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Abstract:
Recently, the first mixed C/P phosphatetrahedranes (tBuC)3P and (tBuCP)2 were reported. Unlike (tBuCP)2, (tBuC)3P exhibits remarkable thermal stability, which can be partially attributed to a network of nine hydrogen–hydrogen bonds (HHBs) localized between the tert-butyl substituents. The stabilizing contribution arising from this network of HHBs was obtained from local energy decomposition (LED) analysis calculated at the domain-based local pair natural orbital CCSD(T) (DLPNO-CCSD(T)) level of theory. These calculations suggest that each HHB contributes approximately −0.7 kcal/mol of stabilization; however, the net stabilization energy likely lies between −0.25 and −0.5 kcal/mol because of steric repulsion. Spatial analysis of the London dispersion energy via a dispersion interaction density (DID) plot reveals that the DID surface is localized at key C–H groups involved in HHBs, consistent with London dispersion interactions predominantly arising from HHBs. In addition, we present a computed mechanism that supports a phosphinidenoid species as a key reaction intermediate in the synthesis of (tBuC)3P.
