3-Rhoda-1,2-dioxolanes through Dioxygenation of a Rhodium-Ethene Complex by Air

Guanidinato Complexes of Iridium: Ligand-Donor Strength, O2Reactivity, and (Alkene)peroxoiridium(III) Intermediates

“…The monooxygenated products are consistent with (oxo-η 2 -cyclooctenyl) complexes, [Ir(L)(η 2 -C 8 H 11 O- κC )(OH)], upon dissociation of hydroxide ion. Mechanisms for alkene oxygenation via (alkene)peroxo intermediates usually invoke conversion into 3-metalla-1,2-dioxolanes, if the reaction takes place at a single metal center. , Examples of 3-rhoda- and 3-irida-1,2-dioxolanes have been reported, ,, and rearrangement into β- oxoalkyl complexes has been described in several cases. , On the basis of these precedents, we propose that formation of an (oxo-η 2 -cyclooctenyl) complex ( B ) proceeds from 3 by alkene insertion into the Ir–O bond to afford an iridadioxolane, [Ir(L)(η 2 -C 8 H 12 O 2 - κC , κO )] ( A ), which in turn undergoes O–O bond cleavage and hydrogen migration (Scheme ). The dioxygenated species observed in the mass spectra may be related to the iridadioxolanes.…”

“…While heterogeneous methods are effective for the bulk oxidation of selected substrates, homogeneous oxidation catalysis promises to be of broader synthetic utility. − In this context, organometallic O 2 reactivity is an area of growing interest, , because insights into this chemistry provide a basis for the design and development of catalytic methods that use O 2 or air. Complexes of Rh and Ir were extensively investigated in early studies on catalytic alkene oxidation. , These metals have received renewed attention in recent work focusing on stoichiometric O 2 reactions of well-defined alkene complexes. , In particular, the latter studies have led to the characterization of the products from C–O bond formation, such as metallaoxetanes and metalladioxolanes. − …”

Reactivity by Design—Metallaoxetanes as Centerpieces in Reaction Development

“…Interestingly, the cn- and BPA−Rh−COD complexes 192 could also be oxidized by O 2 in the presence of a noncoordinating acid (HBAr f ) . In comparison, the TPA−Rh−ethylene complex 181 formed a 3-rhoda-1,2-dioxolane 195 upon treatment with O 2 under solvent-free conditions . Such dioxolanes had been invoked earlier by Read to transfer one oxygen to PPh 3 with the formation of triphenylphosphine oxide and rhodaoxetane 182 (Scheme )…”

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…”