241165-13-9Relevant academic research and scientific papers
Accelerated ligand metalation in a β-diketiminato scandium dimethyl complex activated with bis(pentafluorophenyl)borane
Conroy, Korey D.,Hayes, Paul G.,Piers, Warren E.,Parvez, Masood
, p. 4464 - 4470 (2008/10/09)
Equimolar reactions of LScMe2 (L = (Ar)NC(tBu)CHC(tBu)N(Ar); Ar = 2,6-iPr2-C6H3) and HB(C6F 5)2 proceed through an isolable ion pair 2 to a metalated scandium borate 3 with loss of methane. Multinuclear NMR experiments confirm the proposed structure, which was also verified by synthesis via alternative routes and derivatization. Deuterium labeling studies offer insight into the mechanism of methane loss, which occurs through C-H activation of an abstracted methide rather than the direct intramolecular metalation commonly observed for β-diketiminato scandium alkyl complexes. A large primary kinetic isotope effect of kH/kD = 8.7(6) was observed for the decomposition of 2, which corroborates the proposed mechanism while also implicating a highly reactive four-membered scandocycle intermediate, LSc((H)CH2B(C6F5)2). Reaction of 2 equiv of HB(C6F5)2 with LScR2 yields μ2-hydridoborate complexes [LScCH3] [(μ-H) 2B(C6F5)2] (5), while 4 equiv of borane react to afford the bis-μ2-hydridoborate complex [LSC][(μ-H) 2B(C6F5)2]2, 6.
Dialkylscandium complexes supported by β-diketiminato ligands: Synthesis, characterization, and thermal stability of a new family of organoscandium complexes
Hayes, Paul G.,Piers, Warren E.,Lee, Lawrence W.M.,Knight, Lisa K.,Parvez, Masood,Elsegood, Mark R.J.,Clegg, William
, p. 2533 - 2544 (2008/10/08)
Several diorganoscandium complexes stabilized by the β-diketiminato ligands (Ar)NC(R)-CHC(R)N(Ar) (Ar = 2,6-iPr-C6H3; R = CH3 (ligand a), R = tBu (ligand b)) have been synthesized. Reaction of the lithium salts of the ligands with ScCl3·3THF leads to the complexes LScCl2(THF)n, which may be readily alkylated to form the dialkyl derivatives. Most are isolated as base-free, four-coordinate complexes. Several have been characterized via X-ray crystallography, and a detailed discussion of their structures is presented. Steric interactions between Ar and the Sc-alkyl groups force the scandium to adopt an out-of-plane bonding mode. In solution, this is manifested via a fluxional process which equilibrates the two diastereotopic alkyl groups and ligand groups as well. The barriers to this process roughly correlate with the steric bulk of the alkyl substituents. At elevated temperatures, the dialkyl derivatives LScR2 undergo a metalation process whereby one of the alkyl groups is eliminated as RH, and a ligand iPr group is metalated in the methyl position. These reactions are first order in scandium complex, and activation parameters of ΔH? = 19.7(6) kcal mol-1 and ΔS? = -17(2) cal mol-1 K-1 were measured for the loss of Me4Si from (Ligb)-Sc(CH2SiMe3)2.
