Synthesis, Characterization, and Materials Chemistry of Group 4 Silylimides

Abstract

This paper focuses on the development of potential single source precursors for M-N-Si (M = Ti, Zr or Hf) thin films. The titanium, zirconium, and hafnium silylimides (Me(2)N)(2)MNSiR(1)R(2)R(3) [R(1) = R(2) = R(3) = Ph, M = Ti(1), Zr (2), Hf (3); R(1) = R(2) = R(3) = Et, M = Ti (4), Zr (5), Hf (6); R(1) = R(2) = Me, R(3) = (t)Bu, M = Ti (7), Zr (8), Hf (9); R(1) = R(2) = R(3) = NMe(2), M = Ti (10), Zr (11), Hf (12)] have been synthesized by the reaction of M(NMe(2))(4) and R(3)R(2)R(1)SiNH(2). All compounds are notably sensitive to air and moisture. Compounds 1, 2, 4, and 7-10 have been structurally characterized, and all are dimeric, with the general formula [M(NMe(2))(2)(μ-NSiR(3))](2), in which the μ(2)-NSiR(3) groups bridges two four-coordinate metal centers. The hafnium compound 3 possesses the same basic dimeric structure but shows additional incorporation of liberated HNMe(2) bonded to one metal. Compounds 11 and 12 are also both dimeric but also incorporate additional μ(2)-NMe(2) groups, which bridge Si and either Zr or Hf metal centers in the solid state. The Zr and Hf metal centers are both five-coordinated in these species. Aerosol-assisted CVD (AA-CVD) using 4-7 and 9-12 as precursors generates amorphous films containing M, N, Si, C, and O; the films are dominated by MO(2) with smaller contributions from MN, MC and MSiON based on XPS binding energies.

Synthesis and Reactivity of Discrete Calcium Imides

“…[12] Moreover,c arefully choosing the amino/amido component according to reactivity (pK a ), solubility,a nd steric demand criteria has proven crucial for imide formation. [13] Therefore,w ec hose 2,6-diisopropylaniline (H 2 NDipp,D ipp = 2,6-iPr 2 C 6 H 3 )a nd triphenylsilylamine (H 2 NSiPh 3 )a sp romising imido precursors.A sp reviously shown for protonolysis (Nb), [14] transimination (Ti), [15] and aminolysis reactions (Ti, Zr,H f) [16,17] as well as the preparation of at etrameric magnesium imide, [4c] bulky triphenylsilylamine seems particularly suitable for double deprotonation. Accordingly,w hen H 2 NDipp was treated with one equivalent of [CaBn 2 ] n in thf,s ingle deprotonation occurred exclusively (even at elevated temperatures), yielding the bis(amide) complex [(thf) x Ca-(NHDipp) 2 ]( see the Supporting Information, Figure S5).…”

Tight Encapsulation of a “Naked” Chloride in an Imidotitanium Hexanuclear Host

“…Imido complexes, and in particular group 4 imido complexes, have attracted intense interest because of their importance in understanding and developing stoichiometric or catalytic transformations. − Imido complexes are known for the majority of the d-block metals, and a wide range of substitution on the imido ligands has been demonstrated, which impacts the properties of the metal–nitrogen bond. , Imido ligands have found practical applications as robust supporting (spectator) ligands, as reactive sites, or as ligands to known precursors to metal nitride materials. − …”

Synthese und Reaktivität von diskreten Calciumimiden

“…Da bereits für Magnesium gezeigt wurde, dass die Wahl der Amin‐/Amidkomponente in Bezug auf Kriterien wie Reaktivität (p K s ), Löslichkeit und sterischem Anspruch von entscheidender Bedeutung für eine erfolgreiche Imidbildung ist, entschieden wir uns für 2,6‐Diisopropylanilin (H 2 NDipp, Dipp=C 6 H 3 i Pr 2 ‐2,6) und Triphenylsilylamin (H 2 NSiPh 3 ) als vielversprechende Aminderivate. Dass das sterisch anspruchsvolle Triphenylsilylamin im Hinblick auf eine zweifache Deprotonierung großes Potential besitzt, wurde bereits in Protonolyse‐ (Nb), Transiminierungs‐ (Ti), und Aminolyseprotokollen (Ti, Zr, Hf) sowie bei der Synthese eines tetrameren Magnesiumimids gezeigt. Während bei der Umsetzung von [CaBn 2 ] n mit einem Äquivalent H 2 NDipp in THF selbst bei höheren Temperaturen nur eine einfache Deprotonierung und das daraus folgende Bis(amid) [(THF) x Ca(NHDipp) 2 ] beobachtet werden konnte (Abbildung S5 in den Hintergrundinformationen), führte die Reaktion mit H 2 NSiPh 3 unter vergleichbaren Bedingungen zur Bildung von Verbindung 1 , deren 1 H‐NMR‐Spektrum keine NH‐Resonanzen zeigte.…”