	(Δ/σ)max < 0.001
91 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.36 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
V	0.65928 (5)	0.70817 (7)	0.20100 (2)	0.01778 (15)
O1	0.7174 (3)	0.6053 (4)	0.12407 (10)	0.0363 (5)
O2	0.4226 (3)	0.7879 (4)	0.18675 (13)	0.0411 (5)
O3	0.8179 (3)	0.9687 (3)	0.23015 (10)	0.0291 (4)
O4	0.2428 (2)	0.9303 (3)	−0.01377 (9)	0.0256 (4)
C1	0.3990 (3)	1.0441 (4)	0.00875 (12)	0.0188 (5)
C2	0.2333 (4)	1.3726 (5)	0.06245 (14)	0.0263 (5)
H2A	0.1252	1.3422	0.0207	0.032*
H2B	0.2613	1.5454	0.0635	0.032*
C3	0.1615 (4)	1.3043 (5)	0.13401 (15)	0.0295 (6)
H3A	0.2711	1.3257	0.1758	0.035*
H3B	0.0530	1.4122	0.1413	0.035*
N1	0.4117 (3)	1.2438 (4)	0.04932 (11)	0.0217 (4)
H1A	0.5286	1.2992	0.0685	0.026*
N2	0.0899 (3)	1.0505 (4)	0.13286 (11)	0.0242 (4)
H2C	0.0491	1.0172	0.1757	0.036*
H2D	0.1898	0.9508	0.1271	0.036*
H2E	−0.0123	1.0308	0.0951	0.036*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
V	0.0180 (2)	0.0148 (2)	0.0203 (2)	0.00000 (14)	0.00284 (15)	0.00046 (14)
O1	0.0497 (12)	0.0343 (11)	0.0263 (9)	−0.0053 (9)	0.0105 (8)	−0.0082 (8)
O2	0.0227 (10)	0.0353 (11)	0.0626 (14)	0.0066 (8)	0.0002 (9)	0.0068 (10)
O3	0.0342 (10)	0.0222 (9)	0.0330 (9)	−0.0085 (7)	0.0114 (8)	−0.0084 (7)
O4	0.0181 (8)	0.0257 (9)	0.0326 (9)	−0.0039 (7)	0.0033 (7)	−0.0019 (7)
C1	0.0182 (11)	0.0218 (11)	0.0165 (10)	−0.0002 (9)	0.0033 (8)	0.0035 (9)
C2	0.0281 (13)	0.0201 (12)	0.0318 (13)	0.0038 (10)	0.0084 (10)	0.0004 (10)
C3	0.0307 (14)	0.0276 (14)	0.0329 (14)	0.0015 (10)	0.0131 (11)	−0.0058 (11)
N1	0.0183 (10)	0.0224 (10)	0.0248 (10)	−0.0021 (8)	0.0052 (8)	−0.0030 (8)
N2	0.0178 (10)	0.0311 (11)	0.0244 (10)	0.0023 (8)	0.0056 (8)	0.0028 (8)

Geometric parameters (Å, º)

V—O1	1.6197 (18)	C2—H2A	0.9700
V—O2	1.6322 (19)	C2—H2B	0.9700
V—O3^i	1.8063 (17)	C3—N2	1.478 (3)
V—O3	1.8127 (17)	C3—H3A	0.9700
O4—C1	1.232 (3)	C3—H3B	0.9700
C1—N1	1.319 (3)	N1—H1A	0.8600
C1—C1^ii	1.532 (4)	N2—H2C	0.8900
C2—N1	1.452 (3)	N2—H2D	0.8900
C2—C3	1.513 (3)	N2—H2E	0.8900
O1—V—O2	109.60 (11)	N2—C3—C2	112.1 (2)
O1—V—O3^i	109.79 (9)	N2—C3—H3A	109.2
O2—V—O3^i	105.57 (10)	C2—C3—H3A	109.2
O1—V—O3	108.03 (9)	N2—C3—H3B	109.2
O2—V—O3	110.13 (9)	C2—C3—H3B	109.2
O3^i—V—O3	113.68 (3)	H3A—C3—H3B	107.9
V^iii—O3—V	139.01 (10)	C1—N1—C2	121.7 (2)
O4—C1—N1	125.3 (2)	C1—N1—H1A	119.2
O4—C1—C1^ii	120.6 (3)	C2—N1—H1A	119.2
N1—C1—C1^ii	114.1 (2)	C3—N2—H2C	109.5
N1—C2—C3	114.8 (2)	C3—N2—H2D	109.5
N1—C2—H2A	108.6	H2C—N2—H2D	109.5
C3—C2—H2A	108.6	C3—N2—H2E	109.5
N1—C2—H2B	108.6	H2C—N2—H2E	109.5
C3—C2—H2B	108.6	H2D—N2—H2E	109.5
H2A—C2—H2B	107.5

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1^iv	0.86	2.24	3.013 (3)	149
N2—H2C···O3^v	0.89	2.01	2.799 (3)	148
N2—H2E···O4^vi	0.89	1.96	2.833 (3)	167
N2—H2D···O2	0.89	1.96	2.705 (3)	140

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