Synthesis and characterization of silazoxy metallacycles

Novel transition-metal-containing metallacycles of the type [{M[O(SiMe2NBut)2]}2](M = MnII2, FeII3, NiII4 or CrII5) as well as six-membered heterocycles of the type O(SiMe2NBut)2M (M = TeII8, GeII9 or SnII10) have been synthesised by the reaction of O(SiMe2NButLi)2 with the corresponding metal halides. Reaction of CuCl2 and CuCl with O(SiMe2NButLi)2 yielded a novel copper amide [Cu4{O(SiMe2NBut)2}2]7 having four copper atoms in a square plane bridged symmetrically from above and below by the diamide ligand. This compound was also prepared by the reaction of O[SiMe2N(But)SnMe3]2 with CuCl2 and CuCl. X-Ray crystallographic data obtained are as follows: 2, triclinic, space group P, a= 8.550(2), b= 9.838(2), c= 11.668(2)Å, α= 83.81(3), β= 70.35(3), γ= 72.55(3)°, Z= 1; 3, triclinic, space group P, a= 11.201(5), b= 11.579(4), c= 14.946(9)Å, α= 106.90(3), β= 97.59(2), γ= 101.27(2)°, Z= 2.