Ruthenium‐Stabilized Low‐Coordinate Phosphorus Atoms: Structural Evidence for Monomeric Metaphosphonate

Abstract

The metaphosphate anion has attracted steady interest since 1955 [1] in connection with wide applications in phosphorylation reactions.[2] It has relevance in biochemistry in particular with respect to ATP hydrolysis.[3] However, despite considerable efforts, monomeric metaphosphates and other dioxophosphoranes are only known as transient species in solution and their existence can be inferred from trapping experiments. [2][3][4] Their high reactivity arises from the powerful electrophilic character at the phosphorus center. Several approaches have been tested to stabilize these highly reactive species. Kinetic stabilization by steric protection [5] proved to be ineffective for dioxophosphorane and led to products that resulted from the insertion of the PO 2 moiety in a neighboring group.[6] The electrophilicity and the tendency to expand the valence shell were exploited for their stabilization as Lewis salts. This strategy allowed only spectroscopic characterization by 31 P NMR in a few cases. [7] Thus, the chemistry of dioxophosphorane suffers from a paucity of information and new approaches to stabilize and enable deeper investigation are highly desirable. This work describes the first isolation and full characterization, including X-ray structural analysis, of stabilized metaphosphonate.We have developed a novel and successful route to ruthenium-stabilized monomeric metaphosphonate by oxidation of a nucleophilic terminal phosphinidene complex of ruthenium. As recently described by Lammerstma and coworkers, the terminal phosphinidene ruthenium complexes [(h 6 -p-cymene)Ru(PR 3 )(PMes*)] (3 a: R = Cy, 3 b: R = Ph [8] ) are formed as dark green solids by the reaction of the primary phosphane complex [(h 6 -p-cymene)RuCl 2 (PH 2 Mes*)](1; pcymene = 4-methyl-iso-propylbenzene; Mes* = 2,4,6-tri-tertbutylphenyl) with two equivalents of 1,8-diazabicyclo[5-4-0]undec-7-ene (DBU) in the presence of PR 3 as a stabilizing ligand (R = Ph, Cy).[8] Alternatively, treatment of [(h 6 -pcymene)RuCl 2 (PR 3 )] (2 a: R = Cy, 2 b: R = Ph) and PH 2 Mes* with DBU affords 3 in high yields (Scheme 1).

Nucleophilic Phosphinidene Complexes: Access and Applicability

“…[40] Ruthenium phosphinidenes [h 6 -pCym(R 3 P)Ru = P-Mes*] 47 a (R = Ph, Cy) are also accessible from [h 6 -pCymRuCl 2 (PR 3 )] by reaction with DBU and PH 2 Mes*. [41] The heavier osmium phosphinidene complexes [h 6 -Ar(L)Os=PÀMes*] (47 b, Ar= benzene, p-cymene; L = PPh 3 , PMe 3 , CO) were obtained equally readily from dehydrohalogenation ligation of the primary complexed phosphine [h 6 -ArOsX 2 (PH 2 Mes*)] (46 b). [40] Similar to the third-row Group 9 transition metal iridium, the CO-ligated osmium complex [h 6 -Ar(CO)Os=PÀMes*] (47 b) could also be isolated.…”

Preparation and Characterization of Parent Phenylphosphinidene and Its Oxidation to Phenyldioxophosphorane: The Elusive Phosphorus Analogue of Nitrobenzene

“…The existence of dioxophosphoranes (RPO 2 ) to date has only been inferred from trapping experiments. − Dioxophosphoranes are extremely electrophilic at phosphorus, and show high reactivity when transiently generated in solution; RPO 2 species instantly undergo self-aggregation to form cyclic or linear polymeric compounds. , For example, the combustion of dimethyl methylphosphonate generates CH 3 PO 2 whose molecular mass was detected using mass spectrometry . Chlorodioxosophosphorane (ClPO 2 ) was IR-spectroscopically characterized in an argon matrix via the photochemical reaction of ozone with POCl .…”

Nucleophile Phosphinidenkomplexe: Synthese und Anwendungen

“…Typische Vertreter von Phosphinidenen der Gruppe 8 sind die Rutheniumkomplexe [η 6 ‐Ar(L)RuPMes*] ( 47 a , Ar=Benzol, p ‐Cymol; L=PPh 3 , PMe 3 , t BuNC) (Schema ) mit 31 P‐NMR‐Resonanzen im Bereich δ =801–846 ppm; der nicht isolierbare CO‐Komplex [η 6 ‐C 6 H 6 (CO)RuPMes*] weist im Vergleich ein Signal bei tieferem Feld auf ( δ =897 ppm) 40. Die Rutheniumphosphinidene [η 6 ‐ p Cym(R 3 P)RuP‐Mes*] 47 a (R=Ph, Cy) sind auch über [η 6 ‐ p CymRuCl 2 (PR 3 )] durch Umsetzung mit DBU und PH 2 Mes* zugänglich 41. Die schwereren Osmiumphosphinidenkomplexe [η 6 ‐Ar(L)OsPMes*] ( 47 b , Ar=Benzol, p ‐Cymol; L=PPh 3 , PMe 3 , CO) wurden ähnlich leicht durch Dehydrohalogenierung und Stabilisierung des primär komplexierten Phosphans [η 6 ‐ArOsX 2 (PH 2 Mes*)] ( 46 b ) hergestellt 40.…”