Heterobimetallic Systems Containing Organometallic and Classical Coordination Sites: Effects of Subtle Changes in the Werner‐Type Site

Abstract

Several highly unsymmetrical heterodinuclear Mn/Zn complexes are reported, in which an organometallic CpMn-(CO) 2 fragment and a classical Werner-type zinc coordination unit are arranged in close proximity by means of a bridging pyrazolate. Ligand scaffolds differing in the chelate size of the tripodal tetradentate {N 4 } binding site, and different coligands for zinc are employed. Both the zinc-devoid precursor compounds and the bimetallic complexes with zinc(II) nested in the tris(pyridylalkyl)amine type {N 4 } compartment

Schiff Base Macrocycles Containing Pyrroles and Pyrazoles

“…19 F NMR spectra were referenced against C 6 F 6 . Where necessary, assignment of the NMR signals was derived from 2D spectra; abbreviations used in the assignments: py = pyr- [16,17] and 3,5-bis(bromomethyl)-1-(tetrahydropyran-2-yl)pyrazole hydrochloride (8 b), [15] 3,5-bis-(chloromethyl)-1H-pyrazole (11), [13] and 3,4-diethylpyrrole (7 c) [25] were prepared according to literature procedures.…”

“…[19] Several possible mechanistic explanations for this observation that find some parallels in the chemistry of pyrrole can be offered (Scheme 3). Anchimeric assistance of the tetrahydropyrane oxygen atom may assist in the substitution reaction (mechanism A), but only the chloromethyl group adjacent to the THP group is susceptible to this activation effect.…”

“…The short diacid, hexafluoroglutaric acid, was predicted to be incapable of forming hydrogen bonds with both macrocyclic cavities of a single molecule of 4 e, f, whereas perfluorosuberic acid was predicted to be able to span both macrocyclic subunits in an intramolecular fashion. A series of 19 Structural variety of 4 and 4·TFA in the solid state: Figure 3 shows the single-crystal X-ray structure of free base 4 a, present as the solvate 4 a·2 EtOH. The macrocycle assumes a nonplanar, shallow bowl-shape conformation.…”

N‐Heterocyclic Carbenes with Neutral Tethers

“…Appreciable metal -metal interactions could not be observed in any of these complexes, with the exception of argentophilic [ 77 , 78 ] or aurophilic [ 79 ] interactions. As with other functionalised carbenes, these pyrazole bridged ones have precedences, in this case amine [ 80 , 81 ], phosphino [ 82 ] and Cp [ 83 ] functionalised pyrazole ligands.…”

Dinuclear Allylpalladium Complexes ofC2-Symmetric Pyrazolate-Bridged Bis(oxazoline) Ligands (pyrbox's): Structures, Dynamic Behavior, and Application in Asymmetric Allylic Alkylation

“…Further enhancement of preorganization of the two metal ions can be achieved by the attachment of chelating side arms to the 3,5-positions of the pyrazole heterocycle, and a variety of symmetrical and unsymmetrical 3,5-disubstituted ligands with mono-, bi-, and tridentate side arms have been developed over the past decade . By varying the lengths of these side arms and the nature or the quantity of the donor atoms, a fine tuning of the metal−metal distance can be achieved. , Such highly preorganized pyrazolate-based bimetallic complexes have been successfully used in metallobiosite modeling, and their favorable properties in two-center organometallic chemistry are increasingly recognized. − While a pyrazolate-bridged bimetallic array has inherent 2-fold symmetry, however, little is known as yet about C 2 -symmetric systems with chiral chelate arms such as the ligand HL bearing two ( R )-2-(methoxymethyl)pyrrolidine substituents at the central pyrazole core …”