Search

Five bis(quinolylmethyl)-(1 H-indolylmethyl)amine (BQIA) compounds, that is, {(quinol-8-yl-CH2)2NCH2(3-Br-1 H-indol-2-yl)} ( L1H) and {[(8-R3-quinol-2-yl)CH2]2NCH(R2)[3-R1-1 H-indol-2-yl]} ( L2-5H) ( L2H: R1=Br, R2=H, R3=H; L3H: R1=Br, R2=H, R3= iPr; L4H: R1=H, R2=CH3, R3= iPr; L5H: R1=H, R2= nBu, R3= iPr) were synthesized and used to prepare calcium complexes. The reactions of L1-5H with silylamido calcium precursors (Ca[N(SiMe2R)2]2(THF)2, R=Me or H) at room temperature gave heteroleptic products ( L1, 2)CaN(SiMe3)2 ( 1, 2), ( L3, 4)CaN(SiHMe2)2 ( 3 a, 4 a) and homoleptic complexes ( L3, 5)2Ca ( D3, D5). NMR and X-ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L3-5)CaN(SiMe3)2) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of ( E)-1,2-bis(8-isopropylquinol-2-yl)ethane. [ABSTRACT FROM AUTHOR]