(2,4,6-Tris(trifluoromethyl)phenyl)palladium(II) Complexes

Abstract

Complexes containing one or two Fmes ligands (Fmes = 2,4,6-tris(trifluoromethyl)phenyl = nonafluoromesityl) either trans or cis are obtained by treating palladium(II) chloro complexes with Li(Fmes): trans-[PdCl2L2] (L = tetrahydrothiophene (tht), PPh3) lead to trans-[Pd(Fmes)ClL2] (L = tht, PPh3) or trans-[Pd(Fmes)2L2] (L = tht); [PdCl2(L-L)] (L-L = 1,5-cyclooctadiene, 2,2‘-bipyridine) give [Pd(Fmes)Cl(L-L)] (L-L = COD, bipy) or [Pd(Fmes)2(bipy)]. The structures of two complexes containing two Fmes ligands in trans and cis arrangement, trans-[Pd(Fmes)2(tht)2] (2) and [Pd(Fmes)2(bipy)] (6), respectively, have been determined by X-ray diffraction. In spite of the severe steric congestion the complexes are four coordinated. Distortions due to the bulkiness of the ortho substituents and short Pd···F3C-ortho distances are observed. The high degree of steric crowding is also responsible for slow rotation around the Pd−P bonds in the complex trans-[Pd(Fmes)Cl(PPh3)2]. ΔG ⧧ associated with this motion is 12.8 kcal mol-1, one of the highest values reported so far for rotation around M−PPh3 bonds. Complexes 2 and 6 are redox inactive by cyclic voltammetry in the range −1.8 to +1.8 V.

Synthesis, Coordination, and Spectroscopic Properties of 2,2′-Bipyridyldimesitylpalladium(II) and 6-Mesityl-2,2′-bipyridyldimesitylpalladium(II)

“…The molecular structure as shown in Figure 1 exhibits the expected cis square planar coordination sphere for the palladium atom. The bond lengths around the palladium atom and the bite angle of the bipyridine ligand are in the same range to those reported for [(bpy)Pd(FMes) 2 ] (3) (FMes = 2,4,6-Tris-(trifluoromethyl)phenyl) [2]. The poor dataset unfortunately precludes thorough discussion of bond lengths or angles, however some remarkable features in the molecular structure are inequivocal and worth to be mentioned.…”

“…The two mesityl substituents are tilt from the palladium coordination plane defined by N(1)/Pd/N(2) 72°and 66°respectively to a different extent. This contrasts to the findings for 3 or the ing cis-dimesityl arrangement [1,2,4]. A closer look ( Figure 2) reveals a nearly co-planar, graphite-like stacked arrangement of the two mesityl groups with rather short C±C contacts of 3.27 A Ê (C31±C11) or 3.32 A Ê (C35±C13), that is shorter than 3.354 A Ê found in graphite [5].…”

“…Wishing to extent this on the group 10 homologues we wanted to prepare the compound [(bpy)PdMes 2 ] and examine the spectroscopic and electrochemical behaviour. The synthesis and spectroscopic characterization of [(bpy)Pd(FMes) 2 ] (FMes = nonafluoromesityl or 2,4,6-tris-trifluoromethyl-phenyl) was recently reported by Espinet et al [2]. The molecular structure from X-Ray diffraction experiments reveals the effective axial shielding of the palladium atom from each one of the ortho-CF 3 (1) is the first step and under the choosen conditions only this molecule is accessible to arylation of the coordinated bipyridine ligand in the preferred 6-position.…”

Self-Assembly of Pyramidal Tetrapalladium Complexes with a Halide at the Apex

“…The reaction of precursors of “Pd(Fmes)” (Fmes=2,4,6‐tris(trifluoromethyl)phenyl) such as 1 or 2 (Scheme )7 with halides QX (the overall ratio of Pd:X is 4:5) in CH 2 Cl 2 affords high yields of the tetrametallic species Q[Pd 4 (Fmes) 4 X 5 ] ( 3 ) (X=Cl, Br, I; Q=PPh 4 or PPN (bis(diphenylphosphane)iminium)) 8. The formation of compounds 3 involves the displacement of MeCN and becomes easier in the order I>Br>Cl; thus, only for X=I is compound 3 readily formed starting from the MeCN‐rich complex 2 .…”

Straightforward Synthesis of CF3‐Substituted Triarylethenes by Stereoselective Threefold Cross‐Coupling Reactions

“…While elucidation of the origin of the stereochemical outcome awaits further study, a Pd···F interaction in the oxidative addition step may be operative. [12] In summary, we have developed a straightforward stereocontrolled synthesis of CF 3 -substituted triarylethenes. Further study of the coupling reactions of 1,1-dibromo-3,3,3-trifluoro-2-tosyloxypropene with other kinds of nucleophiles is in progress.…”