# Cationic and Neutral Heterometallic Ir-Group 12 Element Polyhydride Compounds: Synthesis, Structure and Reactivity

## TL;DR

This paper describes the synthesis and properties of new iridium-based metal complexes with hydride ligands and group 12 elements.

## Contribution

The study introduces novel heterometallic Ir-group 12 element polyhydride compounds and their reactivity.

## Key findings

- New Ir–Zn and Ir–Cd hydride complexes were synthesized through dehydrogenation and R–H elimination.
- The complexes exhibit unique structures and reactivity under hydrogen exposure and Lewis base interactions.
- Crystallographic and computational analyses reveal diverse hydride ligand characteristics influenced by coordination environments.

## Abstract

The preparation and reactivity of some Ir–Zn and
Ir–Cd
heterometallic hydride complexes are described. Treatment of [Ir­(IPr)2H2]­[BArF
4] (1; IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene; ArF = 3,5-C6H3(CF3)2) with M′R2 (M′ = Zn; R = Ph, Me, Et; M′
= Cd, R = Me) and Me3SiCH=CH2 results in dehydrogenation
of an IPr isopropyl substituent, along with R–H elimination,
to form square-pyramidal [Ir­(IPr)­(IPr″)­(M′R)­H]­[BArF
4] (M′R = ZnPh (4a); ZnMe (4b); ZnEt (4c); CdMe (8); IPr″
= dehydrogenated IPr) featuring apical M′R ligands. Heating 1 with 2 equiv ZnPh2 under H2 forms
[Ir­(IPr)2(ZnPh)2H4]­[BArF
4] (5) featuring trans ZnPh ligands. Exposure
of 4b-c and 8 to H2 yields [Ir­(IPr)­(IPr″)­(M′R)­H3]­[BArF
4] (9b-c, 10) as
intermediates to highly fluxional [Ir­(IPr)2(M′R)­(η2-H2)­H3]­[BArF
4]
(11b-c, 12). Reacting 11b–c with Lewis bases (L) effects [ZnR]+ abstraction
to give pentahydride Ir­(IPr)2H5 (13); with 11c and L = IMes (1,3-bis­(2,4,6-trimethylphenyl)­imidazol-2-ylidene),
[L2ZnEt]­[BArF
4] was characterized,
whereas with L = PMe3, both 13 and [Ir­(IPr)2(ZnEt)­(PMe3)­H3]­[BArF
4] (14c) were formed. Reactions of 13 with M′R2 similarly proceed with R–H elimination
to form Ir­(IPr)2(M′R)­H4 (15a-c, 16). Crystallographic and computational
analyses characterize a range of hydride ligands, the nature of which
depends subtly on the surrounding coordination environment. The new
polyhydride complexes reported here add to the small number of such
species featuring N-heterocyclic carbene ligands.