(Chlorido/bromido)[(1,2,5,6-η)-cyclo-octa-1,5-diene](4-isopropyl-1-methyl-1,2,4-triazol-5-yl-idene)rhodium(I).

Joshua Rushlow,Edward Rajaseelan,Daniel R Albert,Andrei V Astashkin

doi:10.1107/s2414314621008117

Abstract

A new triazole-based neutral RhI complex, [Rh(Cl0.846Br0.154)(C6H11N3)(C8H12)], has been synthesized and structurally characterized. The RhI atom has a distorted square-planar coordination environment, formed by a bidentate cyclo-octa-1,5-diene (COD) ligand, an N-heterocyclic carbene and a halide ligand that shows substitutional disorder (Cl:Br = 0.846:0.154). No significant inter-molecular inter-actions other than van der Waals forces are found in the crystal structure. Diffraction data indicated a two-component inversion twin with a ratio of 0.95 (5):0.05 (5).

Highlights

A new triazole-based neutral RhI complex, [Rh(Cl0.846Br0.154)(C6H11N3)(C8H12)], has been synthesized and structurally characterized
No significant intermolecular interactions other than van der Waals forces are found in the crystal structure
The rhodium–halide bond length in the reported structure is 2.4308 (11) A, which is longer than previously reported Rh—Cl bond lengths, viz. 2.36–2.42 A (Skelton et al, 2019, 2020; Kalidasan et al, 2015), and shorter than previously reported Rh—Br bond lengths, viz 2.49–2.55 A (Benaissa et al, 2017; Aznarez et al, 2018), consistent with a Cl/Br substitutional disorder

Summary

Structure description

Transition-metal complexes containing N-heterocyclic carbene (NHC) ligands have been studied extensively in homogeneous catalysis (Dıez-Gonzales et al, 2009), especially in transfer hydrogenation of unsaturated bonds (Ruff et al, 2016; Zuo et al, 2014). Many imidazole- and triazole-based NHC rhodium and iridium complexes have been synthesized and structurally characterized (Herrmann et al, 2006; Wang & Lin, 1998; Chianese et al, 2004; Nichol et al, 2009, 2010, 2011, 2012; Idrees et al, 2017a,b; Rood et al, 2021). Their catalytic activities in the transfer hydrogenation of ketones and imines have been studied and reported (Hillier et al, 2001; Albrecht et al, 2002; Gnanamgari et al, 2007). The substitutional bromide likely comes from the triazolium salt (2) in the synthesis (Fig. 3)

Data collection Diffractometer Absorption correction

Data collection

Special details