A straightforward and scalable eight‐step synthesis of new N‐heterocyclic carbenes (NHCs) has been developed from inexpensive and readily available 2‐nitro‐m‐xylene. This process allows for the preparation of a novel class of NHCs coined ITent (“Tent” for “tentacular”) of which the well‐known IMes (N,N′‐bis(2,4,6‐trimethylphenyl)imidazol‐2‐ylidene), IPr (N,N′‐bis(2,6‐di(2‐propyl)phenyl)imidazol‐2‐ylidene) and IPent (N,N′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene) NHCs are the simplest and already known congeners. The synthetic route was successfully used for the preparation of three members of the ITent family: IPent (N,N′‐bis(2,6‐di(3‐pentyl)phenyl)imidazol‐2‐ylidene), IHept (N,N′‐bis(2,6‐di(4‐heptyl)phenyl)imidazol‐2‐ylidene) and INon (N,N′‐bis(2,6‐di(5‐nonyl)phenyl)imidazol‐2‐ylidene). The electronic and steric properties of each NHC were studied through the preparation of both nickel and palladium complexes. Finally the effect of these new ITent ligands in Pd‐catalyzed Suzuki–Miyaura and Buchwald–Hartwig cross‐couplings was investigated.

Thes ynthesis andc haracterization of abnormal N-heterocyclic carbene,c yclic (alkyl)(amino)carbene,a nd mesoionic carbene copper(I) complexesa re reported.T hese organometallic species are obtained via aversatile and inexpensive synthetic pathwayu sing readily available reactants,n amely copper oxide andi miniums alts.T he catalytic activity of this series of complexes was evaluated in the [3+ +2] cycloaddition of alkynes with azides (CuAAC). Outstanding catalytic properties were observed for the abnormal NHC-a nd triazolylidenebased copper(I) complexes.

DEDICATION: Dedicated to Wolf-Walther du Mont on the occasion of his 70 th birthday.KEYWORDS: peri-substitution, phosphorus-tellurium, through-space spin-spin coupling, acenaphthene 2 ABSTRACT: A series of peri-substituted phosphorus-tellurium systems R'Te-Acenap-PR 2 (R' = Ph, pAn, Nap, Mes, Tip; R = i Pr, Ph) exhibiting large "through space" spin-spin coupling constants and the "onset" of three-centre four-electron type interactions are presented. The influence of the substituents at the phosphorus and tellurium atoms as well as their behavior upon oxidation (with S, Se) or metalcoordination (Pt, Au) is discussed using NMR spectroscopy, single crystal X-ray diffraction, and advanced DFT studies including NBO, AIM and ELI-D analyses.

A proximate Lewis basic group facilitates the mild dehydrogenative P-As intramolecular coupling in the phosphine-arsine peri-substituted acenaphthene 3, affording thermally and hydrolytically stable arsanylidine-phosphorane 4 with a sterically accessible two-coordinate arsenic atom. The formation of 4 is thermoneutral due to the dehydrogenation being concerted with the donor coordination. Reaction of 4 with a limited amount of oxygen reveals arsinidene-like reactivity via formation of cyclooligoarsines, supporting the formulation of the bonding in 4 as base-stabilized arsinidene R3P→AsR.

is distorted, but notably less so than in bis(sulfide) 4-S. All compounds were fully characterized and except for bis(phosphine) 5 crystal structures were determined.