A Retro Diels–Alder Route to Diphosphorus Chemistry: Molecular Precursor Synthesis, Kinetics of P₂ Transfer to 1,3-Dienes, and Detection of P₂ by Molecular Beam Mass Spectrometry

Abstract

The transannular diphosphorus bisanthracene adduct P2A2 (A = anthracene or C14H10) was synthesized from the 7-phosphadibenzonorbornadiene Me2NPA through a synthetic sequence involving chlorophosphine ClPA (28-35%) and the tetracyclic salt [P2A2Cl][AlCl4] (65%) as isolated intermediates. P2A2 was found to transfer P2 efficiently to 1,3-cyclohexadiene (CHD), 1,3-butadiene (BD), and (C2H4)Pt(PPh3)2 to form P2(CHD)2 (>90%), P2(BD)2 (69%), and (P2)[Pt(PPh3)2]2 (47%), respectively, and was characterized by X-ray diffraction as the complex [CpMo(CO)3(P2A2)][BF4]. Experimental and computational thermodynamic activation parameters for the thermolysis of P2A2 in a solution containing different amounts of CHD (0, 4.75, and 182 equiv) have been obtained and suggest that P2A2 thermally transfers P2 to CHD through two competitive routes: (i) an associative pathway in which reactive intermediate [P2A] adds the first molecule of CHD before departure of the second anthracene, and (ii) a dissociative pathway in which [P2A] fragments to P2 and A prior to addition of CHD. Additionally, a molecular beam mass spectrometry study on the thermolysis of solid P2A2 reveals the direct detection of molecular fragments of only P2 and anthracene, thus establishing a link between solution-phase P2-transfer chemistry and production of gas-phase P2 by mild thermal activation of a molecular precursor.

Mild electrochemical synthesis of metal phosphides with dibenzo-7-phosphanorbornadiene derivatives: mechanistic insights and application to proton reduction in water

“…Solvents, once dried and degassed, were stored under inert atmosphere over activated 4 Å molecular sieves. Me 2 NPA, [2] ClPA, [2] Mg(THF) 3 (C 14 H 10 ), [3] and Me 2 NPCl 2 , [4] were prepared according to literature procedures. Unless indicated otherwise, all chemicals were used as received.…”

“…Unless indicated otherwise, all chemicals were used as received. PCl 3 (vacuum distilled from CaH 2 ), HNMe 2 (condensed trap-to-trap (0 °C to -78 °C)), HCl (4.0 M in dioxane), Ni(COD) 2 (COD = 1,5-cyclooctadiene), and sulfuric acid (99.999%) were purchased from Sigma Aldrich. NiCl 2 (DME) (DME = 1,2-dimethoxyethylene) was purchased from Strem.…”

“…With stirring, Ni(COD) 2 (110 mg, 0.4 mmol) in THF (5 mL) was added dropwise, at room temperature, maintaining a high ClPA concentration relative to Ni(COD) 2 . During the addition, the solution color turned green.…”

EOMCC over excited state Hartree-Fock solutions (ESHF-EOMCC): An efficient approach for the entire ground state potential energy curves of higher-order bonds

“…19,20 The electronic configuration of the reference state determinant selected and the determinant corresponding to the true ground state of P 2 are identical to the configurations that we have chosen for the N 2 molecule. …”

Synthesis, Characterization, and Thermolysis of Dibenzo-7-dimethylgermanorbornadiene

“…11 These results mirror our previous observation that PhPCl 2 and PCl 3 do not give rise to the corresponding 7-phosphanorbornadiene derivatives on treatment with MgA·3THF. 6,12 Probing the thermal stability and chemical behavior toward retro Diels−Alder chemistry, a solution of Me 2 GeA in toluene was heated for ca. 16 crude mixture indicated the formation of anthracene and (Me 2 Ge) 2 A, which after removal of anthracene using a charcoal plug was isolated as a pure substance in 71% yield (based on germanium).…”