Nathanael A Hirscher1, Danny Perez Sierra1, Theodor Agapie1. 1. Division of Chemistry and Chemical Engineering , California Institute of Technology , 1200 East California Boulevard , MC 127-72, Pasadena , California 91125 , United States.
Abstract
We have introduced a new class of stable organometallic Cr reagents (compounds 1-4) that are readily prepared, yet reactive enough to serve as precursors. They were used for ethylene tetramerization catalysis following stoichiometric activation by in situ protonation. This study highlights the importance of balancing stability with reactivity in generating an organometallic precursor that is useful in catalysis. Moreover, precursor 4 allowed for the isolation and crystallographic characterization of a room-temperature stable cationic species, (PNP)CrR2+ (R = o-C6H4(CH2)2OMe, PNP = iPrN(PPh2)2). This complex (5) may be used as a single component precatalyst, without any alkylaluminum reagents. This result provides an unprecedented level of insight into the kind of structures that must be produced from more complicated activation processes.
We have introduced a new class of stable organometallic n class="Chemical">Cr reagents (compounds 1-4) that are readily prepared, yet reactive enough to serve as precursors. They were used for ethylene tetramerization catalysis following stoichiometric activation by in situ protonation. This study highlights the importance of balancing stability with reactivity in generating an organometallic precursor that is useful in catalysis. Moreover, precursor 4 allowed for the isolation and crystallographic characterization of a room-temperature stable cationic species, (PNP)CrR2+ (R = o-C6H4(CH2)2OMe, PNP = iPrN(PPh2)2). This complex (5) may be used as a single component precatalyst, without any alkylaluminum reagents. This result provides an unprecedented level of insight into the kind of structures that must be produced from more complicated activation processes.
Authors: Matthew J Overett; Kevin Blann; Annette Bollmann; John T Dixon; Daleen Haasbroek; Esna Killian; Hulisani Maumela; David S McGuinness; David H Morgan Journal: J Am Chem Soc Date: 2005-08-03 Impact factor: 15.419
Authors: Annette Bollmann; Kevin Blann; John T Dixon; Fiona M Hess; Esna Killian; Hulisani Maumela; David S McGuinness; David H Morgan; Arno Neveling; Stefanus Otto; Matthew Overett; Alexandra M Z Slawin; Peter Wasserscheid; Sven Kuhlmann Journal: J Am Chem Soc Date: 2004-11-17 Impact factor: 15.419