Studies of the Formation and Decomposition Pathways for Cationic Zirconocene Hydrido Silyl Complexes

Abstract

Reactions and intermediates leading to zirconocene complexes [Cp‘2Zr(μ-H)(SiHR)]2 2+[BR‘ n (C6F5)4 - n ]2 2- (Cp‘ = Cp, MeCp, Me5Cp; R = Ph, PhCH2; R‘ = Bu or H; 1a − e) were investigated in situ by NMR and EPR studies and by trapping unstable intermediates with PMe3. Two novel ZrIII complexes, [Cp2ZrIII]+[BBu n (C6F5)4 - n ]- (5) and [Cp2ZrIII(PMe3)2]+[BBu n (C6F5)4 - n ]- (8) were identified by EPR spectroscopy. Redistribution of borate butyl and pentafluorophenyl ligands was found to occur by a direct boron to boron migration and not by a metal-assisted mechanism. The latter was ruled out by an independent synthesis of expected reaction intermediates for both reaction pathways ([Ph3C][BBu(C6F5)3], [Cp2Zr(C6F5)]+[BBu n (C6F5)4 - n ]-, and [Cp2Zr(C6F5)(μ3-HB(C6F5)3)]2) and an investigation of their model redistribution reactions by NMR spectroscopy.

Reaction of AlR3 with [CPh3][B(C6F5)4]: Facile Degradation of [B(C6F5)4]- by Transient “[AlR2]+”

“…The reaction of B(C 6 F 5 ) 3 with AlMe 3 in toluene to afford Al(C 6 F 5 ) 3 ·0.5toluene and BMe 3 via a similar sequence of ligand redistribution processes has recently been described in a patent application by Biagini et al as a convenient synthetic method for Al(C 6 F 5 ) 3 . , …”

EPR Identification of Zr(III) Complexes Formed upon Interaction of (2‐PhInd)2ZrCl2 and rac‐Me2Si(1‐Ind)2ZrCl2 with MAO and MMAO

“…Similar hfs was previously observed for the complex Cp 2 Zr III ( n Bu). [17,18] Thus, the EPR signal at g ¼ 1.968 must belong to the alkyl complex (2-PhInd) 2 Zr III ( i Bu) (3) (Scheme 2).…”

Group 14 triple-decker cations

“…C, 125 MHz;19 F, 470 MHz;27 Al, 130 MHz; 119 Sn, 186 MHz) instrument. NMR samples were flame-sealed or recorded immediately following their removal from the drybox.…”