Synthesis of [(Me₃SiNCH₂CH₂)₃N]³⁻ and [(C₆F₅NCH₂CH₂)₃N]³⁻ Complexes of Molybdenum and Tungsten That Contain CO, Isocyanides, or Ethylene

Paramagnetic complexes of the type [N 3 N]MoL ([N 3 N] 3 - = [(Me 3 SiNCH 2 CH 2 ) 3 N] 3 -; L = CO, RNC, C 2 H 4 ) have been prepared by displacing dinitrogen from [N 3 N]Mo(N 2 ). [N 3 N]Mo(CO) was reduced by magnesium powder in the presence of Me 3 SiCl to yield the diamagnetic oxycarbyne complex [N 3 N]Mo⋮COSiMe 3, while oxidation of [N 3 N]Mo(CN-t-Bu) with [Cp 2 Fe]OTf yielded {[N 3 N]Mo(CN-t-Bu)}OTf. Thermolysis of [N 3 N]Mo(CN-t-Bu) resulted in loss of a t-Bu radical to yield [N 3 N]Mo(CN), which was structurally characterized. [N 3 N F ]ML ([N 3 N F ] 3 - = [(C 6 F 5 NCH 2 CH 2 ) 3 N] 3 -; M = Mo, W; L = CO, RNC) complexes have been prepared by one-electron reduction of [N 3 N F ]M(OTf) in the presence of L. An X-ray study of [N 3 N F ]W(CN-t-Bu) showed it to contain a bent isocyanide ligand. Anionic CO complexes were prepared by the two-electron reduction of [N 3 N F ]M(OTf) in the presence of CO. An X-ray study of {[N 3 N F ]W(CO) 2 }Na(ether) 3 revealed it to have a pseudo-octahedral structure in which sodium is bound to the CO trans to the amine donor atom. Treatment of {[N 3 N F ]M(CO)} - complexes with Me 3 SiCl gave oxycarbyne complexes [N 3 N F ]M⋮COSiMe 3 . Reaction of [N 3 N F ]WCO with V(Mes) 3 (THF) yielded [N 3 N F ]W(CO)V(Mes) 3, the structure of which was determined in an X-ray study. Cationic [N 3 N F ] 3 - complexes could be prepared that contain up to 3 equiv of isocyanide. An X-ray study of {[N 3 N F ]W(CN-t-Bu) 3 }BPh 4 showed it to be a seven-coordinate species with one isocyanide located in the equatorial plane and the other two isocyanide ligands in the apical pocket. Reduction of [N 3 N F ]W(OTf) under ethylene gave [N 3 N F ]W(C 2 H 4 ), which could be oxidized to yield diamagnetic {[N 3 N F ]W(C 2 H 4 )}OTf.