[{Cp₂(^tBuSe)Nb}₂E] (E = O and Se) with bridging oxide or selenide ligands

The title compounds, μ-oxido-bis­[(tert-butyl­seleno­lato)bis­(η⁵-cyclo­penta­dien­yl)niobium(IV)] toluene solvate, [Nb₂(C₅H₅)₄(C₄H₉Se)₂O]·C₇H₈, and μ-selenido-bis­[(tert-butyl­selenol­ato)bis­(η⁵-cyclo­penta­dien­yl)niobium(IV)], [Nb₂(C₅H₅)₄(C₄H₉Se)₂Se], consist of niobium(IV) centres each bonded to two η⁵-coordinated cyclo­penta­dienyl groups and one tert-butyl­seleno­late ligand and are the first organometallic niobium seleno­lates to be structurally characterized. A bridging oxide or selenide completes the niobium coordination spheres of the discrete dinuclear mol­ecules. In the oxide, the O atom lies on an inversion centre, resulting in a linear Nb—O—Nb linkage, whereas the selenide has a bent bridging group [Nb—Se—Nb = 139.76 (2)°]. The difference is attributable to strong π bonding in the oxide case, although the effects on the Nb—C and Nb—Se^tBu bond lengths are small.

S1. Comment

Thiolate ligands (RS^-) form complexes with most metals and metalloids. Much less is known about the corresponding compounds with the heavier chalcogens, the selenolates (RSe^-) and tellurolates (RTe^-) (Arnold, 1995). Current interest in selenolates derives from the observation that they can be useful precursors in the synthesis of metal selenide materials by chemical vapour deposition (CVD). The early transition metal diselenides adopt layered CdI₂-type structures with various stacking sequences and are potential sensor and photovoltaic materials, as well as being useful solid lubricants. NbSe₂ is a low-dimensional superconductor (Frindt, 1972) and has previously been deposited under CVD conditions from NbCl₅ and ^tBu₂Se (Boscher et al., 2006). [(η⁵-Cp)₂M(Se^tBu)₂] complexes (M = Ti, Zr or Hf) were recently shown to deposit MSe₂ films by CVD (Hector et al., 2008). The title compounds were derived from attempts to crystallize the very air-sensitive [(η⁵-Cp)₂Nb(Se^tBu)₂] complex for use in the CVD of NbSe₂.

Only two niobium selenolates have been structurally characterized to date. These are the [Se₃Nb(Se^tBu)]^- anion (Lorenz & Fenske, 2001) and a copper–niobium cluster, [{Et₃PCu(µ-SePh)₃}₂Nb] (Feuerhake & Fenske, 2003). [(η⁵-Cp)₂Nb(SePh)₂] (Sato & Yoshida, 1975) and [Nb(SePh)₃] (Andrä, 1970) have also been reported but without structural characterization.

Blue crystals of the title compounds were isolated from solutions of [(η⁵-Cp)₂Nb(Se^tBu)₂], presumably as minor by-product phases due to hydrolysis by trace water or condensation of two of the selenolate groups with elimination of ^tBu₂Se. Crystals of [{(η⁵-Cp)₂(Se^tBu)Nb}₂(µ-O)].C₇H₈, (I), are needle-shaped [From the Co-Editor: A needle has one dimension >> the other two, so may not be appropriate?], whereas those of [{(η⁵-Cp)₂(Se^tBu)Nb}₂(µ-Se)], (II), are blocks. The discrete molecules are bimetallic, with oxide or selenide bridges between the two Nb atoms. The remainder of the Nb coordination environment shows a typical metallocene geometry, each with two η⁵-coordinated Cp rings and one tert-butylselenolate group. The Nb—C distances are in the ranges 2.403 (2)–2.487 (2) Å in (I) and 2.387 (5)–2.477 (4) Å in (II). The C—C distances are normal and similar to those observed in bis(η⁵-Cp) selenolates of zirconium and hafnium (Hector et al., 2008).

The most striking difference between the structures of (I) and (II) is the geometry of the bridging atom between the two Nb centres. The oxide in (I) forms a linear Nb—O—Nb linkage, whereas the corresponding angle in the selenide in (II) is markedly bent [139.76 (2)°]. This difference can be attributed to a high level of π(O)—Nb bonding in the oxide case that is not present with selenide (i.e. in simple terms the selenide has a stereochemically active lone pair). In [{(η⁵-Cp)₂(SeMe)Zr}₂(µ-O)], the Zr—O—Zr angle is 173.92 (9)° (Hector et al., 2008).

The selenolate Nb—Se distance in (I) [2.6307 (4) Å] is shorter than those in [{(η⁵-Cp)₂(SeMe)Zr}₂(µ-O)] [2.6645 (5)/2.6689 (5) Å] by the amount expected from the ionic radii of Nb⁴⁺ and Zr⁴⁺ (Shannon, 1976). In (II) this distance is longer [2.6630 (11)/2.6326 (11) Å], reflecting the strong π-donation from the bridging oxide. The Nb—Se—C angles of 115.38 (6)° (I) and 115.22 (14)/117.06 (14)° (II) are wider than those observed in [{(η⁵-Cp)₂(SeMe)Zr}₂(µ-O)] [103.71 (6)/104.31 (7)°] or [(η⁵-Cp)₂Hf(SeMe)₂] [105.37 (15)°], as expected due to the steric bulk of the tert-butyl groups, but not as wide as in [(η⁵-Cp)₂Zr(Se^tBu)₂] [127.4 (3)°], where two tert-butylselenolate groups are in close proximity.

From the Co-Editor: In (II) there is a very short intermolecular H12···H12 contact of only 2.08 Å - please check.

Related literature

For related literature, see: Andrä (1970); Arnold (1995); Boscher et al. (2006); Feuerhake & Fenske (2003); Frindt (1972); Hector et al. (2008); Lorenz & Fenske (2001); Sato & Yoshida (1975); Shannon (1976).

S2. Experimental

LiSe^tBu was produced by dissolving ^tBuLi [Quantity?] and Se powder [Quantity?] in tetrahydrofuran–pentane [Ratio of solvents? Volume?]. LiSe^tBu (10 mmol) was added to a suspension of [Cp₂NbCl₂] (1.0 g, 3.52 mmol) in toluene (20 ml) and the mixture stirred for 2 h. The solvent was removed at reduced pressure and the resulting dark-blue solid extracted with Et₂O and then filtered through Celite. The solvent volume was reduced to ca 10 ml and dark-blue crystals of (II) were isolated by decantation (yield 147 mg). Attempts to crystallize further material from the cold supernatant solutions resulted in crystals of (I).

S3. Refinement

H atoms were placed in calculated positions, with C—H = 0.95 (Cp) or 0.98 Å (methyl). U_iso(H) values for methyl H atoms were set at 1.5U_eq(C) and the rest at 1.2U_eq(C). For (I), the disordered toluene solvent was modelled as two overlapping orientations related by a centre of symmetry.

From the Co-Editor: The methyl H atoms in toluene cannot be placed in calculated positions: they must be located in a difference Fourier synthesis and refined as part of a rigid rotating group. From the Co-Editor: Please supply a complete file of structure factors for (II).

Computing details

For both compounds, data collection: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); cell refinement: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); data reduction: COLLECT (Nonius, 1998) and DENZO (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures

Fig. 1. The discrete centrosymmetric molecule of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity. [Symmetry code: (a) 2 - x, - y, 2 - z.] [From the Co-Editor: You need to mention the omission of the toluene solvent molecule. More generally, ensure that you use "(I)" consistently to identify the solvate throughout the text.]

Fig. 2. The discrete molecule of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms have been omitted for clarity.

(I) µ-oxido-bis[(tert-butylselenolato)bis(η⁵-cyclopentadienyl)niobium(IV)] toluene solvate

Crystal data

[Nb2(C5H5)4(C4H9Se)2O]·C7H8	F(000) = 828
Mr = 826.46	Dx = 1.689 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 24097 reflections
a = 8.0288 (10) Å	θ = 2.9–27.5°
b = 12.7685 (15) Å	µ = 2.97 mm^−1
c = 15.873 (2) Å	T = 120 K
β = 92.848 (6)°	Needle, blue
V = 1625.3 (3) Å^3	0.14 × 0.06 × 0.02 mm
Z = 2

Data collection

Bruker Nonius 95mm CCD camera on κ-goniostat diffractometer	3729 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	3323 reflections with I > 2σ(I)
10cm confocal mirrors monochromator	Rint = 0.030
ϕ and ω scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2007)	h = −8→10
Tmin = 0.731, Tmax = 0.940	k = −16→16
21963 measured reflections	l = −20→18

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)] = 0.024	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.051	H-atom parameters constrained
S = 1.17	w = 1/[σ^2(Fo^2) + (0.0086P)^2 + 1.6817P] where P = (Fo^2 + 2Fc^2)/3
3729 reflections	(Δ/σ)max = 0.001
206 parameters	Δρmax = 0.44 e Å^−3
0 restraints	Δρmin = −0.57 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	Occ. (<1)
Nb1	0.86675 (2)	0.045165 (15)	0.902140 (12)	0.01596 (6)
Se1	1.16711 (3)	0.088095 (17)	0.852676 (13)	0.01894 (6)
O1	1.0000	0.0000	1.0000	0.0175 (4)
C1	0.8267 (3)	0.23334 (18)	0.88319 (15)	0.0280 (5)
H1	0.8904	0.2699	0.8438	0.034*
C2	0.6699 (3)	0.1887 (2)	0.86687 (16)	0.0332 (6)
H2	0.6077	0.1900	0.8144	0.040*
C3	0.6197 (3)	0.14135 (19)	0.94186 (17)	0.0311 (6)
H3	0.5183	0.1045	0.9483	0.037*
C4	0.7445 (3)	0.15800 (18)	1.00495 (15)	0.0245 (5)
H4	0.7426	0.1354	1.0619	0.029*
C5	0.8736 (3)	0.21437 (17)	0.96879 (14)	0.0217 (5)
H5	0.9748	0.2360	0.9971	0.026*
C6	0.7174 (3)	−0.03132 (19)	0.77639 (15)	0.0265 (5)
H6	0.6745	0.0126	0.7321	0.032*
C7	0.6332 (3)	−0.06054 (19)	0.84833 (16)	0.0280 (5)
H7	0.5233	−0.0402	0.8610	0.034*
C8	0.7408 (3)	−0.12557 (18)	0.89862 (15)	0.0267 (5)
H8	0.7168	−0.1563	0.9512	0.032*
C9	0.8900 (3)	−0.13632 (17)	0.85629 (14)	0.0235 (5)
H9	0.9844	−0.1762	0.8754	0.028*
C10	0.8760 (3)	−0.07818 (18)	0.78117 (14)	0.0229 (5)
H10	0.9589	−0.0717	0.7408	0.028*
C11	1.1745 (3)	0.16368 (18)	0.74104 (14)	0.0219 (5)
C12	1.3076 (3)	0.1089 (2)	0.69162 (15)	0.0300 (5)
H12A	1.2755	0.0357	0.6819	0.045*
H12B	1.4147	0.1117	0.7239	0.045*
H12C	1.3179	0.1442	0.6373	0.045*
C13	1.0094 (3)	0.16079 (19)	0.68959 (14)	0.0256 (5)
H13A	0.9226	0.1939	0.7217	0.038*
H13B	0.9786	0.0879	0.6774	0.038*
H13C	1.0208	0.1987	0.6365	0.038*
C14	1.2255 (3)	0.27681 (19)	0.75989 (15)	0.0284 (5)
H14A	1.2388	0.3143	0.7068	0.043*
H14B	1.3314	0.2776	0.7934	0.043*
H14C	1.1391	0.3111	0.7916	0.043*
C15	0.930 (3)	−0.073 (3)	0.540 (2)	0.038 (3)	0.50
H15	0.9500	−0.1398	0.5652	0.046*	0.50
C16	0.7745 (8)	−0.0246 (4)	0.5405 (4)	0.0386 (13)	0.50
H16	0.6845	−0.0594	0.5652	0.046*	0.50
C17	0.750 (5)	0.069 (3)	0.507 (2)	0.0479 (19)	0.50
H17	0.6428	0.1000	0.5090	0.058*	0.50
C18	0.8708 (9)	0.1250 (4)	0.4686 (3)	0.0435 (15)	0.50
H18	0.8506	0.1920	0.4442	0.052*	0.50
C15A	1.028 (3)	0.075 (3)	0.4684 (19)	0.038 (3)	0.50
H15A	1.1166	0.1110	0.4432	0.046*	0.50
C19	1.0579 (7)	−0.0164 (4)	0.5009 (3)	0.0360 (13)	0.50
C17A	1.239 (5)	−0.069 (3)	0.499 (3)	0.0479 (19)	0.50
H17A	1.2603	−0.1101	0.5510	0.072*	0.50
H17B	1.3236	−0.0145	0.4958	0.072*	0.50
H17C	1.2430	−0.1155	0.4502	0.072*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nb1	0.01481 (10)	0.01642 (10)	0.01657 (10)	0.00070 (7)	−0.00005 (7)	−0.00092 (7)
Se1	0.01581 (11)	0.02261 (12)	0.01830 (11)	−0.00004 (9)	−0.00005 (8)	0.00289 (8)
O1	0.0135 (10)	0.0206 (11)	0.0184 (10)	−0.0021 (9)	0.0021 (8)	0.0019 (8)
C1	0.0378 (14)	0.0204 (11)	0.0262 (12)	0.0093 (10)	0.0053 (10)	0.0011 (9)
C2	0.0350 (14)	0.0297 (13)	0.0334 (14)	0.0178 (11)	−0.0138 (11)	−0.0106 (11)
C3	0.0166 (11)	0.0261 (12)	0.0509 (16)	0.0053 (10)	0.0041 (10)	−0.0116 (11)
C4	0.0251 (12)	0.0228 (11)	0.0262 (12)	0.0032 (10)	0.0058 (9)	−0.0021 (9)
C5	0.0230 (11)	0.0167 (10)	0.0253 (12)	0.0053 (9)	−0.0003 (9)	−0.0037 (9)
C6	0.0286 (13)	0.0255 (12)	0.0244 (12)	0.0019 (10)	−0.0073 (10)	−0.0063 (9)
C7	0.0188 (11)	0.0286 (12)	0.0364 (14)	−0.0055 (10)	−0.0001 (10)	−0.0120 (10)
C8	0.0318 (13)	0.0218 (11)	0.0267 (12)	−0.0100 (10)	0.0020 (10)	−0.0030 (9)
C9	0.0260 (12)	0.0186 (11)	0.0255 (12)	0.0014 (10)	−0.0033 (9)	−0.0051 (9)
C10	0.0238 (12)	0.0240 (11)	0.0209 (11)	−0.0012 (9)	0.0002 (9)	−0.0078 (9)
C11	0.0223 (11)	0.0253 (12)	0.0183 (11)	−0.0015 (9)	0.0020 (8)	0.0028 (9)
C12	0.0294 (13)	0.0371 (14)	0.0242 (12)	0.0032 (11)	0.0068 (10)	0.0016 (10)
C13	0.0262 (12)	0.0300 (13)	0.0203 (11)	0.0007 (10)	−0.0012 (9)	0.0047 (9)
C14	0.0328 (13)	0.0255 (12)	0.0268 (12)	−0.0040 (11)	0.0010 (10)	0.0047 (10)
C15	0.059 (10)	0.036 (2)	0.021 (5)	−0.023 (8)	0.008 (6)	0.001 (3)
C16	0.048 (3)	0.032 (3)	0.035 (3)	−0.009 (3)	0.005 (3)	−0.004 (2)
C17	0.060 (4)	0.0447 (18)	0.039 (4)	−0.005 (3)	−0.005 (3)	−0.009 (2)
C18	0.071 (4)	0.028 (3)	0.030 (3)	−0.014 (3)	−0.011 (3)	0.001 (2)
C15A	0.059 (10)	0.036 (2)	0.021 (5)	−0.023 (8)	0.008 (6)	0.001 (3)
C19	0.051 (4)	0.032 (3)	0.024 (2)	−0.012 (3)	0.000 (3)	−0.007 (2)
C17A	0.060 (4)	0.0447 (18)	0.039 (4)	−0.005 (3)	−0.005 (3)	−0.009 (2)

Geometric parameters (Å, º)

Nb1—O1	1.9300 (3)	C7—H7	0.9500
Nb1—Se1	2.6307 (4)	C8—C9	1.409 (3)
Se1—C11	2.021 (2)	C8—H8	0.9500
C11—C12	1.526 (3)	C9—C10	1.404 (3)
C11—C13	1.523 (3)	C9—H9	0.9500
C11—C14	1.527 (3)	C10—H10	0.9500
Nb1—C8	2.403 (2)	C12—H12A	0.9800
Nb1—C5	2.405 (2)	C12—H12B	0.9800
Nb1—C4	2.421 (2)	C12—H12C	0.9800
Nb1—C7	2.431 (2)	C13—H13A	0.9800
Nb1—C9	2.439 (2)	C13—H13B	0.9800
Nb1—C1	2.441 (2)	C13—H13C	0.9800
Nb1—C3	2.442 (2)	C14—H14A	0.9800
Nb1—C2	2.466 (2)	C14—H14B	0.9800
Nb1—C6	2.477 (2)	C14—H14C	0.9800
Nb1—C10	2.487 (2)	C15—C16	1.40 (3)
O1—Nb1^i	1.9300 (3)	C15—C19	1.42 (3)
C1—C2	1.394 (4)	C15—H15	0.9500
C1—C5	1.413 (3)	C16—C17	1.33 (4)
C1—H1	0.9500	C16—H16	0.9500
C2—C3	1.412 (4)	C17—C18	1.36 (4)
C2—H2	0.9500	C17—H17	0.9500
C3—C4	1.398 (3)	C18—C15A	1.41 (3)
C3—H3	0.9500	C18—H18	0.9500
C4—C5	1.407 (3)	C15A—C19	1.30 (4)
C4—H4	0.9500	C15A—H15A	0.9500
C5—H5	0.9500	C19—C17A	1.60 (4)
C6—C10	1.405 (3)	C17A—H17A	0.9800
C6—C7	1.406 (4)	C17A—H17B	0.9800
C6—H6	0.9500	C17A—H17C	0.9800
C7—C8	1.416 (3)
Nb1—O1—Nb1^i	180	Nb1—C3—H3	119.3
O1—Nb1—Se1	79.791 (11)	C3—C4—C5	107.6 (2)
C11—Se1—Nb1	115.38 (6)	C3—C4—Nb1	74.15 (14)
O1—Nb1—C8	87.90 (6)	C5—C4—Nb1	72.43 (13)
O1—Nb1—C5	85.11 (5)	C3—C4—H4	126.2
C8—Nb1—C5	145.65 (8)	C5—C4—H4	126.2
O1—Nb1—C4	82.08 (6)	Nb1—C4—H4	119.1
C8—Nb1—C4	111.80 (8)	C4—C5—C1	108.3 (2)
C5—Nb1—C4	33.90 (8)	C4—C5—Nb1	73.67 (13)
O1—Nb1—C7	120.27 (6)	C1—C5—Nb1	74.44 (13)
C8—Nb1—C7	34.06 (8)	C4—C5—H5	125.9
C5—Nb1—C7	130.82 (8)	C1—C5—H5	125.9
C4—Nb1—C7	103.64 (8)	Nb1—C5—H5	118.0
O1—Nb1—C9	84.76 (5)	C10—C6—C7	108.3 (2)
C8—Nb1—C9	33.84 (8)	C10—C6—Nb1	73.95 (13)
C5—Nb1—C9	169.87 (8)	C7—C6—Nb1	71.54 (13)
C4—Nb1—C9	143.73 (8)	C10—C6—H6	125.8
C7—Nb1—C9	55.72 (8)	C7—C6—H6	125.8
O1—Nb1—C1	117.24 (6)	Nb1—C6—H6	120.4
C8—Nb1—C1	146.88 (9)	C6—C7—C8	108.0 (2)
C5—Nb1—C1	33.89 (8)	C6—C7—Nb1	75.18 (13)
C4—Nb1—C1	56.07 (8)	C8—C7—Nb1	71.87 (13)
C7—Nb1—C1	114.11 (9)	C6—C7—H7	126.0
C9—Nb1—C1	155.52 (8)	C8—C7—H7	126.0
O1—Nb1—C3	111.55 (7)	Nb1—C7—H7	118.8
C8—Nb1—C3	96.66 (9)	C9—C8—C7	107.3 (2)
C5—Nb1—C3	55.65 (8)	C9—C8—Nb1	74.49 (13)
C4—Nb1—C3	33.40 (8)	C7—C8—Nb1	74.06 (13)
C7—Nb1—C3	75.38 (8)	C9—C8—H8	126.3
C9—Nb1—C3	129.06 (8)	C7—C8—H8	126.3
C1—Nb1—C3	55.46 (9)	Nb1—C8—H8	117.2
O1—Nb1—C2	136.73 (6)	C10—C9—C8	108.6 (2)
C8—Nb1—C2	113.89 (9)	C10—C9—Nb1	75.35 (13)
C5—Nb1—C2	55.43 (8)	C8—C9—Nb1	71.67 (13)
C4—Nb1—C2	55.54 (8)	C10—C9—H9	125.7
C7—Nb1—C2	81.87 (9)	C8—C9—H9	125.7
C9—Nb1—C2	134.12 (8)	Nb1—C9—H9	119.1
C1—Nb1—C2	32.99 (9)	C9—C10—C6	107.8 (2)
C3—Nb1—C2	33.43 (9)	C9—C10—Nb1	71.55 (13)
O1—Nb1—C6	139.23 (6)	C6—C10—Nb1	73.17 (13)
C8—Nb1—C6	55.76 (8)	C9—C10—H10	126.1
C5—Nb1—C6	135.08 (8)	C6—C10—H10	126.1
C4—Nb1—C6	125.57 (8)	Nb1—C10—H10	120.9
C7—Nb1—C6	33.28 (9)	C13—C11—C12	109.04 (19)
C9—Nb1—C6	54.98 (8)	C13—C11—C14	110.22 (19)
C1—Nb1—C6	103.48 (8)	C12—C11—C14	110.3 (2)
C3—Nb1—C6	92.27 (8)	C13—C11—Se1	113.31 (15)
C2—Nb1—C6	80.28 (8)	C12—C11—Se1	106.49 (15)
O1—Nb1—C10	113.30 (5)	C14—C11—Se1	107.41 (15)
C8—Nb1—C10	55.68 (8)	C11—C12—H12A	109.5
C5—Nb1—C10	155.16 (8)	C11—C12—H12B	109.5
C4—Nb1—C10	157.79 (8)	H12A—C12—H12B	109.5
C7—Nb1—C10	55.20 (8)	C11—C12—H12C	109.5
C9—Nb1—C10	33.11 (8)	H12A—C12—H12C	109.5
C1—Nb1—C10	122.47 (8)	H12B—C12—H12C	109.5
C3—Nb1—C10	124.99 (8)	C11—C13—H13A	109.5
C2—Nb1—C10	109.80 (8)	C11—C13—H13B	109.5
C6—Nb1—C10	32.88 (8)	H13A—C13—H13B	109.5
C8—Nb1—Se1	124.97 (6)	C11—C13—H13C	109.5
C5—Nb1—Se1	86.73 (6)	H13A—C13—H13C	109.5
C4—Nb1—Se1	119.04 (6)	H13B—C13—H13C	109.5
C7—Nb1—Se1	135.52 (6)	C11—C14—H14A	109.5
C9—Nb1—Se1	91.37 (6)	C11—C14—H14B	109.5
C1—Nb1—Se1	82.84 (6)	H14A—C14—H14B	109.5
C3—Nb1—Se1	137.78 (6)	C11—C14—H14C	109.5
C2—Nb1—Se1	111.34 (7)	H14A—C14—H14C	109.5
C6—Nb1—Se1	104.82 (6)	H14B—C14—H14C	109.5
C10—Nb1—Se1	80.71 (6)	C16—C15—C19	116 (3)
C2—C1—C5	107.7 (2)	C16—C15—H15	121.9
C2—C1—Nb1	74.50 (14)	C19—C15—H15	121.9
C5—C1—Nb1	71.67 (13)	C17—C16—C15	121 (2)
C2—C1—H1	126.2	C17—C16—H16	119.6
C5—C1—H1	126.2	C15—C16—H16	119.6
Nb1—C1—H1	119.5	C16—C17—C18	124 (3)
C1—C2—C3	108.2 (2)	C16—C17—H17	118.0
C1—C2—Nb1	72.50 (13)	C18—C17—H17	118.0
C3—C2—Nb1	72.36 (13)	C17—C18—C15A	115 (2)
C1—C2—H2	125.9	C17—C18—H18	122.5
C3—C2—H2	125.9	C15A—C18—H18	122.5
Nb1—C2—H2	121.0	C19—C15A—C18	123.5 (19)
C4—C3—C2	108.3 (2)	C19—C15A—H15A	118.2
C4—C3—Nb1	72.46 (13)	C18—C15A—H15A	118.2
C2—C3—Nb1	74.21 (14)	C15A—C19—C15	120.7 (19)
C4—C3—H3	125.8	C15A—C19—C17A	121.6 (18)
C2—C3—H3	125.8	C15—C19—C17A	118 (2)

Symmetry code: (i) −x+2, −y, −z+2.

(II) µ-selenido-bis[(tert-butylselenolato)bis(η⁵-cyclopentadienyl)niobium(IV)]

Crystal data

[Nb2(C5H5)4(C4H9Se)2Se]	F(000) = 3120
Mr = 797.28	Dx = 1.860 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 10429 reflections
a = 31.583 (8) Å	θ = 2.9–27.5°
b = 7.9548 (15) Å	µ = 4.66 mm^−1
c = 26.520 (7) Å	T = 120 K
β = 121.29 (2)°	Block, blue
V = 5694 (3) Å^3	0.12 × 0.09 × 0.06 mm
Z = 8

Data collection

Bruker Nonius 95mm CCD camera on κ-goniostat diffractometer	6538 independent reflections
Radiation source: Bruker Nonius FR591 rotating anode	4694 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.083
ϕ and ω scans	θmax = 27.6°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 2007)	h = −40→40
Tmin = 0.514, Tmax = 0.756	k = −10→10
31432 measured reflections	l = −34→34

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.075	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0168P)^2 + 15.270P] where P = (Fo^2 + 2Fc^2)/3
6538 reflections	(Δ/σ)max = 0.001
298 parameters	Δρmax = 0.79 e Å^−3
1 restraint	Δρmin = −0.82 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
Nb1	0.063734 (15)	0.52132 (5)	0.144254 (19)	0.01341 (10)
Nb2	0.198133 (15)	0.32688 (5)	0.125843 (18)	0.01238 (10)
Se1	0.134400 (17)	0.44206 (6)	0.25388 (2)	0.01579 (11)
Se2	0.134871 (17)	0.52506 (5)	0.12505 (2)	0.01444 (11)
Se3	0.124085 (18)	0.23327 (6)	0.02186 (2)	0.01689 (12)
C1	0.11269 (18)	0.3866 (6)	0.3112 (2)	0.0188 (11)
C2	0.16075 (19)	0.3821 (7)	0.3716 (2)	0.0288 (13)
H2A	0.1827	0.2950	0.3717	0.043*
H2B	0.1530	0.3569	0.4022	0.043*
H2C	0.1772	0.4916	0.3797	0.043*
C3	0.07857 (19)	0.5230 (6)	0.3110 (2)	0.0258 (12)
H3A	0.0478	0.5253	0.2724	0.039*
H3B	0.0951	0.6325	0.3187	0.039*
H3C	0.0710	0.4987	0.3417	0.039*
C4	0.0873 (2)	0.2148 (6)	0.2982 (2)	0.0266 (12)
H4A	0.0564	0.2179	0.2597	0.040*
H4B	0.0799	0.1876	0.3288	0.040*
H4C	0.1094	0.1289	0.2978	0.040*
C5	0.14054 (18)	0.0507 (5)	−0.0190 (2)	0.0189 (11)
C6	0.19286 (18)	−0.0164 (6)	0.0181 (2)	0.0226 (12)
H6A	0.1975	−0.0653	0.0545	0.034*
H6B	0.2165	0.0757	0.0278	0.034*
H6C	0.1984	−0.1029	−0.0042	0.034*
C7	0.1325 (2)	0.1278 (6)	−0.0755 (2)	0.0286 (13)
H7A	0.0985	0.1703	−0.0990	0.043*
H7B	0.1379	0.0422	−0.0982	0.043*
H7C	0.1558	0.2206	−0.0660	0.043*
C8	0.10316 (19)	−0.0903 (6)	−0.0334 (2)	0.0279 (13)
H8A	0.0695	−0.0456	−0.0575	0.042*
H8B	0.1077	−0.1366	0.0034	0.042*
H8C	0.1083	−0.1791	−0.0552	0.042*
C9	0.04568 (17)	0.2209 (5)	0.1467 (2)	0.0169 (11)
H9	0.0674	0.1508	0.1789	0.020*
C10	0.00674 (17)	0.3205 (5)	0.1427 (2)	0.0175 (11)
H10	−0.0017	0.3312	0.1722	0.021*
C11	−0.01703 (18)	0.4002 (6)	0.0874 (2)	0.0244 (12)
H11	−0.0449	0.4728	0.0722	0.029*
C12	0.00814 (19)	0.3526 (5)	0.0591 (2)	0.0260 (13)
H12	0.0002	0.3891	0.0210	0.031*
C13	0.04664 (19)	0.2436 (5)	0.0952 (2)	0.0217 (12)
H13	0.0694	0.1939	0.0864	0.026*
C14	0.05650 (18)	0.7993 (5)	0.1043 (2)	0.0169 (11)
H14	0.0632	0.8145	0.0735	0.020*
C15	0.09097 (18)	0.8104 (5)	0.1654 (2)	0.0165 (11)
H15	0.1253	0.8348	0.1830	0.020*
C16	0.06628 (19)	0.7796 (5)	0.1961 (2)	0.0220 (12)
H16	0.0808	0.7806	0.2377	0.026*
C17	0.0164 (2)	0.7471 (6)	0.1541 (3)	0.0258 (13)
H17	−0.0088	0.7203	0.1622	0.031*
C18	0.01032 (19)	0.7614 (6)	0.0975 (2)	0.0240 (12)
H18	−0.0199	0.7476	0.0609	0.029*
C19	0.17465 (18)	0.1478 (5)	0.1818 (2)	0.0189 (11)
H19	0.1433	0.1615	0.1781	0.023*
C20	0.21813 (18)	0.2346 (6)	0.2217 (2)	0.0187 (11)
H20	0.2214	0.3170	0.2495	0.022*
C21	0.25566 (19)	0.1768 (6)	0.2129 (2)	0.0200 (11)
H21	0.2893	0.2115	0.2345	0.024*
C22	0.23512 (17)	0.0582 (5)	0.1664 (2)	0.0169 (11)
H22	0.2521	0.0024	0.1504	0.020*
C23	0.18491 (18)	0.0382 (5)	0.1484 (2)	0.0173 (11)
H23	0.1621	−0.0365	0.1188	0.021*
C24	0.27442 (17)	0.4879 (6)	0.1641 (2)	0.0204 (11)
H24	0.2979	0.4889	0.2053	0.024*
C25	0.23515 (18)	0.5995 (6)	0.1337 (2)	0.0206 (11)
H25	0.2274	0.6910	0.1505	0.025*
C26	0.20886 (19)	0.5536 (6)	0.0736 (2)	0.0224 (12)
H26	0.1800	0.6070	0.0430	0.027*
C27	0.23307 (19)	0.4147 (6)	0.0675 (2)	0.0221 (12)
H27	0.2237	0.3582	0.0317	0.027*
C28	0.27310 (18)	0.3733 (6)	0.1229 (2)	0.0230 (12)
H28	0.2956	0.2833	0.1313	0.028*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Nb1	0.0124 (2)	0.0117 (2)	0.0151 (2)	−0.00047 (17)	0.00641 (19)	−0.00036 (17)
Nb2	0.0131 (2)	0.0117 (2)	0.0123 (2)	0.00000 (16)	0.00653 (19)	−0.00005 (17)
Se1	0.0136 (3)	0.0200 (3)	0.0144 (3)	0.00012 (19)	0.0077 (2)	0.0003 (2)
Se2	0.0157 (3)	0.0132 (2)	0.0150 (2)	0.00153 (19)	0.0084 (2)	0.00067 (19)
Se3	0.0151 (3)	0.0189 (3)	0.0128 (3)	0.0020 (2)	0.0046 (2)	−0.0016 (2)
C1	0.021 (3)	0.022 (3)	0.016 (3)	−0.002 (2)	0.012 (2)	0.001 (2)
C2	0.027 (3)	0.043 (3)	0.016 (3)	0.001 (3)	0.010 (3)	0.004 (2)
C3	0.027 (3)	0.031 (3)	0.030 (3)	−0.002 (2)	0.023 (3)	−0.004 (2)
C4	0.032 (3)	0.025 (3)	0.026 (3)	−0.003 (2)	0.018 (3)	0.004 (2)
C5	0.020 (3)	0.016 (3)	0.020 (3)	−0.001 (2)	0.010 (2)	−0.002 (2)
C6	0.025 (3)	0.022 (3)	0.020 (3)	0.001 (2)	0.011 (2)	−0.005 (2)
C7	0.031 (3)	0.037 (3)	0.016 (3)	0.006 (3)	0.011 (3)	0.000 (2)
C8	0.029 (3)	0.026 (3)	0.030 (3)	−0.007 (2)	0.017 (3)	−0.013 (2)
C9	0.019 (3)	0.009 (2)	0.022 (3)	−0.0036 (19)	0.010 (2)	−0.003 (2)
C10	0.012 (3)	0.019 (3)	0.021 (3)	−0.007 (2)	0.008 (2)	−0.004 (2)
C11	0.011 (3)	0.016 (3)	0.032 (3)	−0.007 (2)	0.001 (3)	−0.004 (2)
C12	0.033 (3)	0.020 (3)	0.014 (3)	−0.013 (2)	0.004 (3)	−0.002 (2)
C13	0.030 (3)	0.009 (2)	0.029 (3)	−0.005 (2)	0.018 (3)	−0.004 (2)
C14	0.021 (3)	0.008 (2)	0.021 (3)	0.0024 (19)	0.011 (2)	0.003 (2)
C15	0.015 (3)	0.010 (2)	0.022 (3)	−0.0010 (19)	0.008 (2)	−0.002 (2)
C16	0.031 (3)	0.011 (2)	0.026 (3)	0.002 (2)	0.016 (3)	−0.001 (2)
C17	0.027 (3)	0.014 (3)	0.050 (4)	0.002 (2)	0.030 (3)	0.003 (2)
C18	0.017 (3)	0.016 (3)	0.031 (3)	0.008 (2)	0.007 (3)	0.002 (2)
C19	0.019 (3)	0.020 (3)	0.022 (3)	0.002 (2)	0.014 (2)	0.007 (2)
C20	0.027 (3)	0.016 (2)	0.009 (2)	0.006 (2)	0.007 (2)	0.0042 (19)
C21	0.017 (3)	0.020 (3)	0.019 (3)	0.007 (2)	0.007 (2)	0.005 (2)
C22	0.017 (3)	0.013 (2)	0.021 (3)	0.008 (2)	0.010 (2)	0.004 (2)
C23	0.022 (3)	0.010 (2)	0.020 (3)	0.000 (2)	0.011 (2)	0.005 (2)
C24	0.014 (3)	0.024 (3)	0.021 (3)	−0.009 (2)	0.008 (2)	−0.002 (2)
C25	0.021 (3)	0.015 (3)	0.034 (3)	−0.008 (2)	0.020 (3)	−0.005 (2)
C26	0.023 (3)	0.021 (3)	0.024 (3)	−0.005 (2)	0.013 (3)	0.005 (2)
C27	0.030 (3)	0.020 (3)	0.028 (3)	−0.006 (2)	0.023 (3)	−0.007 (2)
C28	0.016 (3)	0.018 (3)	0.043 (3)	−0.005 (2)	0.021 (3)	−0.001 (2)

Geometric parameters (Å, º)

Nb1—Se1	2.6630 (11)	C7—H7B	0.9800
Nb1—Se2	2.5488 (9)	C7—H7C	0.9800
Nb2—Se2	2.5366 (7)	C8—H8A	0.9800
Nb2—Se3	2.6326 (11)	C8—H8B	0.9800
Se1—C1	2.014 (5)	C8—H8C	0.9800
Se3—C5	2.034 (5)	C9—C13	1.392 (6)
C1—C2	1.532 (7)	C9—C10	1.421 (6)
C1—C3	1.527 (6)	C9—H9	0.9500
C1—C4	1.530 (6)	C10—C11	1.405 (7)
C5—C6	1.515 (6)	C10—H10	0.9500
C5—C7	1.514 (6)	C11—C12	1.400 (7)
C5—C8	1.526 (6)	C11—H11	0.9500
Nb1—C11	2.390 (5)	C12—C13	1.392 (7)
Nb1—C10	2.391 (4)	C12—H12	0.9500
Nb1—C14	2.411 (4)	C13—H13	0.9500
Nb1—C15	2.417 (4)	C14—C18	1.406 (7)
Nb1—C18	2.420 (5)	C14—C15	1.409 (6)
Nb1—C12	2.422 (5)	C14—H14	0.9500
Nb1—C17	2.436 (5)	C15—C16	1.411 (7)
Nb1—C16	2.450 (5)	C15—H15	0.9500
Nb1—C9	2.465 (4)	C16—C17	1.402 (7)
Nb1—C13	2.477 (4)	C16—H16	0.9500
Nb2—C21	2.387 (5)	C17—C18	1.417 (7)
Nb2—C20	2.395 (4)	C17—H17	0.9500
Nb2—C26	2.402 (5)	C18—H18	0.9500
Nb2—C22	2.405 (4)	C19—C23	1.396 (6)
Nb2—C25	2.421 (4)	C19—C20	1.405 (6)
Nb2—C27	2.422 (5)	C19—H19	0.9500
Nb2—C19	2.434 (4)	C20—C21	1.400 (7)
Nb2—C24	2.436 (4)	C20—H20	0.9500
Nb2—C28	2.438 (5)	C21—C22	1.414 (6)
Nb2—C23	2.462 (4)	C21—H21	0.9500
C2—H2A	0.9800	C22—C23	1.408 (6)
C2—H2B	0.9800	C22—H22	0.9500
C2—H2C	0.9800	C23—H23	0.9500
C3—H3A	0.9800	C24—C25	1.392 (6)
C3—H3B	0.9800	C24—C28	1.408 (7)
C3—H3C	0.9800	C24—H24	0.9500
C4—H4A	0.9800	C25—C26	1.409 (7)
C4—H4B	0.9800	C25—H25	0.9500
C4—H4C	0.9800	C26—C27	1.400 (6)
C6—H6A	0.9800	C26—H26	0.9500
C6—H6B	0.9800	C27—C28	1.390 (7)
C6—H6C	0.9800	C27—H27	0.9500
C7—H7A	0.9800	C28—H28	0.9500
Nb2—Se2—Nb1	139.76 (2)	H3A—C3—H3B	109.5
Se2—Nb1—Se1	83.97 (3)	C1—C3—H3C	109.5
Se2—Nb2—Se3	84.24 (3)	H3A—C3—H3C	109.5
C1—Se1—Nb1	117.06 (14)	H3B—C3—H3C	109.5
C5—Se3—Nb2	115.22 (14)	C1—C4—H4A	109.5
C3—C1—Se1	111.0 (3)	C1—C4—H4B	109.5
C4—C1—Se1	111.7 (3)	H4A—C4—H4B	109.5
C2—C1—Se1	104.7 (3)	C1—C4—H4C	109.5
C6—C5—Se3	113.6 (3)	H4A—C4—H4C	109.5
C7—C5—Se3	106.3 (3)	H4B—C4—H4C	109.5
C8—C5—Se3	106.2 (3)	C6—C5—C7	110.6 (4)
C11—Nb1—C10	34.17 (16)	C6—C5—C8	110.2 (4)
C11—Nb1—C14	105.42 (17)	C7—C5—C8	109.8 (4)
C10—Nb1—C14	134.96 (16)	C5—C6—H6A	109.5
C11—Nb1—C15	131.63 (16)	C5—C6—H6B	109.5
C10—Nb1—C15	144.46 (16)	H6A—C6—H6B	109.5
C14—Nb1—C15	33.94 (15)	C5—C6—H6C	109.5
C11—Nb1—C18	76.30 (17)	H6A—C6—H6C	109.5
C10—Nb1—C18	101.55 (16)	H6B—C6—H6C	109.5
C14—Nb1—C18	33.84 (16)	C5—C7—H7A	109.5
C15—Nb1—C18	55.78 (16)	C5—C7—H7B	109.5
C11—Nb1—C12	33.83 (17)	H7A—C7—H7B	109.5
C10—Nb1—C12	55.90 (16)	C5—C7—H7C	109.5
C14—Nb1—C12	103.94 (16)	H7A—C7—H7C	109.5
C15—Nb1—C12	137.88 (16)	H7B—C7—H7C	109.5
C18—Nb1—C12	89.10 (17)	C5—C8—H8A	109.5
C11—Nb1—C17	81.44 (18)	C5—C8—H8B	109.5
C10—Nb1—C17	89.74 (16)	H8A—C8—H8B	109.5
C14—Nb1—C17	56.51 (16)	C5—C8—H8C	109.5
C15—Nb1—C17	55.83 (16)	H8A—C8—H8C	109.5
C18—Nb1—C17	33.93 (16)	H8B—C8—H8C	109.5
C12—Nb1—C17	108.69 (18)	C13—C9—C10	108.3 (4)
C11—Nb1—C16	113.89 (17)	C13—C9—Nb1	74.1 (3)
C10—Nb1—C16	112.00 (16)	C10—C9—Nb1	70.2 (2)
C14—Nb1—C16	56.34 (16)	C13—C9—H9	125.8
C15—Nb1—C16	33.70 (15)	C10—C9—H9	125.8
C18—Nb1—C16	55.74 (17)	Nb1—C9—H9	121.6
C12—Nb1—C16	141.68 (18)	C11—C10—C9	107.5 (4)
C17—Nb1—C16	33.36 (16)	C11—C10—Nb1	72.9 (3)
C11—Nb1—C9	55.96 (16)	C9—C10—Nb1	75.9 (3)
C10—Nb1—C9	33.98 (15)	C11—C10—H10	126.2
C14—Nb1—C9	158.42 (16)	C9—C10—H10	126.2
C15—Nb1—C9	167.31 (16)	Nb1—C10—H10	117.1
C18—Nb1—C9	131.99 (16)	C12—C11—C10	107.1 (4)
C12—Nb1—C9	54.66 (15)	C12—C11—Nb1	74.3 (3)
C17—Nb1—C9	123.27 (16)	C10—C11—Nb1	73.0 (3)
C16—Nb1—C9	137.65 (16)	C12—C11—H11	126.5
C11—Nb1—C13	55.90 (17)	C10—C11—H11	126.5
C10—Nb1—C13	55.85 (16)	Nb1—C11—H11	118.3
C14—Nb1—C13	129.93 (16)	C13—C12—C11	109.6 (4)
C15—Nb1—C13	157.61 (16)	C13—C12—Nb1	75.7 (3)
C18—Nb1—C13	122.05 (17)	C11—C12—Nb1	71.8 (3)
C12—Nb1—C13	33.00 (16)	C13—C12—H12	125.2
C17—Nb1—C13	137.33 (17)	C11—C12—H12	125.2
C16—Nb1—C13	167.79 (17)	Nb1—C12—H12	119.0
C9—Nb1—C13	32.73 (15)	C12—C13—C9	107.4 (5)
C11—Nb1—Se2	129.92 (13)	C12—C13—Nb1	71.3 (3)
C10—Nb1—Se2	137.60 (11)	C9—C13—Nb1	73.2 (3)
C14—Nb1—Se2	78.08 (12)	C12—C13—H13	126.3
C15—Nb1—Se2	77.91 (11)	C9—C13—H13	126.3
C18—Nb1—Se2	109.90 (13)	Nb1—C13—H13	121.0
C12—Nb1—Se2	96.18 (13)	C18—C14—C15	107.0 (4)
C17—Nb1—Se2	131.82 (12)	C18—C14—Nb1	73.4 (3)
C16—Nb1—Se2	109.07 (12)	C15—C14—Nb1	73.3 (2)
C9—Nb1—Se2	104.84 (11)	C18—C14—H14	126.5
C13—Nb1—Se2	83.10 (12)	C15—C14—H14	126.5
C11—Nb1—Se1	127.43 (13)	Nb1—C14—H14	118.8
C10—Nb1—Se1	93.27 (12)	C14—C15—C16	108.9 (4)
C14—Nb1—Se1	122.10 (11)	C14—C15—Nb1	72.8 (2)
C15—Nb1—Se1	88.66 (11)	C16—C15—Nb1	74.4 (3)
C18—Nb1—Se1	135.43 (13)	C14—C15—H15	125.5
C12—Nb1—Se1	132.65 (11)	C16—C15—H15	125.5
C17—Nb1—Se1	105.68 (14)	Nb1—C15—H15	119.0
C16—Nb1—Se1	79.71 (12)	C17—C16—C15	107.7 (5)
C9—Nb1—Se1	79.41 (11)	C17—C16—Nb1	72.8 (3)
C13—Nb1—Se1	101.11 (12)	C15—C16—Nb1	71.9 (3)
C21—Nb2—C20	34.05 (16)	C17—C16—H16	126.1
C21—Nb2—C26	131.94 (17)	C15—C16—H16	126.1
C20—Nb2—C26	143.47 (16)	Nb1—C16—H16	121.0
C21—Nb2—C22	34.31 (15)	C16—C17—C18	107.7 (4)
C20—Nb2—C22	56.88 (16)	C16—C17—Nb1	73.8 (3)
C26—Nb2—C22	138.06 (17)	C18—C17—Nb1	72.4 (3)
C21—Nb2—C25	105.89 (17)	C16—C17—H17	126.2
C20—Nb2—C25	109.51 (16)	C18—C17—H17	126.2
C26—Nb2—C25	33.97 (16)	Nb1—C17—H17	119.5
C22—Nb2—C25	131.06 (16)	C14—C18—C17	108.7 (5)
C21—Nb2—C27	113.02 (17)	C14—C18—Nb1	72.7 (3)
C20—Nb2—C27	144.07 (17)	C17—C18—Nb1	73.7 (3)
C26—Nb2—C27	33.74 (15)	C14—C18—H18	125.6
C22—Nb2—C27	105.39 (16)	C17—C18—H18	125.6
C25—Nb2—C27	55.72 (16)	Nb1—C18—H18	119.8
C21—Nb2—C19	55.78 (17)	C23—C19—C20	109.1 (4)
C20—Nb2—C19	33.82 (15)	C23—C19—Nb2	74.6 (3)
C26—Nb2—C19	165.82 (16)	C20—C19—Nb2	71.6 (3)
C22—Nb2—C19	55.81 (15)	C23—C19—H19	125.4
C25—Nb2—C19	139.33 (16)	C20—C19—H19	125.4
C27—Nb2—C19	160.37 (15)	Nb2—C19—H19	120.1
C21—Nb2—C24	76.63 (17)	C21—C20—C19	107.0 (4)
C20—Nb2—C24	93.46 (17)	C21—C20—Nb2	72.7 (3)
C26—Nb2—C24	55.97 (16)	C19—C20—Nb2	74.6 (3)
C22—Nb2—C24	97.77 (16)	C21—C20—H20	126.5
C25—Nb2—C24	33.30 (15)	C19—C20—H20	126.5
C27—Nb2—C24	55.56 (17)	Nb2—C20—H20	118.3
C19—Nb2—C24	127.04 (17)	C20—C21—C22	108.7 (4)
C21—Nb2—C28	80.95 (17)	C20—C21—Nb2	73.3 (3)
C20—Nb2—C28	110.85 (18)	C22—C21—Nb2	73.5 (3)
C26—Nb2—C28	55.78 (17)	C20—C21—H21	125.7
C22—Nb2—C28	83.96 (16)	C22—C21—H21	125.7
C25—Nb2—C28	55.48 (16)	Nb2—C21—H21	119.3
C27—Nb2—C28	33.24 (16)	C23—C22—C21	107.3 (4)
C19—Nb2—C28	135.80 (17)	C23—C22—Nb2	75.4 (2)
C24—Nb2—C28	33.58 (15)	C21—C22—Nb2	72.1 (2)
C21—Nb2—C23	55.86 (16)	C23—C22—H22	126.3
C20—Nb2—C23	56.01 (15)	C21—C22—H22	126.3
C26—Nb2—C23	158.81 (16)	Nb2—C22—H22	118.1
C22—Nb2—C23	33.59 (15)	C19—C23—C22	107.8 (4)
C25—Nb2—C23	161.75 (17)	C19—C23—Nb2	72.3 (3)
C27—Nb2—C23	127.93 (15)	C22—C23—Nb2	71.0 (2)
C19—Nb2—C23	33.11 (14)	C19—C23—H23	126.1
C24—Nb2—C23	130.15 (16)	C22—C23—H23	126.1
C28—Nb2—C23	116.05 (16)	Nb2—C23—H23	122.3
C21—Nb2—Se2	121.30 (12)	C25—C24—C28	107.7 (4)
C20—Nb2—Se2	88.37 (12)	C25—C24—Nb2	72.7 (3)
C26—Nb2—Se2	82.81 (12)	C28—C24—Nb2	73.3 (3)
C22—Nb2—Se2	138.89 (11)	C25—C24—H24	126.1
C25—Nb2—Se2	77.72 (11)	C28—C24—H24	126.1
C27—Nb2—Se2	115.69 (12)	Nb2—C24—H24	119.7
C19—Nb2—Se2	83.15 (11)	C24—C25—C26	108.3 (4)
C24—Nb2—Se2	106.32 (11)	C24—C25—Nb2	74.0 (3)
C28—Nb2—Se2	132.83 (11)	C26—C25—Nb2	72.3 (3)
C23—Nb2—Se2	110.45 (11)	C24—C25—H25	125.8
C21—Nb2—Se3	133.43 (12)	C26—C25—H25	125.8
C20—Nb2—Se3	128.80 (12)	Nb2—C25—H25	119.7
C26—Nb2—Se3	85.59 (12)	C27—C26—C25	107.4 (5)
C22—Nb2—Se3	100.27 (11)	C27—C26—Nb2	73.9 (3)
C25—Nb2—Se3	118.04 (12)	C25—C26—Nb2	73.7 (3)
C27—Nb2—Se3	82.20 (13)	C27—C26—H26	126.3
C19—Nb2—Se3	94.99 (12)	C25—C26—H26	126.3
C24—Nb2—Se3	137.17 (12)	Nb2—C26—H26	118.0
C28—Nb2—Se3	110.99 (13)	C28—C27—C26	108.5 (4)
C23—Nb2—Se3	79.64 (11)	C28—C27—Nb2	74.0 (3)
C3—C1—C4	110.3 (4)	C26—C27—Nb2	72.3 (3)
C3—C1—C2	109.5 (4)	C28—C27—H27	125.8
C4—C1—C2	109.4 (4)	C26—C27—H27	125.8
C1—C2—H2A	109.5	Nb2—C27—H27	119.7
C1—C2—H2B	109.5	C27—C28—C24	108.1 (4)
H2A—C2—H2B	109.5	C27—C28—Nb2	72.8 (3)
C1—C2—H2C	109.5	C24—C28—Nb2	73.1 (3)
H2A—C2—H2C	109.5	C27—C28—H28	126.0
H2B—C2—H2C	109.5	C24—C28—H28	126.0
C1—C3—H3A	109.5	Nb2—C28—H28	119.9
C1—C3—H3B	109.5