220278-65-9Relevant articles and documents
Synthesis of zirconium complexes that contain the diamidophosphine ligands [(Me3SiNCH2CH2)2PPh]2- or [(RNSiMe2CH2)2PPh]2- (R = t-Bu or 2,6-Me2C6H3)
Schrock, Richard R.,Seidel, Scott W.,Schrodi, Yann,Davis, William M.
, p. 428 - 437 (2008/10/08)
A new synthesis of PhP(CH2CH2NH3Cl)2 is reported that involves the addition of 2 equiv of butyllithium to a mixture of PhPH2 and 2 equiv of ClCH2CH2(cyclo-NSiMe2CH2CH 2SiMe2). The reaction between PhP(CH2CH2NH3Cl)2 and 4 equiv of butyllithium followed by 2 equiv of Me3SiCl then yielded (Me3SiNHCH2CH2)2PPh (H2[N2P]) quantitatively. Addition of H2-[N2P] to Zr(NMe2)4 in pentane gave intermediate [N2P]Zr(NMe2)2 that was converted without purification to white, crystalline [N2P]ZrCl2 in 80% yield overall upon treatment with 2 equiv of Me3SiCl. The alkyl complexes that were prepared include [N2P]Zr(THF)MeCl, [N2P]Zr-(i-Bu)Cl, [N2P]ZrMe2, [N2P]Zr(CH2Ph)2, and [N2P]Zr(CH3)(CH2Ph). An X-ray diffraction study showed that the basic structure of [N2P]Zr(CH3)(CH2Ph) is a distorted trigonal bipyramid in which the methyl group is in the apical position trans to phosphorus and the η2-benzyl group is cis to phosphorus. Compounds of the type PhP(CH2SiMe2NHR)2 (R = t-Bu or 2,6-Me2C6H3; H2[R2NPN]) were prepared by treating ClCH2SiMe2Cl with LiNHR to give ClCH2-SiMe2NHR followed by a reaction between PhPH2, ClCH2SiMe2NHR, and butyllithium. Zirconium complexes that were prepared include [t-Bu2NPN]ZrMeCl, [Ar2NPN]ZrMeCl, and [Ar2NPN]ZrMe2. An attempted synthesis of [t-Bu2NPN]ZrMe2 led to loss of a feri-butyl group and formation of a dimeric complex containing imido-type bridging nitrogen ligands, as confirmed in an X-ray study. X-ray studies of [t-Bu2NPN]ZrMeCl and [Ar2NPN]ZrMeCl demonstrate that extensive steric crowding exerted by a tert-butyl group in complexes of this type contributes to the inability to form a simple complex such as [PhP(CH2SiMe2N-t-Bu)2]ZrMe2.
