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BY-NC-ND 3.0 license Open Access Published by De Gruyter (O) March 20, 2017

Crystal structure of chlorido{[3-(η5-cyclopenta-dienyl)-2,2,3-trimethyl-1-phenylbutylidene] azanido-κN}[η2(N,O)-N,N-dimethylhydroxylaminato]titanium(IV), C20H27ClN2OTi

Miloš Večeřa, Róbert Gyepes and Martin Lamač

Abstract

C20H27ClN2OTi, monoclinic, P21/c (no. 14), a = 9.4006(2) Å, b = 10.8185(3) Å, c = 19.4821(5) Å, β = 97.941(1)°, V = 1962.34(9) Å3, Z = 4, Rgt(F) = 0.0270, wRref(F2) = 0.0731, T = 150(2) K.

CCDC no.:: 1535293

The asymmetric unit of the title crystal structure is shown in the figure. Tables 1 and 2 contain details of the measurement method and a list of the atoms including atomic coordinates and displacement parameters.

Table 1

Data collection and handling.

Crystal:Red prism
Size:0.76 × 0.26 × 0.16 mm
Wavelength:Mo Kα radiation (0.71073 Å)
μ:5.8 cm−1
Diffractometer, scan mode:Bruker APEX-II, φ and ω
2θmax, completeness:55°, >99%
N(hkl)measured, N(hkl)unique, Rint:31967, 4511, 0.019
Criterion for Iobs, N(hkl)gt:Iobs > 2 σ(Iobs), 4047
N(param)refined:232
Programs:SHELX [1], Bruker programs [2, 3] , PLATON [4]

Table 2

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

AtomxyzUiso*/Ueq
Ti10.39233(2)0.72268(2)0.05916(2)0.01812(7)
Cl10.35931(4)0.74202(3)−0.06246(2)0.02734(9)
C10.24075(15)0.63584(12)0.13522(7)0.0226(3)
C20.37101(16)0.56768(12)0.14078(8)0.0267(3)
H20.44050.56300.18100.032*
C30.38117(19)0.50806(13)0.07722(9)0.0340(3)
H30.45770.45670.06730.041*
C40.25819(19)0.53828(14)0.03154(8)0.0350(4)
H40.23620.5103−0.01490.042*
C50.17244(16)0.61722(14)0.06604(7)0.0282(3)
H50.08350.65240.04640.034*
C60.17921(15)0.70290(13)0.19326(7)0.0237(3)
C70.01808(16)0.72491(16)0.17098(9)0.0347(3)
H7A0.00490.78620.13360.052*
H7B−0.02550.75550.21060.052*
H7C−0.02800.64710.15460.052*
C80.1943(2)0.61380(15)0.25581(8)0.0363(4)
H8A0.14540.53580.24210.055*
H8B0.15070.65130.29370.055*
H8C0.29620.59770.27130.055*
C90.25705(14)0.83111(12)0.21449(6)0.0211(3)
C100.18060(18)0.90025(14)0.26789(7)0.0311(3)
H10A0.17000.84510.30680.047*
H10B0.08550.92710.24600.047*
H10C0.23760.97260.28490.047*
C110.41417(16)0.81311(14)0.24663(7)0.0265(3)
H11A0.46060.89390.25450.040*
H11B0.46450.76440.21510.040*
H11C0.41760.76940.29090.040*
C120.25342(13)0.90590(12)0.14670(6)0.0182(2)
N10.30410(12)0.86165(10)0.09510(5)0.0197(2)
C130.18667(14)1.03220(12)0.13918(7)0.0212(3)
C140.25301(19)1.13288(14)0.17428(8)0.0341(3)
H140.33661.12100.20700.041*
C150.1977(2)1.25080(15)0.16178(11)0.0484(5)
H150.24491.31960.18520.058*
C160.0753(2)1.26878(17)0.11587(11)0.0529(6)
H160.03741.34970.10780.064*
C170.00728(19)1.16927(19)0.08144(10)0.0462(5)
H17−0.07831.18160.05010.055*
C180.06328(16)1.05091(15)0.09240(8)0.0305(3)
H180.01710.98280.06790.037*
O10.58651(11)0.70922(9)0.09743(5)0.0277(2)
N20.58926(13)0.82452(11)0.06261(6)0.0235(2)
C190.63339(17)0.92363(15)0.11208(8)0.0342(3)
H19A0.56780.92670.14700.051*
H19B0.63071.00280.08750.051*
H19C0.73130.90780.13490.051*
C200.68516(17)0.81764(17)0.00943(8)0.0360(4)
H20A0.78390.80400.03160.054*
H20B0.68010.8953−0.01670.054*
H20C0.65550.7490−0.02220.054*

Source of material

The title compound was obtained as a by-product during the preparation of [{η5-C5H4CMe2CMe2C(Ph) = N-κN}TiCl2] from [{η5-C5H4CMe2CMe2C(Ph) = N-κN}TiCl(NMe2)] as described in literature [5]. The by-product was formed in low yield (less than 10%) by a yet undisclosed mechanism (see the Discussion section) and crystallized from a concentrated toluene solution at 277 K as red prisms. NMR (benzene-d8) 1H: δ 0.86, 0.91, 0.94, 0.99(4x s, 3 H, CMe2), 2.45, 2.86(2x s, 3 H, NMe2) 5.68, 5.96, 6.04, 6.90(4x m, 1 H, C5H4), 6.98–7.17 (m, 5 H, Ph) ppm.

Experimental details

The structure was solved by direct methods (SHELXS [1]) and refined by full-matrix least-squares based on F2 (SHELXL [1]). All hydrogen atoms were included at their calculated positions and treated as riding atoms with the Uiso values assigned to a multiple of Ueq of their bonding carbon atom. The structural drawing and all numerical parameters were obtained with a recent version of the PLATON program [4].

Discussion

The chemistry of group 4 metal complexes bearing bifunctional cyclopentadienyl-ketimide ligands was recently studied aiming at functional group transformations and potential utilization in catalysis [5], [6], [7]. The title compound resulted as an undesired side-product of the conversion of titanium half-sandwich complex [{η5-C5H4CMe2CMe2C(Ph)=N-κN}TiCl(NMe2)] to the corresponding dichloride using Me3SiCl in toluene under exclusion of air and moisture [5]. The η2-N,N-dimethylhydroxylaminato moiety (cf. the figure) formed from the original dimethylamido ligand by an unknown mechanism, however, adventitious oxidation by air might be suspected as a plausible pathway since a similar transformation of the dimethylamido ligand by dioxygen was observed for tantalum(V) amido silyl complexes [8]. Related cyclopentadienyl titanium complexes with the η2-hydroxylaminato moiety were previously obtained by different approaches including reactions of Me2NOSiMe3 with CpTiCl3 [9] or N,N-dialkylhydroxylamines or nitroso compounds with methyl titanium precursors [10, 11] .

The title compound crystallizes in a centrosymmetric monoclinic space group P21/c as a racemate (the chiral center being situated at the unsymmetrically substituted titanium atom). The Cp-tethered ketimide moiety forms a formally six-membered azametallacycle with a non-planar conformation. The intramolecular tethering causes a significant distorsion of the ketimide from the ideal (close to linear) arrangement for its coordination to titanium. This distorsion can be characterized by the C12—N1—Ti1 angle of 145.62(9)° and it compares well with the values for related structurally characterized half sandwich Ti complexes [{η5-C5H4CMe2CMe2C(Ph)=N-κN}TiCl(NMe2)] (145.71(8)°) and [{η5-C5H4CMe2CMe2C(Ph)=N-κN}TiCl2] (146.52(12)°) or the metallocene compound [(η5-C5Me5){η5-C5H4CMe2CMe2C(Ph)=N-κN}TiCl] (150.16(11)°) [5]. The overall conformation of the Cp-ketimide ligand in the title compound is similar to the mentioned reference complexes. The distance Ti1—N1 1.8971(11) Å is only slightly longer than in [{η5-C5H4CMe2CMe2C(Ph)=N-κN}TiCl(NMe2)] (1.8877(10) Å). The Ti1—N2 bond of the η2-hydroxylaminato moiety is obviously much longer than in the above dimethylamido complex (2.1473(12) Å vs. 1.8797(10) Å), the value, however, compares reasonably well with that of the complex [(η5-C5H5)TiCl22-ONMe2)] (Ti-N distance of 2.128(2) Å) [9]. The Ti-O distance in the title compound, 1.8796(10) Å, is again only slightly longer than that reported for the discussed reference complex (1.866(1) Å) [9]. It shall be noted that no significant intermolecular interactions were detected in the title structure.

Acknowledgement

This work was supported by the Czech Science Foundation (project No. 14–08531S).

References

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Received: 2016-11-15
Accepted: 2017-2-28
Published Online: 2017-3-20
Published in Print: 2017-5-24

©2017 Miloš Večeřa et al., published by De Gruyter, Berlin/Boston

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.