Synthesis, Characterization, and Reactivity Studies of New Cyclam-Based Y(III) Complexes

[(Bn₂Cyclam)Y(N(SiMe₃)₂)] was prepared by reaction of H₂Bn₂Cyclam with Y[N(SiMe₃)₂]₃. The protonation of the macrocycle ligand in [(Bn₂Cyclam)Y(N(SiMe₃)₂)] is observed upon reaction with [HNMe₃][BPh₄] leading to the formation of [(HBn₂Cyclam)Y(N(SiMe₃)₂)][BPh₄]. DFT analysis of [(Bn₂Cyclam)Y(N(SiMe₃)₂)] showed that the HOMO is located on the anionic nitrogen atoms of the cyclam ring indicating that protonation follows orbital control. Addition of H₂Bn₂Cyclam and H₂(^3,5-tBu2Bn)₂Cyclam to a 1:3 mixture of YCl₃ and LiCH₂SiMe₃ in THF resulted in the formation of [((C₆H₄CH₂)BnCyclam)Y(THF)(µ-Cl)Li(THF)₂] and [Y{(η³-^3,5-tBu2Bn)₂Cyclam}Li(THF)], respectively. The reaction of H₂^3,5-tBu2Bn₂Cyclam with Y(CH₂SiMe₃)₃(THF)₂ was studied and monitored by a temperature variation NMR experiment revealing the formation of [(^3,5-tBu2Bn₂Cyclam)Y(CH₂SiMe₃)]. Preliminary catalytic assays have shown that [Y{(η³-^3,5-tBu2Bn)₂Cyclam}Li(THF)] is a very efficient catalyst for the intramolecular hydroamination of 2,2-diphenyl-pent-4-enylamine.