Isolation of a hexanuclear chromium cluster with a tetrahedral hydridic core and its catalytic behavior for ethylene oligomerization

Abstract

A chromium complex [2-(NHCH2PPh2)C5H 4N]CrCl3·THF2 (1) of the ligand PyNHCH2PPh2 has been synthesized, characterized, and examined for its catalytic behavior toward ethylene oligomerization. When complex 1 was treated with (i-Bu)3Al, an unprecedented divalent polyhydride chromium cluster μ,κ1,κ2, κ3-N,N,P-{[2-(NCH2PPh2)C 5H4N]Cr(μ-H)}4[(μ-Cl)Cr(μ-Cl)Al(i-Bu) 2Cl]2 (2) was obtained. The complex contains a Cr 4H4 core, which is expected to be diamagnetic, and which remains coordinated to two additional divalent high-spin Cr atoms via bridging interactions. Two aluminate residues remain bonded to the peripheral chromium atoms. The structure, magnetism, and electronic configuration are herein discussed. © 2014 American Chemical Society.