= Solution
In <borazine>, each B and N is approximately trigonal planar. The alternating ring contains a sigma framework with perpendicular p orbitals; the <nitrogen> <lone pairs> can donate into the boron acceptor orbitals. Six pi <electrons> can therefore be distributed around the ring, giving partial B–N multiple-bond character rather than six ordinary isolated single bonds. Equal ring distances are compatible with this symmetric delocalization.
The <electronegativity> difference makes each B–N bond strongly polar, $\mathrm{B^{\delta+}{-}N^{\delta-}}$. The occupied pi orbitals are weighted toward N, and the empty acceptors toward B. In <benzene>, equivalent <carbon> centers give much more even pi distribution and strong resistance to addition that destroys the aromatic system. \b[<borazine> resembles <benzene> geometrically but has substantially more polarized, more reactive bonding.] It presents electrophilic boron sites to <nucleophiles> and <nitrogen> donors to <Lewis acids>. Polar reagents can add across B–N, and <water> can cleave the ring; <benzene> ordinarily favors substitution under suitable conditions rather than facile polar addition or <hydrolysis>. The label “inorganic <benzene>” should therefore not be interpreted as identical aromatic stabilization or reactivity. <nitrogen>-bound Lewis-acid adducts and hydrogen-halide additions demonstrate this contrast experimentally.<Aluminium and gallium trihalide adducts of 2,4,6-triorganylborazines and the synthesis of triorganylborazinium tetrabromoaluminates by B. Gemünd and others>[2008, p. 136 introduction and pp. 137–142, addition chemistry and nitrogen-bound adducts]{ref}
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