inorganic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2414-3146

Hexa­aquadodeca-μ2-chlorido-octa­hedro-hexa­niobium diiodide

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aUniversität Rostock, Institut für Chemie, Anorganische Festkörperchemie, Albert-Einstein-Str. 3a, D-18059 Rostock, Germany
*Correspondence e-mail:

Edited by M. Bolte, Goethe-Universität Frankfurt, Germany (Received 1 June 2021; accepted 6 July 2021; online 20 July 2021)

The title compound, [Nb6Cl12(H2O)6]I2, consists of the niobium cluster cation [Nb6Cl12(H2O)6]2+ and two non-coordinating, charge-balancing iodide ions. The edges of the Nb6 octa­hedron are bridged by chlorido ligands. Each Nb atom is further coordinated by a water ligand. The cluster cation has a charge of +2, which is balanced by that of two iodide anions.

3D view (loading...)
[Scheme 3D1]
Chemical scheme
[Scheme 1]

Structure description

Cluster complexes of transition metals have been an inter­esting research area for many years (Cotton, 1964[Cotton, F. A. (1964). Inorg. Chem. 3, 1217-1220.]; Simon, 1988[Simon, A. (1988). Angew. Chem. 100, 163-188.]). Ligand-exchange reactions in solvents have opened up a wide field of new cluster compounds (Lemoine et al., 2019[Lemoine, P., Halet, J.-F. & Cordier, S. (2019). In Ligated Transition Metal Clusters in Solid-State Chemistry: The Legacy of Marcel Sergent, edited by J.-F. Halet, pp. 143-190. Berlin, Heidelberg: Springer.]), of which so far iodides have been investigated much less than chlorides.

The title compound crystallizes in the trigonal space group P[\overline{3}]1m. The asymmetric unit consists of an [NbCl2(H2O)]0.5 unit, which is located close to the Wyckoff site 1a with [\overline{3}]m symmetry, and one-sixth of an iodide ion. The Nb6 unit is a metal atom octa­hedron with an Nb—Nb bond length of 2.8960 (4) Å. The twelve μ2 bridging positions of the inner ligand sphere are occupied by chlorido ligands. An average Nb—Cl bonding length of 2.456 Å and an average Nb—Cl—Nb angle of 72.31° are present. The six positions of the outer ligand sphere are occupied by water ligands, reaching Nb—O bond lengths of 2.250 (2) Å. The structure of the cluster cation and the packing are shown in Figs. 1[link] and 2[link]. The charge of the two iodide anions are counter-balanced by that of the doubly positive charged cluster cation [Nb6Cl12(H2O)6]2+. Based on the ion ratio and Nb—Nb bond lengths of comparable structures, 16 cluster-based electrons (CBE) are present. Even though six water molecules are present per formula unit, hydrogen bonding is essentially not present in crystals of the title compound, because the large iodide anions separate the cluster units such that the shortest O⋯O distance is 4.432 (2) Å. The only weak hydrogen-type bonding contact exists between I1 and O1 with an O1—H1A⋯O1 distance of 3.501 (1) Å.

[Figure 1]
Figure 1
Perspective view of the title compound with atom labelling for the asymmetric unit. Displacement ellipsoids are shown at the 50% probability level.
[Figure 2]
Figure 2
Packing of the cluster cations and iodide anions in the crystal of the title compound.

Synthesis and crystallization

Starting from the compound [Nb6Cl12I2(H2O)4]·4H2O (Schäfer et al., 1972[Schäfer, H., Plautz, B. & Plautz, H. (1972). Z. Anorg. Allg. Chem. 392, 10-22.]; Brnicevic et al., 1981[Brnicevic, N., Kojic, B. & Plavsic, D. (1981). Z. Anorg. Allg. Chem. 472, 200-204.]), the compound [Nb6Cl12(H2O)6]I2 can be synthesized in acceptable yields.

Amounts of 100 mg (72.42 µmol) of [Nb6Cl12I2(H2O)4]·4H2O and 100 mg (667.16 µmol) of NaI were dissolved in 8 ml (444.07 mmol) of degassed water at room temperature and then filtered. The obtained dark-green solution was evaporated in a crystallizing shell for 4 d. Large black single crystals were obtained in remnants of NaI. After washing several times with acetone, 65.0 mg (48.34 µmol, yield: 65%) of [Nb6Cl12(H2O)6]I2 were obtained. The cluster compound was further characterized as follows: Elemental analysis: M [H12Cl12I2O6Nb6] = 1344.764: found H = 1.01% (calc. 0.90%); 1H NMR: (MeCN-d3 was refluxed for several hours with CaH2 and finally distilled under Schlenk conditions) (MeCN-d3, 300 MHz, 300 K, p.p.m.): δ = 2.14 (s, 12H, H2O); IR (300 K, ATR, cm−1): ν = 406 (s), 600 (s), 692 (s), 1587 (vs), 3140 (s), 3256 (s).


Crystal data, data collection and structure refinement details are summarized in Table 1[link]. Two reflections (001 and 010) were omitted from the structure refinement because their intensities were affected by the beam stop.

Table 1
Experimental details

Crystal data
Chemical formula [Nb6Cl12(H2O)6]I2
Mr 1344.76
Crystal system, space group Trigonal, P[\overline{3}]1m
Temperature (K) 123
a, c (Å) 9.3911 (8), 8.6576 (9)
V3) 661.2 (1)
Z 1
Radiation type Mo Kα
μ (mm−1) 6.08
Crystal size (mm) 0.20 × 0.20 × 0.16
Data collection
Diffractometer Bruker APEXII CCD
Absorption correction Multi-scan (SADABS; Bruker, 2017[Bruker (2017). APEX3, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.])
No. of measured, independent and observed [I > 2σ(I)] reflections 43489, 1059, 1058
Rint 0.031
(sin θ/λ)max−1) 0.806
R[F2 > 2σ(F2)], wR(F2), S 0.013, 0.034, 1.38
No. of reflections 1059
No. of parameters 27
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 0.72, −0.81
Computer programs: APEX3 and SAINT (Bruker, 2017[Bruker (2017). APEX3, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS2014 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]), SHELXL2014 (Sheldrick, 2015[Sheldrick, G. M. (2015). Acta Cryst. C71, 3-8.]), DIAMOND (Brandenburg & Putz, 2019[Brandenburg, K. & Putz, H. (2019). DIAMOND. Crystal Impact GbR, Bonn, Germany.]) and publCIF (Westrip, 2010[Westrip, S. P. (2010). J. Appl. Cryst. 43, 920-925.]).

Structural data

Computing details top

Data collection: APEX3 (Bruker, 2017); cell refinement: SAINT (Bruker, 2017); data reduction: SAINT (Bruker, 2017); program(s) used to solve structure: SHELXS2014 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg & Putz, 2019); software used to prepare material for publication: publCIF (Westrip, 2010).

Hexaaquadodeca-µ2-chlorido-octahedro-hexaniobium diiodide top
Crystal data top
[Nb6Cl12(H2O)6]I2Dx = 3.377 Mg m3
Mr = 1344.76Mo Kα radiation, λ = 0.71073 Å
Trigonal, P31mCell parameters from 9268 reflections
a = 9.3911 (8) Åθ = 2.5–34.9°
c = 8.6576 (9) ŵ = 6.08 mm1
V = 661.2 (1) Å3T = 123 K
Z = 1Block, black
F(000) = 6160.20 × 0.20 × 0.16 mm
Data collection top
1058 reflections with I > 2σ(I)
Radiation source: microfocus sealed tubeRint = 0.031
φ and ω scansθmax = 35.0°, θmin = 3.4°
Absorption correction: multi-scan
(SADABS, Bruker, 2017)
h = 1515
k = 1515
43489 measured reflectionsl = 1313
1059 independent reflections
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.013H-atom parameters constrained
wR(F2) = 0.034 w = 1/[σ2(Fo2) + (0.005P)2 + 1.1433P]
where P = (Fo2 + 2Fc2)/3
S = 1.38(Δ/σ)max < 0.001
1059 reflectionsΔρmax = 0.72 e Å3
27 parametersΔρmin = 0.81 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0071 (3)
Special details top

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. The H atom was located in a difference maps, but refined using a riding model with O—H = 0.85 Å and with U(H) = 1.5 Ueq(O).

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
Nb10.00000.17816 (2)0.13652 (2)0.00709 (5)
Cl10.21059 (3)0.21059 (3)0.00000.01203 (9)
Cl20.21271 (6)0.21271 (6)0.32300 (6)0.01238 (9)
O10.00000.3770 (2)0.2816 (2)0.0167 (3)
I10.3333330.6666670.50000.01368 (6)
Atomic displacement parameters (Å2) top
Nb10.00681 (8)0.00640 (6)0.00821 (8)0.00340 (4)0.000.00114 (4)
Cl10.0111 (1)0.0111 (1)0.0173 (2)0.0082 (2)0.0021 (1)0.0021 (1)
Cl20.0136 (2)0.0136 (2)0.0106 (2)0.0072 (2)0.0044 (1)0.0044 (1)
O10.0135 (7)0.0154 (5)0.0205 (7)0.0067 (3)0.000.0085 (5)
I10.01186 (7)0.01186 (7)0.0173 (1)0.00593 (4)0.000.00
Geometric parameters (Å, º) top
Nb1—O12.250 (2)Nb1—Nb1i2.8960 (4)
Nb1—Cl12.4502 (4)Nb1—Nb1ii2.8980 (4)
Nb1—Cl1i2.4502 (4)Nb1—Nb1iv2.8980 (4)
Nb1—Cl2ii2.4605 (4)Cl1—Nb1iii2.4501 (4)
Nb1—Cl22.4605 (4)Cl2—Nb1iv2.4605 (4)
Nb1—Nb1iii2.8960 (4)O1—H1A0.8500
O1—Nb1—Cl180.29 (4)Nb1iii—Nb1—Nb1i60.04 (1)
O1—Nb1—Cl1i80.28 (4)O1—Nb1—Nb1ii135.94 (3)
Cl1—Nb1—Cl1i88.699 (7)Cl1—Nb1—Nb1ii96.180 (6)
O1—Nb1—Cl2ii82.02 (4)Cl1i—Nb1—Nb1ii143.773 (8)
Cl1—Nb1—Cl2ii88.26 (1)Cl2ii—Nb1—Nb1ii53.922 (8)
Cl1i—Nb1—Cl2ii162.30 (1)Cl2—Nb1—Nb1ii96.56 (1)
O1—Nb1—Cl282.02 (4)Nb1iii—Nb1—Nb1ii59.977 (5)
Cl1—Nb1—Cl2162.30 (1)Nb1i—Nb1—Nb1ii90.0
Cl1i—Nb1—Cl288.26 (1)O1—Nb1—Nb1iv135.94 (3)
Cl2ii—Nb1—Cl289.35 (3)Cl1—Nb1—Nb1iv143.773 (8)
O1—Nb1—Nb1iii134.05 (4)Cl1i—Nb1—Nb1iv96.180 (6)
Cl1—Nb1—Nb1iii53.773 (8)Cl2ii—Nb1—Nb1iv96.56 (1)
Cl1i—Nb1—Nb1iii96.23 (1)Cl2—Nb1—Nb1iv53.922 (8)
Cl2ii—Nb1—Nb1iii96.00 (1)Nb1iii—Nb1—Nb1iv90.0
Cl2—Nb1—Nb1iii143.919 (8)Nb1i—Nb1—Nb1iv59.977 (5)
O1—Nb1—Nb1i134.05 (4)Nb1ii—Nb1—Nb1iv60.0
Cl1—Nb1—Nb1i96.23 (1)Nb1iii—Cl1—Nb172.45 (2)
Cl1i—Nb1—Nb1i53.773 (8)Nb1—Cl2—Nb1iv72.16 (2)
Cl2ii—Nb1—Nb1i143.919 (8)Nb1—O1—H1A122.0
Cl2—Nb1—Nb1i96.01 (1)
Symmetry codes: (i) y, x+y, z; (ii) y, xy, z; (iii) xy, x, z; (iv) x+y, x, z.


We gratefully acknowledge the maintenance of the XRD equipment through Dr Alexander Villinger (University of Rostock).

Funding information

Funding for this research was provided by: Deutsche Forschungsgemeinschaft (grant No. KO1616-8 to MK).


First citationBrandenburg, K. & Putz, H. (2019). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBrnicevic, N., Kojic, B. & Plavsic, D. (1981). Z. Anorg. Allg. Chem. 472, 200–204.  CAS Google Scholar
First citationBruker (2017). APEX3, SADABS and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCotton, F. A. (1964). Inorg. Chem. 3, 1217–1220.  CrossRef CAS Web of Science Google Scholar
First citationLemoine, P., Halet, J.-F. & Cordier, S. (2019). In Ligated Transition Metal Clusters in Solid-State Chemistry: The Legacy of Marcel Sergent, edited by J.-F. Halet, pp. 143–190. Berlin, Heidelberg: Springer.  Google Scholar
First citationSchäfer, H., Plautz, B. & Plautz, H. (1972). Z. Anorg. Allg. Chem. 392, 10–22.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSheldrick, G. M. (2015). Acta Cryst. C71, 3–8.  Web of Science CrossRef IUCr Journals Google Scholar
First citationSimon, A. (1988). Angew. Chem. 100, 163–188.  CrossRef CAS Google Scholar
First citationWestrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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