A rigid NON-donor pincer ligand was employed for the synthesis of neutral lutetium and anionic lanthanum alkyl complexes; the former is highly active for both intra- and inter-molecular hydroamination.
Reaction of H 2 XN 2 {4,5-bis(2,4,6-triisopropylanilino)-2,7-di- tert -butyl-9,9-dimethylxanthene} with [Lu(CH 2 SiMe 3 ) 3 (THF) 2 ], and crystallization from O(SiMe 3 ) 2 , yielded [(XN 2 )Lu(CH 2 SiMe 3 )(THF)]·(O(SiMe 3 ) 2 ) 1.5 ( 1 ·(O(SiMe 3 ) 2 ) 1.5 ). Lanthanum complexes of the XN 2 dianion were also prepared by salt metathesis; treatment of H 2 XN 2 with excess KH in DME produced the dipotassium salt, [K 2 (XN 2 )(DME) x ] ( x = 2–2.5), and subsequent reaction with [LaCl 3 (THF) 3 ] afforded [{(XN 2 )LaCl(THF)} x ]·(O(SiMe 3 ) 2 ) 0.25x ( 2 ·(O(SiMe 3 ) 2 ) 0.25x ; x = 1 or 2) after crystallization from O(SiMe 3 ) 2 . Compound 2 reacted with two equivalents of LiCH 2 SiMe 3 , to form the dialkyl-‘ate’ complex, [Li(THF) x ][(XN 2 )La(CH 2 SiMe 3 ) 2 ]·Toluene·LiCl ( 3 ·toluene·LiCl; x = 3). Both 1 and 3 ( x = 4) were structurally characterized, and were evaluated as catalysts for intramolecular hydroamination; while 3 showed poor activity, 1 is highly active for both intramolecular hydroamination and more challenging intermolecular hydroamination. Reactions with unsymmetrical alkenes yielded Markovnikov products, and the activity of 1 surpassed that of the previously reported yttrium analogue in the reaction of diphenylacetylene with 4- tert -butylbenzylamine.