μ-Oxido-bis­[dichlorido­(diethyl­amido-κN)(diethyl­amine-κN)titanium(IV)]

In the title compound, [Ti₂(C₄H₁₀N)₂Cl₄O(C₄H₁₁N)₂], the bridging O atom resides on an inversion center, resulting in a 180° Ti—O—Ti bond angle.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.058
• wR factor = 0.153
• Data-to-parameter ratio = 18.9

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT360_ALERT_2_B Short  C(sp3)-C(sp3) Bond  C13    -   C14    ...       1.32 Ang.

Alert level C
PLAT128_ALERT_4_C Non-standard setting of Space group C2/c    ....    I2/a
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for        C13
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Ti1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N1
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        C11
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          9

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Ti1         (9)       4.06

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   6 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   5 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The structure of I was determined as part of an investigation into the effects of water on the synthesis of Ti(IV) complexes derived from secondary amines. Because the two titanium atoms in I are related by an inversion center on the bridging oxygen atom, the Ti—O—Ti bond angle is 180° indicating complete sp hybridization of the oxygen atom. This arises from dπpπ bonding through overlap of the p_x and p_y orbitals on oxygen with titanium d_xy and d_yz orbitals. Perfectly linear Ti—O—Ti complexes with oxygen as an inversion center have been reported (Krug & Müller, 1990; Thewalt & Schomburg, 1977). However, µ-oxo homodinuclear titanium species with Ti—O—Ti bond angles slightly less than 180° appear to be more common. (Honzíček et al., 2004; Levason et al., 2003; Mahrwald et al., 2001; Schormann, 2003)

In addition to the bridging oxygen in I, there is one diethylamido (N2) and one diethylamino (N1) group, as well as two chlorides (Cl1 and Cl2) coordinated to the titanium. Each titanium atom is best viewed as having distorted square pyramidal coordination geometry as judged by the τ-descriptor (Addison et al., 1984) which is 0.13 for this molecule. The amido group occupies the axial position, and Cl1, Cl2, N1 and O1 create the equatorial pseudo-square base. One chloride (Cl2) is trans to the bridging oxygen and the other chloride (Cl1) is trans to the amino group.

The diethylamido N atoms are nearly planar (N2 deviates from the Ti–C21–C23 plane by 0.077 (6) Å) as a result of strong pi interactions with the d⁰ Ti⁴⁺. Three of the four bond angles making up the base of the square pyramid in I are smaller than the ideal 90° (O1—Ti1—N1 = 82.49 (10)°, N1—Ti1—Cl2 = 83.20 (11)°, Cl2—Ti1—Cl1 = 89.73 (7)°). The four bond angles from the respective equatorial positions to the axial nitrogen are all larger than the ideal 90° and range from 102.09 (17)° to 108.65 (11)°. Deviation from ideal square pyramidal geometry can be attributed to electrostatic repulsions, particularly from the diethylamido nitrogen, and significant steric crowding around the Ti⁴⁺ centers.

Related literature

For related literature, see: Addison et al. (1984); Honzíček et al. (2004); Krug & Müller (1990); Levason et al. (2003); Mahrwald et al. (2001); Schormann (2003); Thewalt & Schomburg (1977).

S2. Experimental

While stirring under a nitrogen atmosphere, 2 ml (18.24 mmol) of TiCl₄ were added to approximately 60 ml of n-hexane in a Schlenk flask. Next, 0.16 ml (8.90 mmol) of distilled water mixed with 7.54 ml (72.90 mmol) of diethylamine was added dropwise to the solution. After 16 h of stirring, solid white diethylammonium chloride was removed by no-air filtration. The orange filtrate was evaporated to a minimal volume over a period of two days with a slow stream of nitrogen yielding X-ray quality crystals of I.

S3. Refinement

Hydrogen atoms were positioned geometrically and allowed to ride on their bonding partners with C—H distances = 0.96 Å and U_iso(H) = 1.5U_eq(C) for the methyl H atoms, C—H distances = 0.97 Å and U_iso(H) = 1.2U_eq(C) for the methylene H atoms, and N—H distance = 0.91 Å and U_iso(H) = 1.2U_eq(N) for the amino hydrogen.

Computing details

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 2003b); software used to prepare material for publication: SHELXTL (Sheldrick, 2003b).

Figures

Fig. 1. Thermal ellipsoid plot of I shown at the 30% probability level. Hydrogen atoms have been omitted for clarity. Square pyramidal coordination geometry around the titanium atoms shown inset. [Symmetry operation (i): -x + 1/2, -y + 1/2, -z + 1/2].

µ-Oxo-bis[dichlorido(diethylamido-κN)(diethylamine-κN)titanium(IV)]

Crystal data

[Ti2(C4H10N)2Cl4O(C4H11N)2]	F(000) = 1144
Mr = 544.14	Dx = 1.319 Mg m^−3
Monoclinic, I2/a	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2ya	Cell parameters from 3400 reflections
a = 13.204 (3) Å	θ = 4.5–49.2°
b = 10.131 (2) Å	µ = 0.99 mm^−1
c = 20.795 (5) Å	T = 298 K
β = 99.973 (3)°	Block, orange
V = 2739.7 (10) Å^3	0.40 × 0.35 × 0.20 mm
Z = 4

Data collection

Bruker SMART APEX diffractometer	2421 independent reflections
Radiation source: fine-focus sealed tube	1446 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.093
ω scans	θmax = 25.0°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003a)	h = −15→15
Tmin = 0.693, Tmax = 0.827	k = −12→12
10591 measured reflections	l = −24→24

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)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.153	H-atom parameters constrained
S = 0.93	w = 1/[σ^2(Fo^2) + (0.0883P)^2] where P = (Fo^2 + 2Fc^2)/3
2421 reflections	(Δ/σ)max = 0.004
128 parameters	Δρmax = 0.45 e Å^−3
0 restraints	Δρmin = −0.29 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
Ti1	0.21205 (5)	0.21280 (9)	0.32732 (4)	0.0574 (3)
Cl1	0.12134 (10)	0.02633 (18)	0.28158 (7)	0.0953 (6)
Cl2	0.09047 (11)	0.24341 (17)	0.39498 (9)	0.1030 (6)
O1	0.2500	0.2500	0.2500	0.0595 (11)
N1	0.2372 (3)	0.4269 (4)	0.34308 (18)	0.0729 (12)
H1A	0.2879	0.4479	0.3202	0.087*
C11	0.1437 (4)	0.4984 (6)	0.3087 (3)	0.0835 (16)
H11A	0.1142	0.4468	0.2707	0.100*
H11B	0.0935	0.5004	0.3377	0.100*
C12	0.1579 (6)	0.6342 (7)	0.2870 (4)	0.128 (3)
H12A	0.1932	0.6850	0.3230	0.192*
H12B	0.0920	0.6732	0.2713	0.192*
H12C	0.1978	0.6330	0.2526	0.192*
C13	0.2737 (5)	0.4784 (10)	0.4096 (3)	0.144 (3)
H13A	0.2316	0.5544	0.4155	0.173*
H13B	0.2593	0.4115	0.4401	0.173*
N2	0.3284 (2)	0.1426 (4)	0.37576 (16)	0.0595 (10)
C21	0.3131 (4)	0.0542 (6)	0.4290 (2)	0.0805 (17)
H21A	0.2433	0.0646	0.4369	0.097*
H21B	0.3592	0.0806	0.4684	0.097*
C22	0.3315 (5)	−0.0908 (7)	0.4159 (3)	0.111 (2)
H22A	0.2891	−0.1168	0.3757	0.166*
H22B	0.3145	−0.1433	0.4510	0.166*
H22C	0.4025	−0.1039	0.4129	0.166*
C23	0.4344 (3)	0.1478 (7)	0.3616 (2)	0.0812 (16)
H23A	0.4377	0.2151	0.3289	0.097*
H23B	0.4505	0.0637	0.3435	0.097*
C24	0.5138 (4)	0.1774 (8)	0.4206 (3)	0.116 (2)
H24A	0.4975	0.2594	0.4395	0.175*
H24B	0.5802	0.1839	0.4080	0.175*
H24C	0.5146	0.1077	0.4520	0.175*
C14	0.3706 (6)	0.5140 (10)	0.4276 (4)	0.163 (4)
H14A	0.4143	0.4526	0.4103	0.244*
H14B	0.3876	0.5145	0.4744	0.244*
H14C	0.3804	0.6008	0.4112	0.244*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ti1	0.0338 (4)	0.0910 (7)	0.0502 (5)	0.0052 (4)	0.0148 (3)	0.0161 (4)
Cl1	0.0633 (8)	0.1336 (14)	0.0909 (10)	−0.0350 (8)	0.0190 (7)	0.0076 (9)
Cl2	0.0806 (10)	0.1190 (13)	0.1287 (12)	0.0258 (8)	0.0724 (9)	0.0354 (10)
O1	0.054 (2)	0.078 (3)	0.048 (2)	0.004 (2)	0.0136 (19)	0.009 (2)
N1	0.052 (2)	0.111 (4)	0.059 (2)	−0.017 (2)	0.0183 (18)	−0.014 (2)
C11	0.072 (4)	0.083 (4)	0.094 (4)	−0.006 (3)	0.009 (3)	0.001 (3)
C12	0.137 (6)	0.090 (6)	0.169 (7)	0.000 (5)	0.060 (5)	0.008 (5)
C13	0.084 (4)	0.261 (10)	0.092 (5)	−0.041 (6)	0.023 (4)	−0.076 (6)
N2	0.0385 (18)	0.096 (3)	0.045 (2)	0.0096 (19)	0.0109 (15)	0.0081 (19)
C21	0.064 (3)	0.116 (5)	0.061 (3)	0.015 (3)	0.010 (2)	0.020 (3)
C22	0.102 (5)	0.101 (5)	0.123 (5)	0.019 (4)	0.002 (4)	0.022 (4)
C23	0.038 (2)	0.143 (5)	0.064 (3)	0.009 (3)	0.011 (2)	0.001 (3)
C24	0.051 (3)	0.188 (8)	0.105 (5)	−0.003 (4)	−0.002 (3)	0.001 (5)
C14	0.127 (7)	0.205 (10)	0.140 (7)	−0.053 (7)	−0.024 (6)	−0.050 (6)

Geometric parameters (Å, º)

Ti1—O1	1.8048 (8)	N2—C21	1.465 (6)
Ti1—N2	1.828 (3)	N2—C23	1.480 (5)
Ti1—N1	2.210 (5)	C21—C22	1.521 (8)
Ti1—Cl2	2.3314 (14)	C21—H21A	0.9700
Ti1—Cl1	2.3480 (18)	C21—H21B	0.9700
O1—Ti1^i	1.8049 (8)	C22—H22A	0.9600
N1—C13	1.479 (7)	C22—H22B	0.9600
N1—C11	1.502 (6)	C22—H22C	0.9600
N1—H1A	0.9100	C23—C24	1.499 (7)
C11—C12	1.470 (9)	C23—H23A	0.9700
C11—H11A	0.9700	C23—H23B	0.9700
C11—H11B	0.9700	C24—H24A	0.9600
C12—H12A	0.9600	C24—H24B	0.9600
C12—H12B	0.9600	C24—H24C	0.9600
C12—H12C	0.9600	C14—H14A	0.9600
C13—C14	1.320 (9)	C14—H14B	0.9600
C13—H13A	0.9700	C14—H14C	0.9600
C13—H13B	0.9700
O1—Ti1—N2	103.63 (10)	H13A—C13—H13B	106.9
O1—Ti1—N1	82.49 (10)	C21—N2—C23	115.5 (4)
N2—Ti1—N1	102.09 (17)	C21—N2—Ti1	116.2 (3)
O1—Ti1—Cl2	146.75 (6)	C23—N2—Ti1	127.6 (3)
N2—Ti1—Cl2	108.65 (11)	N2—C21—C22	114.1 (4)
N1—Ti1—Cl2	83.20 (11)	N2—C21—H21A	108.7
O1—Ti1—Cl1	90.46 (5)	C22—C21—H21A	108.7
N2—Ti1—Cl1	103.37 (14)	N2—C21—H21B	108.7
N1—Ti1—Cl1	154.52 (11)	C22—C21—H21B	108.7
Cl2—Ti1—Cl1	89.73 (7)	H21A—C21—H21B	107.6
Ti1—O1—Ti1^i	180.00	C21—C22—H22A	109.5
C13—N1—C11	112.5 (5)	C21—C22—H22B	109.5
C13—N1—Ti1	120.1 (5)	H22A—C22—H22B	109.5
C11—N1—Ti1	108.2 (3)	C21—C22—H22C	109.5
C13—N1—H1A	104.9	H22A—C22—H22C	109.5
C11—N1—H1A	104.9	H22B—C22—H22C	109.5
Ti1—N1—H1A	104.9	N2—C23—C24	113.4 (4)
C12—C11—N1	117.3 (5)	N2—C23—H23A	108.9
C12—C11—H11A	108.0	C24—C23—H23A	108.9
N1—C11—H11A	108.0	N2—C23—H23B	108.9
C12—C11—H11B	108.0	C24—C23—H23B	108.9
N1—C11—H11B	108.0	H23A—C23—H23B	107.7
H11A—C11—H11B	107.2	C23—C24—H24A	109.5
C11—C12—H12A	109.5	C23—C24—H24B	109.5
C11—C12—H12B	109.5	H24A—C24—H24B	109.5
H12A—C12—H12B	109.5	C23—C24—H24C	109.5
C11—C12—H12C	109.5	H24A—C24—H24C	109.5
H12A—C12—H12C	109.5	H24B—C24—H24C	109.5
H12B—C12—H12C	109.5	C13—C14—H14A	109.5
C14—C13—N1	120.3 (6)	C13—C14—H14B	109.5
C14—C13—H13A	107.3	H14A—C14—H14B	109.5
N1—C13—H13A	107.3	C13—C14—H14C	109.5
C14—C13—H13B	107.3	H14A—C14—H14C	109.5
N1—C13—H13B	107.3	H14B—C14—H14C	109.5

Symmetry code: (i) −x+1/2, −y+1/2, −z+1/2.