Sc³⁺ Chloro and Alkyl Complexes Coordinated by Pincer NHC‐Tethered Bis(phenolate) Ligands

Abstract

Bis(phenolate) ligands with benzimidazole‐2‐ylidene (L1) and tetrahydropyrimidine‐2‐ylidene (L2) linkers proved to be suitable coordination environments for the synthesis of isolable Sc3+ chloro and alkyl complexes. The treatment of Sc(CH2SiMe3)3(THF)2 with equimolar amounts of [L1,2H3]Cl afforded chloro complexes L1,2ScCl(solv)2 (solv = THF, Py) in 76–85% yields. L1,2ScCl(THF)2 were also prepared by the salt metathesis reactions of ScCl3 with [L1,2]Na2 generated from [L1,2H3]Cl and 3 equiv. of NaN(SiMe3)2 (−40 °C, THF) and isolated in somewhat lower yields (68–73%). L2ScCl(THF)2 was subjected to the alkylation reaction with LiCH2SiMe3 affording alkyl derivative [L2Sc(CH2SiMe3)]2. This compound can be alternatively prepared by the subsequent reactions of [L2H3]Cl with equimolar amount of NaN(SiMe3)2 and Sc(CH2SiMe3)3(THF)2. In the dimeric alkyl compound [L2Sc(CH2SiMe3)]2, one of the phenoxide groups of the dianionic ligand is coordinated to one scandium center, while the second one features μ‐bridging coordination with two metal centers.