Carbene-Anchored Boryl- and Stibanyl-Phosphaalkenes as Precursors for Bis-Phosphaalkenyl Dichlorogermane and Mixed-Valence Ag/Ag Phosphinidenide.

Cyclic alkyl(amino) carbene (cAAC)-anchored boryl- and stibanyl-phosphaalkenes with general formula cAAC = P-ER [E = B, R = (NPr) (); E = Sb, R = 2,4,6-triisopropylphenyl ()] have been synthesized and utilized as precursors for the bis-phosphaalkenyl dichlorogermane [(cAAC = P)GeCl] () and the first molecular example of a neutral polymeric mixed-valence Ag/Ag phosphinidenide complex [(cAACP)AgAgCl] (). All compounds have been characterized by single-crystal X-ray diffraction and further investigated by nuclear magnetic resonance (NMR), mass spectrometric analysis, and UV-vis/fluorescence measurements. The paramagnetic complex has been characterized by ESR spectroscopy. Cyclic voltammetry studies of compounds / have suggested possible one-electron quasi-reversible reductions, indicating their redox noninnocent behavior in solution. Quantum chemical studies revealed the electron-sharing nature of the P-B and P-Sb σ bonds in compounds and , and the polar C = P bonds in compounds , , and prevailing their phosphaalkene structures over phosphinidenes.