Formation of a new class of 7π radicals via sterically induced P–P bond cleavage of the dimers [(CH)2(NR)2P]2

Abstract

The 2c-2e- P-P bonded dimers [(CH)2(NR)2P]2 dissociate in solution to give the persistent new 7pi radicals [(CH)2(NR)2P]*, which are isoelectronic with the well known S/N thiazolyl radicals.

Recent Developments in the Chemistry of N-Heterocyclic Phosphines

“…Chemical shifts of P-halogen-1,3,2-diazaphospholenes vary over an overall range of 200-110 ppm and decrease in the order I (205-190 ppm) > Br (194-185 ppm; two compounds known) > Cl (160 -140 ppm) > F (110 ppm; one compound known), thus displaying an inverse halogen dependence. Signals of P-phosphino-derivatives (170-135 ppm) appear generally more deshielded than those of P-amino-1,3,2-diazaphospholenes (95-75 ppm) but bis-1,3,2-diazaphospholenyls seem to be an exception and exhibit chemical shifts around 80 ppm [46] . P-Hydrogen substituted derivatives are characterized by the lowest shifts (75-55 ppm) and the occurrence of rather low values for 1 J PH (140-220 Hz).…”

“…Coupling of a P-chloro-1,3,2-diazaphospholene with a P-stannyl-phosphine via dehydrostannylation has been reported in one case [45] but this reaction is likewise not generally applicable and its reversion (i.e., cleavage of the P-P bond in a phosphinyl-NHP upon reaction with trimethylstannyl chloride) has likewise been observed [39] . Symmetrical bis-1,3,2-diazaphospholenyls were obtained from magnesium reduction of P-chloro-substituted derivatives [46] . Alkylation of P-chloro-NHPs was mainly studied in reactions with metal cyclopentadienides to give P-cyclopentadienyl-1,3,2-diazaphospholenes [47] but coupling with reactive Grignard reagents like allyl or alkinyl magnesium halides was likewise successful [48] .…”

A Persistent Dipotassium 1,2,4‐Diazaphospholide Radical Complex: Synthesis, X‐Ray Structure, and Bonding

“…[4b] The observed significantly lower phosphorus coupling (A iso ( 31 P) = 11.63 G) than observed in noncyclic phosphinyls (A iso ( 31 P) = 63-108 G) [7] and in the p system of fivemembered heterocyclic phenyl-substituted phospholes (A iso -( 31 P) = 23.5-31.3 G) [4b] suggests greater delocalization of the unpaired electron on 1,2,4-diazaphospholide (to the coplanar phenyl rings) rather than the electron being restricted to the heterocycle.…”

“…Probably owing to their high reactivity, anion radicals derived by reduction of five-membered heterocyclic aromatic systems have never been characterized structurally [7] before the present work. The deprotonated 1H-1,2,4-diazaphosphole group [3,5-R 2 dp] À (B) is a mixed nitrogen-phosphorus (s 2 l 3 ) analogue of Cp À and may be viewed as the combination of phospholyl [3,8] and pyrazolato (pz) [9] ions.…”

Extended 2,5‐Diazaphosphole Oxides: Promising Electron‐Acceptor Building Blocks for π‐Conjugated Organic Materials

“…The observed g iso value of 2.0049 is typical of thiadiazole-and phosphole-based ring systems. [19] To verify the observed results, the EPR spectrum was also modeled by using Winsim2002 providing a goodness of fit of 99.9 % with the experimental data. [20] The DFT-calculated hyperfine coupling constants for the radical anion 3 a À C were used as starting values for the simulation (for details, see the Supporting Information).…”