supplementary materials


hg5360 scheme

Acta Cryst. (2013). E69, m676-m677    [ doi:10.1107/S1600536813031504 ]

Bis([mu]-2-hy­droxy­methyl-2-methyl­propane-1,3-diolato)bis­[di­chlorido­titanium(IV)] diethyl ether disolvate

A. J. Nielson, C. Shen and J. M. Waters

Abstract top

The title complex, [Ti2Cl4{CH3C(CH2O)2(CH2OH)}2], lies across a centre of symmetry with a diethyl ether solvent mol­ecule hydrogen bonded to the -CH2OH groups on either side of it. The TiIV atom is coordinated in a distorted octa­hedral geometry by a tripodal ligand and two terminal chloride atoms. There are three coordination modes for the tripodal ligand distinguishable on the basis of their very different Ti-O bond lengths. For the terminal alkoxo ligand, the Ti-O distance is 1.760 (1) Å, the asymmetric bridge system has Ti-O bond lengths of 1.911 (1) and 2.048 (1) Å. The Ti-O bond length for the alcohol O atom is the longest at 2.148 (1) Å.

Comment top

Transition metal complexes that arise from the tris-hydroxymethyl ethane ligand CH3C(CH2OH)3 are not widely reported in the literature. Structures identified by X-ray crystallography include the triply deprotonated form in cluster compounds of molybdenum and tungsten (Liu et al. 1990; Delmont et al. 2000) and dimeric and cluster compounds of chromium (Talbot-Eeckelaers et al. 2006), the doubly deprotonated form in dimeric vanadium-oxo complexes (Chang et al. 1993; Salta & Zubieta 1997) and the fully protonated form in monomeric yttrium complexes (Chen et al. 1997). For titanium only µ3–O and µ2–O coordination modes have been identified (Boyle et al. 1995).

When TiCl4 in diethyl ether was reacted with a mixture of CH3C(CH2OSiMe3)3 and CH3C(CH2OSiMe3)2(CH2OH) we obtained a small amount of colourless crystals analysing as TiCl2[(OCH2)2(HOCH2)CCH3]. 0.5 diethyl ether. One crystal was characterized by X-ray crystallography. The structure consists of a centrosymmetric dimer made up of two [(OCH2)2(HOCH2)CCH3] ligands forming a tripodal bridging system across two titanium atoms each of which also contain two terminal chloro ligands. One tripodal ligand is positioned above the two Ti atoms and out towards the rear of the molecule and the other is below and out the front with the two related by an inversion centre. The distorted octahedral geometry about Ti is made from one arm of a terminal alkoxo ligand (O2), another from an alcohol ligand (O3) and a third arm from the bridging alkoxo atoms (O1 and O1i). These latter each lie in trans-positions to the two cis-related chloro ligands.

For the terminal alkoxo ligand the Ti–O2 distance is 1.760 (1) Å which is indicative of strong π-bonding (see later). The asymmetric bridge system has Ti–O bond lengths of 1.991 (1) and 2.048 (7) Å and the Ti–Cl bonds trans to these bridging O atoms also show differences in length, 2.3184 (4) Å for Ti–Cl1 which is trans to the longer Ti–O1 and 2.3292 (4) Å for Ti–Cl2 which lies trans to the shorter Ti–O1i bond. The Ti–O bond length for the alcohol oxygen (Ti–O3) is the longest at 2.148 (1) Å. The strongly π-bonded terminal alkoxo ligand O atoms (O2, O2i) lie trans to the weak dative bonds made by the alcohol ligand O atoms (O3i, O3).

The overall coordination geometry and deprotonation features of the two ligands are identical with that found in the vanadium (v) complex {V2O2Cl2([(OCH2)2(HOCH2)CCH3]2} (Chang et al. 1993; Salta & Zubieta 1997). In {M2O4[(OCH2)3CCH3]2}2- (M = Mo, W) all three arms of the tripod are deprotonated (Liu et al. 1990; Delmont et al. 2000). Single deprotonation occurs in {Cr2Cl4([(OCH2)HOCH2)2(CEt]2} (Talbot-Eeckelaers et al. 2006).

The Ti–O bond lengths in the present complex reflect the various coordination modes in the molecule. The Ti–O1 bond lengths [1.991 (1) and 2.048 (1) Å] show the asymmetric nature of the bridging system across the two Ti atoms. The short Ti–O2 bond length [1.760 (1) Å] is associated with an alkoxo ligand. In comparison, terminal alkoxo ligand Ti–O bond lengths range from 1.702 (4) to 1.742 (6) Å in a variety of iso-propoxo Ti complexes (Gau et al. 1996). The dative nature of the alcohol ligand is shown by the longer Ti–O3 bond length [2.148 (1) Å] in the present complex being slightly longer than observed for isopropyl alcohol ligated to titanium [bond lengths 2.087 (4) and 2.093 (4) Å] (Wu et al. 1996). The Ti–Cl1 and Ti–Cl2 bond lengths [2.3184 (4) and 2.3292 (4) Å] do not differ significantly from each other and are typical of Ti–Cl bonds observed elsewhere. (Gau et al. 1996; Wu et al. 1996).

The strong π-donor nature of the alkoxo ligand oxygen is shown by the way other coordinated atoms push away from it [O2–Ti–O1, 86.71 (4); O2–Ti–O1i, 101.78 (5); O–2–Ti–Cl1, 97.18 (4); O2–Ti–Cl2, 93.95 (4)°]. For the dative Ti–O bond all the associated O3i–Ti–Y angles are 90° or below [range 80.17 (4) to 90.02 (3)°]. The bond angle associated with the bridging Ti–O1–Tii system [103.17 (4)°] does not differ significantly from comparable angles observed in other complexes. In this regard, it is noted that all known complexes have an alkoxo ligand making up the bridging system. The largest terminal Ti–O–C bond angle is associated with the alkoxo ligand [alkoxo Ti–O2–C3 angle 138.33 (9)° cf. alcohol Tii–O3–C4 angle 126.66 (9)°]. To accommodate the coordination mode of the various oxygen ligands across the two Ti atoms, the O–C–C bond angles of the tripod [range, 112.4 (1) to 113.3 (1)°] are slightly greater than the ideal tetrahedral angle.

Related literature top

For general background to Ti—O and Ti—Cl bonds, see: Gau et al. (1996); Wu et al. (1996). For closely related structures, see: Talbot-Eeckelaers et al. (2006); Chang et al. (1993); Salta & Zubieta (1997); Chen et al. (1997). For cluster compounds of this ligand type, see: Boyle et al. (1995); Delmont et al. (2000); Liu et al. (1990).

Experimental top

Using normal bench-top techniques for air-sensitive compounds, TiCl4 (1.25 g, 6.59 mmol) was cooled to dry-ice temperature and diethyl ether (50 ml) chilled to -20 °C was added. The mixture was warmed to room temperature, heated until all the yellow solid had dissolved and 1,1,1-tris(hydroxymethyl)ethane (2.2 g, 6.6 mmol) in diethyl ether (50 ml) was added to the rapidly stirred solution whereupon a dense colourless precipitate was formed. The mixture was refluxed for 3 h, cooled to room temperature and the remaining solid allowed to settle and the solution was filtered. The volume was reduced to ca 30 ml and the solution stood at -20 ° C whereupon a mass of crystalline colourless material was deposited. Found: C, 31.06; H, 6.15%. C14H30Cl4O6Ti2 (i.e. C10H20Cl4O6Ti2.diethyl ether) requires C, 31.61; H, 5.69%. A crystal was chosen from the mass and the X-ray crystal structure obtained. This molecule corresponded to C10H20Cl4O6Ti2.bis-diethyl ether.

Refinement top

All H atoms (except H3) were included in calculated positions and refined using a riding model with Uiso = 1.2Ueq(C) for H on secondary C atoms and 1.5Ueq(C) for those on tertiary C atoms. C—H distances of 0.99Å and 0.96Å were assumed for tertiary C and secondary C atoms respectively. H3 was located on a difference map and its x, y, z co-ordinates and isotropic thermal parameter refined.

Computing details top

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Siemens, 1995); data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. ORTEP diagram of molecule, at the 50% probability level, showing the numbering system. Symmetry code: (i) -x + 1, -y + 1, -z + 1.
Bis(µ-2-hydroxymethyl-2-methylpropane-1,3-diolato)bis[dichloridotitanium(IV)] diethyl ether disolvate top
Crystal data top
[Ti2Cl4(C5H10O3)2]·2C4H10OZ = 1
Mr = 622.10F(000) = 324
Triclinic, P1Dx = 1.462 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.9617 (3) ÅCell parameters from 5595 reflections
b = 9.6379 (4) Åθ = 2–25°
c = 10.5783 (5) ŵ = 0.98 mm1
α = 71.351 (1)°T = 150 K
β = 82.023 (1)°Plate, colourless
γ = 66.757 (1)°0.26 × 0.24 × 0.10 mm
V = 706.60 (5) Å3
Data collection top
Siemens SMART CCD
diffractometer
2661 independent reflections
Radiation source: fine-focus sealed tube2417 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.015
Area detector ω scansθmax = 25.7°, θmin = 2.0°
Absorption correction: multi-scan
(Blessing, 1995)
h = 99
Tmin = 0.766, Tmax = 0.892k = 1011
6510 measured reflectionsl = 012
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.022Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.061H atoms treated by a mixture of independent and constrained refinement
S = 1.04 w = 1/[σ2(Fo2) + (0.0325P)2 + 0.2355P]
where P = (Fo2 + 2Fc2)/3
2661 reflections(Δ/σ)max < 0.001
152 parametersΔρmax = 0.31 e Å3
0 restraintsΔρmin = 0.27 e Å3
Crystal data top
[Ti2Cl4(C5H10O3)2]·2C4H10Oγ = 66.757 (1)°
Mr = 622.10V = 706.60 (5) Å3
Triclinic, P1Z = 1
a = 7.9617 (3) ÅMo Kα radiation
b = 9.6379 (4) ŵ = 0.98 mm1
c = 10.5783 (5) ÅT = 150 K
α = 71.351 (1)°0.26 × 0.24 × 0.10 mm
β = 82.023 (1)°
Data collection top
Siemens SMART CCD
diffractometer
2661 independent reflections
Absorption correction: multi-scan
(Blessing, 1995)
2417 reflections with I > 2σ(I)
Tmin = 0.766, Tmax = 0.892Rint = 0.015
6510 measured reflectionsθmax = 25.7°
Refinement top
R[F2 > 2σ(F2)] = 0.022H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.061Δρmax = 0.31 e Å3
S = 1.04Δρmin = 0.27 e Å3
2661 reflectionsAbsolute structure: ?
152 parametersAbsolute structure parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 (Å2) top
xyzUiso*/Ueq
Ti0.58094 (3)0.61520 (3)0.39188 (2)0.01725 (9)
Cl10.74357 (5)0.59557 (5)0.19464 (4)0.02805 (11)
Cl20.47954 (5)0.88725 (4)0.35265 (4)0.02495 (10)
O10.43149 (13)0.59722 (11)0.56614 (9)0.0177 (2)
O20.76654 (13)0.57443 (12)0.48899 (10)0.0217 (2)
O30.66826 (14)0.32177 (13)0.70683 (10)0.0197 (2)
C10.4634 (2)0.65978 (17)0.66438 (14)0.0209 (3)
H1A0.37640.64900.74000.025*
H1B0.43840.77370.62370.025*
C20.6586 (2)0.57709 (17)0.71785 (15)0.0211 (3)
C30.7972 (2)0.60351 (19)0.60594 (15)0.0248 (3)
H3A0.78970.71370.58320.030*
H3B0.92210.53280.63820.030*
H30.721 (3)0.236 (3)0.737 (2)0.038 (6)*
C40.6997 (2)0.40296 (17)0.78961 (15)0.0227 (3)
H4A0.82880.35140.81780.027*
H4B0.62160.39340.87090.027*
C50.6733 (2)0.65305 (19)0.82181 (16)0.0296 (4)
H5A0.59240.63230.89810.044*
H5B0.63710.76720.78130.044*
H5C0.79970.60790.85220.044*
O110.89033 (14)0.03405 (12)0.82316 (10)0.0220 (2)
C110.7018 (2)0.0355 (2)1.01998 (16)0.0309 (4)
H11A0.76720.08911.04640.046*
H11B0.66350.03161.09990.046*
H11C0.59390.11430.96870.046*
C120.8258 (2)0.06469 (18)0.93561 (16)0.0276 (3)
H12A0.93060.14960.98890.033*
H12B0.75840.11420.90410.033*
C131.0030 (2)0.0498 (2)0.73231 (17)0.0305 (4)
H13A0.93180.09100.69450.037*
H13B1.10900.14010.77970.037*
C141.0679 (2)0.0633 (2)0.62220 (18)0.0375 (4)
H14A0.96240.14970.57320.056*
H14B1.14920.00740.56100.056*
H14C1.13430.10640.66090.056*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ti0.01564 (14)0.01876 (14)0.01493 (14)0.00583 (10)0.00015 (10)0.00266 (10)
Cl10.0258 (2)0.0379 (2)0.01864 (19)0.01292 (16)0.00543 (15)0.00699 (16)
Cl20.0292 (2)0.01963 (18)0.0251 (2)0.01055 (15)0.00415 (15)0.00208 (14)
O10.0167 (5)0.0178 (5)0.0160 (5)0.0040 (4)0.0002 (4)0.0047 (4)
O20.0178 (5)0.0266 (5)0.0192 (5)0.0073 (4)0.0004 (4)0.0058 (4)
O30.0222 (5)0.0149 (5)0.0202 (5)0.0041 (4)0.0047 (4)0.0046 (4)
C10.0239 (7)0.0196 (7)0.0181 (7)0.0051 (6)0.0006 (6)0.0084 (6)
C20.0241 (7)0.0200 (7)0.0196 (7)0.0070 (6)0.0026 (6)0.0070 (6)
C30.0248 (8)0.0308 (8)0.0221 (8)0.0129 (6)0.0025 (6)0.0078 (6)
C40.0273 (8)0.0217 (7)0.0188 (7)0.0074 (6)0.0051 (6)0.0057 (6)
C50.0405 (9)0.0274 (8)0.0245 (8)0.0122 (7)0.0050 (7)0.0108 (7)
O110.0222 (5)0.0197 (5)0.0201 (5)0.0051 (4)0.0000 (4)0.0042 (4)
C110.0341 (9)0.0376 (9)0.0224 (8)0.0189 (8)0.0021 (7)0.0046 (7)
C120.0321 (9)0.0237 (8)0.0244 (8)0.0124 (7)0.0032 (7)0.0002 (6)
C130.0270 (8)0.0294 (8)0.0296 (9)0.0014 (7)0.0008 (7)0.0130 (7)
C140.0289 (9)0.0492 (11)0.0312 (9)0.0110 (8)0.0069 (7)0.0151 (8)
Geometric parameters (Å, º) top
Ti—O21.7601 (10)C3—H3B0.9900
Ti—O1i1.9911 (10)C4—H4A0.9900
Ti—O12.0478 (10)C4—H4B0.9900
Ti—O3i2.1481 (11)C5—H5A0.9800
Ti—Cl12.3184 (4)C5—H5B0.9800
Ti—Cl22.3292 (4)C5—H5C0.9800
Ti—Tii3.1649 (5)O11—C131.4374 (19)
O1—C11.4501 (17)O11—C121.4413 (18)
O1—Tii1.9911 (10)C11—C121.502 (2)
O2—C31.4243 (18)C11—H11A0.9800
O3—C41.4473 (18)C11—H11B0.9800
O3—Tii2.1481 (11)C11—H11C0.9800
O3—H30.74 (2)C12—H12A0.9900
C1—C21.533 (2)C12—H12B0.9900
C1—H1A0.9900C13—C141.509 (3)
C1—H1B0.9900C13—H13A0.9900
C2—C41.523 (2)C13—H13B0.9900
C2—C31.533 (2)C14—H14A0.9800
C2—C51.542 (2)C14—H14B0.9800
C3—H3A0.9900C14—H14C0.9800
O2—Ti—O1i101.78 (5)C2—C3—H3A109.1
O2—Ti—O186.71 (4)O2—C3—H3B109.1
O1i—Ti—O176.83 (4)C2—C3—H3B109.1
O2—Ti—O3i172.39 (5)H3A—C3—H3B107.9
O1i—Ti—O3i80.17 (4)O3—C4—C2112.55 (12)
O1—Ti—O3i86.59 (4)O3—C4—H4A109.1
O2—Ti—Cl197.18 (4)C2—C4—H4A109.1
O1i—Ti—Cl193.21 (3)O3—C4—H4B109.1
O1—Ti—Cl1169.89 (3)C2—C4—H4B109.1
O3i—Ti—Cl190.02 (3)H4A—C4—H4B107.8
O2—Ti—Cl293.95 (4)C2—C5—H5A109.5
O1i—Ti—Cl2158.75 (3)C2—C5—H5B109.5
O1—Ti—Cl290.05 (3)H5A—C5—H5B109.5
O3i—Ti—Cl282.46 (3)C2—C5—H5C109.5
Cl1—Ti—Cl298.956 (16)H5A—C5—H5C109.5
O2—Ti—Tii95.24 (4)H5B—C5—H5C109.5
O1i—Ti—Tii39.05 (3)C13—O11—C12112.91 (12)
O1—Ti—Tii37.78 (3)C12—C11—H11A109.5
O3i—Ti—Tii81.61 (3)C12—C11—H11B109.5
Cl1—Ti—Tii132.238 (18)H11A—C11—H11B109.5
Cl2—Ti—Tii125.940 (16)C12—C11—H11C109.5
C1—O1—Tii124.13 (8)H11A—C11—H11C109.5
C1—O1—Ti118.13 (8)H11B—C11—H11C109.5
Tii—O1—Ti103.17 (4)O11—C12—C11108.69 (13)
C3—O2—Ti138.33 (9)O11—C12—H12A110.0
C4—O3—Tii126.66 (9)C11—C12—H12A110.0
C4—O3—H3106.5 (16)O11—C12—H12B110.0
Tii—O3—H3117.1 (16)C11—C12—H12B110.0
O1—C1—C2113.32 (11)H12A—C12—H12B108.3
O1—C1—H1A108.9O11—C13—C14108.13 (14)
C2—C1—H1A108.9O11—C13—H13A110.1
O1—C1—H1B108.9C14—C13—H13A110.1
C2—C1—H1B108.9O11—C13—H13B110.1
H1A—C1—H1B107.7C14—C13—H13B110.1
C4—C2—C1110.95 (12)H13A—C13—H13B108.4
C4—C2—C3112.76 (13)C13—C14—H14A109.5
C1—C2—C3110.72 (12)C13—C14—H14B109.5
C4—C2—C5107.06 (12)H14A—C14—H14B109.5
C1—C2—C5108.02 (12)C13—C14—H14C109.5
C3—C2—C5107.07 (13)H14A—C14—H14C109.5
O2—C3—C2112.41 (12)H14B—C14—H14C109.5
O2—C3—H3A109.1
Symmetry code: (i) x+1, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O110.74 (2)1.89 (2)2.6233 (14)168 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H3···O110.74 (2)1.89 (2)2.6233 (14)168 (2)
Acknowledgements top

We are grateful to Massey University for the award of a Post-Doctoral Fellowship to CS, and to Ms T. Groutso of the University of Auckland for the data collection.

references
References top

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