Strong Evidence of a Phosphanoxyl Complex: Formation, Bonding, and Reactivity of Ligated Phosphorus Analogues of Nitroxides

Abstract

Facile access to [W(CO) (Ph P-OTEMP)] is used to initiate a study on the generation, properties, and reactions of transient phosphanoxyl complexes [ML (R PO)], the first example of which could be trapped via heterocoupling with the trityl radical. It is also demonstrated that the phosphorus nitroxyl complex acts as radical initiator in the polymerization of styrene. The quest for P-O versus O-N bond homolysis, as well as the initial steps of the polymerization were studied by DFT methods.

Styrene Polymerization under Ambient Conditions by using a Transient 1,3,2‐Diazaphospholane‐2‐oxyl Complex

“…In contrastt ot he conditions useda nd reported in the precedings tudy, [9] the reactiono f6 with styrene was carriedo ut under ambient conditions [29] (ratio of 1:200 of 6 to styrene;S cheme 5) and after 69 hp olystyrene could be precipitated from methanol. In contrastt ot he conditions useda nd reported in the precedings tudy, [9] the reactiono f6 with styrene was carriedo ut under ambient conditions [29] (ratio of 1:200 of 6 to styrene;S cheme 5) and after 69 hp olystyrene could be precipitated from methanol.…”

“…More recently,w ep resented ar ational protocol to access stable complexes I by using ubiquitouss ubstituents at phosphorus such as R = Ph and Z = W(CO) 5 ,that is, [(CO) 5 W(Ph 2 POTEMP)]( 1). [9] In particular, complex 1 was used effectively for the thermal formation of transientc omplexes with open-shell ligands such as phosphanyl II [10] ([(CO) 5 W(Ph 2 PC)] (2)) and phosphanoxyl complexes III ([(CO) 5 W(Ph 2 POC)] (3); compare with Figure 1). The latter radicalw as trapped with the Ph 3 Cr adical( trityl), thus leading to ac ross-coupling product with aP -O-CPh 3 unit, [9] andw ith group 14 hydrides (Ph 3 EH) formationo fp hosphine complexes with P-O-EPh 3 motif (E = Si, Ge, Sn) was observed.…”

“…[9] In particular, complex 1 was used effectively for the thermal formation of transientc omplexes with open-shell ligands such as phosphanyl II [10] ([(CO) 5 W(Ph 2 PC)] (2)) and phosphanoxyl complexes III ([(CO) 5 W(Ph 2 POC)] (3); compare with Figure 1). The latter radicalw as trapped with the Ph 3 Cr adical( trityl), thus leading to ac ross-coupling product with aP -O-CPh 3 unit, [9] andw ith group 14 hydrides (Ph 3 EH) formationo fp hosphine complexes with P-O-EPh 3 motif (E = Si, Ge, Sn) was observed. [11] Without any trapping reagent, heatingo ft oluene solutionsy ieldedc omplexes 4 [12] and 5 in a1 :1 ratio ( Figure 2).…”

“…Our early attempts resulted in a thermally unstable W 0 complex bearing another P‐X functionality, but some indications for radical formation were obtained. More recently, we presented a rational protocol to access stable complexes I by using ubiquitous substituents at phosphorus such as R=Ph and Z=W(CO) 5 , that is, [(CO) 5 W(Ph 2 POTEMP)] ( 1 ) …”

Lewis Acid‐Mediated One‐Electron Reduction of Nitrous Oxide

“…Ferrocene (Alfa Aesar) and decamethylferrocene (Sigma Aldrich) were sublimed under vacuum before use. Cp* 2 Co, B(C 6 F 5 ) 3 , B(C 6 Cl 5 ) 3 , Al(C 6 F 5 ) 3 , and Gomberg dimer were prepared according to literature. (Cp* 2 Co) + [B(C 6 Cl 5 ) 3 ] .−[19c] was prepared by mixing an equimolar amount of Cp* 2 Co and B(C 6 Cl 5 ) 3 in a cold well cooled by liquid nitrogen in the glovebox, and the mixture was immediately filtered.…”