(5,10,15,20-Tetraphenylporphyrinato-κ4 N)(2,2,2-trifluoro-1-phenylethylidene-κC 1)ruthenium(II): a stable fluorinated alkylidene complex of a ruthenium(II) porphyrin

In the title compound, [Ru(C44H28N4)(C8H5F3)], the fluorinated alkylidene group is bound to a five-coordinate Ru atom, which is located toward the carbene C atom, 0.3301 (5)Å from the least-squares plane of the C20N4 porphyrin core. The Ru=C bond is tilted slightly from the normal to the C20N4 least-squares plane due to steric repulsion between the porphyrinate ligand and the bulky trifluoromethyl group. The Ru=C bond length of 1.838 (2) Å is comparable with those in bis(subsituted phenyl)carbene analogs.

In the title compound, [Ru(C 44 H 28 N 4 )(C 8 H 5 F 3 )], the fluorinated alkylidene group is bound to a five-coordinate Ru atom, which is located toward the carbene C atom, 0.3301 (5)Å from the least-squares plane of the C 20 N 4 porphyrin core. The Ru C bond is tilted slightly from the normal to the C 20 N 4 least-squares plane due to steric repulsion between the porphyrinate ligand and the bulky trifluoromethyl group. The Ru C bond length of 1.838 (2) Å is comparable with those in bis(subsituted phenyl)carbene analogs.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LX2062). (5,10,15, N)(2,2,2-trifluoro-1-phenylethylidene-C 1 )ruthenium(II): a stable fluorinated alkylidene complex of a ruthenium(II) porphyrin H. Yuge, N. Arakawa, S. Wada and T. K. Miyamoto Comment Ruthenium(II)-porphyrin-carbene complexes have been studied as effective and stereoselective catalysts for cyclopropanation or epoxidation of some alkenes (Che & Huang, 2002). In order to improve their robustness, activity or selectivity toward the reactions a number of compounds have been invented and applied for the reactions under different conditions (Li et al., 2004;Wada et al., 2008). It is important to introduce fluorine atom(s) for a tuning of the catalysts, taking advantage of its high electronegativity (Seebach, 1990). Surveying the carbene complexes of transition metals, few crystal structures of fluorinated alkylidene complexes have been known, especially in that fluorine atom(s) is attached to the β-carbon atom adjacent to the carbene carbon (α-carbon) atom. With ruthenium(II)-tetraphenylporphyrinate (tpp), we have prepared a highly stable fluorinated alkylidene complex [Ru(tpp){═C(CF 3 )Ph}] (I), and present here its X-ray structure that features the trifluoromethyl group attached to the carbene carbon atom directly.
As shown in Fig. 1, the five-coordinate ruthenium atom is bound to the carbene carbon atom to which the phenyl and trifluoromethyl groups are attached, lying in a distorted square-pyramidal geometry in (I). There seems to be no remarkable difference in the bond lengths and angles about the carbene carbon atom, compared with those for the five-coordinate ruthenium(II)-porphyrin analogs reported so far, in the ranges 1.82-1.87 Å and 111-118° (Li et al., 2004;Wada et al., 2008). The porphyrin core in (I) is deformed in domed conformation with maximum and minimum deviations from the C 20 N 4 least-squares plane of 0.205 (2) and -0.209 (2) Å for N1 and C17, respectively. The trifluoromethyl group has so large van der Waals radius (2.7 Å) (Seebach, 1990) that the steric repulsion toward the porphyrin core would affect some structural features. The ruthenium atom is situated at 0.3301 (5) Å out of the C 20 N 4 least-squares plane toward the carbene moiety in (I), while the displacements are 0.216 (2)-0.287 (1) Å in other tetraphenyl-or tetra(p-tolyl)porphyrin complexes (Wada et al., 2008). In addition, the Ru═C45 bond is slightly tilted from the normal to the C 20 N 4 least-squares plane, as  (Table 1; Hunter et al., 2001).

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.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.