Carbazole Substituted Amidinato Silylene: Synthesis, Bonding, and Coordination Behavior with Coinage Metals

Abstract

In this work, the synthesis and characterization of a new carbazole substituted amidinatosilylene (1) and its coinage metal complexes 3–8 are being reported. Before the complexation reactions, we prepared [PhC­(NtBu)2Si­(Cbz)→Co­(CO)­Cp] complex (2) to estimate the σ-donating strength of the newly synthesized silylene 1. Further, several commonly available coinage metal salts were utilized for the complexation reactions with 1, which afforded complexes 3–8. The solid-state structures of 1–8 have been validated by single-crystal X-ray diffraction studies, NMR spectroscopy, and mass spectroscopy. DFT studies were also performed to understand the bonding scenario of 1 and 3–7. Of note, 1 consists of a HOMO on its carbazolide moiety, and the HOMO-1 features the silylene character. We also compared the HOMO-LUMO gap of 1 with other amidinato silylenes having different N-substitutions.

Diverse structural reactivity patterns of a POCOP ligand with coinage metals

“…The trigonal planar Cu centre possesses a P1–Cu1 bond length of 2.137(1) Å and the latter one possesses a P2–Cu2 bond length of 2.143 (1) Å, which match well with our previously isolated NHSi-coordinated copper( i ) triflate complex. 19 Lewis acidic copper( i ) triflate has found application as a pre-catalyst in enantioselective erogorgiaene synthesis by Hoveyda and co-workers, 20 but the isolation of a well-defined phosphinite-coordinated catalyst was never achieved.…”

“…The peak at δ 104.7 ppm can be assigned to the terminal phosphines attached to the tri-coordinate copper(I) centre, whereas the peak at δ 94.5 can be assigned to the phosphines bound to the tetra-coordinate copper(I) centre. The protondecoupled 19 F and 11 B NMR spectra show sharp singlets at δ −151.8 and −0.664 ppm, respectively. Complex 7 crystallises in the triclinic P1 ˉspace group and uniquely displays two different coordinations of copper, i.e., tri-and tetra-coordination (Fig.…”

“…A broad peak indicates the formation of 10 at δ 111.7 ppm in the 31 P NMR spectrum. The proton-decoupled 19 F NMR spectrum shows a broad peak at δ −176 ppm, defining the fluxional behaviour of the SbF 6 − moiety in the solution state. 27 10 crystallises in the triclinic P1 ˉspace group where the silver(I) centre is tetra-coordinate (Fig.…”

Silylenes with a Small Chalcogenide Substituent: Tuning Frontier Orbital Energies from O to Te

“…The most obvious way of generating new acyclic silylenes after obtaining the bromosilylene [( dtbp Cbz)SiBr] is salt metathesis with any other metalated nucleophile RÀ M, in analogy to methods frequently used with Roesky's amidinato chlorosilylene. [35][36][37][38][39] Unfortunately, with the carbazolyl substituent these metathesis reactions generally do not work as intended, because the alkali metal complexes [( dtbp Cbz)M] are formed as major product. [40] Consequently, other methods had to be explored.…”

Silylene mit kleinen Chalcogenolato‐Substituenten: Variation der Grenzorbitalenergien von O bis Te

“…Der naheliegendste Weg neuartige, acyclische Silylene herzustellen besteht in der Salzmetathese des Bromosilylens [( dtbp Cbz)SiBr] mit einem metallierten Nucleophil RÀ M. Diese Synthesestragie wurde in der Literatur vielfach unter Verwendung des von Roesky dargestellten Amidinatochlorosilylens beschrieben. [35][36][37][38][39] Bei Einsatz des Carbazolyl-Liganden führen diese Salzmetathesen generell nicht zu dem gewünschten Ergebnis, da als Hauptprodukte die Alkalimetallcarbazolide [( dtbp Cbz)M] isoliert wurden. [40] Folglich war es erforderlich, andere Methoden anzuwenden.…”