Reactivity of phosphonitriles with low-coordinated phosphorus double-bonded compounds

Azidophosphenium Cations: Versatile Reagents in Inorganic Synthesis

“…In the 31 P NMR spectrum of isolated 15 , two resonances were detected for the NP(Cl)N group at 142.6 ppm, in good agreement with other strained NP III heterocyclic compounds [cf. 6 δ( 31 P) = 102.5 ppm; Scheme ], and for the tetracoordinated P V at 23.9 ppm, with both signals being split into doublets with a 2 J ( 31 P– 31 P) coupling of 64.5 Hz, which is in good agreement with the few examples of 1,3,2λ 3 ,4λ 5 -diazaphosphetidines, which were shown to form by a 1,3-SiMe 3 shift from iminophosphane–iminophosphoranes (Scheme ). , 15 crystallizes in the orthorhombic space group Pbca with eight molecules in the cell (Figure , left). The characteristic structural feature of 15 is the (Me 3 Si) 2 N 2 P 2 Cl 2 four-membered ring with two long P2–N amino bonds [1.733(2) and 1.736(2) Å] and two significantly shorter P1–N amino distances [1.640(2) and 1.636(2) Å], in accordance with related systems that also incorporate a four-coordinated phosphorus atom [cf.…”

“…As expected, the tricoordinated P III resonates in the 31 P NMR spectrum at 156.2 ppm (cf. 12 129.9 ppm; Figure ), ,, whereas P V is high-field-shifted compared to the starting material 7[GaCl 4 ] [δ P V ( 31 P) = −6.4; cf. 7[GaCl 4 ] 27.4 ppm], indicating the loss of positive charge.…”

“…Moreover, they display an N–P–N–P–N backbone similar to that found in 3 2+ . Furthermore, 5a was shown to be in equilibrium with its cyclic form 5b , which undergoes a 1,3-trimethylsilyl migration to yield a cyclic 1,3,2λ 3 ,4λ 5 -diazadiphosphetidine ( 6 ; Scheme ) …”

Palladium Coordination Compounds of σ3λ5-Phosphoranes: First Examples of Phosphonio−Methylene(imino)metallophosphorane [(R3P)(Me3Si)CP(MLn)NSiMe3] and Phosphonio−Methylene(oxo)phosphorane [(R3P)(Me3Si)CP(O)NSiMe3] Ligands

“…Intermediate VII is analogous to the nickel complex Ni 2 Cl 2 (PPh 3 ) 2 [µ 2 -η 2 :η 2 -C(PPh 3 )dPN(SiMe 3 ) 2 ] (4, eq 3) that was previously characterized by X-ray diffraction studies. 17 This intermediate must isomerize quickly to VIIa-b by undergoing a 1,3 SiMe 3 migration from nitrogen to carbon, a process that is well documented in the chemistry of phosphaalkenes 39 and amino methylene phosphoranes 40 and has also been proposed to occur (eq 6) in the formation of an imino(phosphoranylidenemethylene)phosphine (7) from a phosphavinylidene phosphorane intermediate (6). 33 The proposed intermediate (6) is the same as the ligand in VII, but with a P(Me 2 N) 3 group on carbon instead of PPh 3 , while compound 7, which was characterized by an X-ray diffraction study, is analogous to the ligand in VIIa-b, thus supporting VII as a reasonable intermediate that undergoes 1,3 SiMe 3 migration to form VIIa-b.…”

Azidophosphanes: Attractive starting materials for the preparation of phosphazenes

“…Their photolysis or thermolysis in the absence of trapping agents yields oligomers or polymers [ 1, 2,5]. Irradiation in the presence of suitable agents leads to addition products of the transient phosphonitriles [3,4]. Covalent azides generally oxidize phosphanes (Staudinger reaction), and although phosphorylazides have been frequently used for synthesizing N-phosphoryl phosphazenes [6-91, surprisingly only very little information exists on azidophosphanes for the synthesis of defined phosphanyl phosphazenes.…”