Functionalization reactions characteristic of a robust bicyclic diphosphane framework

Daniel Tofan, Manuel Temprado, Subhojit Majumdar, Carl D. Hoff, Christopher C. Cummins

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

The 3,4,8,9-tetramethyl-1,6-diphospha-bicyclo-[4.4.0]deca-3,8-diene (P 2(C6H10)2) framework containing a P-P bond has allowed for an unprecedented selectivity toward functionalization of a single phosphorus lone pair with reference to acyclic diphosphane molecules. Functionalization at the second phosphorus atom was found to proceed at a significantly slower rate, thus opening the pathway for obtaining mixed functional groups for a pair of P-P bonded λ5-phosphorus atoms. Reactivity with the chalcogen-atom donors MesCNO (Mes = 2,4,6-C 6H2Me3) and SSbPh3 has allowed for the selective synthesis of the diphosphane chalcogenides OP2(C 6H10)2 (87%), O2P2(C 6H10)2 (94%), SP2(C 6H10)2 (56%), and S2P 2(C6H10)2 (87%). Computational studies indicate that the oxygen-atom transfer reactions involve penta-coordinated phosphorus intermediates that have four-membered {PONC} cycles. The P-E bond dissociation enthalpies in EP2(C 6H10)2 were measured via calorimetric studies to be 134.7 ± 2.1 kcal/mol for P-O, and 93 ± 3 kcal/mol for P-S, respectively, in good agreement with the computed values. Additional reactivity with breaking of the P-P bond and formation of diphosphinate O3P 2(C6H10)2 was only observed to occur upon heating of dimethylsulfoxide solutions of the precursor. Reactivity of diphosphane P2(C6H10)2 with azides allowed the isolation of monoiminophosphoranes (RN)P2(C 6H10)2(R = Mes, CPh3, SiMe 3), and treatment with additional MesN3 yielded symmetric and unsymmetric diiminodiphosphoranes (RN)(MesN)P2(C 6H10)2 (91% for R = Mes). Metalation reactions with the bulky diiminodiphosphorane ligand (MesN)2P 2(C6H10)2 (nppn) allowed for the isolation and characterization of (nppn)Mo(η3-C3H 5)Cl(CO)2 (91%), (nppn)NiCl2 (76%), and [(nppn)Ni(η3-2-C3H4Me)][OTf] showing that these ligands provide an attractive preorganized binding pocket for both late and early transition metals.

Original languageEnglish (US)
Pages (from-to)8851-8864
Number of pages14
JournalInorganic Chemistry
Volume52
Issue number15
DOIs
StatePublished - Aug 5 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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