Reactivity of the Radical NO with a Masked Form of 14 Valence Electron (PNP)Rh: Forming Rh(0, I or II)?

Abstract

The reaction of NO with [(tBu2PCH2SiMe2)NSiMe2CH2PtBu(CMe2CH2)]RhH, a functional equivalent of “(PNP)Rh,” rapidly forms (PNP)Rh(N2) and (PNP)Rh(NO)(NO2). Detected intermediates include (PNP)Rh(NO), characterized by its NMR, EPR and IR spectra as well as by DFT calculation, as having the neutral NO‐centered radical Lewis base donating to RhI. One other intermediate is detected, using a combination of spectroscopic and DFT methods, as containing a nitrite (O–N=O) ligand that is O‐bound to Rh, giving an overall Cs symmetry. The overall reaction is thus the disproportionation of NO catalyzed by RhI, and the reaction serves to produce nonradical products from radical NO. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

NO˙ disproportionation by a {RhNO}9pincer-type complex

“…6 The novel {RhNO} 9 • ) was well characterized in solution and its reactivity with organic halides was studied, resulting in C-X bond activation; a reactivity that had not been documented for the only previously reported square planar {MNO} 9 complex, [Rh(PNP)(NO)] • (PNP = N( t Bu 2 PCH 2 SiMe 2 ) 2 -). 7 This bond activation reactivity reflects the ability of the nitrosyl ligand to act as an electron reservoir. disproportionation by metal complexes to give N 2 O and metal nitrite complexes, 7,[9][10][11][12][13][14] although in one case dinitrogen (N 2 ) was reported as the reduced product.…”

“…7 This bond activation reactivity reflects the ability of the nitrosyl ligand to act as an electron reservoir. disproportionation by metal complexes to give N 2 O and metal nitrite complexes, 7,[9][10][11][12][13][14] although in one case dinitrogen (N 2 ) was reported as the reduced product. 7 This disproportionation reaction (eq.…”

Azanone (HNO): generation, stabilization and detection

“…126 NOstabilization by complexes with pincer scaffolds is far better known. Several structural analyses of this kind of species exist in bibliography, 124,[127][128][129][130][131][132][133] along with reports of their catalytic activity. [134][135][136] Within our group, several rhodium-based pincer ligand systems have been studied (the most relevant are highlighted in Figure 3b).…”

Structure and Reactivity of NO/NO+/NO−Pincer and Porphyrin Complexes

“…DFT calculations of half-bent systems showed large spin densities to be located on the nitrosyl ligand, which could be more reasonably thought of as radical NO * coordinating via a lone pair in the N atom. [26,27] Interestingly, this {MNO} 10 system should have a "full" bent nitrosyl in a square planar conformation (Ni II NO À ) or a linear nitrosyl in a a tetrahedral geometry (Ni 0 NO + ). Since the PNP ligand prohibits reaching a tetrahedral coordination geometry, the system stays at an intermediate point with the NiNO bend at an intermediate value.…”

“…Most used is the direct method of nitrosylation by injection of gaseous nitric oxide into a solution of the pincer precursor complex. [22,26,27,30,[33][34][35] This route was first employed by Milstein's group, who proved Rh(PNP)(NO)(Cl) (1 + ) obtention could be achieved both by reaction of a Rh(II) precursor and NO * and by reaction of Rh(I) and NO + , as is depicted in Scheme 1. [33] This last alternative has been scarcely reported thereafter.…”