We describe a novel "long-bonding" motif that appears in the framework of natural bond orbital (NBO) analysis as a surprising form of 3-center, 4-electron (3c/4e) L center dot center dot center dot A center dot center dot center dot L' bonding with "inverted" electronegativity pattern Xi(A) > Xi(L), Xi(L) Such long-bonding (denoted (LL)-L-boolean AND') underlies the predicted (meta)stability of exotic rare gas species with highly electronegative ligands (e.g., HeF2, NeF2) as well as the absolute stability of low-electronegativity metallic triads (e g, BeLi2, ZnCu2, and related species) that are experimentally unknown but can be anticipated from simple valency and electronegativity trends. We focus particularly on the BeLi2 triad, whose Lewis type (LiLi)-Li-boolean AND' long bond is of paradoxical antibonding phase pattern, denoted (sigma) over cap*(LiLi), to suggest its essential 2(-1/2)(s(Li) - s(Li)) orbital composition. We demonstrate how the long bonded triad serves as a fundamental building-block for numerous 1-, 2-, and 3-d structures that are predicted to exhibit extraordinary calorimetric, vibrational, and electric polarizability properties, commonly associated with the delocalized metallic limit Both thermodynamic and kinetic results support the NI30 inference that (sigma) over cap/(sigma) over cap*-type long bonding signals the transition to a fundamentally new regime of chemical association, separated by significant activation barriers from the covalent molecular domain and characterized by reversed perturbative precedence of Lewis type vs resonance type donor-acceptor contributions. Long bond resonance therefore appears to be of central importance to a broadened conceptual picture of molecular and metallic interaction phenomena.