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

Cyclic alkyl(amino) carbene (cAAC)-anchored boryl- and stibanyl-phosphaalkenes with general formula cAAC = P-ER 2 [E = B, R = (N i Pr 2 ) 2 ( 3a-c ); E = Sb, R = 2,4,6-triisopropylphenyl ( 5a-b )] have been synthesized and utilized as precursors for the bis-phosphaalkenyl dichlorogermane [(cAAC = P) 2 GeCl 2 ] ( 6 ) and the first molecular example of a neutral polymeric mixed-valence Ag I /Ag II phosphinidenide complex [(cAACP) 2 Ag 4 I Ag II Cl 4 ] n ( 7 ). 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 7 has been characterized by ESR spectroscopy. Cyclic voltammetry studies of compounds 3 / 5 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 3 and 5 , and the polar C cAAC = P bonds in compounds 3 , 5 , and 6 prevailing their phosphaalkene structures over phosphinidenes.