# Azobenzene Reduction and Derivatization and Al–H Bond Insertion with β‑Diketiminate Gallium(I) Complexes

## TL;DR

This paper explores new gallium(I) complexes and their reactions with azobenzene and aluminum hydrides, revealing structural transformations and coordination patterns.

## Contribution

The study introduces new β-diketiminate gallium(I) complexes and their reactivity with azobenzene and aluminum hydrides, leading to novel gallium(III) and Ga–Al-bonded complexes.

## Key findings

- Gallium(I) complexes [(EtDipnacnac)Ga] 2a and [iPrDipnacnac)Ga] 2b were synthesized with varying yields based on ligand substitution.
- Azobenzene reacted with gallium(I) complexes to form gallium(III) complexes with N,ortho-C(H)-chelating coordination.
- Complex 2a reacted with aluminum hydrides to form Ga–Al-bonded complexes and a gallium hydride derivative.

## Abstract

Using backbone modification
of popular β-diketiminate ligands, RDipnacnac = HC­(RCNDip)2, with R = Et, iPr (Dip = 2,6-iPr2C6H3), we have prepared the new
β-diketiminate gallium­(I)
complexes [(EtDipnacnac)­Ga] 2a and [(
iPrDipnacnac)­Ga] 2b by salt metathesis/reduction
using “GaI” in moderate to good (68%, 2a) and poor (10%, 2b) isolated yields, respectively,
highlighting the influence of the ligand backbone substitution on
the reaction success. The gallium­(I) complexes were converted with
azobenzene to the gallium­(III) complexes [(RDipnacnac)­Ga­{(C6H5)­NNPh}] 4a (R = Et) and 4b (R = iPr) with reduced former azobenzene fragments
showing an N,ortho-C­(H)-chelating
coordination to the Ga centers. Complex 4a was further
converted to its C–H-activated tautomer [(EtDipnacnac)­Ga­{(C6H4)­N­(H)­NPh}] 5, and reaction with
DMSO and benzaldehyde afforded [(EtDipnacnac)­Ga­(PhNNHPh)­(CH2S­(O)­Me)] 6 after DMSO deprotonation and [(EtDipnacnac)­Ga­(PhNN­(Ph)­CH­(Ph)­O)] 7 from C–N
coupling, respectively. Compound 2a also reacted with
the aluminum­(III) hydride complexes (NHC)­AlH3 (NHC = {MeCN­(iPr)}2C) and (Me3N)­AlH3 to the Ga–Al-bonded complex [(EtDipnacnac)­Ga­(H)–Al­(H2)­(NHC)] 8 and [(EtDipnacnac)­GaH2] 9, respectively. Gallium­(I) complex 2a is a good alternative to commonly used [(MeDipnacnac)­Ga]
(R = Me) for the study and application of low-oxidation-state gallium
complexes.