208852-44-2Relevant academic research and scientific papers
Ortho-substituted aryl diamido complexes of zirconium : Observation of rotameric isomers
Guerin, Frederic,Del Vecchio, Orin,McConville, David H.
, p. 917 - 923 (1998)
Zirconium complexes bearing a series of ortho-substituted aryl diamido ligands [2,6-(RNCH2)2NC5H3]2- (R = 2-PhC6H4 (BPhP); 2-iPrC6H4 (BMPP); 2-tBuC6H4 (BMBP), 2-iPr-O-MeC6H3 (MPPP)) have been synthesized. The mixed amide complexes [2,6-(RNCH2)2NC5H3]Zr(NMe 2)2 are prepared in high yield from 2,6-(RHNCH2)2NC5H3 and Zr(NMe2)4. The mixed amides react with excess ClSiMe3 to afford the dichlorides [2,6-(RNCH2)2NC5H3]ZrCl2 in nearly quantitative yield. Dimethyl complexes are prepared from [2,6-(RNCH2)2NC5H3]ZrCl2 and 2 equiv. of MeMgCl. NMR spectroscopy has been used to identify rotameric isomers derived from restricted rotation about the N - Cipso bond of the ligand. The aryl groups in (BPhP)ZrX2 complexes freely rotate at all temperatures (-80 to +80°C) while (BMPP)ZrX2 (X = NMe2, Cl, Me) derivatives adopt meso and rac rotamers at low temperatures. In contrast, (BMBP)ZrX2 and (MPPP)ZrX2 (X = NMe2, Cl, Me) compounds are locked at all temperatures. (BMBP)ZrCl2 is isolated as a single isomer, likely the meso rotamer, while (MPPP)ZrCl2 is a near statistical mixture of meso and rac isomers. ° 1998 Elsevier Science Ltd. All rights reserved.
