Synthesis and structural characterization of scandium SALEN complexes

Abstract

A series of heteroleptic scandium SALEN complexes, [(SALEN)Sc(mu-Cl)]2 and (SALEN)Sc[N(SiHMe2)2] is obtained via amine elimination reactions using [Sc(N(i)Pr2)2(mu-Cl)(THF)]2 and Sc[N(SiHMe2)2]3(THF) as metal precursors, respectively. H(2)SALEN ligand precursors comprising H2Salen [(1,2-ethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salpren [(2,2-dimethylpropanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol], H2Salcyc [(1R,2R)-(-)-1,2-cyclohexanediyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] and H2Salphen [((1S,2S)-(-)-1,2-diphenylethandiyl)bis(nitrilomethylidyne)bis(2,4-di-tert-butyl)phenol] are selected according to solubility and ligand backbone variation ("=N-(R)-N=" bite angle) criteria. Consideration is given to the feasibility of [Cl --> NR2] and [N(SiHMe2)2--> OSiR3] secondary ligand exchange reactions. X-ray crystal structure analyses of donor-free (Salpren)Sc(N(i)Pr2), (R,R)-(Salcyc)Sc[N(SiHMe2)2], (Salen)Sc(OSi(t)BuPh2) and (Salphen)Sc(OSiH(t)Bu2) reveal (i) a very short Sc-N bond distance of 2.000(3) A, (ii) weak beta(Si-H)(amido)-Sc agostic interactions and (iii) an exclusive intramolecularly tetradentate and intrinsically bent coordination mode of the SALEN ligands with angle(Ph,Ph) dihedral angles and Sc-[N(2)O(2)] distances in the 124.27(9)-127.7(3) degrees and 0.638(1)-0.688(1) A range, respectively.

A DFT Exploration of Efficient Catalysts Based on Metal‐Salen Monomers for the Cycloaddition Reaction of CO2 to Propylene Oxide

“…Moreover, our experiments measured that the catalytic yield of Co III ‐CMP is larger than that of Al III ‐CMP, which is also in agreement with the present theoretical work. In addition, among heteroleptic scandium Salen complexes, [(Salen)Sc(μ‐Cl)] 2 and (Salen)Sc[N(SiHMe 2 ) 2 ] were first synthesized in experiments approximately ten years ago . However, the cycloaddition reaction of CO 2 to epoxides catalysed by Sc III ‐Salen has not been studied.…”

“…In addition, among heteroleptic scandium Salen complexes, [(Salen)Sc(m-Cl)] 2 and (Salen)Sc[N(SiHMe 2 ) 2 ] were first synthesized in experiments approximately ten years ago. [43,44] However, the cycloaddition reaction of CO 2 to epoxides catalysed by Sc III -Salen has not been studied. Our calculations establish that the Sc III -Salen monomer from Sc-CMP has a low apparent barrier, which is beneficial for CO 2 conversion at room temperature.…”

An unsymmetrical dinuclear scandium complex comprising salophen ligands [H2salophen = N,N′-bis(salicylidene)-1,2-phenylenediamine]

“…Scandium complexes comprising salen-type Schiff-base ligands are fairly rare, with the majority of such compounds having been reported by Anwander and co-workers (Meermann et al, 2006(Meermann et al, , 2009. Access to these complexes was achieved via treatment of the scandium silylamide precursor Sc[N(SiHMe 2 ) 3 ] 3 (THF) with substituted H 2 salen precursors under anaerobic conditions.…”

Synthesis and Crystal Structure of bis [2-(3-(2-((2-Hydroxybenzylidene) Amino)Ethyl)Oxazolidin-2-yl)Phenol]Cerium (IV) 1,4-Dioxane Monosolvate

“…Its chemical behavior as a tetravalent metal is similar to those of Zr, Hf, Th, U, Np, and Pu. Further, complexes of Schiff base (salen-type) ligands with lanthanides were studied in the recent past [4][5][6][7][8]. In our previous papers, we investigated the coordination ability of the multidentate ligand (N-salicylidene-N'-(2-hydroxyethyl) ethylenediamine (L)) with copper (II), chromium (III), and indium (III) [9][10][11].…”