Unsaturated chiral-only-at-metal rhodium(III) complexes bearing SiN-type ligands.

Enantiopure chiral-at-metal rhodium(III) unsaturated 16e complexes have been obtained from racemic [Rh(SiN)Cl] (SiN= 8-(dimethylsilyl)quinoline) using a readily accessible chiral spiroborate as chiral resolution agent. This strategy allows an easy access to enantiopure neutral Δ/Λ-Rh(SiN)2Cl and cationic Δ/Λ-Rh(SiN)2[BAr4F] unsaturated complexes, wherein rhodium(III) is coordinated to two inert silylquinoline ligands in a propeller-like arrangement.

Formation of Irida-β-ketoimines and PCN-Ir(III) Complexes by Reacting Irida-β-diketones with Aliphatic Diamines: Catalytic Activity in Hydrogen Release by Methanolysis of HN-BH.

Aliphatic diamines [(HN(CH)NHR) () = 2: R = H (), R = CH (), R = CH (), = 3, R = H () or -2-(aminomethyl)piperidine ()] react with [IrH(Cl){(PPh(-CHCO))H}] in THF to afford ketoimine complexes [IrH(Cl){(PPh(-CHCO))(PPh(-CHCN(CH)NHR))H}] (-) or [IrH(Cl){(PPh(-CHCO))(PPh(-CHCNCH(CHNH)))H}] (), containing a bridging N-H···O hydrogen bond and a dangling amine. Complex consists of an almost equimolar mixture of two diastereomers. In protic solvents, the dangling amine in complexes displaces chloride to afford cationic acyl-iminium compounds, [IrH(PPh(-CHCO))(PPh(-CHCNH(CH)NHR))]X (-, X = Cl) or [IrH(PPh(-CHCO))(PPh(-CHCNHCH(CHNH)))]Cl () and (-, X = ClO), with new hemilabile terdentate PCN ligands adopting a facial disposition.

Stability and C-H Bond Activation Reactions of Palladium(I) and Platinum(I) Metalloradicals: Carbon-to-Metal H-Atom Transfer and an Organometallic Radical Rebound Mechanism.

One-electron oxidation of palladium(0) and platinum(0) bis(phosphine) complexes enables isolation of a homologous series of linear d metalloradicals of the form [M(PR)] (M = Pd, Pt; R = Bu, Ad), which are stable in 1,2-difluorobenzene (DFB) solution for >1 day at room temperature when partnered with the weakly coordinating [BAr] (Ar = 3,5-(CF)CH) counterion. The metalloradicals exhibit reduced stability in THF, decreasing in the order palladium(I) > platinum(I) and PAd > PBu, especially in the case of [Pt(PBu)], which is converted into a 1:1 mixture of the platinum(II) complexes [Pt(PBuCMeCH)(PBu)] and [Pt(PBu)H] upon dissolution at room temperature. Cyclometalation of [Pt(PBu)] can also be induced by reaction with the 2,4,6-tri-butylphenoxyl radical in DFB, and a common radical rebound mechanism involving carbon-to-metal H-atom transfer and formation of an intermediate platinum(III) hydride complex, [Pt(PBuCMeCH)H(PBu)], has been substantiated by computational analysis.

Iridium complexes of an -trifluoromethylphenyl substituted PONOP pincer ligand.

The synthesis and iridium coordination chemistry of a new pyridine-based phosphinito pincer ligand 2,6-(ArPO)CHN (PONOP-Ar; Ar = 2-(CF)CH) are described, where the P-donors have -trifluoromethylphenyl substituents. The iridium(III) 2,2'-biphenyl (biph) derivative [Ir(PONOP-Ar)(biph)Cl] was obtained by reaction with [Ir(biph)(COD)Cl] (COD = 1,5-cyclooctadiene) and subsequent halide ion abstraction enabled isolation of [Ir(PONOP-Ar)(biph)] which features an Ir ← F-C bonding interaction in the solid state. Hydrogenolysis of the biphenyl ligand and formation of [Ir(PONOP-Ar)(H)] was achieved by prolonged reaction of [Ir(PONOP-Ar)(biph)] with dihydrogen.

Irida-β-ketoimines Derived from Hydrazines To Afford Metallapyrazoles or N-N Bond Cleavage: A Missing Metallacycle Disclosed by a Theoretical and Experimental Study.

Unprecedented metallapyrazoles [IrH{PhP(o-CH)CNNHC(o-CH)PPh}] (3) and [IrHCl{PhP(o-CH)CNNHC(o-CH)PPh}] (4) were obtained by the reaction of the irida-β-ketoimine [IrHCl{(PPh(o-CHCO))(PPh(o-CHCNNH))H}] (2) in MeOH heated at reflux in the presence and absence of KOH, respectively. In solution, iridapyrazole 3 undergoes a dynamic process due to prototropic tautomerism with an experimental barrier for the exchange of ΔG = 53.7 kJ mol.