Title

Ancillary Steric Effects on the Activation of SiH Bonds in Arylsilazido Rare-Earth Compounds

Publication Date

6-2-2021

Department

Ames Laboratory; Chemistry

Campus Units

Ames Laboratory, Chemistry

OSTI ID+

1797581

Report Number

IS-J 10503

DOI

10.1021/acs.organomet.1c00162

Journal Title

Organometallics

Volume Number

40

Issue Number

11

First Page

1654

Last Page

1669

Abstract

Three new hydridosilazido ligands, −N(SiHMe2)Aryl (Aryl = Ph, 2,6-C6Me2H3 (dmp), 2,6-C6iPr2H3 (dipp)) and their rare-earth complexes Ln{N(SiHMe2)Aryl}3(THF)n (Ln = Sc, Y, Lu; Aryl = Ph, n = 2; Aryl = dmp, n = 1; Aryl = dipp, n = 0) were synthesized to study the relationships among ligand steric properties, secondary Ln↼H–Si bonding, and the reactivity of amide and SiH groups. In these compounds, the steric encumbrance of the aryl group was systematically increased from phenyl to 2,6-dimethylphenyl to 2,6-diisopropylphenyl. NMR, IR, and X-ray diffraction studies of the complexes characterize the number of secondary interactions and additional THF ligands coordinated to the rare-earth centers. The complexes with the smallest phenylsilazido ligands, Ln{N(SiHMe2)Ph}3(THF)2, contain features associated with three nonbridging 2-center-2-electron (2c-2e) Si–H bonds. Characterization of intermediate-sized Ln{N(SiHMe2)dmp}3THF reveals three and two Ln↼H–Si interactions for yttrium and lutetium analogues, respectively, with both metals having one coordinated THF per complex. Ln{N(SiHMe2)dipp}3 is formed solvent-free, and all three ligands adopt Ln↼H–Si bonding modes. The reaction between Ln{N(SiHMe2)dipp}3 and ketones provides the hydrosilylated product via addition of C═O and Si–H bonds, which occurs rapidly even at low temperature. This reaction is proposed to occur through an associative mechanism on the basis of negative activation entropy measured for substitution of pyridine in Ln{N(SiHMe2)dipp}3·NC5H5.

DOE Contract Number(s)

AC02-07CH11358; 58627-DNI6

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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