Dative Bonding\nin Quasimetallatranes Containing Group\n15 Donors (Y = N, P, and As)\nand Group 14 Acceptors (M = Si, Ge, Sn, and Pb)

Metallatranes and their analogous fused ring [3.3.0]\nbicyclic compounds,\nquasimetallatranes, have emerged as fascinating molecular systems\nwith intriguing structural, bonding, and conformational properties.\nWe present a comprehensive investigation aimed at unraveling the nature\nof dative bonding and exploring the conformational flexibility of\nthese compounds. We extensively characterize the dative bond between\nthe metal center and the electron pair donor, using a range of modeling\ntechniques. Our analyses involve structural optimizations, molecular\norbital examinations, and covalency ratio calculations, which provide\na thorough understanding of the bonding interactions responsible for\nthe stability of these systems. The results confirmed the presence\nof dative bonds, supported by the close proximity between the metal\nand the electron-donating group, and the observation of overlapping\nelectron density. Our studies reveal a correlation between the size\nof the electron-donor and the coordinating metal atom, and the strength\nof the dative interaction, as indicated by the bond length and the\nWiberg bond indices. This bond strength, in turn, influences the conformational\npreferences adopted by these compounds. This investigation sheds light\non the fundamental aspects of the fused ring [3.3.0] bicyclic quasimetallatrane\ncompounds and offers valuable insights into their unique properties.