Syntheses of 2,4-Disubstituted 1,3,5-Triazapentadienyl Ligands Having Two Guanidinato Moieties and Their Use in the Isolation of Copper(I) Complexes

2,4-N,N′-Disubstituted 1,3,5-triazapentadienyl ligands as their lithium salts [Li{(N(R)C(R′))2N}]2 [where R = SiMe3 here and hereafter and R′ = dimethylamino (1) or 1-piperidino (2)] were synthesized via the reactions of LiN(SiMe3)2 with 2 equiv of the α-hydrogen-free carbonitrile dimethylcyanamide or 1-piperdinecarbonitrile and used in the isolation of the two-coordinate copper(I) complexes [Cu{(N(R)C(R′))2N}]2 [R′ = dimethylamino (3) and 1-piperidino (4)]. Complex 2 features a twisted W-shaped ligand backbone in the solid state. Complexes 3 and 4 show an unusual 12-membered ring dinuclear copper(I) triazapentadienyl and a less expressed ability to form a stable delocalized triazapentadienyl system.