Synthesis, structure and reactivity of NO⁺, NO˙ and NO⁻pincer PCN-Rh complexes

Abstract

Synthesis of a rhodium PCN pincer-type nitrosyl complex is described. Coordination to the metallic center by weakly coordinating anions was found, as well as a slight stabilization of higher oxidation states when compared to a PCP analogue.

Azanone (HNO): generation, stabilization and detection

“…124 A PCN ligand system proved particularly prone to yield Rh(III)NO -, even leading to the stabilization of adducts with the weakly-coordinating anions PF 6and BF 4 -. 137 Most of our studies on pincer nitrosyls focus on the exploration of their rich redox chemistry. 125,137…”

“…137 Most of our studies on pincer nitrosyls focus on the exploration of their rich redox chemistry. 125,137…”

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

“…Although most of the work published by our group has been focused on these complexes, [28,41,42] in recent years we have also explored reactivity of a complex with an asymmetric PCN pincer scaffold. [40] In this case, obtention of the tetradentate species proved to be challenging, since the route analogous to that shown in Scheme 2 yielded pentacoordinate Rh(PCN)(NO)(Cl) (20) due to residual chloride in solution. Three separate nitrosylation pathways were tested: using a dinitrogen precursor with NOBF 4 , using a hydride precursor and isoamyl nitrite, and using a hydride precursor and Diazald� R (N-methyl-N-nitroso-p-toluenesulfonamide).…”

“…Instability of complex (6 * ) in CH 2 Cl 2 hinted of an interesting reactivity of the sort for our {RhNO} 9 complexes with organic halides which has been further explored. [40,41] However, a more controlled-and thus, more tunable-reactivity would result from coordination of the organic moiety to the metallic center. This has not been observed for either complex, although reduction of the steric bulk by changing from PCP to PCN could have been expected to favor it.…”

“…An extreme case was seen in the case of (19 + ), where exposure of the complex to CH 3 CN resulted in formation of the pentacoordinate species [Rh-(PCN)(NO)(NCCH 3 )] + that could not be reversed even under high vacuum for several hours. [40] This relative stability when compared to PCP of coordinated CH 3 CN introduced by the PCN ligand could be attributed to the reduced steric hindrance of the latter. However, it could be also related to the more electron-donating character of the PCN ligand, favoring Rh(III) complexes.…”