ABSTRACT
The overall neutral α-borylated phosphorus ylide Ph3PC(Me)BEt2 behaves like a polar borataalkene and can act as acyclic, ambiphilic π-type ligand with L- and Z-type functionalities side by side. In the complexes [MX{η2-Ph3PC(Me)BEt2}] (M = Cu, (Ag), Au; X = Cl, NTf2), the bonding is dominated by the highly nucleophilic ylidic carbon atom (L-type ligand). The Lewis acidic boron atom furnishes nonetheless a small but significant bonding contribution (Z-type ligand).
ABSTRACT
The influence of substituents on α-borylated phosphorus ylides (α-BCPs) has been investigated in a combined experimental and quantum chemical approach. The synthesis and characterization of Me3 PC(H)B(iBu)2 (1), consisting of small Me substituents on phosphorous and iBu residues on boron, is reported. Compound 1 is accessible through a novel synthetic approach, which has been further elucidated through DFT studies. The reactivity of 1 towards various small molecules was probed and compared with that of a previously published derivative, Ph3 PC(Me)BEt2 (2). Both α-BCPs react with NH3 to undergo heterolytic N-H bond cleavage. Different di- and trimeric ring structures were observed in the reaction products of 1 with CO and CO2 . With PhNCO and PHNCS, the expected insertion products [Me3 PC(H)(PhNCO)B(iBu)2 ] and [Me3 PC(H)(PhNCS)B(iBu)2 ], respectively, were isolated.
ABSTRACT
Known for about 25 years, the bis(trimethylsilyl)amides of Group 3 metals and lanthanides, M[N(SiMe3 )2 ]3 , are well suited as highly efficient catalysts for the dimerization of aldehydes [Tishchenko reaction, Eq. (1)].
