“…For boron hydrides with more than 12 skeletal atoms, the structures of the so-called macropolyhedral boranes are formed by the fusion of two or more polyhedra or polyhedral fragments, analogous to polycyclic hydrocarbons . Two of the largest known macropolyhedral boranes are the isomeric docosahydrooctadecaboranes B 18 H 22 . , They exhibit a unique molecular structure with two open faces and six acidic bridging hydrogen atoms (μ H -BB). − Their structural and chemical properties, together with their interaction with light, make B 18 H 22 a promising candidate for a wide range of applications, from energy storage, , semiconductor doping ,− to nano- and optoelectronic devices. − The molecular structure of B 18 H 22 can be viewed as two decaborane molecules condensed together, with each subcluster sharing atoms B(5) and B(6) in the decaborane numbering system, in common (Figure B,C). The isomer syn -B 18 H 22 on which this study focuses is a much less-studied (“forgotten”) system compared to its anti -B 18 H 22 isomer, and it has a 2-fold symmetry axis due to the fusion of two {B10} units sharing the B(5)–B(6) edge so that B(5)B(5′) and B(6)B(6′) (Figure B); in the anti -B 18 H 22 isomer, B(5)B(6′) and B(6)B(5′), which results in the inversion symmetry (Figure C). ,, What has stimulated most of the recent interest in anti -B 18 H 22 and its substituted derivatives has mainly been their luminescence properties. − Our interest in the “forgotten”, nonluminescent isomer, syn -B 18 H 22 , has been stimulated mainly by its unique geometry and size with respect to its use as constituents of purely borane, carbon-free self-assembled monolayers and its further use toward 2-dimensional membranes with thickness below 1 nm and with a 3D-aromatic character, as well as capping ligands of atomically precise metal nanoclusters, a newly emerging class of materials with adjustable geometry, size, and properties. , …”