catena-Poly[bis­(μ-2,2′-bipyridin-6-ol­ato)-κ³N,N′:O;O:N,N′-dicopper(I,II) [[tetra­fluorido­niobium(V)]-μ-oxido]]

A novel copper–niobium oxyfluoride, {[Cu₂(C₁₀H₇N₂O)₂][NbOF₄]}_n, has been synthesized by a hydro­thermal method and characterized by elemental analysis, EDS, IR, XPS and single-crystal X-ray diffraction. The structural unit consists of one C₂-symmetric [NbOF₄]⁻ anion and one centrosymmetric coordinated [Cu₂(obpy)₂]⁺ cation (obpy is 2,2′-bipyridin-6-olate). In the [NbOF₄]⁻ anion, each Nb^V metal centre is five-coordinated by four F atoms and one O atom in the first coordination shell, forming a square-pyramidal coordination geometry. These square pyramids are then further connected to each other via trans O atoms [Nb—O = 2.187 (3) Å], forming an infinite linear {[NbOF₄]⁻}_n polyanion. In the coordinated [Cu₂(obpy)₂]⁺ cation, the oxidation state of each Cu site is disordered, which is confirmed by the XPS results. The disordered Cu sites are coordinated by two N atoms and one O atom from two different obpy ligands. The [NbOF₄]⁻ and [Cu₂(obpy)₂]⁺ units are assembled via weak C—H...F hydrogen bonds, resulting in the formation of a three-dimensional supra­molecular structure. π–π stacking inter­actions between the pyridine rings [centroid–centroid distance = 3.610 (2) Å] may further stabilize the crystal structure.

S1. Introduction

In recent years, increasing attention has been paid to niobium oxyfluorides due to their specific structure-related properties, such as ferroelectricity, piezoelectricity and second-order nonlinear optical activity (Hagerman & Poeppelmeier, 1995). The [NbOF₅]^2- anion has been employed as a building block to construct niobium oxyfluorides with isolated cluster or linear chain structures. This fact stems not only from their unique architectures but also from their wide applications. Up to now, niobium oxyfluorides based on the [NbOF₅]^2- anion have been synthesized and reported, e.g. [H₂N(C₂H₄)₂NH₂][NbOF₅] (Feng et al., 2010), (HNC₆H₆OH)₂[Cu(py)₄(NbOF₅)₂] (py is pyridine; Welk et al., 2002), (pyH)₂[Cu(py)₄(NbOF₅)₂] (Halasyamani et al., 1996), Cd(py)₄NbOF₅ (Guillory et al., 2006), (4-apyH)₂[Cu(4-apy)₄(NbOF₅)₂] (4-apy is pyridin-4-amine; Izumi et al., 2005), and Cd(3-apy)₄NbOF₅ and Cu(3-apy)₄NbOF₅ (3-apy is pyridin-3-amine; Izumi et al., 2005). However, in comparison with such well characterized niobium oxyfluorides based on the [NbOF₅]^2- anion, investigations on the [NbOF₄]^- anion are relatively rare, examples being (Hphen)[NbOF₄].H₂O (Hphen is 1,10-phenanthrolinium; Zhao et al., 2009), and NH₄NbOF₄, Ag(pyz)NbOF₄ (pyz is pyrazine) and Cu(bpy)NbOF₄.2H₂O (bpy = bi­pyridine) (Lin & Maggard, 2010). It is of particular inter­est that the incorporation of a second transition metal, copper, may lead to novel niobium oxyfluorides with unexpected structures and properties. Accordingly, our research group is paying special attention to synthesizing and exploring copper oxyfluorides based on the [NbOF₄]^- anion. As an extension of known materials with structure-related properties, we have successfully isolated the title novel niobium–copper oxyfluoride, [Cu₂(obpy)₂][NbOF₄], (I) (obpy is 2,2'-bipyridin-6-olate), based on the linear [NbOF₄]^- anion, by the hydro­thermal method and characterized it by elemental analysis, energy-dispersive X-ray spectroscopy (EDS), IR spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray single-crystal diffraction.

S2. Experimental

S2.1. Synthesis and crystallization

All chemicals were of reagent grade quality obtained from commercial sources and were used without further purification. Compound (I) was obtained by a hydro­thermal method. Nb₂O₅ (0.27 g, 1 mmol) was dissolved in HF (0.56 g, 40 wt.%, 11.2 mmol) and kept at 383 K for 12 h. The solution was then cooled, and CuO (0.20 g, 2.5 mmol), 2,2'-bi­pyridine (0.24 g, 1.5 mmol), KOH (0.12 g, 2 mmol) and H₂O (10 ml, 556 mmol) were added. The mixture was stirred for 30 min, and then transferred into a Teflon-lined stainless steel autoclave (50 ml) and heated at 443 K for 8 d. After the mixture had been cooled slowly to room temperature, dark-red crystals were obtained. The product was filtered off, washed with deionized water, purified ultrasonically and dried in a vacuum desiccator at ambient temperature. (yield 62%, based on Nb₂O₅). It is noted that 0.12 g KOH provided an alkaline environment for the formation of the 2,2'-bipyridin-6-olate ligand according to the Gillard mechanism (Gillard, 1975). Elemental analysis of C, H and N was performed with a Perkin–Elmer 240 analyser. Analysis, calculated for (I): C 36.62, H 2.29, N 8.54%; found: C 36.39, H 2.43, N 8.72%.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. All H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C). In addition, the Cu atom was split into two sites with different oxidation states (Cu1 and Cu1'), according to the XPS results. The Cu1 and Cu1' sites were freely refined with a site-occupancy factor ratio of 0.5:0.5 (1:1).

S3. Results and discussion

The structural unit of (I) consists of one C₂-symmetric [NbOF₄]^- anion and one C₂-symmetric coordinated [Cu₂(obpy)₂]⁺ cation (Fig. 1). In the coordinated [Cu₂(obpy)₂]⁺ cation, the oxidation state of each Cu atom is disordered [Cu1 is Cu^I and Cu1' is Cu^II]; such disordered Cu sites are similar to what was observed in [Cu₂(obpy)₂][CuCl₂] (Guo et al., 2007). Besides the weak Cu···Cu inter­action of 2.39 Å, the disordered Cu sites are also coordinated by two N atoms from one obpy ligand and by one O atom from the other obpy ligand, respectively. The whole structure of the [NbOF₄]^- anion can be viewed as an infinite linear chain in which the central NbF₄ fragments are connected to each other through two µ₂-O atoms. The Nb^V metal centre is five-coordinated by four F atoms and one O atom in the first coordination shell, forming a square-pyramidal coordination geometry. The Nb—F and Nb—O bond lengths are 1.9151 (16)–1.9158 (16) and 1.749 (3) Å, respectively, consistent with those reported for known niobium oxyfluorides (Heier et al., 1998). These square pyramids are further connected to each other via trans O atoms [Nb—O = 2.185 (3) Å], forming an infinite linear {[NbOF₄]^-}_n polyanion (Fig. 2a).

In addition, besides the electrostatic inter­actions between the [NbOF₄]^- and [Cu₂(obpy)₂]⁺ units, there are π–π stacking inter­actions between pyridine rings along the b axis. These pyridine rings are parallel to each other, with a centroid-to-centroid distance of 3.610 (2) Å. Such π–π stacking inter­actions between aromatic groups are rather common in coordination polymers (Li et al., 2003). It is worth noting that the [NbOF₄]^- and [Cu₂(obpy)₂]⁺ units are linked via nonclassical C—H···F hydrogen-bonding inter­actions; each [NbOF₄]^- anion is linked to four surrounding [Cu₂(obpy)₂]⁺ coordinated cations (Fig. 2b), giving rise to the supra­molecular architecture (Fig. 3a). Obviously, these electrostatic, π–π stacking and hydrogen-bonding inter­actions are responsible for the chemical stability of (I). To understand fully the structure of (I), the topological approach is applied to simplify the supra­molecular architecture. By considering the coordination and hydrogen bonding between linear [NbOF₄]^- anions and [Cu₂(obpy)₂]⁺ cations (each [Cu₂(obpy)₂]⁺ cation is considered as a single node), the supra­molecular structure can be simplified as a (4,6)-connected network with the Schläfli symbol (4⁴.6²)(4⁴.6¹⁰.8) (Fig. 3b).

The EDS results for the single crystal of (I) indicate the presence of the elements Nb, Cu, F, O, C and N. The EDS results and elemental analysis are in agreement with the single-crystal X-ray structural analysis.

In the IR spectrum of (I) (Fig. 4), there are three characteristic asymmetric vibrations resulting from the [NbOF₄]^- anion, namely, ν(Nb═O), ν(Nb—O) and ν(Nb—F) at 900, 779 and 567 cm^-1, respectively (Zhao et al., 2009). Comparing the IR spectrum of (I) with that of (Hphen)[NbOF₄].H₂O (Zhao et al., 2009), the Nb═O stretch is shifted from 906 to 900 cm^-1, and the Nb—O and Nb—F vibrations are shifted from 791 to 779 cm^-1 and from 582 to 567 cm^-1, respectively. This is probably due to the fact that the [NbOF₄]^- anion is affected by the surrounding metal-coordinated [Cu₂(obpy)₂]⁺ cations. The peak at 418 cm^-1 can be ascribed to ν(Cu—O) (Alimaje et al., 2011). In addition, in the high-frequency region of the IR spectrum, weak absorption bands observed at 3110 and 3062 cm^-1 can be attributed to the ν_C—H vibration of the obpy groups, while in the low-frequency region, a series of absorptions in the range of 1621–1102 cm^-1 (1621, 1600, 1547, 1494, 1462, 1378, 1298, 1266, 1171, 1123 and 1102 cm^-1) should be assigned to the obpy ligands (Wang et al., 2009). The vibrations of the OH group were not found in the IR spectrum of (I), indicating that atoms O1 are not protonated. These results further confirm that the coordinated [Cu₂(obpy)₂]⁺ cation contains disordered oxidation states Cu^I and Cu^II. Again, these results are in agreement with the single-crystal X-ray diffraction analysis.

In order to confirm the oxidation states of Cu further by means of an additional experimental technique, XPS measurement of (I) was performed. The spin-orbit components (2p_3/2 and 2p_1/2) of the Cu2p peak were deconvoluted into two curves at approximately 932.2 and 952.0 eV (Fig. 5), confirming the presence of Cu^I in (I) (Cheng et al., 2005; Brust et al., 1997). Meanwhile, the typical shake-up lines (935–945 eV) of Cu^II were also observed, revealing the presence of a bivalent oxidation state in (I) (Avgouropoulos & Loannides, 2003). These results futher indicate that (I) contains disordered oxidation states Cu^I and Cu^II.

In summary, the title copper–niobium oxyfluoride, [Cu₂(obpy)₂][NbOF₄], has been obtained by the hydro­thermal method. Compound (I) enriches the family of known niobium oxyfluorides and features the first copper–niobium oxyfluoride based on the linear {[NbOF₄]^-}_n polyanion. The successful synthesis of (I) indicates that many copper–niobium oxyfluorides with unexpected structures and inter­esting physical properties may be accessible using a similar method.

Related literature

For related literature, see: Alimaje et al. (2011); Avgouropoulos & Loannides (2003); Brust et al. (1997); Cheng et al. (2005); Feng et al. (2010); Gillard (1975); Guillory et al. (2006); Guo et al. (2007); Hagerman & Poeppelmeier (1995); Halasyamani et al. (1996); Heier et al. (1998); Izumi et al. (2005); Li et al. (2003); Lin & Maggard (2010); Wang et al. (2009); Welk et al. (2002); Zhao et al. (2009).

Computing details

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

Figures

	Fig. 1. The structure of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Only one position of disordered atom Cu1 is shown. Dashed lines indicate what? [One is a hydrogen bond, the other an intermetallic contact. Use different styles of lines?] [Symmetry code: (A) -x + 1, y, -z + 3/2.]
	Fig. 2. (a) The structure of the infinite linear {[NbOF4]^-}n polyanion along the c axis. (b) A packing diagram for (I), viewed down the b axis.
	Fig. 3. (a) A view of the supramolecular architecture of (I), formed through hydrogen bonding and π–π stacking interactions. (b) A topological view of the (4,6)-connected network with the Schläfli symbol (4^4.6^2)(4^4.6^10.8).
	Fig. 4. The IR spectrum of (I).
	Fig. 5. The XPS spectrum of the disordered oxidation states Cu^I and Cu^II in (I).

catena-Poly[bis(µ-2,2'-bipyridin-6-olato)-κ³N,N':O;O:N,N'-dicopper(I,II) [[tetrafluoridoniobium(V)]-µ-oxido]]

Crystal data

[Cu(C10H7N2O)][NbF4O]	F(000) = 1284
Mr = 654.34	Dx = 2.118 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C2yc	Cell parameters from 4143 reflections
a = 18.2718 (12) Å	θ = 2.3–28.3°
b = 3.9347 (3) Å	µ = 2.67 mm^−1
c = 29.0066 (19) Å	T = 296 K
β = 100.188 (1)°	Block, dark-red
V = 2052.5 (2) Å^3	0.25 × 0.22 × 0.18 mm
Z = 4

Data collection

Bruker APEXII CCD area-detector diffractometer	1803 independent reflections
Radiation source: fine-focus sealed tube	1744 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.020
ϕ and ω scans	θmax = 25.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −21→19
Tmin = 0.555, Tmax = 0.645	k = −4→3
4803 measured reflections	l = −29→34

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)] = 0.021	H-atom parameters constrained
wR(F^2) = 0.058	w = 1/[σ^2(Fo^2) + (0.0285P)^2 + 3.5708P] where P = (Fo^2 + 2Fc^2)/3
S = 1.07	(Δ/σ)max = 0.001
1803 reflections	Δρmax = 0.31 e Å^−3
165 parameters	Δρmin = −0.46 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00189 (14)

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	Occ. (<1)
Cu1'	0.22824 (17)	1.2301 (9)	0.53642 (14)	0.0252 (11)	0.50
Cu1	0.2283 (2)	1.2231 (11)	0.53647 (16)	0.0444 (16)	0.50
Nb1	0.5000	0.17503 (7)	0.7500	0.02394 (13)
C1	0.36714 (13)	0.9089 (7)	0.53007 (8)	0.0348 (6)
C2	0.43305 (15)	0.7326 (7)	0.54958 (10)	0.0411 (6)
H2	0.4691	0.6880	0.5315	0.049*
C3	0.44304 (15)	0.6294 (7)	0.59498 (10)	0.0413 (6)
H3	0.4859	0.5105	0.6076	0.050*
C4	0.38995 (15)	0.6991 (7)	0.62298 (10)	0.0373 (6)
H4	0.3971	0.6302	0.6541	0.045*
C5	0.32704 (13)	0.8721 (6)	0.60317 (8)	0.0308 (5)
C6	0.26597 (13)	0.9676 (6)	0.62803 (8)	0.0310 (5)
C7	0.26389 (15)	0.8821 (7)	0.67426 (9)	0.0391 (6)
H7	0.3027	0.7612	0.6920	0.047*
C8	0.20307 (16)	0.9801 (8)	0.69326 (9)	0.0444 (7)
H8	0.2002	0.9223	0.7240	0.053*
C9	0.14667 (16)	1.1629 (7)	0.66682 (10)	0.0436 (7)
H9	0.1058	1.2318	0.6795	0.052*
C10	0.15164 (15)	1.2424 (7)	0.62124 (10)	0.0397 (6)
H10	0.1136	1.3665	0.6032	0.048*
F1	0.51425 (10)	0.2299 (4)	0.68656 (5)	0.0438 (4)
F2	0.39560 (9)	0.2446 (5)	0.72939 (6)	0.0516 (5)
O2	0.5000	−0.2695 (6)	0.7500	0.0539 (8)
N1	0.31612 (11)	0.9730 (5)	0.55723 (6)	0.0312 (5)
N2	0.21043 (12)	1.1443 (6)	0.60217 (7)	0.0331 (5)
O1	0.14525 (10)	1.4915 (6)	0.51323 (6)	0.0460 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1'	0.0199 (17)	0.0338 (16)	0.021 (2)	0.0082 (12)	0.0007 (13)	0.0010 (13)
Cu1	0.045 (3)	0.063 (3)	0.025 (3)	0.0097 (18)	0.0095 (18)	0.0014 (17)
Nb1	0.03008 (19)	0.01473 (17)	0.02723 (18)	0.000	0.00566 (12)	0.000
C1	0.0333 (13)	0.0404 (14)	0.0305 (13)	0.0051 (11)	0.0051 (10)	−0.0019 (11)
C2	0.0331 (14)	0.0477 (16)	0.0425 (16)	0.0093 (11)	0.0068 (12)	0.0008 (12)
C3	0.0340 (14)	0.0412 (15)	0.0459 (15)	0.0070 (12)	−0.0009 (11)	0.0047 (13)
C4	0.0376 (14)	0.0402 (15)	0.0315 (13)	−0.0014 (11)	−0.0006 (10)	0.0080 (11)
C5	0.0323 (12)	0.0294 (12)	0.0290 (12)	−0.0057 (10)	0.0011 (9)	−0.0002 (10)
C6	0.0341 (13)	0.0326 (13)	0.0261 (12)	−0.0095 (10)	0.0043 (10)	−0.0024 (10)
C7	0.0460 (15)	0.0385 (14)	0.0317 (13)	−0.0128 (12)	0.0036 (11)	0.0010 (11)
C8	0.0579 (17)	0.0490 (17)	0.0298 (13)	−0.0174 (14)	0.0170 (12)	−0.0041 (12)
C9	0.0488 (16)	0.0435 (16)	0.0448 (15)	−0.0144 (13)	0.0252 (13)	−0.0104 (13)
C10	0.0351 (14)	0.0420 (15)	0.0435 (15)	−0.0038 (11)	0.0111 (12)	−0.0062 (12)
F1	0.0567 (10)	0.0464 (9)	0.0302 (8)	0.0028 (7)	0.0129 (7)	0.0028 (6)
F2	0.0295 (8)	0.0691 (12)	0.0539 (10)	0.0000 (7)	0.0012 (7)	−0.0072 (8)
O2	0.089 (2)	0.0160 (12)	0.0587 (19)	0.000	0.0174 (17)	0.000
N1	0.0301 (10)	0.0377 (12)	0.0249 (10)	0.0026 (9)	0.0029 (8)	−0.0003 (9)
N2	0.0328 (11)	0.0383 (12)	0.0286 (10)	−0.0020 (9)	0.0066 (8)	−0.0029 (9)
O1	0.0418 (10)	0.0704 (14)	0.0267 (9)	0.0222 (10)	0.0086 (7)	0.0059 (9)

Geometric parameters (Å, º)

Cu1—O1	1.874 (4)	C3—C4	1.398 (4)
Cu1—N1	1.888 (4)	C3—H3	0.9300
Cu1—N2	2.014 (5)	C4—C5	1.372 (4)
Cu1'—O1	1.857 (4)	C4—H4	0.9300
Cu1'—N1	1.903 (4)	C5—N1	1.371 (3)
Cu1'—N2	2.019 (5)	C5—C6	1.480 (3)
Cu1'—Cu1'^i	2.391 (8)	C6—N2	1.344 (3)
Cu1'—Cu1^i	2.3932 (10)	C6—C7	1.390 (3)
Nb1—O2	1.749 (3)	C7—C8	1.380 (4)
Nb1—F2^ii	1.9151 (16)	C7—H7	0.9300
Nb1—F2	1.9151 (16)	C8—C9	1.374 (4)
Nb1—F1^ii	1.9158 (16)	C8—H8	0.9300
Nb1—F1	1.9158 (16)	C9—C10	1.377 (4)
Nb1—O2^iii	2.185 (3)	C9—H9	0.9300
C1—O1^i	1.297 (3)	C10—N2	1.349 (3)
C1—N1	1.346 (3)	C10—H10	0.9300
C1—C2	1.418 (4)	O2—Nb1^iv	2.185 (2)
C2—C3	1.359 (4)	O1—C1^i	1.297 (3)
C2—H2	0.9300
O1—Cu1'—N1	176.5 (3)	C3—C2—H2	120.3
O1—Cu1'—N2	100.20 (19)	C1—C2—H2	120.3
N1—Cu1'—N2	83.08 (16)	C2—C3—C4	121.1 (3)
O1—Cu1'—Cu1'^i	91.2 (2)	C2—C3—H3	119.5
N1—Cu1'—Cu1'^i	85.49 (19)	C4—C3—H3	119.5
N2—Cu1'—Cu1'^i	168.6 (2)	C5—C4—C3	118.1 (2)
O1—Cu1'—Cu1^i	90.83 (14)	C5—C4—H4	121.0
N1—Cu1'—Cu1^i	85.87 (14)	C3—C4—H4	121.0
N2—Cu1'—Cu1^i	168.92 (9)	N1—C5—C4	121.2 (2)
Cu1'^i—Cu1'—Cu1^i	0.65 (19)	N1—C5—C6	114.0 (2)
O1—Cu1—N1	175.7 (3)	C4—C5—C6	124.8 (2)
O1—Cu1—N2	99.8 (2)	N2—C6—C7	121.1 (2)
N1—Cu1—N2	83.62 (19)	N2—C6—C5	114.8 (2)
O1—Cu1—Cu1'^i	90.74 (16)	C7—C6—C5	124.1 (2)
N1—Cu1—Cu1'^i	85.76 (16)	C8—C7—C6	118.6 (3)
N2—Cu1—Cu1'^i	169.30 (15)	C8—C7—H7	120.7
O1—Cu1—Cu1^i	90.3 (3)	C6—C7—H7	120.7
N1—Cu1—Cu1^i	86.1 (2)	C9—C8—C7	120.1 (2)
N2—Cu1—Cu1^i	169.6 (3)	C9—C8—H8	120.0
Cu1'^i—Cu1—Cu1^i	0.65 (19)	C7—C8—H8	120.0
O2—Nb1—F2^ii	98.22 (5)	C8—C9—C10	119.0 (3)
O2—Nb1—F2	98.22 (6)	C8—C9—H9	120.5
F2^ii—Nb1—F2	163.56 (11)	C10—C9—H9	120.5
O2—Nb1—F1^ii	96.47 (5)	N2—C10—C9	121.4 (3)
F2^ii—Nb1—F1^ii	88.91 (8)	N2—C10—H10	119.3
F2—Nb1—F1^ii	89.24 (8)	C9—C10—H10	119.3
O2—Nb1—F1	96.47 (5)	Nb1—O2—Nb1^iv	180.0
F2^ii—Nb1—F1	89.24 (8)	C1—N1—C5	121.2 (2)
F2—Nb1—F1	88.91 (8)	C1—N1—Cu1	123.3 (2)
F1^ii—Nb1—F1	167.05 (10)	C5—N1—Cu1	115.5 (2)
O2—Nb1—O2^iii	180.000 (2)	C1—N1—Cu1'	123.1 (2)
F2^ii—Nb1—O2^iii	81.78 (5)	C5—N1—Cu1'	115.6 (2)
F2—Nb1—O2^iii	81.78 (6)	C6—N2—C10	119.8 (2)
F1^ii—Nb1—O2^iii	83.53 (5)	C6—N2—Cu1	112.0 (2)
F1—Nb1—O2^iii	83.53 (5)	C10—N2—Cu1	128.2 (2)
O1^i—C1—N1	119.3 (2)	C6—N2—Cu1'	112.44 (18)
O1^i—C1—C2	121.7 (2)	C10—N2—Cu1'	127.8 (2)
N1—C1—C2	119.0 (2)	C1^i—O1—Cu1'	120.6 (2)
C3—C2—C1	119.5 (3)	C1^i—O1—Cu1	120.7 (2)

Symmetry codes: (i) −x+1/2, −y+5/2, −z+1; (ii) −x+1, y, −z+3/2; (iii) x, y+1, z; (iv) x, y−1, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···F1	0.93	2.51	3.162 (3)	127
C8—H8···F2^v	0.93	2.49	3.252 (3)	139

Symmetry code: (v) −x+1/2, y+1/2, −z+3/2.