Ion Pairing and Allyl Dynamics in a Series of [Pd(η3-allyl)(N,N-chelate)](anion) Salts. On the Influence of the BPh4− Anion

Ion-pairs as a gateway to transmetalation: aryl transfer from boron to nickel and magnesium

Gas-phase ion-ion reactions between tris-1,10-phenantholine metal dications, [(phen)₃M]²⁺ (where M = Ni and Mg), and the tetraphenylborate anion yield the ion-pairs {[(phen)₃M]²⁺[BPh₄]^-}⁺. The ion-pairs undergo transmetalation upon loss of a phen ligand to give the organometallic complexes [(phen)₂M(Ph)]⁺. DFT calculations, used to determine the energy barriers for the transmetalation reactions and the hydrolysis reactions, are entirely consistent with the experimental results.

Synthesis of Double-Bridged Cofacial Nickel Porphyrin Dimers with 2,2'-Bipyridyl Pillars and Their Restricted Coordination Space

Double-bridged cofacial Ni porphyrin dimers 2 with 2,2'-bipyridyl pillars were effectively prepared by a one-step reductive homocoupling reaction of bis(chloropyridyl)-substituted Ni porphyrin derivatives followed by a specific separation of a cyanopropyl-modified silica gel column using pyridine eluent systems. The structural analyses of 2 and its Pd complex were carried out in their solid and solution states by means of X-ray single crystal analysis and NMR, respectively. The complexation of η³-allylpalladium chloride (Pd) with 2 on the spatially restricted 2,2-bipyridine moieties on 2 gave a 2:1 (Pd:2) complex, in which the 2,2'-bipyridine ligands only provided one of the N atoms on a 2,2'-bipyridine ligand to a Pd. Therefore, the 2,2-bipyridine moieties acted as a monodentate ligand.

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

Synthesis of a pincer-type linear nitrosyl complex [Rh(P^tBu₂CN^Et₂)(NO)]⁺ (3⁺) is described. The product and all intermediates involved were fully characterized by FTIR, NMR, cyclic voltammetry and X-ray crystallography. Attempts at obtaining (3⁺) from its chlorinated precursor Rh(PCN)(NO)Cl (2) revealed that a relative stabilization of this complex ion is introduced by the BArF^- counteranion, as other counteranions-PF₆^-, BF₄^- and triflate-proved to coordinate to the metal center. Redox reactivity both of (3⁺) and of that of its five-coordinate derivatives (2) and [Rh(PCN)(NO)(CH₃CN)]⁺ (4⁺) was found to distinguish itself from analogous PCP complexes due to a relative stabilization of higher oxidation states. Oxidation of these three complexes was studied by FTIR spectroelectrochemistry. Reduction of complex (3⁺) to yield a short-lived {RhNO}⁹ species [Rh(PCN)(NO)]˙ (3˙) was also carried out. Complex (3˙) was proved able to activate carbon-halogen bonds in aryl halides, in much a similar way as that of its PCP analogue. Complex (3⁺) was also seen to establish a linear ↔ bent nitrosyl equilibrium upon addition of CO which could not be fully displaced with excess CO.

Applications of NMR diffusion methods with emphasis on ion pairing in inorganic chemistry: a mini-review

This mini-review provides a brief overview of the use of NMR diffusion methods in connection with estimating molecular weights in solution, recognizing hydrogen bonding and encapsulation processes and, primarily, identifying and estimating the varying degrees of ion pairing. Copyright © 2016 John Wiley & Sons, Ltd.