set of base metal catalysts has been developed for regiodivergent alkene hydrosilylations: iron complexes of phosphine‐iminopyridine are selective for anti‐Markovnikov hydrosilylations (linear/branched up to >99:1), while the cobalt complexes bearing the same type of ligands provide an unprecedented high level of Markovnikov selectivity (branched/linear up to >99:1). Both systems exhibit high efficiency
Cobalt Phosphino-α-Iminopyridine-Catalyzed Hydrofunctionalization of Alkenes: Catalyst Development and Mechanistic Analysis
作者:Wan-Yi Chu、Ryan Gilbert-Wilson、Thomas B. Rauchfuss、Maurice van Gastel、Frank Neese
DOI:10.1021/acs.organomet.6b00457
日期:2016.9.12
A family of CoCl2(PNpy) complexes were prepared, where PNpy = 2-iminopyridyl-phosphine ligands derived from amino-alkyl and aminoaryl phosphines and 2-keto- and 2-formylpyridines. Reduction of CoCl2(PNpy) complexes in the presence of PPh3 gave CoH(PNpy)(PPh3) and CoMe(PNpy)(PPh3), which were active for hydrofunctionalization of alkenes. According to DFT calculations, the CoMe(PNpy)(PPh3) complexes are best described as Co (II) derivatives of the anion [PNpy](-), with a labile PPh3 coligand. Metalation of Na[(Ph2)PC(2)N(H)py] gave the dimers [CoCl2(P(C2)N(H)py)](2). Monomeric complexes catalyze hydrosilylation of 1-octene with Ph2SiH2, with the CoCl2 ((iPr2)P(C3)N(H)py)/2NaBEt(3)H system exhibiting the highest rate and selectivity for anti-Markovnikov product. In situ NMR studies established the following: (i) silanes protonolyze catalyst precursors to give the. Co-silylcomplexes Co (SiR3) ((Ph2)P(C6H4)N(Ph)py)(pph(3)), (ii) alkenes compete with PPh3 to give Co(SiHPh2)((Ph2)P(C6H4)N(Ph)py) (eta(2)-alkene), (iii) ethylene inserts into the Co-Si bond to give Co(CH2CH3SiR3)((Ph2)P(C6H4)N(Ph)py)(pph(3)).
[EN] LIGAND COMPONENTS, ASSOCIATED REACTION PRODUCTS, ACTIVATED REACTION PRODUCTS, HYDROSILYLATION CATALYSTS AND HYDROSILYLATION CURABLE COMPOSITIONS INCLUDING THE LIGAND COMPONENTS, AND ASSOCIATED METHODS FOR PREPARING SAME<br/>[FR] COMPOSANTS DE LIGANDS, PRODUITS RÉACTIONNELS ASSOCIÉS, PRODUITS RÉACTIONNELS ACTIVÉS, CATALYSEURS D'HYDROSILYLATION ET COMPOSITIONS DURCISSABLES PAR HYDROSILYLATION COMPRENANT LES COMPOSANTS DE LIGAND ET LEURS PROCÉDÉS DE PRÉPARATION