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Rhodium Complexes Promoting C−O Bond Formation in Reactions with Oxygen: The Role of Superoxo Species
Author(s) -
VilellaArribas Laia,
GarcíaMelchor Max,
Balcells David,
Lledós Agustí,
López José A.,
Sancho Sofía,
Villarroya B. Eva,
del Río M. Pilar,
Ciriano Miguel A.,
Tejel Cristina
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201605959
Subject(s) - chemistry , rhodium , singlet oxygen , bimetallic strip , photochemistry , bond cleavage , oxygen , singlet state , catalysis , derivative (finance) , medicinal chemistry , organic chemistry , excited state , physics , nuclear physics , financial economics , economics
Abstract C−O bond formation in reactions of olefins with oxygen is a long standing challenge in chemistry for which the very complicated—sometimes controversial—mechanistic panorama slows down the design of catalysts for oxygenations. In this regard, the mechanistic details of the oxidation of the complex [Rh(cod)(Ph 2 N 3 )] ( 1 ) (cod=1,5‐cyclooctadiene) with oxygen to the unique 2‐rhodaoxetane compound [{Rh(OC 8 H 12 )(Ph 2 N 3 )} 2 ] ( 2 ) has been investigated by DFT calculations. The results of this study provide evidences for a novel bimetallic mechanism in which two rhodium atoms redistribute the four electrons involved in the cleavage of the O=O bond. Furthermore, both oxygen atoms are used to create two new C−O bonds in a controlled fashion with 100 % atom economy. The key intermediates that we have found in this process are a mononuclear open‐shell triplet superoxo compound, an open‐shell singlet “μ‐(peroxo)” derivative, and a closed‐shell singlet “bis(μ‐oxo)” complex. Some of the findings are used to predict the reactions of Rh I complexes with oxygen, exemplified by that of the complex [Rh(cod)(OnapyMe 2 )] ( 3 ). Starting from 3 , [{Rh(OC 8 H 12 )(OnapyMe 2 )} 2 ] ( 4 ) has been prepared and characterized, which represents the second example of a 2‐rhodaoxetane compound coming from an oxygenation reaction with oxygen.