Synthesis and characterization of a tert-butyl ester-substituted titanocene dichloride: ^t-BuOOCCp₂TiCl₂

The synthesis and characterization of a new titanocene dichloride complex with tert-butyl esters appended to the cyclo­penta­diene rings is reported.

Abstract

Bis[η⁵-(tert-butoxyca­rbonyl)­cyclo­penta­dien­yl]di­chlorido­titanium(IV), [Ti(C₁₀H₁₃O₂)₂Cl₂], was synthesized from LiCp^COOt-Bu using TiCl₄, and was characterized by single-crystal X-ray diffraction and ¹H NMR spectroscopy. The distorted tetra­hedral geometry about the central titanium atom is relatively unchanged compared to Cp₂TiCl₂. The complex exhibits elongation of the titanium–cyclo­penta­dienyl centroid distances [2.074 (3) and 2.070 (3) Å] and a contraction of the titanium–chlorine bond lengths [2.3222 (10) Å and 2.3423 (10) Å] relative to Cp₂TiCl₂. The dihedral angle formed by the planes of the Cp rings [52.56 (13)°] is smaller than seen in Cp₂TiCl₂. Both ester groups extend from the same side of the Cp rings, and occur on the same side of the complex as the chlorido ligands. The complex may serve as a convenient synthon for titanocene complexes with carboxyl­ate anchoring groups for binding to metal oxide substrates.

Chemical context  

Mol­ecules exhibiting charge-separated excited states have been shown to be useful in photocatalysis (Prier et al., 2013 ▸), dye-sensitized photoelectrochemical cells (Hammarström, 2015 ▸; Kalyanasundaram & Grätzel, 1998 ▸) and dye-sensitized solar cells (DSSCs) (Ji et al., 2018 ▸; Kalyanasundaram & Grätzel, 1998 ▸). One architecture used in compounds of this type is the Donor–π bridge–Acceptor (D–π–A) architecture, where absorption of a photon results in the transfer of charge from an electron-rich donor portion of the mol­ecule to an electron-poor acceptor portion through a conjugated π-linkage (Ji et al., 2018 ▸). Alkynyl titanocenes utilizing titanocene acceptors and ferrocenyl or aryl­amine donors are promising candidates for sensitizers in DSSCs (Turlington et al., 2016 ▸; Pienkos et al., 2016 ▸, 2018 ▸; Livshits et al., 2019 ▸). In photovoltaic technologies, the sensitizer must be attached to a semiconductor substrate, commonly TiO₂, using an anchoring group exhibiting a high binding affinity for the substrate (Zhang & Cole, 2015 ▸; Kalyanasundaram & Grätzel, 1998 ▸). The most common anchoring group used with TiO₂ semiconductors is the carboxyl­ate, chosen for its strong binding and conjugated π-electron system (Galoppini, 2004 ▸). Anchoring groups with conjugated π systems allow for improved device efficiency in DSSCs compared to anchoring groups with aliphatic or unconjugated linkages (Zhang & Cole, 2015 ▸). In alkynyl titanocene sensitizers, the alkyn­yl–titanium bond is sensitive to acid hydrolysis. As a result, the carboxyl­ate anchor must be masked with a protecting group to avoid carb­oxy­lic acid inter­mediates. Our research group has focused primarily on the tert-butyl protecting group, because t-butyl esters are relatively stable and have well documented deprotection strategies under mild conditions (Jung & Lyster, 1977 ▸; Theodorou et al., 2018 ▸; Shaw et al., 2008 ▸). Herein, we report the synthesis, crystallization, and structural analysis of a t-butyl ester substituted titanocene dichloride that will serve as a convenient synthon for D–π–A titanocenes with carboxyl­ate anchoring groups.

Structural commentary  

While many titanocene and metallocene compounds have been characterized by X-ray diffraction, structures of ester-substituted metallocenes are comparatively rare. Here we present the structure of the t-butyl ester-substituted complex ^t-BuOOCCp₂TiCl₂ (Fig. 1 ▸). Though the data pool is small, our findings follow trends seen in previously reported structures. In the metallocenes of both vanadium and titanium, the addition of the ester shortens the metal–chlorine bond length by 0.02-0.04 Å [2.3222 (10) and 2.3423 (10) Å in the present titanocene] compared to the parent Cp₂VCl₂ (Tzavellas et al., 1996 ▸) and Cp₂TiCl₂ (Clearfield et al., 1975 ▸) complexes. A similar M—Cl bond contraction was not observed in the recent report of a titanocene with a bulky alkyl substituent appended to the Cp ring, (CpC(CH₃)₂CH₂CH(CH₃)₂)₂TiCl₂ (Ceballos-Torres et al., 2019 ▸), suggesting that the change is likely due to the inter­play of the electron-withdrawing nature of the ester and the π-donor character of the chlorido ligand. Furthermore, substitution at the Cp ring results in a slight elongation of the titanium–cyclo­penta­diene centroid distance [2.070 (3) and 2.074 (3) Å] by 0.011 to 0.015 Å in the ester-substituted titanocene here and as much as 0.016 Å in the alkyl substituted titanocene (Ceballos-Torres et al., 2019 ▸). However, this trend is not noticeable between ester-substituted and unsubstituted vanadocene dichloride (Klepalová et al., 2013 ▸; Tzavellas et al., 1996 ▸). Substitution of esters at the Cp ring has little effect on the bond angles formed about the central metal in both titanium and vanadium compounds, with a centroid—Ti—centroid angle of 129.90 (12)° and a Cl—Ti—Cl angle of 95.23 (4)° observed here. In titanocenes, substitution at the Cp ring results in a decrease of the dihedral angle formed between the planes of the two Cp rings. This angle is 58.5° in titanocene dichloride (Clearfield et al., 1975 ▸), but is 52.56 (13)° in this titanocene and 52.2° in the alkyl substituted titanocene (Ceballos-Torres et al., 2019 ▸). This trend is not observed between substituted and unsubstituted vanadocene dichloride, where the dihedral angle is approximately 48° for both (Tzavellas et al., 1996 ▸; Klepalová et al., 2013 ▸). The dihedral angle formed between the esters and their associated Cp rings differs more in the titanocene than in other ester-substituted metallocenes. In ^t-BuOOCCp₂TiCl₂, these two angles are 8.2 (6)° and 15.7 (3)°. In the other ester substituted metallocenes, the angles differ by less than a degree (18.37 and 18.37° in ^PhOOCCp₂VCl₂ and 10.78 and 11.36° in ^PhOOCCp₂NbCl₂) (Klepalová et al., 2013 ▸). The appended esters in ^t-BuOOCCp₂TiCl₂ extend from the same sides of both Cp rings, and occur on the same side of the complex as the chlorido ligands (Fig. 2 ▸). This is a similar arrangement to what occurs in ^EtOOCCp₂NbBr₂ and ^MeOOCCp₂NbBr₂·CH₂Cl₂, but differs from ^PhOOCCp₂VCl₂, ^PhOOCCp₂NbCl₂, and ^MeOOCCp₂NbBr₂, where the substituting esters are on opposing sides of their respective Cp rings, and also do not overlap with the halides (Klepalova et al., 2013 ▸).

Figure 1.

Structure of ^t-BuOOCCp₂TiCl₂ shown as 50% probability ellipsoids, with H atoms as small arbitrary spheres.

Figure 2.

Ligand orientation in the structure of ^t-BuOOCCp₂TiCl₂.

Supra­molecular features  

Inter­molecular contact geometries are shown in Table 1 ▸. Neighboring mol­ecules are connected along the c-axis direction via C9—H9⋯O1, C8—H8⋯Cl1, and C4—H4⋯Cl1 inter­actions to form chains (Fig. 3 ▸). Both Cp groups are angled toward the neighboring chlorine atom to enable these inter­actions. Neighboring mol­ecules along the a-axis are connected in a dimerized fashion via C7—H7⋯Cl1 inter­actions. The resulting packing diagram is shown in Fig. 4 ▸.

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4⋯Cl1i	0.95	2.78	3.632 (4)	149
C7—H7⋯Cl1ii	0.95	2.80	3.511 (4)	132
C8—H8⋯Cl1i	0.95	2.76	3.521 (3)	137
C9—H9⋯O1i	0.95	2.30	3.245 (4)	170

Symmetry codes: (i) ; (ii) .

Figure 3.

Chains of ^t-BuOOCCp₂TiCl₂ propagating along the c axis. Close contacts are depicted as dotted lines.

Figure 4.

Packing of mol­ecules viewed along the b axis.

Database survey  

A CSD search revealed nearly 200 hits for metallocene dichloride complexes, where the two cyclo­penta­diene ligands were monosubstituted (CSD Version 5.41, Update 2, May 2020; Groom et al., 2016 ▸). Of these, only two, CSD entries CICPIP (vanadium) and CICPOV (niobium) are substituted by a protected carboxyl­ate (Klepalová et al., 2013 ▸). Both of these utilize a phenyl-protecting group, and the carboxyl­ate carbon is bound to the Cp ring, similar to the tert-butyl-protected titanocene of the present study. Methyl- and ethyl-protected carboxyl­ate-substituted Cp ligands are reported in the niobium dibromide complexes CICPUB, CICQAI, and CICQEM (Klepalová et al., 2013 ▸).

Synthesis and crystallization  

Lithium tert-butyl ester cyclo­penta­dienide (Shaw et al., 2008 ▸) (2.0278 g, 11.78 mmol, 1 eq) was dissolved by the addition of THF (15 mL) under an argon atmosphere. The reaction solution was chilled to 195 K and 1 M TiCl₄ solution in toluene (6 ml, 6 mmol, 0.5 eq) was added via syringe. The solution changed from pale yellow to red–brown. After 5 minutes, the reaction was allowed to gradually warm to room temperature and stirred overnight. Solid impurities were filtered from the reaction mixture and the solvent was removed from the filtrate. Pentane (5 mL) was added, the mixture was filtered, and the solid impurities were washed with pentane and toluene. The solvent was removed from the filtrate and the resulting red porous solid was dissolved in CH₂Cl₂ (3 mL), and pentane (50 mL) was added to the solution. The solution was filtered, and the filtrate immediately began to form a precipitate in the filter flask. The resulting suspension was filtered yielding a red–orange powder (0.2823 g, 5.3% yield). ¹H NMR (400 MHz, C₆D₆) δ 6.95 (2H), 6.04 (2H), 1.42 (9H).

Single crystals suitable for X-ray analysis were grown by slow evaporation of a hexa­nes solution of the crude product, following the removal of solid impurities. The mixture was chilled to 243 K to encourage further crystallization.

Refinement  

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. Hydrogen atoms were placed in calculated positions using riding models, with C—H = 0.95 Å and U _iso(H) = 1.2U _eq(C) for aromatic hydrogen atoms, and C—H = 0.98 Å with U _iso(H) = 1.5U _eq(C) for methyl hydrogen atoms.

Table 2. Experimental details.

Crystal data
Chemical formula	[Ti(C10H13O2)2Cl2]
M r	449.21
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	100
a, b, c (Å)	29.3802 (19), 10.8106 (7), 13.6002 (9)
β (°)	91.214 (3)
V (Å3)	4318.7 (5)
Z	8
Radiation type	Mo Kα
μ (mm−1)	0.67
Crystal size (mm)	0.21 × 0.04 × 0.04
Data collection
Diffractometer	Bruker D8 Venture Photon 2
Absorption correction	Multi-scan (SADABS; Bruker, 2016 ▸)
T min, T max	0.923, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	18758, 4007, 3053
R int	0.057
(sin θ/λ)max (Å−1)	0.606
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.048, 0.106, 1.16
No. of reflections	4007
No. of parameters	250
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.43, −0.40

Computer programs: APEX3 (Bruker, 2017 ▸), SAINT (Bruker, 2013 ▸), SHELXT2016 (Sheldrick, 2015a ▸), SHELXL2016 (Sheldrick, 2015b ▸), Mercury (Macrae et al., 2020 ▸) and SHELXTL (Sheldrick, 2008 ▸).

Supplementary Material

CCDC reference: 2025817

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

supplementary crystallographic information

Crystal data

[Ti(C10H13O2)2Cl2]	F(000) = 1872
Mr = 449.21	Dx = 1.382 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 29.3802 (19) Å	Cell parameters from 8394 reflections
b = 10.8106 (7) Å	θ = 2.5–27.5°
c = 13.6002 (9) Å	µ = 0.67 mm−1
β = 91.214 (3)°	T = 100 K
V = 4318.7 (5) Å3	Column, orange
Z = 8	0.21 × 0.04 × 0.04 mm

Data collection

Bruker D8 Venture Photon 2 diffractometer	3053 reflections with I > 2σ(I)
Radiation source: Incoatec IµS	Rint = 0.057
φ and ω scans	θmax = 25.5°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Bruker, 2016)	h = −35→35
Tmin = 0.923, Tmax = 1.000	k = −13→13
18758 measured reflections	l = −16→16
4007 independent reflections

Refinement

Refinement on F2	Primary atom site location: dual
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.106	H-atom parameters constrained
S = 1.16	w = 1/[σ2(Fo2) + 22.4903P] where P = (Fo2 + 2Fc2)/3
4007 reflections	(Δ/σ)max = 0.001
250 parameters	Δρmax = 0.43 e Å−3
0 restraints	Δρmin = −0.40 e Å−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Ti1	0.39985 (2)	0.57278 (5)	0.53051 (4)	0.01683 (15)
Cl1	0.44127 (3)	0.55491 (8)	0.38592 (6)	0.0260 (2)
Cl2	0.33931 (3)	0.67945 (8)	0.45795 (7)	0.0306 (2)
O1	0.32753 (8)	0.3882 (2)	0.32835 (17)	0.0271 (6)
O2	0.27453 (7)	0.4207 (2)	0.44453 (16)	0.0209 (5)
O3	0.49135 (8)	0.8281 (2)	0.41841 (17)	0.0225 (5)
O4	0.42031 (7)	0.9091 (2)	0.43313 (16)	0.0189 (5)
C1	0.34941 (11)	0.4018 (3)	0.4973 (2)	0.0198 (7)
C2	0.39394 (11)	0.3550 (3)	0.4942 (3)	0.0224 (7)
H2	0.408032	0.320221	0.438385	0.027*
C3	0.41406 (12)	0.3689 (3)	0.5889 (3)	0.0249 (8)
H3	0.444351	0.347138	0.607694	0.030*
C4	0.38100 (12)	0.4210 (3)	0.6508 (3)	0.0258 (8)
H4	0.384986	0.438050	0.718950	0.031*
C5	0.34166 (12)	0.4429 (3)	0.5947 (2)	0.0213 (7)
H5	0.314378	0.479004	0.617586	0.026*
C6	0.44378 (11)	0.7612 (3)	0.5464 (2)	0.0178 (7)
C7	0.47120 (11)	0.6638 (3)	0.5840 (2)	0.0213 (7)
H7	0.499233	0.636551	0.558028	0.026*
C8	0.44979 (12)	0.6147 (3)	0.6661 (2)	0.0224 (8)
H8	0.460880	0.548674	0.705931	0.027*
C9	0.40869 (12)	0.6805 (3)	0.6796 (2)	0.0230 (7)
H9	0.387053	0.665144	0.729112	0.028*
C10	0.40562 (12)	0.7728 (3)	0.6066 (2)	0.0196 (7)
H10	0.381985	0.832252	0.599266	0.024*
C11	0.31673 (11)	0.4038 (3)	0.4130 (2)	0.0204 (7)
C12	0.23511 (11)	0.4317 (3)	0.3749 (2)	0.0225 (7)
C13	0.24101 (13)	0.5488 (4)	0.3142 (3)	0.0320 (9)
H13A	0.244351	0.620112	0.358322	0.048*
H13B	0.214238	0.560587	0.271051	0.048*
H13C	0.268247	0.541147	0.274311	0.048*
C14	0.23064 (13)	0.3153 (4)	0.3134 (3)	0.0340 (9)
H14A	0.255778	0.311161	0.267262	0.051*
H14B	0.201607	0.316717	0.276553	0.051*
H14C	0.231637	0.242684	0.356518	0.051*
C15	0.19555 (12)	0.4444 (4)	0.4438 (3)	0.0360 (10)
H15A	0.194513	0.371980	0.487035	0.054*
H15B	0.167056	0.450003	0.405259	0.054*
H15C	0.199488	0.519323	0.483578	0.054*
C16	0.45507 (11)	0.8354 (3)	0.4583 (2)	0.0194 (7)
C17	0.42166 (11)	0.9853 (3)	0.3432 (2)	0.0195 (7)
C18	0.45974 (11)	1.0803 (3)	0.3530 (3)	0.0229 (7)
H18A	0.457586	1.122955	0.416323	0.034*
H18B	0.456899	1.140675	0.299477	0.034*
H18C	0.489240	1.038412	0.349535	0.034*
C19	0.42567 (12)	0.9024 (3)	0.2540 (2)	0.0261 (8)
H19A	0.455422	0.861398	0.255688	0.039*
H19B	0.422678	0.952354	0.194043	0.039*
H19C	0.401518	0.839944	0.254504	0.039*
C20	0.37525 (11)	1.0482 (3)	0.3442 (3)	0.0249 (8)
H20A	0.351282	0.985237	0.344936	0.037*
H20B	0.371433	1.099788	0.285353	0.037*
H20C	0.373206	1.100149	0.403042	0.037*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Ti1	0.0185 (3)	0.0171 (3)	0.0147 (3)	−0.0010 (2)	−0.0016 (2)	0.0002 (2)
Cl1	0.0363 (5)	0.0266 (5)	0.0153 (4)	−0.0001 (4)	0.0043 (4)	−0.0021 (3)
Cl2	0.0258 (5)	0.0207 (4)	0.0448 (6)	−0.0005 (4)	−0.0140 (4)	0.0035 (4)
O1	0.0229 (13)	0.0381 (15)	0.0205 (13)	−0.0010 (11)	0.0017 (11)	−0.0086 (11)
O2	0.0158 (12)	0.0252 (13)	0.0217 (12)	−0.0017 (10)	0.0014 (10)	0.0020 (10)
O3	0.0187 (12)	0.0261 (13)	0.0227 (12)	0.0010 (10)	0.0046 (10)	0.0040 (10)
O4	0.0189 (12)	0.0203 (12)	0.0174 (11)	−0.0005 (9)	0.0000 (9)	0.0033 (9)
C1	0.0230 (17)	0.0133 (16)	0.0230 (17)	−0.0040 (13)	0.0005 (14)	0.0014 (13)
C2	0.0239 (18)	0.0147 (16)	0.0288 (19)	0.0003 (14)	0.0032 (15)	−0.0022 (14)
C3	0.0271 (19)	0.0163 (17)	0.0309 (19)	−0.0023 (14)	−0.0047 (16)	0.0086 (15)
C4	0.031 (2)	0.0252 (19)	0.0208 (17)	−0.0079 (16)	−0.0035 (15)	0.0067 (15)
C5	0.0246 (18)	0.0190 (17)	0.0204 (17)	−0.0033 (14)	0.0014 (14)	0.0055 (14)
C6	0.0196 (17)	0.0192 (17)	0.0145 (15)	−0.0056 (13)	−0.0012 (13)	−0.0012 (13)
C7	0.0165 (17)	0.0283 (19)	0.0187 (17)	−0.0089 (14)	−0.0064 (14)	0.0032 (14)
C8	0.0256 (18)	0.0264 (19)	0.0150 (16)	−0.0097 (15)	−0.0039 (14)	0.0011 (14)
C9	0.0262 (18)	0.0268 (18)	0.0159 (16)	−0.0079 (15)	0.0009 (14)	−0.0040 (14)
C10	0.0256 (18)	0.0169 (17)	0.0164 (16)	−0.0043 (14)	0.0032 (14)	−0.0054 (13)
C11	0.0220 (18)	0.0162 (16)	0.0230 (18)	−0.0051 (14)	0.0015 (15)	−0.0022 (14)
C12	0.0149 (16)	0.0302 (19)	0.0223 (17)	−0.0018 (14)	−0.0017 (14)	−0.0001 (15)
C13	0.025 (2)	0.037 (2)	0.034 (2)	−0.0052 (17)	−0.0070 (17)	0.0057 (18)
C14	0.028 (2)	0.031 (2)	0.043 (2)	−0.0076 (17)	−0.0038 (18)	−0.0079 (18)
C15	0.0198 (19)	0.044 (2)	0.044 (2)	0.0008 (17)	0.0000 (18)	0.000 (2)
C16	0.0194 (17)	0.0187 (17)	0.0200 (17)	−0.0021 (13)	−0.0020 (14)	0.0008 (14)
C17	0.0219 (17)	0.0231 (17)	0.0135 (16)	−0.0003 (14)	0.0012 (14)	0.0057 (13)
C18	0.0211 (17)	0.0216 (18)	0.0258 (18)	−0.0040 (14)	0.0000 (15)	0.0051 (15)
C19	0.0289 (19)	0.031 (2)	0.0183 (17)	−0.0029 (16)	−0.0023 (15)	−0.0005 (15)
C20	0.0214 (18)	0.0267 (19)	0.0265 (19)	0.0006 (15)	0.0018 (15)	0.0053 (15)

Geometric parameters (Å, º)

Ti1—Cl2	2.3222 (10)	C7—C8	1.397 (5)
Ti1—Cl1	2.3423 (10)	C7—H7	0.9500
Ti1—C9	2.348 (3)	C8—C9	1.417 (5)
Ti1—C8	2.376 (3)	C8—H8	0.9500
Ti1—C3	2.377 (3)	C9—C10	1.409 (5)
Ti1—C4	2.391 (3)	C9—H9	0.9500
Ti1—C5	2.392 (3)	C10—H10	0.9500
Ti1—C10	2.401 (3)	C12—C15	1.514 (5)
Ti1—C1	2.406 (3)	C12—C14	1.516 (5)
Ti1—C2	2.411 (3)	C12—C13	1.523 (5)
Ti1—C7	2.414 (3)	C13—H13A	0.9800
Ti1—C6	2.419 (3)	C13—H13B	0.9800
O1—C11	1.212 (4)	C13—H13C	0.9800
O2—C11	1.333 (4)	C14—H14A	0.9800
O2—C12	1.485 (4)	C14—H14B	0.9800
O3—C16	1.209 (4)	C14—H14C	0.9800
O4—C16	1.334 (4)	C15—H15A	0.9800
O4—C17	1.476 (4)	C15—H15B	0.9800
C1—C2	1.404 (5)	C15—H15C	0.9800
C1—C5	1.420 (5)	C17—C19	1.515 (5)
C1—C11	1.480 (5)	C17—C18	1.522 (4)
C2—C3	1.414 (5)	C17—C20	1.524 (5)
C2—H2	0.9500	C18—H18A	0.9800
C3—C4	1.415 (5)	C18—H18B	0.9800
C3—H3	0.9500	C18—H18C	0.9800
C4—C5	1.392 (5)	C19—H19A	0.9800
C4—H4	0.9500	C19—H19B	0.9800
C5—H5	0.9500	C19—H19C	0.9800
C6—C10	1.407 (5)	C20—H20A	0.9800
C6—C7	1.415 (5)	C20—H20B	0.9800
C6—C16	1.485 (4)	C20—H20C	0.9800
Cl2—Ti1—Cl1	95.23 (4)	Ti1—C4—H4	120.6
Cl2—Ti1—C9	100.97 (9)	C4—C5—C1	108.1 (3)
Cl1—Ti1—C9	135.73 (9)	C4—C5—Ti1	73.0 (2)
Cl2—Ti1—C8	133.62 (10)	C1—C5—Ti1	73.32 (19)
Cl1—Ti1—C8	110.13 (9)	C4—C5—H5	126.0
C9—Ti1—C8	34.90 (12)	C1—C5—H5	126.0
Cl2—Ti1—C3	136.89 (9)	Ti1—C5—H5	119.5
Cl1—Ti1—C3	96.52 (10)	C10—C6—C7	108.1 (3)
C9—Ti1—C3	98.96 (12)	C10—C6—C16	128.0 (3)
C8—Ti1—C3	79.42 (12)	C7—C6—C16	123.9 (3)
Cl2—Ti1—C4	116.44 (9)	C10—C6—Ti1	72.34 (18)
Cl1—Ti1—C4	130.53 (10)	C7—C6—Ti1	72.78 (18)
C9—Ti1—C4	76.84 (12)	C16—C6—Ti1	120.7 (2)
C8—Ti1—C4	75.41 (12)	C8—C7—C6	108.0 (3)
C3—Ti1—C4	34.53 (12)	C8—C7—Ti1	71.54 (18)
Cl2—Ti1—C5	84.24 (9)	C6—C7—Ti1	73.17 (18)
Cl1—Ti1—C5	130.25 (9)	C8—C7—H7	126.0
C9—Ti1—C5	92.44 (12)	C6—C7—H7	126.0
C8—Ti1—C5	105.26 (11)	Ti1—C7—H7	121.0
C3—Ti1—C5	57.00 (12)	C7—C8—C9	108.2 (3)
C4—Ti1—C5	33.83 (11)	C7—C8—Ti1	74.55 (18)
Cl2—Ti1—C10	77.43 (9)	C9—C8—Ti1	71.50 (18)
Cl1—Ti1—C10	113.76 (8)	C7—C8—H8	125.9
C9—Ti1—C10	34.50 (11)	C9—C8—H8	125.9
C8—Ti1—C10	57.10 (12)	Ti1—C8—H8	119.9
C3—Ti1—C10	132.89 (12)	C10—C9—C8	107.8 (3)
C4—Ti1—C10	109.79 (12)	C10—C9—Ti1	74.81 (18)
C5—Ti1—C10	114.57 (12)	C8—C9—Ti1	73.60 (19)
Cl2—Ti1—C1	80.71 (8)	C10—C9—H9	126.1
Cl1—Ti1—C1	96.20 (9)	C8—C9—H9	126.1
C9—Ti1—C1	126.83 (12)	Ti1—C9—H9	117.5
C8—Ti1—C1	131.31 (12)	C6—C10—C9	107.9 (3)
C3—Ti1—C1	56.87 (12)	C6—C10—Ti1	73.71 (18)
C4—Ti1—C1	56.65 (11)	C9—C10—Ti1	70.69 (18)
C5—Ti1—C1	34.43 (11)	C6—C10—H10	126.1
C10—Ti1—C1	144.11 (12)	C9—C10—H10	126.1
Cl2—Ti1—C2	110.28 (9)	Ti1—C10—H10	121.3
Cl1—Ti1—C2	77.53 (9)	O1—C11—O2	126.1 (3)
C9—Ti1—C2	131.86 (12)	O1—C11—C1	123.7 (3)
C8—Ti1—C2	112.71 (12)	O2—C11—C1	110.2 (3)
C3—Ti1—C2	34.35 (12)	O2—C12—C15	102.2 (3)
C4—Ti1—C2	56.84 (12)	O2—C12—C14	110.1 (3)
C5—Ti1—C2	56.80 (12)	C15—C12—C14	111.0 (3)
C10—Ti1—C2	166.30 (12)	O2—C12—C13	108.4 (3)
C1—Ti1—C2	33.89 (11)	C15—C12—C13	111.0 (3)
Cl2—Ti1—C7	125.31 (9)	C14—C12—C13	113.6 (3)
Cl1—Ti1—C7	79.83 (9)	C12—C13—H13A	109.5
C9—Ti1—C7	57.19 (12)	C12—C13—H13B	109.5
C8—Ti1—C7	33.92 (11)	H13A—C13—H13B	109.5
C3—Ti1—C7	97.59 (12)	C12—C13—H13C	109.5
C4—Ti1—C7	106.61 (11)	H13A—C13—H13C	109.5
C5—Ti1—C7	138.78 (11)	H13B—C13—H13C	109.5
C10—Ti1—C7	56.64 (12)	C12—C14—H14A	109.5
C1—Ti1—C7	153.80 (12)	C12—C14—H14B	109.5
C2—Ti1—C7	121.21 (12)	H14A—C14—H14B	109.5
Cl2—Ti1—C6	91.27 (8)	C12—C14—H14C	109.5
Cl1—Ti1—C6	81.89 (8)	H14A—C14—H14C	109.5
C9—Ti1—C6	57.05 (11)	H14B—C14—H14C	109.5
C8—Ti1—C6	56.65 (11)	C12—C15—H15A	109.5
C3—Ti1—C6	131.42 (12)	C12—C15—H15B	109.5
C4—Ti1—C6	130.38 (11)	H15A—C15—H15B	109.5
C5—Ti1—C6	147.78 (12)	C12—C15—H15C	109.5
C10—Ti1—C6	33.95 (11)	H15A—C15—H15C	109.5
C1—Ti1—C6	171.57 (11)	H15B—C15—H15C	109.5
C2—Ti1—C6	151.26 (12)	O3—C16—O4	126.9 (3)
C7—Ti1—C6	34.05 (11)	O3—C16—C6	122.8 (3)
C11—O2—C12	121.6 (3)	O4—C16—C6	110.3 (3)
C16—O4—C17	120.8 (3)	O4—C17—C19	109.7 (3)
C2—C1—C5	108.0 (3)	O4—C17—C18	109.7 (3)
C2—C1—C11	124.8 (3)	C19—C17—C18	113.6 (3)
C5—C1—C11	127.2 (3)	O4—C17—C20	101.6 (3)
C2—C1—Ti1	73.25 (19)	C19—C17—C20	110.9 (3)
C5—C1—Ti1	72.25 (18)	C18—C17—C20	110.8 (3)
C11—C1—Ti1	121.4 (2)	C17—C18—H18A	109.5
C1—C2—C3	107.8 (3)	C17—C18—H18B	109.5
C1—C2—Ti1	72.85 (19)	H18A—C18—H18B	109.5
C3—C2—Ti1	71.51 (19)	C17—C18—H18C	109.5
C1—C2—H2	126.1	H18A—C18—H18C	109.5
C3—C2—H2	126.1	H18B—C18—H18C	109.5
Ti1—C2—H2	121.3	C17—C19—H19A	109.5
C2—C3—C4	107.7 (3)	C17—C19—H19B	109.5
C2—C3—Ti1	74.14 (19)	H19A—C19—H19B	109.5
C4—C3—Ti1	73.3 (2)	C17—C19—H19C	109.5
C2—C3—H3	126.1	H19A—C19—H19C	109.5
C4—C3—H3	126.1	H19B—C19—H19C	109.5
Ti1—C3—H3	118.4	C17—C20—H20A	109.5
C5—C4—C3	108.3 (3)	C17—C20—H20B	109.5
C5—C4—Ti1	73.13 (19)	H20A—C20—H20B	109.5
C3—C4—Ti1	72.21 (19)	C17—C20—H20C	109.5
C5—C4—H4	125.8	H20A—C20—H20C	109.5
C3—C4—H4	125.8	H20B—C20—H20C	109.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···Cl1i	0.95	2.78	3.632 (4)	149
C7—H7···Cl1ii	0.95	2.80	3.511 (4)	132
C8—H8···Cl1i	0.95	2.76	3.521 (3)	137
C9—H9···O1i	0.95	2.30	3.245 (4)	170

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

Funding Statement

This work was funded by National Science Foundation grants CHE-1362516 and OIA-1655740.