Poly[tris­(μ-2-amino­benzene-1,4-dicarboxyl­ato)tetra­kis­(N,N-dimethyl­formamide)­diyttrium(III)]

Mathivathani Kandiah; David Stephen Wragg; Mats Tilset; Karl Petter Lillerud

doi:10.1107/S1600536810050555

. 2010 Dec 8;67(Pt 1):m44–m45. doi: 10.1107/S1600536810050555

Poly[tris(μ-2-aminobenzene-1,4-dicarboxylato)tetrakis(N,N-dimethylformamide)diyttrium(III)]

Mathivathani Kandiah ^a, David Stephen Wragg ^a,^*, Mats Tilset ^a, Karl Petter Lillerud ^a

PMCID: PMC3050248 PMID: 21522565

Abstract

The asymmetric unit of the title coordination polymer, [Y₂(C₈H₅NO₄)₃(C₃H₇NO)₄]_n, contains one Y³⁺ ion, three half-molecules of the 2-aminobenzene-1,4-dicarboxylate (abz) dianion and two O-bonded N,N-dimethylformamide (DMF) molecules. Each abz half-molecule is completed by crystallographic inversion symmetry and its –NH₂ group is disordered in each case [relative occupancies within the asymmetric unit = 0.462 (18):0.538 (18), 0.93 (2):0.07 (2) and 0.828 (16):0.172 (16)]. The combination of disorder and crystal symmetry means that each of the four C—H atoms of the benzene ring of each of the dianions bears a statistical fraction of an –NH₂ group. The coordination geometry of the yttrium ion is a fairly regular YO₈ square antiprism arising from its coordination by two DMF molecules, four monodentate abz dianions and one O,O-bidentate abz dianion. The polymeric building unit is a dimeric paddle-wheel with two metal ions linked by four bridging abz dianions. Further bridging linkages connect the dimers into a three-dimensional framework containing voids in which highly disordered DMF molecules are presumed to reside.

Related literature

For a related structure containing a similar paddle-wheel motif, see: Braun et al. (2001 ▶).

Experimental

Crystal data

[Y₂(C₈H₅NO₄)₃(C₃H₇NO)₄]
M _r = 1007.59
Triclinic,
a = 10.525 (3) Å
b = 11.034 (3) Å
c = 12.855 (3) Å
α = 99.359 (3)°
β = 111.301 (3)°
γ = 101.265 (2)°
V = 1318.8 (6) Å³
Z = 1
Mo Kα radiation
μ = 2.25 mm⁻¹
T = 150 K
0.25 × 0.22 × 0.05 mm

Data collection

Bruker APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T _min = 0.575, T _max = 0.894
7363 measured reflections
2345 independent reflections
2111 reflections with I > 2σ(I)
R _int = 0.027
θ_max = 19.7°

Refinement

R[F ² > 2σ(F ²)] = 0.043
wR(F ²) = 0.123
S = 1.11
2345 reflections
298 parameters
46 restraints
H-atom parameters constrained
Δρ_max = 0.71 e Å⁻³
Δρ_min = −0.41 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2001 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Crystal Impact, 2004) ▶; software used to prepare material for publication: PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810050555/hb5707sup1.cif

e-67-00m44-sup1.cif^{(29.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810050555/hb5707Isup2.hkl

e-67-00m44-Isup2.hkl^{(112.9KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Y1—O3	2.252 (5)
Y1—O1	2.311 (4)
Y1—O5	2.322 (5)
Y1—O7	2.335 (4)
Y1—O8	2.358 (6)
Y1—O2	2.361 (6)
Y1—O6	2.409 (4)
Y1—O4	2.416 (4)

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Acknowledgments

The authors thank the Research Council of Norway and inGAP for funding.

supplementary crystallographic information

Comment

The title compound (I) is a metal-organic framework (MOF) which is a weak scatterer of X-rays and data were collected from a very small crystal. These were sufficient for refinement of the framework structure but not the disordered solvent. The asymmetric unit (Fig. 1) of the title compound consists of an yttrium atom coordinated by 8 oxygen atoms, 6 from 2-amino-1,4-benzenedicarboxylic acid (BDC-NH₂) moieties and 2 from coordinated dimethylformamide solvent. The inorganic cornerstone of the MOF is a paddle wheel type unit comprising two yttrium atoms linked by four bridging Y-BDC-NH₂ molecules (Fig. 2). Such units are well known in transition metal MOF structures (Braun, 2001). The paddle wheel carboxylates clearly show one long and one short C—O bond indicating single and double bond character. The single bonded, charge carrying oxygen of the carboxylate group has a shorter Y—O bond distance as would be expected. The axles of the paddle wheel are connected to one BDC-NH₂ and 2 DMF molecules at each end.

The BDC-NH₂ linkers at the ends of the paddle wheel are offset in a trans-type conformation and link the units in chains which, when the structure is viewed along the a-axis (Fig. 3), bisect the angle of the b and c axes. When we view the structure along the axis of the paddle wheel unit (Fig. 4) we see that the bridging BDC-NH₂ molecules also link to further units in chains parallel to the a and b-axes producing a three-dinemsional network. The amino groups are disordered over all four possible positions of the benzene rings of the BDC-NH₂ linker molecules, except in the case of the ring described by C10, C11 and C12, in which the NH₂ was found to be localized on C12. All of the disordered C—N bonds were restrained to have the same bond distance.

1 molecule of DMF solvent per ASU was located in the void space of the MOF using difference Fourier maps but the resulting model gave a poor refinement. The program Squeeze from the PLATON suite (Spek, 2009 ) was used to remove residual electron density from the solvent accessible voids giving a chemically sensible structure and acceptable refinemnt statistics. The squeeze calculation suggests voids containing 90 electrons or 2.25 DMF molecules in each unit cell. This is in reasonable agreement with the disordered solvent observed in the difference Fourier map.

Experimental

The Title complex Y-BDC-NH₂ was prepared by dissolving Y(NO₃)₃.6H₂O (0.383 g, 1 mmol) and 2-amino 1,4-benzenedicarboxylic acid (H₂N—H₂BDC) (0.181 g, 1 mmol) in N,N`-dimethylformamide (DMF) (20 ml) at room temperature in a test tube. The mixture thus obtained was placed in a pre-heated oven at 80°C for 24 hrs. Colourless plates of (I) were selected directly from the mother liquor as prepared and mounted on cryoloops.