Mesityl bridges

Despite the absence of crystal structures, the presence of the mesityl bridging groups is confirmed in their IR spectra, which display the characteristic absorptions of these groups. 

The deviation from the linearity at the gold atom (C-Au-As angle of 166.8(4)°) is only moderate if compared with other complexes with bridging mesityl groups, e.g., [Au5(mes)5].83 It is noteworthy that the mesityl bridge is not symmetrically disposed, in contrast with the usual symmetrical disposition of the aryl ligand in the examples mentioned above. 

Now, to produce an Mes3Si" cation, we need to carry out an Mes/Me ligand exchange between the MeMes2Si" cation produced above and the third molecule of MeMes2SiH that has not reacted so far. A mesityl-bridged intermediate appears plausible for the process ... 

Even after the boron s electrophilicity has been arrested intermolecularly, intramolecular reorganization of the boraethene may still proceed. A remarkable instance is the structure 60 (by XRD) resulting from the oxidation of 57 by SnCl2. Intermediates in this impressive transformation might well be carbene 58 and boraethene 59. The borons in 59 are still sufficiently electrophilic to cause the mesityl group to bridge (Scheme l).61... 

Jakle and Wagner have communicated the synthesis of bromo-substituted, boranediyl-bridged poly(ferrocenylene)s (40) (Fig. 28) by the reaction of Fc(BBr2)2 with three equivalents of HSiEt3. The polymer 40 was transformed into the corresponding mesityl-substituted polymer (40Mes) by treating its slurry in toluene with... 

Organotellurium(II) derivatives, ArTeS2P(OR)2 (Ar = 4-MeOC6H4 or 4-EtOC6H4, R = Me or Et Ar = mesityl, R = Pr7) are supramolecular chain-like compounds, self-assembled through Te- S secondary bonds and bridging... 

A], with each of the heterometallic bonds supported by a bridging mesityl group of type A (Figure 4.51). In contrast with 451, which contains discrete tetranuclear cations, the trinuclear cations of 452 are further associated through Au-Au contacts of 3.132(2) A to form a unidimensional chain polymer (Figure 4.52a) [611]. 

Fig. 7. Energy-minimized structures of acetone and mesityl oxide adsorption complexes on a cluster model of HZSM-5 using DFT calculation. Note that in the case of the acetone complex, the proton remains bonded to the bridging oxygen, while in the case of the mesityl oxide complex, the proton is more fully transferred to the ketone. (Reprinted with permission from Haw et al. (7). Copyright 1996 American Chemical Society.)...

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