Search

Heterobimetallic cationic sandwich complexes [M(μ‐Cp)M′Cp]+ of group 13 (M=Ga, In) and group 14 (M′=Ge, Sn) elements have been prepared as [WCA]− salts (WCA=Al(ORF)4; ORF=OC(CF3)3). Their molecular structures include free apical gallium or indium atoms. The sandwich complexes were formed in the reactions of [M(HMB)]+[WCA]− (HMB=C6Me6) with the free metallocenes [M′Cp2]. Their structures are related to known stannocene and stannocenium salts; the unprecedented germanium analogues, namely the free germanocenium cation [GeCp]+ and the corresponding triple‐decker complex cation [CpGe(μ‐Cp)GeCp]+, are described herein. By variation of the reaction conditions, these sandwich complexes can be transformed into the group 13/14 mixed cationic coordination polymer [{In(HMB)(μ‐SnCp2)}n][WCA]n. This polymeric chain motif was also successfully replicated by the synthesis of complexes [{Ga/In(HMB)(μ‐FeCp2)}n][WCA]n containing FeCp2 as a bridging ligand., One, two, three, infinity… The syntheses of the free germanocenium cation, a series of heterobimetallic sandwich cations of groups 13 and 14, as well as cationic sandwich polymers containing group 13 hexamethylbenzene cations bridged by stannocene and ferrocene are described.

A convenient access to a triad of triazoles with ferrocenyl and cobaltoceniumyl substituents is reported. N‐Alkylation, deprotonation and metalation with CuI/AgI/AuI synthons affords the heteroleptic triazolylidene complexes. Due to the combination of neutral, electron‐donating ferrocenyl substituents and cationic, strongly electron‐withdrawing cobaltocenium substituents, the mesoionic carbene (MIC) ligands of these complexes are electronically interesting “push–pull”, “pull–push” and “pull–pull” metalloligands with further switchable redox states based on their fully reversible FeII/FeIII, (ferrocene/ferrocenium) and CoIII/CoII, (cobaltocenium/cobaltocene) redox couples. These are the first examples of metal complexes of (di)cationic NHC ligands based on cobaltoceniumyl substituents. DFT calculated Tolman electronic parameter (TEP) of the new MIC ligands, show these metalloligands to be extremely electron‐poor NHCs with properties unmatched in other carbene chemistry. Utilization of these multimetallic electronically tunable compounds in catalytic oxazoline synthesis and in antitumor studies are presented. Remarkably, 1 mol % of the AuI complex with the dicationic MIC ligand displays full catalytic conversion, without the need for any other additives, in less than 2 hours at ambient temperatures. These results thus firmly establish these new classes of cobaltoceniumyl based (di)cationic MIC ligands as prominent players in several branches of chemistry.