Dichloro(isopropylamido)bis(iso­propylamine)(isopropylimido)­tantalum(V), a monomeric Ta^V compound with imido, amido and amino moieties

The title compound, [Ta(C₃H₇N)(C₃H₈N)Cl₂(C₃H₉N)₂], is the first monomeric example of a metal complex that features imido, amido and amino moieties in the same mol­ecule. The Ta atom has distorted octahedral coordination, with the imido moiety trans to chlorine and the pseudo-axial ligands bent away from the imido moiety. Principal dimensions include Ta=N = 1.763 (8) Å, Ta-N(H) = 1.964 (7) Å, and Ta-N(H₂) = 2.247 (7) and 2.262 (7) Å.

S1. Comment

The synthesis of the title compound Ta(NⁱPr)(NHⁱPr)(NH₂ⁱPr)₂Cl₂, (I) was first reported by Bates et al., (1985) and it was originally proposed to be dimeric with the formula [TaCl(µ-Cl)(NⁱPr)(NHⁱPr)(NH₂ⁱPr)Cl₂]₂ by analogy with the previously reported structure of the dimeric [TaCl(µ-Cl)(N^tBu)(NH^tBu)(NH₂^tBu)Cl₂]₂ (Jones et al., 1984). Compound (I) was later studied by Jayaratne et al., (1996) who proposed a monomeric formulation based on ¹H and ¹³C NMR spectroscopy data.

Our interest in this compound was sparked by our studies of imine metathesis by metal imido complexes of the general formula CpTa(=NR)Cl₂ (Burland et al., 2002). Our mechanistic work had suggested the possible involvement of metal amido complexes in the reaction mechanism. We decided to survey metal amido complexes previous reported in the literature in order to develop the tools necessary to help us identify possible intermediates in our reactions. We were immediately struck by the title compound as it contained all three N-moieties that were of interest to us. A search of the Cambridge Structural Database (Allen, 2002) for metal complexes with imido, amido and amino groups yielded hits for only two complexes, both centrosymmetric dimers; the Ta complex reported by Jones et al., (1984) and mentioned above (CSD Refcode CEDTOU), and the isostructural vanadium complex (CSD Refcode DAJCOG, Preuss et al., 1985).

In the structure of the title imide/amide/amine compound (I) (Fig. 1) the distinction between imide, amide and amine N atoms was clear from the Ta—N dimensions (Table 1) and also by the location of the amide and amine H atoms via difference maps. The imido Ta=N bond length of 1.763 (8) Å, is typical for monomeric tantalum imides (Wigley, 1994), but long compared with the unusually short Ta=N bond length of 1.61 (3) Å reported for the dimeric ^tBu analog by Jones et al., (1984). The nearly linear C—N—Ta bond angle [173.8 (8)°] is consistent with a high degree of π-bonding with the metal.

The Ta—N(H) bond length [1.964 (8) Å] of the amido moiety has a formal bond order of one and is nearly 0.2 Å longer than the Ta=N bond length. The Ta—N—C bond angle [135.9 (11)°] indicates that, as with the imide, there is some metal–lone pair overlap. In the dimeric ^tBu analog the Ta—N amide bond is short at 1.86 (3) Å and exhibits an unusually almost linear Ta—N—C bond angle of 160 (2)°.

The Ta—N(H₂) bond lengths of the two amine moieties of (I) (Table 1) are similar with a mean value 2.255 (8) Å and a mean Ta—NH₂—C bond angle of [118.8 (19)°]. The amine dative interaction is again weaker than the amide as indicated by the approximately 0.3 Å elongation of the Ta—N bond length. The dative amine bond for the dimeric ^tBu analog is similar with a 2.23 (3) Å Ta—N bond length and 126 (2)° Ta—N—C angle.

In the crystal, molecules of (I) are linked by N—H···Cl hydrogen bonds (Table 2) about inversion centers to generate chains extending in the b direction.

As proposed by Jayaratne et al., (1996) we have shown that the structure of (I) is indeed monomeric and as such is potentially a very useful reference compound for comparison of amino, amido and imido bond lengths and angles. It is analogous to the structure of the alkyl/alkylidene/alkylidyne compound W(CH₂CMe₃)(CHCMe₃)(CCMe₃)(dmpe) [dmpe is 1,2-bis(dimethylphosphino)ethane] reported by Churchill & Youngs (1979) [CSD Refcode DMPMPW10] which is often cited for comparisons of metal-carbon bond lengths.

We used two-dimensional heteronuclear multiple bond correlation (HMBC) NMR spectroscopy to fully assign the ¹H and ¹³C NMR spectra of (I). We also report ¹⁴N and ¹⁵N NMR spectroscopy data for this compound. The ¹H NMR spectrum of the (I) depends on concentration. At low concentrations the NH₂ protons for the amine moiety appear as a broad singlet in the δ 3.2–3.4 region of the spectrum. At higher concentrations, the amine protons shift upfield and become distinctive multiplets. It seems likely that the title compound is in equilibrium with a dimeric form that is analogous to that reported previously for the ^tBu derivative.

S2. Experimental

The title compound was synthesized as described by Jayaratne et al. (1996) from the reaction on TaCl₅ with ⁱPrNH₂. Recrystallization by slow evaporation of toluene from a solution of the compound afforded colourless crystals suitable for X-ray analysis. ¹H NMR spectroscopy of the crystals showed that little or no decomposition had occurred during the recrystallization.

NMR data: ¹H, ¹³C and ¹⁵N NMR spectra were recorded with a Bruker AF500 or AF300 NMR spectrometer. Chemical shifts for ¹H and ¹³C are referenced to the residual protio impurity in the deuterated solvent. ¹⁵N chemical shifts are referenced to formamide used as an external standard. ¹⁴N NMR spectra were recorded by Dr M. Minelli, Grinnell College, Iowa. They were measured on a Bruker AC 300 MHz NMR spectrometer with a 10 mm broadband probehead (109 A g-31P) with digital tuning. Nitromethane neat was used as external reference (0 p.p.m.).

¹H NMR (300.13 MHz, C₆D₆, 25°C): δ 0.83 (d, 6H, ³J_HH = 6.00 Hz, NH₂CH(C~H₃)₂), 0.86 (d, 6H, ³J_HH = 6.00 Hz, NH₂CH(C~H₃)₂), 1.10 (d, 6H, ³J_HH = 6.00 Hz, NHCH(C~H₃)₂), 1.30 (d, 6H, ³J_HH = 6.00 Hz, NCH(C~H₃)₂), 3.38 (br, 6H, N~H₂CH(CH₃)₂, NH₂C~H(CH₃)₂), 4.52 (sept, 1H, 6.00 Hz, NC~H(CH₃)₂), 4.70 (m, 1H, NHC~H(CH₃)₂), 7.80 (d, 1H, ³J_HH = 10.00 Hz, N~HCH(CH₃)₂). ¹³C {1H} NMR (75.4 MHz, CDCl₃, 25°C): δ 24.9 (NH₂CH(~CH₃)₂, 26.5 (NHCH(~CH₃)₂), 27.8 (NCH(~CH₃)₂), 49.5 (NH₂~CH(CH₃)₂, 60.0 (N~CH(CH₃)₂), 60.2 (NH~CH(CH₃)₂). ¹⁴N {1H} NMR (21.69 MHz, CH₂Cl₂, 25°C): δ −31 (ÑCH(CH₃)₂), −122 (ÑHCH(CH₃)₂), −321 (ÑH₂CH(CH₃)₂), −335 (ÑH₂CH(CH₃)₂). ¹⁵N NMR (50.68 MHz, C₆D₆, 25°C): δ −30.0 (s, ÑCH(CH₃)₂), −115 (d, ÑHCH(CH₃)₂, J_NH=66 Hz), −314 (t, ÑH₂CH(CH₃)₂, J_NH = 66 Hz).

S3. Refinement

The compound crystallized in the triclinic system; space group P1 chosen and confirmed by the successful refinement. It became obvious during the refinement that two of the isopropyl groups (C4,C5,C6 and C10,C11,C12) were disordered. This was dealt with by generating models (C4,C5,C6/C4',C5',C6' and C10,C11,C12/C10',C11',C12') using appropriate DFIX restraints (Csp³—Csp³ 1.52 (1), Csp³—N 1.48 (1), CH₃···CH₃ 2.54 (1) Å). Initially tied occupancy free-variables were refined for each disordered isopropyl group, but as the refined values were not significantly different from 1/2, these occupancies were subsequently fixed at 0.5. Difference map plots clearly revealed the amino- and amido-H atoms. In the final refinement cycles all H atoms were allowed for as riding atoms using the SHELXL HFIX commands (N—H 0.90, C—H 0.96 and 0.98 Å). The maxima and minima in the final difference map are within 1 Å of the Ta atom.

Computing details

Data collection: Siemens P3/PC (Siemens 1990); cell refinement: Siemens P3/PC (Siemens 1990); data reduction: SHELXTL (version 5.10) (Sheldrick, 1997a); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997b); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997b); molecular graphics: PLATON (Spek 2002); software used to prepare material for publication: SHELXTL (version 5.10) (Sheldrick 1997a).

Figures

Scheme. The proposed monomer/dimer equilibrium. Fig. 1. An ORTEP diagram of (I) with ellipsoids drawn at the 30% probability level. Methyl H atoms are omitted for clarity and only one of the two possible orientations of the disordered isopropyl groups is shown.

Isopropylimidoisopropyamido-bis(isopropylamine)dichlorotantalum(V)

Crystal data

[Ta(C3H7N)(C3H8N)(C3H9N)2Cl2]	Z = 2
Mr = 485.27	F(000) = 480
Triclinic, P1	Dx = 1.596 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 9.5970 (19) Å	Cell parameters from 25 reflections
b = 10.073 (2) Å	θ = 10–30°
c = 12.755 (3) Å	µ = 5.70 mm^−1
α = 95.04 (3)°	T = 210 K
β = 111.77 (3)°	Block, colorless
γ = 113.46 (3)°	0.34 × 0.26 × 0.14 mm
V = 1009.5 (6) Å^3

Data collection

Siemens P3 diffractometer	3098 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.072
Graphite monochromator	θmax = 25.1°, θmin = 1.8°
ω scans	h = −11→0
Absorption correction: psi-scan (North et al., 1968)	k = −11→11
Tmin = 0.182, Tmax = 0.450	l = −15→15
4079 measured reflections	3 standard reflections every 200 reflections
3528 independent reflections	intensity decay: 1%

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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.109	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0639P)^2 + 2.1304P] where P = (Fo^2 + 2Fc^2)/3
3528 reflections	(Δ/σ)max = 0.001
219 parameters	Δρmax = 1.44 e Å^−3
22 restraints	Δρmin = −1.36 e Å^−3

Special details

Experimental. NMR Data:

¹H, ¹³C and ¹⁵N NMR spectra were recorded with a Bruker AF500 or AF300 NMR spectrometer. Chemical shifts for ¹H and ¹³C are referenced to the residual protio impurity in the deuterated solvent. ¹⁵N chemical shifts are referenced to formamide used as an external standard. ¹⁴N NMR spectra were recorded by Dr. M. Minelli, Grinnell College, Iowa. They were measured on a Bruker AC 300 MHz NMR spectrometer with a 10 mm broadband probehead (109 A g-31P) with digital tuning. Nitromethane neat was used as external reference (0 p.p.m.).

¹H NMR (300.13 MHz, C6D6, 25°C): d 0.83 (d, 6H, ³J_HH = 6.00 Hz, NH₂CH(CH₃)₂), 0.86 (d, 6H, ³J_HH = 6.00 Hz, NH₂CH(CH₃)₂), 1.10 (d, 6H, ³J_HH = 6.00 Hz, NHCH(CH₃)₂), 1.30 (d, 6H, ³J_HH = 6.00 Hz, NCH(CH₃)₂), 3.38 (br, 6H, NH₂CH(CH₃)₂, NH₂CH(CH₃)₂), 4.52 (sept, 1H, 6.00 Hz, NCH(CH₃)₂), 4.70 (m, 1H, NHCH(CH₃)₂), 7.80 (d, 1H, 3JHH = 10.00 Hz, NHCH(CH₃)₂). ¹³C {1H} NMR (75.4 MHz, CDCl3, 25°C): d 24.9 (NH₂CH(CH₃)₂, 26.5 (NHCH(CH₃)₂), 27.8 (NCH(CH₃)₂), 49.5 (NH₂CH(CH₃)₂, 60.0 (NCH(CH₃)₂), 60.2 (NHCH(CH₃)₂). ¹⁴N {1H} NMR (21.69 MHz, CH₂Cl₂, 25°C): d −31 (NCH(CH₃)₂), −122 (NHCH(CH₃)₂), −321 (NH₂CH(CH₃)₂), −335 (NH₂CH(CH₃)₂). ¹⁵N NMR (50.68 MHz, C6D6, 25°C): d −30.0 (s, NCH(CH₃)₂), −115 (d, NHCH(CH₃)₂, J_NH=66 Hz), −314 (t, NH₂CH(CH₃)₂, J_NH = 66 Hz).

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)
Ta	0.48688 (4)	0.75452 (4)	0.14669 (3)	0.03003 (14)
Cl1	0.5564 (3)	0.7808 (2)	−0.03389 (19)	0.0383 (5)
Cl2	0.2364 (3)	0.5145 (2)	0.0052 (2)	0.0447 (5)
N1	0.4401 (10)	0.7437 (9)	0.2678 (7)	0.0453 (18)
N2	0.6992 (9)	0.9446 (8)	0.2199 (6)	0.0425 (17)
H2	0.7431	0.9689	0.1723	0.051*
N3	0.3155 (9)	0.8502 (8)	0.0502 (7)	0.0371 (16)
H3A	0.3806	0.9501	0.0679	0.045*
H3B	0.2789	0.8128	−0.0271	0.045*
N4	0.6142 (8)	0.6068 (8)	0.1716 (6)	0.0355 (15)
H4A	0.5324	0.5106	0.1376	0.043*
H4B	0.6763	0.6268	0.1313	0.043*
C1	0.3827 (14)	0.7259 (12)	0.3581 (10)	0.068 (3)
H1	0.3313	0.7926	0.3586	0.082*
C2	0.2439 (17)	0.5659 (13)	0.3255 (12)	0.088 (4)
H2A	0.1748	0.5313	0.2420	0.133*
H2B	0.1751	0.5637	0.3646	0.133*
H2C	0.2943	0.5014	0.3491	0.133*
C3	0.5286 (17)	0.775 (2)	0.4788 (11)	0.119 (7)
H3C	0.5564	0.6948	0.4914	0.178*
H3D	0.4965	0.8014	0.5373	0.178*
H3E	0.6254	0.8616	0.4841	0.178*
C4	0.802 (2)	1.056 (2)	0.3366 (15)	0.055 (3)	0.50
H4	0.7607	1.0167	0.3925	0.066*	0.50
C5	0.983 (2)	1.080 (3)	0.375 (4)	0.078 (11)	0.50
H5A	0.9845	0.9855	0.3777	0.117*	0.50
H5B	1.0551	1.1503	0.4514	0.117*	0.50
H5C	1.0227	1.1184	0.3198	0.117*	0.50
C6	0.787 (4)	1.199 (3)	0.324 (3)	0.090 (12)	0.50
H6A	0.6716	1.1788	0.3004	0.135*	0.50
H6B	0.8209	1.2336	0.2649	0.135*	0.50
H6C	0.8590	1.2758	0.3973	0.135*	0.50
C4'	0.802 (3)	1.057 (3)	0.3364 (16)	0.055 (3)	0.50
H4'	0.8056	0.9970	0.3930	0.066*	0.50
C5'	0.986 (3)	1.150 (4)	0.362 (4)	0.13 (2)	0.50
H5D	1.0260	1.0860	0.3365	0.193*	0.50
H5E	1.0533	1.1980	0.4444	0.193*	0.50
H5F	0.9943	1.2256	0.3198	0.193*	0.50
C6'	0.721 (5)	1.149 (4)	0.363 (4)	0.16 (3)	0.50
H6D	0.6095	1.0831	0.3522	0.244*	0.50
H6E	0.7143	1.2116	0.3103	0.244*	0.50
H6F	0.7890	1.2114	0.4424	0.244*	0.50
C7	0.1630 (10)	0.8274 (10)	0.0684 (8)	0.050 (3)
H7	0.1173	0.7291	0.0836	0.060*
C8	0.2188 (16)	0.9487 (12)	0.1763 (9)	0.072 (4)
H8A	0.3242	0.9633	0.2365	0.108*
H8B	0.1340	0.9181	0.2045	0.108*
H8C	0.2332	1.0412	0.1560	0.108*
C9	0.0282 (13)	0.8269 (14)	−0.0418 (10)	0.072 (4)
H9A	0.0691	0.9239	−0.0561	0.109*
H9B	−0.0724	0.8048	−0.0319	0.109*
H9C	0.0023	0.7515	−0.1074	0.109*
C10	0.726 (2)	0.616 (3)	0.2924 (12)	0.047 (3)	0.50
H10	0.7652	0.7148	0.3437	0.057*	0.50
C11	0.619 (3)	0.496 (2)	0.3330 (19)	0.057 (6)	0.50
H11A	0.5276	0.5134	0.3325	0.086*	0.50
H11B	0.6884	0.4994	0.4112	0.086*	0.50
H11C	0.5740	0.3986	0.2811	0.086*	0.50
C12	0.880 (2)	0.603 (3)	0.296 (2)	0.071 (7)	0.50
H12A	0.9435	0.6834	0.2721	0.106*	0.50
H12B	0.8432	0.5080	0.2445	0.106*	0.50
H12C	0.9494	0.6082	0.3751	0.106*	0.50
C10'	0.7534 (19)	0.646 (3)	0.2899 (13)	0.047 (3)	0.50
H10'	0.7347	0.7004	0.3464	0.057*	0.50
C11'	0.752 (4)	0.505 (3)	0.325 (3)	0.114 (14)	0.50
H11D	0.6445	0.4439	0.3233	0.172*	0.50
H11E	0.8408	0.5333	0.4026	0.172*	0.50
H11F	0.7697	0.4491	0.2705	0.172*	0.50
C12'	0.921 (2)	0.751 (3)	0.292 (2)	0.072 (7)	0.50
H12D	0.9135	0.8374	0.2682	0.108*	0.50
H12E	0.9434	0.6996	0.2384	0.108*	0.50
H12F	1.0104	0.7840	0.3697	0.108*	0.50

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ta	0.0323 (2)	0.02502 (19)	0.0349 (2)	0.01388 (14)	0.01641 (15)	0.00899 (13)
Cl1	0.0457 (12)	0.0326 (10)	0.0431 (12)	0.0177 (9)	0.0260 (10)	0.0142 (9)
Cl2	0.0347 (11)	0.0286 (10)	0.0613 (14)	0.0073 (9)	0.0215 (10)	0.0058 (10)
N1	0.051 (5)	0.039 (4)	0.053 (5)	0.025 (4)	0.025 (4)	0.016 (4)
N2	0.037 (4)	0.041 (4)	0.034 (4)	0.013 (3)	0.008 (3)	0.005 (3)
N3	0.041 (4)	0.036 (4)	0.045 (4)	0.023 (3)	0.022 (4)	0.016 (3)
N4	0.036 (4)	0.032 (4)	0.036 (4)	0.015 (3)	0.014 (3)	0.009 (3)
C1	0.096 (9)	0.073 (8)	0.076 (8)	0.051 (7)	0.063 (8)	0.032 (7)
C2	0.101 (11)	0.088 (10)	0.087 (10)	0.030 (9)	0.063 (9)	0.042 (9)
C3	0.094 (12)	0.167 (19)	0.065 (10)	0.027 (12)	0.042 (9)	0.030 (11)
C4	0.054 (6)	0.040 (5)	0.035 (5)	0.003 (5)	0.009 (5)	−0.009 (4)
C5	0.060 (19)	0.044 (17)	0.07 (2)	0.011 (15)	−0.011 (15)	−0.003 (17)
C6	0.12 (3)	0.054 (17)	0.05 (2)	0.037 (18)	0.002 (18)	−0.015 (14)
C4'	0.054 (6)	0.040 (5)	0.035 (5)	0.003 (5)	0.009 (5)	−0.009 (4)
C5'	0.08 (2)	0.10 (3)	0.07 (3)	−0.05 (2)	0.03 (2)	−0.07 (3)
C6'	0.21 (6)	0.12 (4)	0.10 (4)	0.14 (4)	−0.04 (3)	−0.05 (3)
C7	0.034 (5)	0.042 (5)	0.091 (8)	0.023 (4)	0.036 (5)	0.037 (5)
C8	0.112 (11)	0.079 (8)	0.093 (10)	0.072 (8)	0.077 (9)	0.049 (7)
C9	0.043 (6)	0.067 (8)	0.110 (11)	0.029 (6)	0.030 (7)	0.042 (8)
C10	0.057 (8)	0.055 (10)	0.034 (5)	0.034 (7)	0.016 (5)	0.015 (5)
C11	0.102 (19)	0.050 (12)	0.044 (12)	0.045 (13)	0.041 (13)	0.027 (10)
C12	0.051 (14)	0.088 (19)	0.068 (16)	0.040 (14)	0.013 (12)	0.020 (14)
C10'	0.057 (8)	0.055 (10)	0.034 (5)	0.034 (7)	0.016 (5)	0.015 (5)
C11'	0.16 (4)	0.09 (2)	0.048 (17)	0.06 (3)	0.00 (2)	0.024 (16)
C12'	0.028 (10)	0.11 (2)	0.041 (12)	0.021 (12)	−0.002 (9)	−0.003 (13)

Geometric parameters (Å, º)

Ta—Cl1	2.632 (2)	C4'—C5'	1.52 (4)
Ta—Cl2	2.504 (3)	C4'—H4'	0.98
Ta—N1	1.763 (8)	C5'—H5D	0.96
Ta—N2	1.964 (7)	C5'—H5E	0.96
Ta—N3	2.262 (7)	C5'—H5F	0.96
Ta—N4	2.247 (7)	C6'—H6D	0.96
N1—C1	1.446 (13)	C6'—H6E	0.96
N2—C4'	1.478 (10)	C6'—H6F	0.96
N2—C4	1.479 (10)	C7—C9	1.515 (8)
N2—H2	0.86	C7—C8	1.519 (8)
N3—C7	1.498 (11)	C7—H7	0.98
N3—H3A	0.90	C8—H8A	0.96
N3—H3B	0.90	C8—H8B	0.96
N4—C10	1.482 (10)	C8—H8C	0.96
N4—C10'	1.483 (10)	C9—H9A	0.96
N4—H4A	0.90	C9—H9B	0.96
N4—H4B	0.90	C9—H9C	0.96
C1—C3	1.513 (9)	C10—C11	1.517 (10)
C1—C2	1.519 (9)	C10—C12	1.519 (10)
C1—H1	0.98	C10—H10	0.98
C2—H2A	0.96	C11—H11A	0.96
C2—H2B	0.96	C11—H11B	0.96
C2—H2C	0.96	C11—H11C	0.96
C3—H3C	0.96	C12—H12A	0.96
C3—H3D	0.96	C12—H12B	0.96
C3—H3E	0.96	C12—H12C	0.96
C4—C5	1.523 (10)	C10'—C11'	1.517 (10)
C4—C6	1.523 (10)	C10'—C12'	1.523 (10)
C4—H4	0.98	C10'—H10'	0.98
C5—H5A	0.96	C11'—H11D	0.96
C5—H5B	0.96	C11'—H11E	0.96
C5—H5C	0.96	C11'—H11F	0.96
C6—H6A	0.96	C12'—H12D	0.96
C6—H6B	0.96	C12'—H12E	0.96
C6—H6C	0.96	C12'—H12F	0.96
C4'—C6'	1.51 (4)
N1—Ta—Cl1	177.8 (2)	H6B—C6—H6C	109.5
N1—Ta—Cl2	97.7 (3)	N2—C4'—C6'	114 (2)
N1—Ta—N2	98.5 (4)	N2—C4'—C5'	113 (2)
N1—Ta—N3	98.3 (3)	C6'—C4'—C5'	114 (2)
N1—Ta—N4	98.0 (3)	N2—C4'—H4'	104.9
N2—Ta—Cl1	80.4 (2)	C6'—C4'—H4'	104.9
N2—Ta—Cl2	163.7 (2)	C5'—C4'—H4'	104.9
N2—Ta—N3	97.2 (3)	C4'—C5'—H5D	109.5
N2—Ta—N4	95.0 (3)	C4'—C5'—H5E	109.5
N3—Ta—Cl1	80.02 (19)	H5D—C5'—H5E	109.5
N3—Ta—Cl2	81.1 (2)	C4'—C5'—H5F	109.5
N3—Ta—N4	158.0 (3)	C4'—C6'—H6D	109.5
N4—Ta—Cl1	84.06 (18)	C4'—C6'—H6E	109.5
N4—Ta—Cl2	82.11 (18)	H6D—C6'—H6E	109.5
Cl2—Ta—Cl1	83.43 (8)	C4'—C6'—H6F	109.5
Ta—N1—C1	173.8 (8)	H6D—C6'—H6F	109.5
Ta—N2—C4	135.8 (11)	H6E—C6'—H6F	109.5
Ta—N2—C4'	135.9 (14)	N3—C7—C9	109.8 (8)
Ta—N3—C7	120.9 (5)	N3—C7—C8	108.4 (7)
Ta—N4—C10	119.1 (10)	C9—C7—C8	113.4 (8)
Ta—N4—C10'	116.3 (10)	N3—C7—H7	108.4
C4'—N2—H2	112.0	C9—C7—H7	108.4
C4—N2—H2	112.1	C8—C7—H7	108.4
Ta—N2—H2	112.1	C7—C8—H8A	109.5
C7—N3—H3A	107.1	C7—C8—H8B	109.5
Ta—N3—H3A	107.1	H8A—C8—H8B	109.5
C7—N3—H3B	107.1	C7—C8—H8C	109.5
Ta—N3—H3B	107.1	H8A—C8—H8C	109.5
H3A—N3—H3B	106.8	H8B—C8—H8C	109.5
C10—N4—H4A	107.5	C7—C9—H9A	109.5
C10'—N4—H4A	119.0	C7—C9—H9B	109.5
Ta—N4—H4A	107.5	H9A—C9—H9B	109.5
C10—N4—H4B	107.5	C7—C9—H9C	109.5
C10'—N4—H4B	98.1	H9A—C9—H9C	109.5
Ta—N4—H4B	107.5	H9B—C9—H9C	109.5
H4A—N4—H4B	107.0	N4—C10—C11	107.7 (13)
N1—C1—C3	111.8 (10)	N4—C10—C12	110.9 (15)
N1—C1—C2	109.5 (9)	C11—C10—C12	113.4 (12)
C3—C1—C2	114.0 (9)	N4—C10—H10	108.3
N1—C1—H1	107.1	C11—C10—H10	108.3
C3—C1—H1	107.1	C12—C10—H10	108.3
C2—C1—H1	107.1	C10—C11—H11A	109.5
C1—C2—H2A	109.5	C10—C11—H11B	109.5
C1—C2—H2B	109.5	H11A—C11—H11B	109.5
H2A—C2—H2B	109.5	C10—C11—H11C	109.5
C1—C2—H2C	109.5	H11A—C11—H11C	109.5
H2A—C2—H2C	109.5	H11B—C11—H11C	109.5
H2B—C2—H2C	109.5	C10—C12—H12A	109.5
C1—C3—H3C	109.5	C10—C12—H12B	109.5
C1—C3—H3D	109.5	H12A—C12—H12B	109.5
H3C—C3—H3D	109.5	C10—C12—H12C	109.5
C1—C3—H3E	109.5	H12A—C12—H12C	109.5
H3C—C3—H3E	109.5	H12B—C12—H12C	109.5
H3D—C3—H3E	109.5	N4—C10'—C11'	111.2 (17)
N2—C4—C5	106.1 (18)	N4—C10'—C12'	108.8 (13)
N2—C4—C6	108.0 (19)	C11'—C10'—C12'	113.3 (12)
C5—C4—C6	112.8 (13)	N4—C10'—H10'	107.8
N2—C4—H4	110.0	C11'—C10'—H10'	107.8
C5—C4—H4	110.0	C12'—C10'—H10'	107.8
C6—C4—H4	110.0	C10'—C11'—H11D	109.5
C4—C5—H5A	109.5	C10'—C11'—H11E	109.5
C4—C5—H5B	109.5	H11D—C11'—H11E	109.5
H5A—C5—H5B	109.5	C10'—C11'—H11F	109.5
C4—C5—H5C	109.5	H11D—C11'—H11F	109.5
H5A—C5—H5C	109.5	H11E—C11'—H11F	109.5
H5B—C5—H5C	109.5	C10'—C12'—H12D	109.5
C4—C6—H6A	109.5	C10'—C12'—H12E	109.5
C4—C6—H6B	109.5	H12D—C12'—H12E	109.5
H6A—C6—H6B	109.5	C10'—C12'—H12F	109.5
C4—C6—H6C	109.5	H12D—C12'—H12F	109.5
H6A—C6—H6C	109.5	H12E—C12'—H12F	109.5
N1—Ta—N2—C4'	−0.9 (19)	Cl2—Ta—N4—C10	−135.1 (9)
N4—Ta—N2—C4'	−99.7 (19)	Cl1—Ta—N4—C10	140.7 (9)
N3—Ta—N2—C4'	98.6 (19)	N1—Ta—N4—C10'	−52.2 (10)
Cl2—Ta—N2—C4'	−178.5 (17)	N2—Ta—N4—C10'	47.2 (10)
Cl1—Ta—N2—C4'	177.2 (19)	N3—Ta—N4—C10'	170.6 (10)
N1—Ta—N2—C4	−0.5 (13)	Cl2—Ta—N4—C10'	−148.9 (9)
N4—Ta—N2—C4	−99.3 (13)	Cl1—Ta—N4—C10'	126.9 (9)
N3—Ta—N2—C4	99.0 (13)	Ta—N2—C4—C5	129.0 (16)
Cl2—Ta—N2—C4	−178.1 (11)	Ta—N2—C4—C6	−109.8 (18)
Cl1—Ta—N2—C4	177.6 (13)	Ta—N2—C4'—C6'	−70 (4)
N1—Ta—N3—C7	−24.3 (7)	Ta—N2—C4'—C5'	158 (3)
N2—Ta—N3—C7	−124.1 (7)	Ta—N3—C7—C9	−151.0 (7)
N4—Ta—N3—C7	112.9 (8)	Ta—N3—C7—C8	84.6 (8)
Cl2—Ta—N3—C7	72.3 (6)	Ta—N4—C10—C11	93.8 (15)
Cl1—Ta—N3—C7	157.1 (6)	Ta—N4—C10—C12	−141.6 (13)
N1—Ta—N4—C10	−38.4 (10)	Ta—N4—C10'—C11'	142.6 (16)
N2—Ta—N4—C10	61.0 (10)	Ta—N4—C10'—C12'	−91.9 (17)
N3—Ta—N4—C10	−175.6 (10)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3A···Cl1^i	0.90	2.65	3.473 (7)	153
N4—H4A···Cl1^ii	0.90	2.75	3.547 (7)	148
N4—H4B···Cl2^ii	0.90	2.71	3.456 (7)	141

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