(η(4)-Cyclo-octa-tetra-ene)(η(8)-cyclo-octa-tetra-ene)iodido-tantalum(V).

The title complex, [Ta(η(4)-C8H8)(η(8)-C8H8)I], lies across a crystallographic mirror plane that includes the Ta(V) atom and the iodide ligand. One cyclo-octa-tetra-ene (cot) ring is η(4)-coordinating and is bis-ected by the mirror plane. The fold angle between the plane of the coordinating butadiene portion and the middle plane of the ring is 27.4 (4)°. An additional minor fold angle of 9.3 (7)° exists between the final plane in the ring and the middle plane. The other cot ring is η(8)-coordinating and is also cut by the mirror plane. In this case, the ring is disordered over the mirror plane, and one position is modeled with appropriate restraints and constraints with respect to distances, angles and displacement parameters (the second position is generated by symmetry). This ring is nearly planar, with an r.m.s. deviation of only 0.05 Å when all eight C atoms are included in the calculation. Pairs of inter-molecular η(8)-cot rings are parallel stacked and slightly off center, with a centroid-centroid distance of 3.652 Å. No other significant inter-molecular inter-actions are observed. The compound is of inter-est as the first structurally characterized mixed halogen-cot complex of the group 5 metals and contains the longest terminal Ta-I distance [3.0107 (5) Å] reported to date.

Related literature

For synthesis of the precursor tris­(naphthalene)­tantalate, see: Brennessel et al. (2002 ▶). For related MX(cot)2, M = Nb, Ta, X = Cl, Me, Ph, see: Schrock et al. (1976 ▶). For the only other structurally characterized η8-coordinated cyclo­octa­tetra­ene­tantalum species to date, (η-1,4-bis­(tri­methyl­sil­yl)cot)Me3Ta, see: Clegg & McCamley (2005 ▶). For the compound containing the previous longest terminal Ta—I distance, see: Berneri et al. (1998 ▶). For Zr(cot)2, which also contains both η4-cot and η8-cot units, see: Cloke et al. (1994 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

[Ta(C8H8)2I]

M = 516.14

Monoclinic,

a = 14.3626 (14) Å

b = 11.0200 (11) Å

c = 9.3467 (9) Å

β = 113.522 (2)°

V = 1356.4 (2) Å3

Z = 4

Mo Kα radiation

μ = 10.36 mm−1

T = 173 K

0.10 × 0.10 × 0.10 mm

Data collection

Siemens SMART CCD platform diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 2012 ▶) T min = 0.318, T max = 0.431

8110 measured reflections

1636 independent reflections

1520 reflections with I > 2σ(I)

R int = 0.020

Refinement

R[F 2 > 2σ(F 2)] = 0.017

wR(F 2) = 0.040

S = 1.08

1636 reflections

97 parameters

96 restraints

H-atom parameters constrained

Δρmax = 1.04 e Å−3

Δρmin = −0.72 e Å−3

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536814012379/lh5707sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536814012379/lh5707Isup2.hkl

CCDC reference: 1005544

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Ta(C8H8)2I]	F(000) = 952
Mr = 516.14	Dx = 2.527 Mg m−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
a = 14.3626 (14) Å	Cell parameters from 937 reflections
b = 11.0200 (11) Å	θ = 2.4–27.5°
c = 9.3467 (9) Å	µ = 10.36 mm−1
β = 113.522 (2)°	T = 173 K
V = 1356.4 (2) Å3	Block, red-purple
Z = 4	0.10 × 0.10 × 0.10 mm

Siemens SMART CCD platform diffractometer	1520 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.020
ω scans	θmax = 27.5°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2012)	h = −18→18
Tmin = 0.318, Tmax = 0.431	k = −14→14
8110 measured reflections	l = −12→12
1636 independent reflections

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.017	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.040	H-atom parameters constrained
S = 1.08	w = 1/[σ2(Fo2) + (0.018P)2 + 5.3173P] where P = (Fo2 + 2Fc2)/3
1636 reflections	(Δ/σ)max = 0.003
97 parameters	Δρmax = 1.04 e Å−3
96 restraints	Δρmin = −0.72 e Å−3

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. The η8-cot ligand is modeled as disordered over a crystallographic mirror plane (50:50). Bond lengths and angles in the η8-cot ligand were restrained to be similar to those of their neighbors. Anisotropic displacement parameters for pairs of atoms opposite to each other were constrained to be equivalent, and those of symmetry-related atom pair C11 and C12 were heavily restrained to be similar.H atoms were placed geometrically and treated as riding atoms: C—H = 0.95 Å with Uiso(H) = 1.2Ueq(C).

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ta1	0.28337 (2)	0.5000	0.16766 (2)	0.01915 (6)
I1	0.26793 (2)	0.5000	−0.16320 (4)	0.02953 (8)
C1	0.1203 (2)	0.4365 (4)	0.0278 (4)	0.0312 (8)
H1	0.1043	0.4003	−0.0715	0.037*
C2	0.1398 (3)	0.3549 (3)	0.1493 (5)	0.0356 (9)
H2	0.1770	0.2859	0.1413	0.043*
C3	0.1160 (3)	0.3522 (4)	0.2844 (5)	0.0455 (11)
H3	0.1214	0.2729	0.3271	0.055*
C4	0.0875 (3)	0.4358 (5)	0.3660 (5)	0.0531 (13)
H4	0.0626	0.4012	0.4371	0.064*
C5	0.4245 (10)	0.3628 (8)	0.2362 (15)	0.039 (3)	0.5
H5	0.4396	0.2896	0.1962	0.047*	0.5
C6	0.3753 (8)	0.3428 (9)	0.3361 (12)	0.038 (4)	0.5
H6	0.3574	0.2602	0.3398	0.046*	0.5
C7	0.3473 (7)	0.4163 (9)	0.4297 (10)	0.042 (2)	0.5
H7	0.3298	0.3703	0.5013	0.050*	0.5
C8	0.3375 (6)	0.5382 (8)	0.4486 (9)	0.042 (3)	0.5
H8	0.3127	0.5560	0.5266	0.051*	0.5
C9	0.3558 (12)	0.6407 (8)	0.3790 (17)	0.039 (3)	0.5
H9	0.3318	0.7123	0.4097	0.047*	0.5
C10	0.4007 (7)	0.6649 (8)	0.2747 (12)	0.038 (4)	0.5
H10	0.4011	0.7488	0.2518	0.046*	0.5
C11	0.4453 (7)	0.5925 (8)	0.1965 (11)	0.042 (2)	0.5
H11	0.4749	0.6393	0.1400	0.050*	0.5
C12	0.4570 (5)	0.4667 (6)	0.1811 (8)	0.042 (3)	0.5
H12	0.4949	0.4481	0.1208	0.051*	0.5

	U11	U22	U33	U12	U13	U23
Ta1	0.01532 (9)	0.02046 (10)	0.01810 (10)	0.000	0.00291 (7)	0.000
I1	0.03124 (17)	0.03438 (18)	0.02409 (16)	0.000	0.01224 (13)	0.000
C1	0.0182 (15)	0.045 (2)	0.0268 (17)	−0.0062 (15)	0.0053 (13)	−0.0106 (16)
C2	0.0215 (17)	0.0272 (18)	0.049 (2)	−0.0006 (14)	0.0037 (16)	−0.0047 (16)
C3	0.0277 (19)	0.047 (2)	0.047 (2)	−0.0136 (18)	−0.0006 (18)	0.020 (2)
C4	0.0250 (18)	0.105 (4)	0.027 (2)	−0.011 (2)	0.0080 (16)	0.017 (2)
C5	0.024 (6)	0.055 (6)	0.029 (6)	0.012 (5)	0.001 (3)	−0.019 (5)
C6	0.027 (9)	0.027 (3)	0.045 (13)	−0.007 (3)	−0.002 (5)	0.008 (3)
C7	0.0205 (16)	0.079 (8)	0.0247 (18)	−0.008 (2)	0.0078 (14)	0.001 (2)
C8	0.0210 (15)	0.079 (8)	0.0248 (17)	−0.008 (2)	0.0071 (13)	0.000 (2)
C9	0.024 (6)	0.055 (6)	0.029 (6)	0.012 (5)	0.001 (3)	−0.019 (5)
C10	0.027 (9)	0.027 (3)	0.045 (13)	−0.007 (3)	−0.002 (5)	0.008 (3)
C11	0.0205 (16)	0.079 (8)	0.0247 (18)	−0.008 (2)	0.0078 (14)	0.001 (2)
C12	0.0210 (15)	0.079 (8)	0.0248 (17)	−0.008 (2)	0.0071 (13)	0.000 (2)

Ta1—C1	2.290 (3)	C3—H3	0.9500
Ta1—C1i	2.290 (3)	C4—C4i	1.416 (11)
Ta1—C6	2.359 (10)	C4—H4	0.9500
Ta1—C9	2.397 (13)	C5—C6	1.396 (9)
Ta1—C5	2.402 (12)	C5—C12	1.410 (9)
Ta1—C10	2.408 (9)	C5—H5	0.9500
Ta1—C7	2.429 (9)	C6—C7	1.365 (9)
Ta1—C11	2.454 (9)	C6—H6	0.9500
Ta1—C8	2.459 (8)	C7—C8	1.369 (9)
Ta1—C12	2.474 (7)	C7—H7	0.9500
Ta1—C2	2.560 (4)	C8—C9	1.381 (9)
Ta1—C2i	2.560 (4)	C8—H8	0.9500
Ta1—I1	3.0107 (5)	C9—C10	1.392 (9)
C1—C2	1.386 (5)	C9—H9	0.9500
C1—C1i	1.400 (8)	C10—C11	1.399 (9)
C1—H1	0.9500	C10—H10	0.9500
C2—C3	1.435 (6)	C11—C12	1.410 (9)
C2—H2	0.9500	C11—H11	0.9500
C3—C4	1.359 (7)	C12—H12	0.9500
C1—Ta1—C1i	35.6 (2)	C7—Ta1—I1	151.54 (19)
C1—Ta1—C6	109.2 (3)	C11—Ta1—I1	77.9 (2)
C1i—Ta1—C6	141.1 (2)	C8—Ta1—I1	163.56 (16)
C1—Ta1—C9	132.6 (3)	C12—Ta1—I1	73.25 (16)
C1i—Ta1—C9	106.3 (3)	C2—Ta1—I1	101.77 (9)
C6—Ta1—C9	89.0 (3)	C2i—Ta1—I1	101.77 (9)
C1—Ta1—C5	121.5 (3)	C2—C1—C1i	130.4 (2)
C1i—Ta1—C5	155.1 (3)	C2—C1—Ta1	84.5 (2)
C6—Ta1—C5	34.1 (2)	C1i—C1—Ta1	72.20 (10)
C9—Ta1—C5	98.3 (3)	C2—C1—H1	114.8
C1—Ta1—C10	148.7 (2)	C1i—C1—H1	114.8
C1i—Ta1—C10	113.2 (2)	Ta1—C1—H1	118.6
C6—Ta1—C10	99.5 (3)	C1—C2—C3	133.9 (4)
C9—Ta1—C10	33.7 (2)	C1—C2—Ta1	62.89 (19)
C5—Ta1—C10	89.3 (3)	C3—C2—Ta1	115.0 (2)
C1—Ta1—C7	110.4 (3)	C1—C2—H2	113.0
C1i—Ta1—C7	125.5 (2)	C3—C2—H2	113.0
C6—Ta1—C7	33.1 (2)	Ta1—C2—H2	92.4
C9—Ta1—C7	63.2 (3)	C4—C3—C2	135.3 (4)
C5—Ta1—C7	63.4 (3)	C4—C3—H3	112.4
C10—Ta1—C7	87.0 (3)	C2—C3—H3	112.4
C1—Ta1—C11	154.0 (2)	C3—C4—C4i	132.7 (3)
C1i—Ta1—C11	130.1 (2)	C3—C4—H4	113.7
C6—Ta1—C11	88.8 (3)	C4i—C4—H4	113.7
C9—Ta1—C11	63.9 (3)	C6—C5—C12	134.7 (8)
C5—Ta1—C11	64.5 (3)	C6—C5—Ta1	71.3 (5)
C10—Ta1—C11	33.4 (2)	C12—C5—Ta1	76.0 (6)
C7—Ta1—C11	95.0 (3)	C6—C5—H5	112.7
C1—Ta1—C8	118.50 (19)	C12—C5—H5	112.7
C1i—Ta1—C8	111.9 (2)	Ta1—C5—H5	136.9
C6—Ta1—C8	63.8 (3)	C7—C6—C5	133.8 (8)
C9—Ta1—C8	33.0 (2)	C7—C6—Ta1	76.2 (6)
C5—Ta1—C8	87.1 (3)	C5—C6—Ta1	74.6 (6)
C10—Ta1—C8	63.7 (3)	C7—C6—H6	113.1
C7—Ta1—C8	32.5 (2)	C5—C6—H6	113.1
C11—Ta1—C8	86.0 (3)	Ta1—C6—H6	129.8
C1—Ta1—C12	139.89 (19)	C6—C7—C8	137.5 (9)
C1i—Ta1—C12	148.81 (18)	C6—C7—Ta1	70.7 (6)
C6—Ta1—C12	64.7 (2)	C8—C7—Ta1	75.0 (6)
C9—Ta1—C12	87.5 (4)	C6—C7—H7	111.3
C5—Ta1—C12	33.6 (2)	C8—C7—H7	111.3
C10—Ta1—C12	64.3 (3)	Ta1—C7—H7	144.5
C7—Ta1—C12	85.7 (3)	C7—C8—C9	133.9 (9)
C11—Ta1—C12	33.2 (2)	C7—C8—Ta1	72.5 (6)
C8—Ta1—C12	95.1 (2)	C9—C8—Ta1	71.0 (6)
C1—Ta1—C2	32.60 (13)	C7—C8—H8	113.1
C1i—Ta1—C2	62.58 (13)	C9—C8—H8	113.1
C6—Ta1—C2	78.9 (2)	Ta1—C8—H8	143.0
C9—Ta1—C2	122.1 (2)	C8—C9—C10	135.7 (8)
C5—Ta1—C2	101.3 (2)	C8—C9—Ta1	76.0 (6)
C10—Ta1—C2	155.6 (2)	C10—C9—Ta1	73.6 (6)
C7—Ta1—C2	78.5 (3)	C8—C9—H9	112.2
C11—Ta1—C2	165.8 (2)	C10—C9—H9	112.2
C8—Ta1—C2	94.66 (19)	Ta1—C9—H9	134.1
C12—Ta1—C2	132.81 (18)	C9—C10—C11	133.9 (9)
C1—Ta1—C2i	62.58 (13)	C9—C10—Ta1	72.7 (6)
C1i—Ta1—C2i	32.60 (13)	C11—C10—Ta1	75.1 (6)
C6—Ta1—C2i	136.4 (2)	C9—C10—H10	113.0
C9—Ta1—C2i	74.0 (3)	C11—C10—H10	113.0
C5—Ta1—C2i	169.2 (3)	Ta1—C10—H10	135.0
C10—Ta1—C2i	88.2 (2)	C10—C11—C12	135.4 (8)
C7—Ta1—C2i	106.0 (2)	C10—C11—Ta1	71.5 (5)
C11—Ta1—C2i	116.8 (2)	C12—C11—Ta1	74.2 (5)
C8—Ta1—C2i	82.4 (2)	C10—C11—H11	112.3
C12—Ta1—C2i	149.84 (18)	C12—C11—H11	112.3
C2—Ta1—C2i	77.28 (17)	Ta1—C11—H11	141.1
C1—Ta1—I1	76.97 (9)	C11—C12—C5	133.7 (8)
C1i—Ta1—I1	76.97 (9)	C11—C12—Ta1	72.6 (5)
C6—Ta1—I1	118.5 (2)	C5—C12—Ta1	70.4 (6)
C9—Ta1—I1	132.5 (2)	C11—C12—H12	113.1
C5—Ta1—I1	89.0 (3)	C5—C12—H12	113.1
C10—Ta1—I1	100.3 (2)	Ta1—C12—H12	143.8
C1i—C1—C2—C3	38.6 (5)	C7—C8—C9—C10	−8 (3)
Ta1—C1—C2—C3	99.6 (4)	Ta1—C8—C9—C10	−47.7 (16)
C1i—C1—C2—Ta1	−60.97 (17)	C7—C8—C9—Ta1	39.5 (14)
C1—C2—C3—C4	−18.5 (8)	C8—C9—C10—C11	1 (2)
Ta1—C2—C3—C4	57.1 (5)	Ta1—C9—C10—C11	−47.7 (12)
C2—C3—C4—C4i	−13.5 (6)	C8—C9—C10—Ta1	48.4 (16)
C12—C5—C6—C7	−7 (2)	C9—C10—C11—C12	6 (2)
Ta1—C5—C6—C7	−52.8 (12)	Ta1—C10—C11—C12	−41.4 (14)
C12—C5—C6—Ta1	46.1 (13)	C9—C10—C11—Ta1	47.0 (12)
C5—C6—C7—C8	14 (2)	C10—C11—C12—C5	3 (2)
Ta1—C6—C7—C8	−37.9 (15)	Ta1—C11—C12—C5	−38.2 (13)
C5—C6—C7—Ta1	52.2 (12)	C10—C11—C12—Ta1	40.7 (14)
C6—C7—C8—C9	−2 (3)	C6—C5—C12—C11	−6 (2)
Ta1—C7—C8—C9	−39.1 (15)	Ta1—C5—C12—C11	38.8 (13)
C6—C7—C8—Ta1	36.9 (15)	C6—C5—C12—Ta1	−44.7 (13)