Synthesis, structure, and reactions of a nitroxyl complex of iridium(iii), cis,trans-IrHCl2(NHO)(PPh3)2

Abstract

Reaction of Ir(NO)(PPh3)3 with anhydrous HCl results in addition of 2 equivalents of HCl with formal protonation of the nitrosyl ligand, affording the unusual six-co-ordinate nitroxyl complex cis,trans-IrHCl2(NH=O)(PPh3)2.

A nitrosyl hydride complex of a heme model [Ru(ttp)(HNO)(1-MeIm)] (ttp=tetratolylporphyrinato dianion)

“…The marked drop in t NO from that of free HNO [32] at 1563 cm À1 is suggestive of the HNO ligand in [Ru(ttp)(HNO)(1-MeIm)] behaving as a strong p-acid. Hillhouse and coworkers [23,31] have previously documented the p-acidity of the HNO ligand in coordination complexes, and we have shown that the related nitrosoarenes (ArNO) are p-acids in [M II (por)(ArNO)]-containing complexes (M ¼ Fe, Ru, Os) [19]. To date, there are four X-ray structural reports of metal-HNO complexes; three of these reveal Nbinding of the HNO ligand attached to the metal (for Os, Ir, Ru) [28,30,31], and one reveals a side-on g 2 binding of the HNO ligand in a Mo complex [33].…”

“…Hillhouse and coworkers [23,31] have previously documented the p-acidity of the HNO ligand in coordination complexes, and we have shown that the related nitrosoarenes (ArNO) are p-acids in [M II (por)(ArNO)]-containing complexes (M ¼ Fe, Ru, Os) [19]. To date, there are four X-ray structural reports of metal-HNO complexes; three of these reveal Nbinding of the HNO ligand attached to the metal (for Os, Ir, Ru) [28,30,31], and one reveals a side-on g 2 binding of the HNO ligand in a Mo complex [33]. The t NO value of 1380 cm À1 in [Ru(ttp)(HNO)(1-MeIm)] suggests that the HNO ligand is N-bound to the Ru center, as this value is similar to the 1306-1332 cm À1 values observed in the related compounds [Ru(por)-(ArNO)(L)] (L ¼ pyridine, 1-MeIm) with N-bound nitrosoarene ligands [34,35].…”

“…2 This is surprising, since nucleophilic attack at bound nitrosyls to give related metal-{N(Nu)@O} derivatives are well-known [37]. Other methods to generate metal-HNO complexes involve (i) formal protonation of bound NO [22,23,[29][30][31][38][39][40], (ii) proton abstraction from coordinated H 2 NO [33], (iii) oxidation of bound hydroxylamine [27], (iv) formal coupling of a H-atom with the NO ligand in a metal nitrosyl radical complex [24], and (v) NO þ insertion into metal-hydride bonds [26]. In addition, the [Ru(ttp)(H-NO)(1-MeIm)] complex is air-and thermally sensitive.…”

Nitrogen Monoxide and Nitrous Oxide Binding and Reduction

“…The complex IrHCl 2 (HNO)(PPh 3 ) 2 , previously described by Roper, was recently structurally characterized by Hillhouse and coworkers [129]. The iridium atom is in a pseudo-octahedral environment possessing cis chlorides and trans phosphine ligands.…”

N‐Methylhydroxylamido(1−)‐ and Nitrosomethaneruthenium Complexes Derived from Nitrosyl Complexes: Reversible N‐Protonation of an N‐Coordinated Nitrosoalkane

“…Indeed, interconversion of these partially reduced nitrogenous species, including their organic derivatives such as nitrosoalkanes (RNO), on late transition-metal centers remains unexplored [3][4][5][6][7][8] compared with that on the early transition metals. [9,10] In an early example, Roper and coworkers [3] reported the reversible protonation of the nitrosyl complex [Ir(NO){P(C 6 H 5 ) 3 [4] the second protonation site of the nitroxyl complex, for example, is still unclear. We now describe the stepwise transformation of nitrosylruthenium complexes to nitrosoalkane and N-alkylhydroxylamido(1À) complexes, as well as the facile interconversion of the latter two species.…”