625-81-0Relevant articles and documents
Coordination to RMg+ and RZn+ cations
Tang, Hui
, p. 4810 - 4819 (2008/10/08)
Addition of a second coordinating agent (coord*) to a solution of RM(coord)+A- (R = ethyl or neopentyl, M = Zn or Mg, A- = 1,2,3,4-tetraphenylcyclopentadienyl) can provide equilibrium mixtures of these compounds, coord, and RM(coord*)+A-. This exchange with RMg(coord)+ requires the addition of a small amount of R2Mg, but added R2Zn is not necessary for exchanges with RZn(coord)+. The equilibrium constants provide information about the relative abilities of different coordinating agents to coordinate to RM+ and reveal significant differences between coordination to RMg+ and RZn+. Reactions of RM(coord)+ with R′2M (R = ethyl or neopentyl for RMg(coord)+ and ethyl, isopropyl, tert-butyl, neopentyl, or p-methylphenyl for RZn(coord)+) provide equilibrium mixtures of these components, R′M(coord)+, and R2M. The equilibrium constants provide information about the effect of R on stability. An X-ray structure of p-methylphenylzinc(2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane)+ shows that just three of the N atoms are coordinated to Zn. The effects of coord, R, and metal on RM(coord)+ stability are discussed, and the abilities of coordinating agents to coordinate to RM+, to slow allylic isomerization of (CH2 double bond CMeCH2)2Zn, and to convert R2Zn to RZn(coord)+ are compared.