Spin State, Structure, and Reactivity of Terminal Oxo and Dioxygen Complexes of the (PNP)Rh Moiety

Abstract

[Rh(III)H{(tBu(2)PCH(2)SiMe(2)NSiMe(2)CH(2)PtBu{CMe(2)CH(2)})}], ([RhH(PNP*)]), reacts with O(2) in the time taken to mix the reagents to form a 1:1 eta(2)-O(2) adduct, for which O--O bond length is discussed with reference to the reducing power of [RhH(PNP*)]; DFT calculations faithfully replicate the observed O-O distance, and are used to understand the oxidation state of this coordinated O(2). The reactivity of [Rh(O(2))(PNP)] towards H(2), CO, N(2), and O(2) is tested and compared to the associated DFT reaction energies. Three different reagents effect single oxygen atom transfer to [RhH(PNP*)]. The resulting [RhO(PNP)], characterized at and above -60 degrees C and by DFT calculations, is a ground-state triplet, is nonplanar, and reacts, above about +15 degrees C, with its own tBu C--H bond, to cleanly form a diamagnetic complex, [Rh(OH){N(SiMe(2)CH(2)PtBu(2))(SiMe(2)CH(2)PtBu{CMe(2)CH(2)})}].