Functionalization Reactions Characteristic of a Robust Bicyclic Diphosphane Framework

Abstract

The 3,4,8,9-tetramethyl-1,6-diphospha-bicyclo-[4.4.0]deca-3,8-diene (P2(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 λ(5)-phosphorus atoms. Reactivity with the chalcogen-atom donors MesCNO (Mes = 2,4,6-C6H2Me3) and SSbPh3 has allowed for the selective synthesis of the diphosphane chalcogenides OP2(C6H10)2 (87%), O2P2(C6H10)2 (94%), SP2(C6H10)2 (56%), and S2P2(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(C6H10)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 O3P2(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(C6H10)2(R = Mes, CPh3, SiMe3), and treatment with additional MesN3 yielded symmetric and unsymmetric diiminodiphosphoranes (RN)(MesN)P2(C6H10)2 (91% for R = Mes). Metalation reactions with the bulky diiminodiphosphorane ligand (MesN)2P2(C6H10)2 (nppn) allowed for the isolation and characterization of (nppn)Mo(η(3)-C3H5)Cl(CO)2 (91%), (nppn)NiCl2 (76%), and [(nppn)Ni(η(3)-2-C3H4Me)][OTf] showing that these ligands provide an attractive preorganized binding pocket for both late and early transition metals.

A family of cis-macrocyclic diphosphines: modular, stereoselective synthesis and application in catalytic CO2/ethylene coupling

“…Previous studies have shown excellent selectivity in functionalizing only one of the phosphorus atoms in 1 . 16 As expected, phosphino-phosphonium salt [Me-P 2 (dmb) 2 ]I ( 2 ) was obtained in 90% yield after treatment of 1 with methyl iodide in diethyl ether at room temperature overnight. The structure of [Me-P 2 (dmb) 2 ]I was confirmed by X-ray crystallography (Fig.…”

On the comparison of oxygen and sulfur transfer reactivities in phosphine and phosphorene: the case of R3Sb(X) carriers (X = O or S)

“…In view of the very similar features of the molecular and 2D material processes and computationally proved their feasibility, we strongly hope that such a reactivity will be addressed in laboratory, also being supported by precedent experimental investigations on diphosphane. 13 The results of the present manuscript will represent the starting point for a more efficient functionalization.…”

“…Sulphur transfer reactions between trisubstituted pnictogens (R 3 E) have been successfully addressed with phosphorus and arsenic with a large variety of organic groups. 12 More recently, Cummins et al 13 reported an efficient method for bringing about the selective sulfuration of a cyclic diphosphane using triphenylstibine sulfide as the S-transfer reagent. Remarkably, the stepwise formation of the P(E) bond (E = O or S) was achieved without affecting the original P-P bond.…”

Functionalization of P4 through Direct P−C Bond Formation

“…[53] The products formed after consecutive [4+ +2]-cycloadditions to afford unique organodiphosphanes 49,w hich have been shownt oc oordinate to Group 10 metals [54] and undergo chalcogenation and alkylation reactions to allow furtherf unctionalization of the bicyclic structures. [55,56] Whereas this photochemical protocol transfersc leanly Pa toms from P 4 into organic frameworks, the isolated yields are only moderate (R = H, 2%;R= Me, 34 %) due to their lability under the harshirradiation conditions. The transfer of aP 2 fragment to an organic substrate was also achieved by Mathey and co-workers, [57] who showed that upon mixing (trimethylsilyl)diazomethanide with P 4 ,aformal [3+ +2]-cycloaddition reactiono ccurs to form diazadiphospholide anion 50 and neutral 51 after protonation (Scheme 21).…”

“…In 2010, the group of Cummins reported on photochemically generated P 2 that was captured in situ by DA reactions with 1,3‐dienes (Scheme ) . The products formed after consecutive [4+2]‐cycloadditions to afford unique organodiphosphanes 49 , which have been shown to coordinate to Group 10 metals and undergo chalcogenation and alkylation reactions to allow further functionalization of the bicyclic structures . Whereas this photochemical protocol transfers cleanly P atoms from P 4 into organic frameworks, the isolated yields are only moderate (R=H, 2 %; R=Me, 34 %) due to their lability under the harsh irradiation conditions.…”