A half-sandwich TaV dichlorido complex containing an O,N,O′-tridentate Schiff base ligand: synthesis, crystal structure and in vitro cytotoxicity

Trávníček, Z.; Štarha, P.; Čajan, M.; Dvořák, Z.

doi:10.1107/S2053229619001323

A half-sandwich Ta^V dichlorido complex containing an O,N,O′-tridentate Schiff base ligand: synthesis, crystal structure and in vitro cytotoxicity

Z. Trávníček, P. Štarha, M. Čajan and Z. Dvořák

A new electroneutral half-sandwich tantalum(V) dichlorido complex containing pentamethylcyclopentadienyl (Cp*) and the double-deprotonated version of the Schiff base 2-ethoxy-6-{(E)-[(2-hydroxyphenyl)imino]methyl}phenol (H₂L) as ligands, namely cis-dichlorido(2-ethoxy-6-{(E)-[(2-oxidophenyl)imino]methyl}phenolato-κ³O,N,O′)(η⁵-pentamethylcyclopentadienyl)tantalum(V), [Ta(C₁₀H₁₅)(C₁₅H₁₃NO₃)Cl₂] or [Ta(η⁵-Cp*)(L)Cl₂], has been prepared and thoroughly characterized by elemental analysis, IR and NMR spectroscopy, mass spectrometry, density functional theory (DFT) calculations and single-crystal X-ray diffraction. The molecular structure revealed that the Ta^V centre is coordinated by a η⁵-Cp* ligand, two monodentate chlorido ligands and one O,N,O′-tridentate L²⁻ ligand. The crystal structure is stabilized by C—H

C, C—H

Cl and C

C intermolecular interactions. Moreover, the complex shows notable in vitro cytotoxicity against the A2780 human ovarian carcinoma cell line, with IC₅₀ = 14.4 µM, which is higher than that of the conventional platinum-based anticancer drug cisplatin (IC₅₀ = 20.1 µM).

Keywords: tantalum(V); half-sandwich; Schiff base; crystal structure; DFT; phenolate; cytotoxicity.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S2053229619001323/jx3031sup1.cif Contains datablocks I, global
	Structure factor file (CIF format) https://doi.org/10.1107/S2053229619001323/jx3031Isup2.hkl Contains datablock I

CCDC reference: 1893190

Computing details top

Data collection: APEX3 (Bruker, 2014); cell refinement: SAINT (Bruker, 2015); data reduction: SAINT (Bruker, 2015); program(s) used to solve structure: SHELXS7 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: SHELXTL (Sheldrick, 2008), DIAMOND (Brandenburg, 2015) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2010).

cis-Dichlorido(2-ethoxy-6-{(E)-[(2-oxidophenyl)imino]methyl}phenolato-κ³O,N,O')(η⁵-pentamethylcyclopentadienyl)tantalum(V) top

Crystal data top

[Ta(C₁₀H₁₅)(C₁₅H₁₃NO₃)Cl₂]	Z = 2
M_r = 642.33	F(000) = 632
Triclinic, P1	D_x = 1.799 Mg m⁻³
a = 8.330 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 11.557 (3) Å	Cell parameters from 9793 reflections
c = 12.426 (3) Å	θ = 2.9–27.5°
α = 84.484 (17)°	µ = 4.89 mm⁻¹
β = 86.070 (11)°	T = 120 K
γ = 86.040 (11)°	Prism, dark red
V = 1185.6 (5) Å³	0.22 × 0.18 × 0.16 mm

Data collection top

Bruker APEXII CCD diffractometer	5154 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.040
Absorption correction: multi-scan (SADABS; Bruker, 2001)	θ_max = 27.6°, θ_min = 2.5°
	h = −10→10
60131 measured reflections	k = −15→15
5446 independent reflections	l = −16→16

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.017	H-atom parameters constrained
wR(F²) = 0.042	w = 1/[σ²(F_o²) + (0.0108P)² + 2.335P] where P = (F_o² + 2F_c²)/3
S = 1.17	(Δ/σ)_max = 0.002
5446 reflections	Δρ_max = 0.87 e Å⁻³
295 parameters	Δρ_min = −0.93 e Å⁻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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Ta	0.61396 (2)	0.77511 (2)	0.29435 (2)	0.00844 (3)
Cl1	0.84157 (8)	0.68580 (6)	0.18972 (5)	0.01830 (13)
Cl2	0.40445 (8)	0.76720 (5)	0.44212 (5)	0.01455 (12)
O1	0.4828 (2)	0.67349 (15)	0.22343 (14)	0.0130 (4)
O2	0.7684 (2)	0.81165 (16)	0.39775 (15)	0.0153 (4)
O3	0.3050 (2)	0.61496 (16)	0.07232 (15)	0.0172 (4)
N1	0.6724 (3)	0.60495 (18)	0.39284 (17)	0.0111 (4)
C1	0.4675 (3)	0.5604 (2)	0.2181 (2)	0.0123 (5)
C2	0.3745 (3)	0.5263 (2)	0.1369 (2)	0.0144 (5)
C3	0.3585 (4)	0.4090 (2)	0.1275 (2)	0.0188 (6)
H3A	0.2976	0.3864	0.0719	0.023*
C4	0.4312 (4)	0.3244 (2)	0.1990 (2)	0.0209 (6)
H4A	0.4195	0.2444	0.1921	0.025*
C5	0.5199 (4)	0.3560 (2)	0.2800 (2)	0.0183 (6)
H5A	0.5673	0.2978	0.3294	0.022*
C6	0.5402 (3)	0.4743 (2)	0.2893 (2)	0.0134 (5)
C7	0.6351 (3)	0.5023 (2)	0.3755 (2)	0.0134 (5)
H7A	0.6734	0.4392	0.4237	0.016*
C8	0.7725 (3)	0.6198 (2)	0.4794 (2)	0.0139 (5)
C9	0.8256 (3)	0.7321 (2)	0.4746 (2)	0.0149 (5)
C10	0.9334 (3)	0.7594 (3)	0.5476 (2)	0.0198 (6)
H10A	0.9729	0.8350	0.5428	0.024*
C11	0.9824 (3)	0.6749 (3)	0.6275 (2)	0.0214 (6)
H11A	1.0565	0.6928	0.6774	0.026*
C12	0.9243 (3)	0.5640 (3)	0.6356 (2)	0.0205 (6)
H12A	0.9562	0.5077	0.6922	0.025*
C13	0.8198 (3)	0.5357 (2)	0.5612 (2)	0.0173 (5)
H13A	0.7809	0.4599	0.5659	0.021*
C14	0.2008 (4)	0.5843 (3)	−0.0065 (2)	0.0208 (6)
H14A	0.1134	0.5379	0.0294	0.025*
H14B	0.2625	0.5374	−0.0598	0.025*
C15	0.1310 (4)	0.6967 (3)	−0.0624 (2)	0.0264 (7)
H15A	0.0580	0.6790	−0.1163	0.040*
H15B	0.2186	0.7413	−0.0984	0.040*
H15C	0.0713	0.7426	−0.0087	0.040*
C16	0.4857 (3)	0.9790 (2)	0.2846 (2)	0.0135 (5)
C17	0.6523 (3)	0.9910 (2)	0.2606 (2)	0.0132 (5)
C18	0.6967 (3)	0.9390 (2)	0.1635 (2)	0.0125 (5)
C19	0.5576 (3)	0.8939 (2)	0.1263 (2)	0.0121 (5)
C20	0.4275 (3)	0.9172 (2)	0.2019 (2)	0.0125 (5)
C21	0.3809 (4)	1.0361 (2)	0.3698 (2)	0.0231 (6)
H21A	0.3315	1.1098	0.3380	0.035*
H21B	0.4465	1.0513	0.4288	0.035*
H21C	0.2962	0.9846	0.3982	0.035*
C22	0.7627 (4)	1.0539 (2)	0.3217 (2)	0.0217 (6)
H22A	0.7892	1.1270	0.2797	0.033*
H22B	0.8618	1.0050	0.3338	0.033*
H22C	0.7092	1.0709	0.3917	0.033*
C23	0.8565 (3)	0.9488 (3)	0.1017 (3)	0.0224 (6)
H23A	0.8660	1.0290	0.0696	0.034*
H23B	0.8652	0.8960	0.0441	0.034*
H23C	0.9431	0.9277	0.1509	0.034*
C24	0.5507 (4)	0.8377 (2)	0.0228 (2)	0.0183 (6)
H24A	0.5187	0.8969	−0.0350	0.027*
H24B	0.4716	0.7780	0.0330	0.027*
H24C	0.6571	0.8016	0.0028	0.027*
C25	0.2549 (3)	0.8919 (3)	0.1932 (3)	0.0226 (6)
H25A	0.1970	0.9605	0.1582	0.034*
H25B	0.2047	0.8728	0.2658	0.034*
H25C	0.2503	0.8258	0.1499	0.034*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ta	0.01023 (5)	0.00706 (5)	0.00769 (5)	0.00022 (3)	−0.00137 (3)	0.00110 (3)
Cl1	0.0180 (3)	0.0165 (3)	0.0176 (3)	0.0058 (2)	0.0053 (2)	0.0035 (2)
Cl2	0.0182 (3)	0.0115 (3)	0.0125 (3)	0.0004 (2)	0.0035 (2)	0.0019 (2)
O1	0.0175 (9)	0.0088 (8)	0.0127 (9)	−0.0004 (7)	−0.0031 (7)	0.0007 (7)
O2	0.0164 (9)	0.0122 (9)	0.0170 (9)	−0.0008 (7)	−0.0072 (7)	0.0038 (7)
O3	0.0208 (10)	0.0151 (9)	0.0170 (9)	−0.0030 (8)	−0.0084 (8)	−0.0017 (7)
N1	0.0126 (10)	0.0112 (10)	0.0090 (10)	0.0021 (8)	−0.0003 (8)	−0.0004 (8)
C1	0.0145 (12)	0.0103 (12)	0.0118 (12)	−0.0018 (9)	0.0016 (9)	−0.0006 (9)
C2	0.0174 (13)	0.0141 (12)	0.0114 (12)	−0.0010 (10)	−0.0001 (10)	0.0006 (10)
C3	0.0254 (15)	0.0156 (13)	0.0166 (13)	−0.0055 (11)	−0.0025 (11)	−0.0042 (10)
C4	0.0349 (17)	0.0100 (12)	0.0187 (14)	−0.0058 (11)	−0.0003 (12)	−0.0038 (10)
C5	0.0287 (15)	0.0116 (12)	0.0135 (13)	−0.0008 (11)	0.0016 (11)	0.0020 (10)
C6	0.0197 (13)	0.0095 (12)	0.0104 (12)	−0.0004 (10)	0.0017 (10)	−0.0002 (9)
C7	0.0160 (13)	0.0107 (12)	0.0121 (12)	0.0015 (9)	0.0005 (10)	0.0026 (9)
C8	0.0125 (12)	0.0168 (13)	0.0120 (12)	0.0030 (10)	−0.0015 (10)	−0.0013 (10)
C9	0.0147 (13)	0.0170 (13)	0.0124 (12)	0.0029 (10)	−0.0019 (10)	0.0005 (10)
C10	0.0185 (14)	0.0197 (14)	0.0217 (14)	0.0009 (11)	−0.0055 (11)	−0.0026 (11)
C11	0.0167 (14)	0.0302 (16)	0.0177 (14)	0.0052 (11)	−0.0072 (11)	−0.0056 (12)
C12	0.0209 (14)	0.0259 (15)	0.0126 (13)	0.0102 (11)	−0.0031 (11)	0.0017 (11)
C13	0.0199 (14)	0.0168 (13)	0.0136 (13)	0.0050 (10)	0.0001 (10)	0.0012 (10)
C14	0.0217 (14)	0.0227 (14)	0.0197 (14)	−0.0058 (11)	−0.0089 (11)	−0.0026 (11)
C15	0.0259 (16)	0.0341 (17)	0.0191 (15)	0.0008 (13)	−0.0079 (12)	0.0004 (12)
C16	0.0192 (13)	0.0079 (11)	0.0119 (12)	0.0023 (10)	0.0007 (10)	0.0030 (9)
C17	0.0192 (13)	0.0066 (11)	0.0134 (12)	−0.0007 (9)	−0.0033 (10)	0.0026 (9)
C18	0.0152 (13)	0.0079 (11)	0.0132 (12)	0.0001 (9)	0.0003 (10)	0.0034 (9)
C19	0.0157 (12)	0.0088 (11)	0.0109 (12)	0.0008 (9)	−0.0025 (9)	0.0037 (9)
C20	0.0118 (12)	0.0094 (11)	0.0150 (12)	0.0016 (9)	−0.0024 (10)	0.0053 (9)
C21	0.0331 (17)	0.0131 (13)	0.0207 (14)	0.0045 (12)	0.0083 (12)	−0.0003 (11)
C22	0.0294 (16)	0.0152 (13)	0.0218 (14)	−0.0059 (11)	−0.0077 (12)	0.0001 (11)
C23	0.0168 (14)	0.0190 (14)	0.0291 (16)	−0.0010 (11)	0.0075 (12)	0.0029 (12)
C24	0.0290 (15)	0.0147 (13)	0.0114 (12)	−0.0013 (11)	−0.0045 (11)	−0.0009 (10)
C25	0.0142 (14)	0.0220 (15)	0.0306 (16)	−0.0008 (11)	−0.0065 (12)	0.0060 (12)

Geometric parameters (Å, º) top

Ta—O1	1.9642 (18)	C12—C13	1.389 (4)
Ta—O2	1.9721 (18)	C12—H12A	0.9500
Ta—N1	2.256 (2)	C13—H13A	0.9500
Ta—C20	2.441 (2)	C14—C15	1.511 (4)
Ta—C19	2.441 (2)	C14—H14A	0.9900
Ta—Cl2	2.4448 (8)	C14—H14B	0.9900
Ta—Cl1	2.4496 (8)	C15—H15A	0.9800
Ta—C18	2.478 (2)	C15—H15B	0.9800
Ta—C16	2.514 (3)	C15—H15C	0.9800
Ta—C17	2.529 (3)	C16—C17	1.413 (4)
O1—C1	1.331 (3)	C16—C20	1.434 (4)
O2—C9	1.348 (3)	C16—C21	1.499 (4)
O3—C2	1.361 (3)	C17—C18	1.415 (4)
O3—C14	1.436 (3)	C17—C22	1.498 (4)
N1—C7	1.288 (3)	C18—C19	1.425 (4)
N1—C8	1.435 (3)	C18—C23	1.496 (4)
C1—C6	1.400 (4)	C19—C20	1.414 (4)
C1—C2	1.414 (4)	C19—C24	1.502 (4)
C2—C3	1.388 (4)	C20—C25	1.500 (4)
C3—C4	1.392 (4)	C21—H21A	0.9800
C3—H3A	0.9500	C21—H21B	0.9800
C4—C5	1.378 (4)	C21—H21C	0.9800
C4—H4A	0.9500	C22—H22A	0.9800
C5—C6	1.407 (4)	C22—H22B	0.9800
C5—H5A	0.9500	C22—H22C	0.9800
C6—C7	1.447 (4)	C23—H23A	0.9800
C7—H7A	0.9500	C23—H23B	0.9800
C8—C13	1.394 (4)	C23—H23C	0.9800
C8—C9	1.395 (4)	C24—H24A	0.9800
C9—C10	1.391 (4)	C24—H24B	0.9800
C10—C11	1.386 (4)	C24—H24C	0.9800
C10—H10A	0.9500	C25—H25A	0.9800
C11—C12	1.392 (4)	C25—H25B	0.9800
C11—H11A	0.9500	C25—H25C	0.9800

O1—Ta—O2	155.48 (7)	C10—C11—C12	120.8 (3)
O1—Ta—N1	80.70 (8)	C10—C11—H11A	119.6
O2—Ta—N1	74.82 (8)	C12—C11—H11A	119.6
O1—Ta—C20	78.53 (8)	C13—C12—C11	120.1 (3)
O2—Ta—C20	125.01 (8)	C13—C12—H12A	119.9
N1—Ta—C20	152.47 (8)	C11—C12—H12A	119.9
O1—Ta—C19	78.21 (8)	C12—C13—C8	119.3 (3)
O2—Ta—C19	124.69 (8)	C12—C13—H13A	120.4
N1—Ta—C19	153.45 (8)	C8—C13—H13A	120.4
C20—Ta—C19	33.67 (9)	O3—C14—C15	107.2 (2)
O1—Ta—Cl2	86.26 (6)	O3—C14—H14A	110.3
O2—Ta—Cl2	88.95 (6)	C15—C14—H14A	110.3
N1—Ta—Cl2	75.63 (6)	O3—C14—H14B	110.3
C20—Ta—Cl2	85.13 (7)	C15—C14—H14B	110.3
C19—Ta—Cl2	118.54 (7)	H14A—C14—H14B	108.5
O1—Ta—Cl1	84.91 (6)	C14—C15—H15A	109.5
O2—Ta—Cl1	88.01 (6)	C14—C15—H15B	109.5
N1—Ta—Cl1	76.29 (6)	H15A—C15—H15B	109.5
C20—Ta—Cl1	119.28 (7)	C14—C15—H15C	109.5
C19—Ta—Cl1	85.91 (7)	H15A—C15—H15C	109.5
Cl2—Ta—Cl1	151.57 (2)	H15B—C15—H15C	109.5
O1—Ta—C18	109.69 (8)	C17—C16—C20	107.8 (2)
O2—Ta—C18	91.52 (8)	C17—C16—C21	126.7 (2)
N1—Ta—C18	150.71 (8)	C20—C16—C21	124.8 (3)
C20—Ta—C18	55.41 (9)	C17—C16—Ta	74.29 (14)
C19—Ta—C18	33.68 (8)	C20—C16—Ta	70.38 (14)
Cl2—Ta—C18	130.88 (6)	C21—C16—Ta	128.22 (18)
Cl1—Ta—C18	77.47 (6)	C16—C17—C18	107.9 (2)
O1—Ta—C16	110.09 (8)	C16—C17—C22	126.9 (2)
O2—Ta—C16	92.03 (8)	C18—C17—C22	125.1 (2)
N1—Ta—C16	149.17 (8)	C16—C17—Ta	73.17 (14)
C20—Ta—C16	33.61 (9)	C18—C17—Ta	71.61 (14)
C19—Ta—C16	55.48 (8)	C22—C17—Ta	123.80 (17)
Cl2—Ta—C16	76.39 (6)	C17—C18—C19	108.8 (2)
Cl1—Ta—C16	131.97 (6)	C17—C18—C23	124.5 (2)
C18—Ta—C16	54.51 (8)	C19—C18—C23	126.0 (2)
O1—Ta—C17	131.28 (8)	C17—C18—Ta	75.56 (14)
O2—Ta—C17	73.23 (8)	C19—C18—Ta	71.74 (14)
N1—Ta—C17	148.02 (8)	C23—C18—Ta	126.74 (18)
C20—Ta—C17	55.13 (9)	C20—C19—C18	107.3 (2)
C19—Ta—C17	55.34 (8)	C20—C19—C24	126.9 (2)
Cl2—Ta—C17	102.36 (6)	C18—C19—C24	125.8 (2)
Cl1—Ta—C17	103.77 (7)	C20—C19—Ta	73.16 (14)
C18—Ta—C17	32.82 (8)	C18—C19—Ta	74.58 (14)
C16—Ta—C17	32.54 (9)	C24—C19—Ta	120.27 (17)
C1—O1—Ta	139.03 (16)	C19—C20—C16	108.2 (2)
C9—O2—Ta	122.69 (16)	C19—C20—C25	126.4 (2)
C2—O3—C14	117.3 (2)	C16—C20—C25	125.2 (2)
C7—N1—C8	120.1 (2)	C19—C20—Ta	73.17 (14)
C7—N1—Ta	128.00 (17)	C16—C20—Ta	76.00 (14)
C8—N1—Ta	111.76 (16)	C25—C20—Ta	121.00 (17)
O1—C1—C6	122.5 (2)	C16—C21—H21A	109.5
O1—C1—C2	118.4 (2)	C16—C21—H21B	109.5
C6—C1—C2	119.0 (2)	H21A—C21—H21B	109.5
O3—C2—C3	124.4 (2)	C16—C21—H21C	109.5
O3—C2—C1	115.6 (2)	H21A—C21—H21C	109.5
C3—C2—C1	120.0 (2)	H21B—C21—H21C	109.5
C2—C3—C4	120.3 (3)	C17—C22—H22A	109.5
C2—C3—H3A	119.8	C17—C22—H22B	109.5
C4—C3—H3A	119.8	H22A—C22—H22B	109.5
C5—C4—C3	120.5 (3)	C17—C22—H22C	109.5
C5—C4—H4A	119.7	H22A—C22—H22C	109.5
C3—C4—H4A	119.7	H22B—C22—H22C	109.5
C4—C5—C6	120.0 (3)	C18—C23—H23A	109.5
C4—C5—H5A	120.0	C18—C23—H23B	109.5
C6—C5—H5A	120.0	H23A—C23—H23B	109.5
C1—C6—C5	120.1 (2)	C18—C23—H23C	109.5
C1—C6—C7	122.3 (2)	H23A—C23—H23C	109.5
C5—C6—C7	117.6 (2)	H23B—C23—H23C	109.5
N1—C7—C6	125.9 (2)	C19—C24—H24A	109.5
N1—C7—H7A	117.0	C19—C24—H24B	109.5
C6—C7—H7A	117.0	H24A—C24—H24B	109.5
C13—C8—C9	120.3 (2)	C19—C24—H24C	109.5
C13—C8—N1	127.1 (2)	H24A—C24—H24C	109.5
C9—C8—N1	112.6 (2)	H24B—C24—H24C	109.5
O2—C9—C10	122.1 (2)	C20—C25—H25A	109.5
O2—C9—C8	117.7 (2)	C20—C25—H25B	109.5
C10—C9—C8	120.2 (2)	H25A—C25—H25B	109.5
C11—C10—C9	119.2 (3)	C20—C25—H25C	109.5
C11—C10—H10A	120.4	H25A—C25—H25C	109.5
C9—C10—H10A	120.4	H25B—C25—H25C	109.5

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···Cl2ⁱ	0.95	2.86	3.691 (3)	147

Symmetry code: (i) −x+1, −y+1, −z+1.

Selected IR spectral data for complex (I) (cm^-1, Exp. = measured and DFT = calculated for the B3PW91/cc-pVDZ/LANL2DZ optimized geometry) top

Assignments	Exp.	DFT
ν(C—H)_aliphatic	2915 (m)	2878
	2976 (m)	2911
		3011
ν(C—H)_aromatic	3060	3077
ν(C═N)	1618(m)	1620
ν(C—O)_aromatic	1263 (s)	1240
Cp* skeletal	1182 (m)	1189
	544 (m)	576–589
	1117 (m)	1130
L skeletal	872 (m)	880
	644 (m)	655

Selected geometric parameters (Å, °) for complexes (I), [Ta(η⁵-Cp*)(L1)Cl₂], [Ta(η⁵-Cp*)(L2)Cl₂].C₇H₈ and [Ta(η⁵-Cp*)(L3)Cl₂] top

	(I) (X-ray)	(I) (DFT)	[Ta(η⁵-Cp*)(L1)Cl₂]	[Ta(η⁵-Cp*)(L2)Cl₂].C₇H₈	[Ta(η⁵-Cp*)(L3)Cl₂]
Distances
Ta—O1	1.9642 (18)	1.984	1.936 (10)	2.043 (4)	1.953 (4)
Ta—O2	1.9721 (18)	1.994	1.979 (11)	2.025 (3)	1.937 (4)
Ta—N1	2.256 (2)	2.277	2.28 (2)	2.159 (4)	2.174 (3)
Ta—Cl2	2.4448 (8)	2.449	2.427 (5)	2.414 (2)	2.4978 (14)
Ta—Cl1	2.4496 (8)	2.449	2.432 (6)	2.421 (2)	2.463 (2)
Ta—Cg	2.1670 (6)	2.175	2.1477 (8)	2.1286 (2)	2.1613 (7)

Angles
O2—Ta—O1	155.48 (7)	155.31	155.3 (4)	146.79 (14)	148.0 (2)
O1—Ta—N1	80.70 (8)	80.97	81.2 (5)	73.3 (2)	74.22 (13)
O2—Ta—N1	74.82 (8)	74.34	74.1 (5)	73.51 (15)	73.8 (2)
Cl2—Ta—Cl1	151.57 (2)	150.13	150.4 (2)	151.14 (6)	152.02 (4)
Cg—Ta—Cl1	104.78 (2)	104.98	104.8 (2)	104.07 (4)	103.94 (3)
Cg—Ta—Cl2	103.51 (2)	104.86	104.76 (12)	104.72 (4)	103.96 (3)
Cg—Ta—N1	176.47 (6)	175.92	177.1 (4)	179.13 (12)	179.37 (9)

Notes: Cg is the centroid of the cyclopentadienyl ring (Cp*); DFT = optimized at B3PW91/cc-pVDZ/LANL2DZ.

Geometric parameters of the selected non-covalent contacts (Å, °) top

D—H···A	D—H	H···A	D···A	DHA
C5—H5A···Cl2ⁱ	0.95	2.89	3.685 (3)	142
C7—H7A···Cl2ⁱ	0.95	2.86	3.691 (3)	147
C23—H23C···C25ⁱⁱ	0.98	2.68	3.579 (4)	152
C24—H24A···C19ⁱⁱⁱ	0.98	2.63	3.550 (3)	157
C24—H24A···C20ⁱⁱⁱ	0.98	2.88	3.786 (3)	155

Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) x+1, y, z; (iii) -x+1, -y+2, -z.

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