Formation of Ethylene-Bridged Dinuclear Ir^III Species via M−C Coupling of Ir^II and Ir^II(ethene)

Abstract

Ethene dissociation from [(Me n tpa)IrII(ethene)]2+, induced by coordination of acetonitrile, causes a rapid and selective M−C coupling between IrII and IrII(ethene), resulting in ethylene-bridged dinuclear iridium(III) complexes of the composition [{(Me n tpa)IrIII(NCMe)}2(μ2-C2H4)]4+ (n = 2, 3).

Paramagnetic (Alkene)Rh and (Alkene)Ir Complexes: Metal or Ligand Radicals?

“…These arguments also imply that formation of "slipped olefin"/ethyl radical species [ 2+ to form an ethylene-bridged species (Figure 18). [7,39] The increased reactivity on going from Me 3 tpa to the less bulky Me 2 tpa complex in formation of the ethylene-bridged species, is in good agreement with the proposed associative addition of acetonitrile to [Ir II -(Me n tpa)(ethene)] 2+ being the first step of the dimerization process.…”

The Organometallic Chemistry of Rh‐, Ir‐, Pd‐, and Pt‐Based Radicals: Higher Valent Species

“…(162,180). The increased reactivity on going from Me 3 tpa to the less bulky Me 2 tpa complex in formation of the ethylene bridged species, is in good agreement with the proposed associative addition of acetonitrile to [Ir II (Me n tpa)(ethene)] 2þ being the first step of the dimerization process.…”

“…61) has been reported, including formation of M III (m 2 -CH 2 CHRÀ À)M III bridged species in reactions with olefins, CÀ ÀN bond cleavage in reactions with isocyanides, OÀ ÀC cleavage in reactions with P(OMe) 3 A series of five-coordinate, dicationic Rh(II) and Ir(II) olefin complexes stabilized by N-donor ligands has been investigated in detail. Species of the type [Ir II (N 4 -ligand)(ethene)] 2þ (162,179,180) [Rh II (N 3 -ligand)(nbd)] 2þ (181) (nbd ¼ norbornadiene) and [M II (N 3 -ligand)(cod)] 2þ (182,183) have been obtained from their M(I) precursors by one-electron oxidation using either [Fc] þ or Ag þ as an oxidant (Fig. 62).…”

Tripodal Tetraamine Ligands Containing Three Pyridine Units: The other Polypyridyl Ligands

“…Notable examples include the metallacyclic Co III complex [Co(tpa)(CH 2 NH 2 )](BPh 4 ) 2 . (CH 3 ) 2 CO, formed from photodecarboxylation of the [Co(tpa)gly] 2+ cation (Figure 15),91 the Cr III alkyl complex [Cr(tpa)(Me) 2 ]BPh 4 · 0.5CH 2 Cl 2 , prepared by treatment of [Cr(tpa)Cl 2 ] + with MeMgCl,92 the Rh III metallaoxetane and metalladioxolane complexes [(6‐Metpa)Rh(κ 2 C 1 , O ‐CH 2 CH 2 O‐)]BPh 4 · 1.5H 2 O93 and [(tpa)Rh(κ 2 C 1 , O 2 ‐CH 2 CH 2 OO‐)]BPh 4 · 0.5MeCN · 0.5ClCH 2 CH 2 Cl · 0.5Et 2 O (Figure 16),94 and the η 1 :η 1 ‐ethylene‐bridged Ir III dimers [(Rtpa)(MeCN)Ir(C 2 H 4 )Ir(MeCN)(Rtpa)](PF 6 ) 4 (Rtpa = 6‐Me 2 tpa, 6‐Me 3 tpa) 95…”