Alkali-Metal Alkyl Complexes with the Tridentate Benzhydryl Ligand [2,2′-(4-MeC₆H₄NMe₂)₂CH]⁻

A series of alkali-metal alkyl complexes containing a tridentate benzhydryl ligand, [2,2′-(4-MeC₆H₄NMe₂)₂CH]­Li­(TMEDA) (1^TMEDA), [2,2′-(4-MeC₆H₄NMe₂)₂CH]­Na­(THF)₃ (2^THF), {[2,2′-(4-MeC₆H₄NMe₂)₂CH]­K­(THF}₂ (3^THF), and [2,2′-(4-MeC₆H₄NMe₂)₂C­(SiMe₃)]K (5), were synthesized and structurally characterized. Smaller Li and Na ions form the monomeric complexes 1^TMEDA and 2^THF featuring η⁴-CCCN coordination of the [2,2′-(4-MeC₆H₄NMe₂)₂CH]⁻ ligand, while the larger K affords the dimeric complex 3^THF, in which two different types of metal–ligand bonding, μ-η⁵-pentadienyl-κ²-NN and μ-κ³-CNN:η⁶-arene are realized. Application of the Me₃Si-substituited analogue [2,2′-(4-MeC₆H₄NMe₂)₂C­(SiMe₃)]⁻ leads to the formation of the 1D coordination polymer {[2,2′-(4-MeC₆H₄NMe₂)₂C­(SiMe₃)]­K}_∞ (5) with μ-η³:η⁶ bridging coordination of the ligands to potassium ions.