Author: Cameron M. E. Graham

0000000000162585

AUTHOR

Cameron M. E. Graham

Phosphorus-Chalcogen Ring Expansion and Metal Coordination

The reactivity of 4-membered (RPCh)2 rings (Ch = S, Se) that contain phosphorus in the +3 oxidation state is reported. These compounds undergo ring expansion to (RPCh)3 with the addition of a Lewis base. The 6-membered rings were found to be more stable than the 4-membered precursors, and the mechanism of their formation was investigated experimentally and by density functional theory calculations. The computational work identified two plausible mechanisms involving a phosphinidene chalcogenide intermediate, either as a free species or stabilized by a suitable base. Both the 4- and 6-membered rings were found to react with coinage metals, giving the same products: (RPCh)3 rings bound to the…

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Preparation and Characterization of P2 BCh Ring Systems (Ch=S, Se) and Their Reactivity with N-Heterocyclic Carbenes

Four-membered rings with a P2BCh core (Ch = S, Se) have been synthesized via reaction of phosphinidene chalcogenide (Ar*P=Ch) and phosphaborene (Mes*P=BNR2). The mechanistic pathways towards these rings are explained by detailed computational work that confirmed the preference for the formation of P–P, not P–B, bonded systems, which seems counterintuitive given that both phosphorus atoms contain bulky ligands. The reactivity of the newly synthesized heterocycles, as well as that of the known (RPCh)n rings (n = 2, 3), was probed by the addition of Nheterocyclic carbenes, which revealed that all investigated compounds can act as sources of low-coordinate phosphorus species. peerReviewed

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Trapping Rare and Elusive Phosphinidene Chalcogenides

Four-membered rings with a P2Ch2 core (Ch=S, Se) and phosphorus in the +3 oxidation state have been synthesized. The utility of these rings as a source of monomeric phosphinidene chalcogenides was probed by the addition of an N-heterocyclic carbene, resulting in a base-stabilized phosphinidene sulfide. Similarly, persistence of the phosphinidene selenide in solution was shown through cycloaddition chemistry with 2,3-dimethylbutadiene at elevated temperatures. The observed reactivity was explained by detailed computational work that established the conditions upon which the P2Ch2 rings can liberate phosphinidene chalcogenides. peerReviewed

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