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A new family of benzimdazolin-2-iminato actinide−(IV) complexes [(Bim 7-Me Dipp/Me N)An(N(SiMe 3 ) 2 ) 3 ] (An = U ( 3 ), Th ( 4 )) and [(Bim 4-Me Dipp/Me N)An(N(SiMe 3 ) 2 ) 3 ] (An = U ( 5 ), Th ( 6 )) were synthesized and their solid state structures were established by single-crystal X-ray diffraction analysis. The catalytic performances of complexes 3 – 6 towards the homo- and cross-coupling of aldehydes (Tishchenko reaction) were studied and the thorium complexes 4 and 6 displayed moderate to high activities for the production of the corresponding symmetric and unsymmetrical esters. Coupling of aldehyde and alcohols, known as the tandem proton-transfer esterification, and the intermolecular coupling reaction between aldehyde and trifluoromethylketones were also investigated by these thorium complexes, indicating a complementary method to obtain unsymmetrical esters selectively. Plausible mechanisms for these reactions are proposed based on stoichiometric studies. [ABSTRACT FROM AUTHOR]

Four aluminum alkoxide complexes containing β-hydroxy-imino ligands, [(2,6-Me 2 C 6 H 3 )NCPhCH 2 CPh 2 O] 2 AlMe ( 3a ), [(2,6- i Pr 2 C 6 H 3 )NCPhCH 2 CPh 2 O] 2 AlMe ( 3b ), [(2,6-Me 2 C 6 H 3 )NCPhCH 2 C(C 12 H 8 )OAlMe 2 ] 2 ( 3c ) and [(2,6- i Pr 2 C 6 H 3 )NCPhCH 2 C(C 12 H 8 )OAlMe 2 ] 2 ( 3d ) were synthesized in high yields, and their structural features were provided. The catalytic behavior of those four complexes about the Tishchenko reaction with a range of aromatic aldehydes as substrates were assessed, and it present a synthetically useful protocol to the solvent-free Tishchenko reaction under mild conditions. [ABSTRACT FROM AUTHOR]

Bulky guanidinate stabilized homoleptic complexes of [LM(thf) n L] [L = {ArNC (N i Pr 2 )NAr} (Ar = 2,6- Me 2 –C 6 H 3 )]; M = Mg, Ca, and Zn; n = 0–1) have been synthesized with three different synthetic routes. First, treatment of bis{bis(trimethylsilyl)amide}s of Mg, Ca, and Zn i.e. [M{(N(SiMe 3 ) 2 } 2 ] (M = Mg, Ca(thf) 2 , and Zn) with free guanidine ligand (LH) at 80 ° C, elimination of NH(SiMe 3 ) 2 and formation of [LM(thf) n L] (M = Mg, Ca and Zn; n = 0–1) ( 3 – 5 ) complexes were occurred. Second, the reaction of two equivalents of potassium salt of LH with metal dihalides via salt metathesis led to the formation of homoleptic complexes. Third, the reaction between MR 2 (M = Mg, Ca, Zn; R = alkyl or OTf) and LH at reflux temperature, formation of bis(guanidinate) magnesium, calcium, and zinc complexes have been observed. The solid state structures of LH( 1 ), LK( 2 ) and all three bis(guanidinate) magnesium, calcium and zinc complexes ( 3 – 5 ) were confirmed by X-ray structural analysis. Furthermore, dimerization of a range of aromatic, heteroaromatic and aliphatic aldehydes (Tishchenko reaction) has been demonstrated by using catalysts 3 – 5 . [ABSTRACT FROM AUTHOR]

The dimerization of aldehydes to the analogous carboxylic esters (Tischenko reaction) has been achieved in impressive yields using the dilithium compounds containing bidentate di-anionic pyrrolyl ligands as initiators. The initiated intermediate {[2-( t BuNCH)C 4 H 3 NLi][PhCH 2 OLi(TMEDA)]} 2 was isolated and characterized by satisfactory C, H and N microanalysis, 1 H, 13 C{ 1 H} and 7 Li NMR spectra in pyridine-d 5 at ambient temperature, and single crystal X-ray structural data. The processes involve a redox reaction of 2-aminopyrrolyl dilithium compound with aldehyde. [ABSTRACT FROM AUTHOR]

Abstract: Treatment of mesoporous silicate SBA-15 with Sm[N(SiMe3)2]3 led to the formation of a novel organolanthanide/inorganic hybrid material [SBA-15]Sm[N(SiMe3)2] x via abstraction of N(SiMe3)2 by terminal silanol groups and subsequent surface silylation. The hybrid material was characterized by elemental analyses, IR spectroscopy, X-ray diffraction, and nitrogen sorption, indicating a successful tailoring inside the silicate SBA-15 and the maintenance of the well-ordered mesostructure. This hybrid material is a promising heterogeneous catalyst for the Tishchenko reaction, where it is superior to the homogeneous correspondent in deactivation behavior, reusability and relative tolerance to oxygen, particularly in the control of selectivity of mixed Tishchenko reaction due to the steric hindrance and the diffusion control derived from the surface confinement. [Copyright &y& Elsevier]