Bis benzamidinate

In general, Group 4 benzamidinates show poor activities as olefin polymerization catalysts.158-162 However, bis(benzamidinate) complex (52) affords isotactic PP (>95% mmmm) at >7 atm propylene pressure 163 at ambient pressure atactic PP is produced.164 An unsymmetrical tris (benzamidinate) zirconium complex has also been shown to afford highly isotactic PP.165... 

Auer et al. [134] presented an example for multilayer formation and controlled deposition of functionalized nanoparticles on SAM of mercaptohexadecanoic acid (MHA) using electrostatic interactions. As a pH-sensitive switchable linker between the SAM of MHA and negatively charged gold nanoparticles, bis-benzami-dine bolaamphiphiles having different alkyl spacers were used [135]. This strategy resulted in a potentially tunable and switchable property of the entire assembly. For example, the kinetics of adsorption as well as the final particle layer thickness can be controlled by the kind of bis-benzamidine used as the linker (Fig. 9.16). 

Fig. 9.16 a) Schematic outline of the consecutive built-up of SAM/nanoparticle composites by means of charge interactions. Three different bis-benzamidines were used to serve as a linking layer, variing their alkyl chain... 

Bis(benzamidinate) zirconium catalysts (Figure 9, complexes F9-1 and F9-2) can polymerize propylene monomers into highly isotactic polypropylene (MAO up to 98% [mmmm, T = A9°C) at 25 °G in CH2CI2 under 9.2atm of propylene monomer, as expected from the G2-symmetric octahedral structure of the catalysts. The polymer-... 

Bis(benzamidinate)zirconium catalysts, for stereoselective propylene polymerization, 11, 708 Bis(r -benzene)tungsten, as metal vapor synthesis milestone, 1, 236... 

Silica-Supported Bis(benzamidinate) Zirconium Dimethyl Complexes. 80... 

Scheme 1 Synthesis route to the bis(benzamidinate) zirconium complexes 1-4 [41]...

Investigations of the bis(benzamidinate) dichloride or dialkyl complexes of Group 4 metals show that these complexes, obtained as a racemic mixture of c/s-octahedral compounds with C2 symmetry, are active catalysts for the polymerization of a-olefins when activated with MAO or perfluoroborane cocatalysts [29-41]. As was demonstrated above, polymerization of propylene with these complexes at atmospheric pressure results in the formation of an oily atactic product, instead of the expected isotactic polymer. The isotactic polypropylene (mmmm>95%, m.p.=153 °C) is formed when the polymerization is carried out at high concentration of olefin (in liquid propylene), which allows faster insertion of the monomer and almost completely suppresses the epimerization reaction. 

Table 6.5 Values Obtained for Tested bis-Benzamidines against Matriptase...

Enyedy IJ, Lee S-L, Kuo AH, Dickson RB, Lin C-Y, Wang S. Structure-based approach for the discovery of bis-benzamidines as novel inhibitors of matriptase. J Med Chem 2001 44 1349-1355. 

CAS 93841-83-9 EINECS/ELINCS 299-055-3 Synonyms Benzoic acid, 4-hydroxy-, hexamidine salt p-Hydroxybenzoic acid, compd. with p,p -[hexane-1,6-diylbis (oxy)] bis (benzamidine) (2 1) 4-Hydroxybenzoic acid, hexamidine salt p-Hydroxybenzoic acid, hexamidine salt... 

SCHEME 8.6 Proposed mechanism of isotactic/atactic stereoblock propylene polymerization with bis(benzamidinate) Zr(IV) complexes. Chain propagation at high monomer concentration would be site-controlled isotactic-selective, whereas at low monomer concentration it would become nonstereoselective owing to intramolecular growing chain epimerization. (Reprinted with permission from Volkis, V. Nelken-baum, E. Lisovskii, A. Hasson, G Semiat, R. Kapon, M. Botonshansky, M. Eishen, Y. Eisen, M. S. J. Am. Chem. Soc. 2003,125, 2179-2194. Copyright 2003 American Chemical Society.)... 

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