Ward T. Robinson

Crystal and molecular structure of (dioxygen){NN′-[2-(2′-pyridyl)ethyl]-ethylenebis(salicylideneiminato)}cobalt–acetonitrile (1/1)

The title complex [Co(salpeen)(O2)]·MeCN crystallises in the monoclinic space group P21/c with the unit-cell parameters a= 9.563(2), b= 19.490(4), c= 12.770(3)A, β= 106.04(2)°, and Z= 4. The structure has been refined using 915 diffractometer-collected reflections having I > σI to give R 0.128 and R′ 0.089. The co-ordination sphere around the cobalt centre is approximately octahedral and the Schiff-base moiety is nearly planar. Dioxygen is co-ordinated in the end-on bent-bond mode and irresolvable disorder and high thermal motion result in an O–O separation of 1.06(3)A and a Co–[graphic omitted] angle of 134(4)°. In contrast to other Co–O2 structures where the axial base bisects the O–Co–N in-plane right angle, here the pyridyl plane is constrained to bisect the N–Co–N in-plane angle. Marked stereochemical changes accompany the co-ordination of dioxygen to [Co(salpeen)]. Structural evidence is accumulated to support a CoIII—O2-formulation.

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)A, 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)A, α= 106.90(3), β= 97.59(2), γ= 101.27(2)°, Z= 2.