An iron-bromoalumanyl complex with a tri-coordinated aluminum was synthesized. Its CO-stretching frequencies are shifted to lower-frequency region compared to those of the related boryl and gallyl complexes. Theoretical investigations suggested the importance of the Br–Al mesomeric effect on the stability of the alumanyl complex.

The first dibromoalumanyl‐iron complex [Br2Al–FeCp(CO)2] was synthesized by the reaction of monobromoalumanyl‐iron complex bearing a bulky substituent on aluminum atom with AlBr3, whose structure was determined by the X‐ray crystallographic analysis and the NMR measurement. The reactions monobromoalumanyl‐iron complex with GaBr3 show that these reactions would proceed by the mutual recombination of substituents.

Although the chemistry of frustrated Lewis pairs (FLPs) has seen tremendous developments, investigations on anionic, mono-molecular FLPs are still scarce and 1,3-zwitterions are unknown, but a functional K/OR phosphinindenoid complex can be used instead.

The novel phosphanylalumanes, Al–P single-bond species, fully bearing carbon protecting groups on aluminum and phosphorus atoms, are synthesized by the reactions of aluminum monohalides [(t-Bu)2AlBr and (C6F5)2AlCl·0.5(toluene)] with Mes2PLi. Regarding the t-Bu system, λ3,λ3-phosphanylalumane is obtained. Concerning the C6F5 system, on the other hand, the corresponding LiCl complex, λ4,λ4-phosphanylalumane, is obtained. The Al–P bond lengths of C6F5-substituted λ3,λ4-, and λ4,λ4-derivatives are much shorter than those of the reported λ3,λ4-phosphanylalumane derivatives and comparable to that observed for the previously reported λ3,λ3-phosphanylalumanes. Theoretical calculations reveal that the binding of the C6F5 groups to Al results in a large contribution of Al and a large s-character in the Al–P bond of phosphanylalumanes. Considering t-Bu-substituted phosphanylalumanes, the Al–P bond lengths reflect the coordination number of Al, showing a longer Al–P bond length in the case of λ4-Al as compared with that of λ3-Al. Combining the structural, spectroscopic, and theoretical results, the t-Bu-substituted λ3,λ3-phosphanylalumane has well separated vacant p orbital and lone pairs, which is suitable for reactivity studies.