Benzonitrile Insertion into Silylarylamides – <i>ansa</i>‐Bis(benzamidinate) Ligand Systems with Rigid <i>o</i>‐ and <i>m</i>‐Phenylene Linkers in the Synthesis of Lithium and Rare Earth Complexes

Abstract

Abstract The reactions of the lithium silylarylamides [1,2‐C 6 H 4 (NSiMe 3 ) 2 Li 2 ] 2 and [1,3‐C 6 H 4 (NSiMe 3 ) 2 Li 2 ] with two equivalents of PhCN [tetrahydrofuran (thf), room temp.] is an efficient synthetic approach to the ansa ‐bis(amidinate) ligand systems [1,2‐C 6 H 4 {NC(Ph)NSiMe 3 } 2 Li 2 (thf)] 2 and [1,3‐C 6 H 4 {NC(Ph)NSiMe 3 } 2 Li 2 (thf) 2 ] 2 , which were isolated in 54 and 60 % yields, respectively. However, lithium silylarylamide [2,6‐C 5 H 3 N(NSiMe 3 ) 2 Li 2 ] containing a pyridine fragment does not undergo PhCN insertion even at elevated temperatures (thf, toluene), and the reaction affords the silylarylamido complex [2,6‐C 5 H 3 N{NSiMe 3 } 2 Li 2 ] 3 · (C 6 H 5 CN) 4 , which contains a coordinated benzonitrile molecule. The different reactivity of the compounds correlates with the changes in the molecular orbital energies estimated by DFT calculations. The salt metathesis reaction of anhydrous YCl 3 with lithium amidinate [1,2‐C 6 H 4 {NC(Ph)NSiMe 3 } 2 Li 2 (thf)] 2 in 2:1 molar ratio (thf, 20 °C) afforded a neutral bis(amidinate) chloro yttrium complex [1,2‐C 6 H 4 {NC(Ph)NSiMe 3 } 2 ]YCl(thf) 2 in 80 % yield. With NdCl 3 , the analogous reaction resulted in a trinuclear neodymium chloro ate complex with a rather unusual μ‐bridging lateral coordination of the amidinate fragment [1,2‐C 6 H 4 {NC(Ph)NSiMe 3 } 2 Nd(thf)(μ‐Cl)(1,2‐C 6 H 4 {NC(Ph)NSiMe 3 } 2 Nd{μ‐Cl} 2 )][Li(thf) 2 ].