Carbodiphosphorane analogues E(PPh3)2 with E=C-Pb: a theoretical study with implications for ligand design

Area of Science:

• Inorganic Chemistry
• Quantum Chemistry
• Organometallic Chemistry

Background:

• Carbodiphosphoranes are known for Group 14 elements.
• Heavy homologues of carbodiphosphorane (E(PPh3)2, E=Si, Ge, Sn, Pb) are experimentally unknown.
• Understanding the stability and bonding of these compounds is crucial.

Purpose of the Study:

• To theoretically investigate the heavy Group 14 homologues of carbodiphosphorane.
• To predict their stability and potential for isolation in condensed phases.
• To analyze their bonding, chemical reactivity, and donor properties.

Main Methods:

• Quantum-chemical calculations were performed.
• The BP86/TZVPP level of theory was employed.
• Analysis included bonding situations, chemical reactivity, and proton affinities.

Main Results:

• Tetrelediphosphoranes E(PPh3)2 are predicted to be stable and isolable.
• These divalent E(0) compounds (ylidones) feature donor-acceptor bonds Ph3P→E←PPh3.
• They exhibit large proton affinities and act as powerful double donors, forming stable complexes with Lewis acids like BH3 and AuCl.

Conclusions:

• The studied tetrelediphosphoranes are stable ylidone compounds with significant donor capabilities.
• Their electronic structure and reactivity distinguish them from related N-heterocyclic carbenes.
• The findings present a compelling challenge for experimental synthesis and verification.