Reaction of 4,5-bis(2,4,6-triisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H 2 XN 2 ) with [Zr-(NMe 2 ) 4 ], followed by crystallization from O(SiMe 3 ) 2 , yielded [(XN 2 )Zr(NMe 2 ) 2 ]•{O(SiMe 3 ) 2 } 0.5 (1•{O(SiMe 3 ) 2 } 0.5 ). The zirconium dimethyl complex [(XN 2 )ZrMe 2 ] (2) was subsequently accessed (a) by treatment of 1•(O(SiMe 3 ) 2 ) 0.5 with excess AlMe 3 or (b) via reaction of 1•(O(SiMe 3 ) 2 ) 0.5 with excess Me 3 SiCl, affording [(XN 2 )ZrCl 2 ] (3) followed by reaction of 3 with 2 equiv of MeLi. Reaction of [(XN 2 )ZrMe 2 ] (2) with one equiv of B(C 6 F 5 ) 3 or [CPh 3 ][B(C 6 F 5 ) 4 ] yielded cationic [(XN 2 )ZrMe][MeB(C 6 F 5 ) 3 ] (4) and [(XN 2 )ZrMe(arene)][B(C 6 F 5 ) 4 ] {arene = η 6 -benzene (5a), η 6 -toluene (5b), or bromobenzene (5c)}, respectively. Both 4 and 5b are active for ethylene polymerization under 1 atm of ethylene at 24 and 80 °C in toluene with activities ranging from 23.5−883 kg mol −1 atm −1 h −1 , yielding polymers with weight-average molecular weights (M w ) of 70,800−88,100 g mol −1 and polydispersities (M w /M n ) of 3.94−4.67.

The palladium-catalyzed coupling of 4,5dibromo-2,7-di-tert-butyl-9,9-dimethylxanthene (XBr 2 ) with 2 equiv of 2,4,6-triisopropylaniline afforded the proligand 4,5bis(2,4,6-triisopropylanilino)-2,7-di-tert-butyl-9,9-dimethylxanthene (H 2 XN 2 ), and reaction of H 2 XN 2 with [Y-(CH 2 SiMe 2 R) 3 (THF) 2 ] (R = Me, Ph) produced the monoalkyl yttrium complexes [(XN 2 )Y(CH 2 SiMe 2 R)(THF)] (R = Me (1a), Ph (1b)). Neutral 1a showed near-zero ethylene polymerization activity (1 atm, 20 and 80 °C), and in the presence of AlMe 3 , 1a converted to [(XN 2 )Y{(μ-Me) 2 AlMe 2 }(THF)] (2). Compound 2 is thermally robust, and transfer of the XN 2 ligand from yttrium to aluminum was not observed even at elevated temperatures. However, [(XN 2 )AlMe] (3) was accessible via the reaction of H 2 XN 2 with AlMe 3 , demonstrating the ability of the wide-bite-angle XN 2 ligand to coordinate to much smaller aluminum(III). Neutral 1a proved to be highly active for both intra-and intermolecular hydroamination with various substrates, yielding Markovnikov products in the intermolecular hydroamination reactions with 1-octene. Article pubs.acs.org/Organometallics

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.

Dilithiation of 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethyl-xanthene (XBr 2 ) followed by addition of 2 equiv. of (2,4,6-triisopropylphenyl)dichlorophosphine (TrippPCl 2 ) afforded 4,5-bis[(2,4,6-triisopropylphenyl)chlorophosphino]-2,7di-tert-butyl-9,9-dimethylxanthene (XP 2 Cl 2 ), which was reduced to 4,5-bis[(2,4,6-triisopropylphenyl)phosphino]-2,7-di-tert-butyl-9,9-dimethylxanthene (H 2 XP 2 ) using excess LiAlH 4 . Deprotonation of H 2 XP 2 with excess KH in DME provided the dipotassium salt, [K 2 (XP 2 )(dme) n ] (1; n = 2.5-4), and stirring 1 in THF followed [a]