Alkyl yttrium complexes of doubly cyclometallated xanthene- and naphthalene-backbone bis(phosphinimine) ligands

The synthesis of a rigid 4,5-bis(triphenylphosphinimino)-2,7-di-tert-butyl-9,9-dimethylxanthene {(Ph3PN)(2)XT} ligand is outlined, along with a modified synthesis for previously reported 1,8-bis(triphenylphosphinimino)naphthalene {(Ph3PN)(2)NAP}. Reaction of neutral (Ph3PN)(2)XT with [Y(CH2SiMe3)(3)(THF)(2)] resulted in double cyclometallation, yielding the base-free monoalkyl complex, [({Ph-2(C6H4)PN2XT)Y(CH2SiMe3)] (1). Layering a concentrated THF solution of 1 with hexanes at -28 degrees C afforded THF-coordinated [({Ph-2(C6H4)PN}(2)XT)Y(CH2SiMe3)(3)(THF)]center dot 2THF (1-THF center dot 2THF), with a distorted pentagonal bipyramidal geometry and approximately meridional coordination of the pentadentate {Ph-2(C6H4)PN}(2)XT dianion. Similarly, (Ph3PN)(2)NAP reacted with [Y(CH2SiMe3)(3)(THF)(2)] to afford a THF-coordinated monoalkyl complex, [{(Ph-2(C6H4)PN)(2)NAP}Y(CH2SiMe3)(THF)] (2-THF). Layering a DME solution of 2-THF with hexanes at -28 degrees C afforded X-ray quality crystals of [[{(Ph-2(C6H4)PN)(2)NAP} Y(CH2SiMe3)(kappa(2)-DME)]center dot hexane (2-DME center dot hexane), with a highly distorted pentagonal bipyramidal geometry and a facial coordination mode of the tetradentate {Ph-2(C6H4)PN}(2)NAP dianion. (c) 2019 Elsevier B.V. All rights reserved.