Über den Phosphandiyl‐Transfer von invers‐polarisierten Phosphaalkenen R¹P=C(NMe₂)₂ (R¹ = tBu, Cy, Ph, H) auf Phospheniumkomplexe [(η⁵‐C₅H₅)(CO)₂M=P(R²)R³] (R² = R³ = Ph; R² = tBu, R³ = H; R² = Ph, R³ = N(SiMe₃)₂)

Abstract

Phosphanediyl Transfer from Inversely Polarized Phosphaalkenes R1P=C(NMe2)2 (R1 = tBu, Cy, Ph, H) onto Phosphenium Complexes [(η5‐C5H5)(CO)2M=P(R2)R3] (R2 = R3 = Ph; R2 = tBu, R3 = H; R2 = Ph, R3 = N(SiMe3)2) Reaction of the freshly prepared phosphenium tungsten complex [(η5‐C5H5)(CO)2W=PPh2] (3) with the inversely polarized phosphaalkenes RP=C(NMe2)2 (1) (a: R = tBu; b: Cy; c: Ph) led to the η2‐diphosphanyl complexes $\rm [(\eta^{5}-C_{5}H_{5})(CO)_{2}\overline {W-P(R)-P}Ph_{2}]$ (9a‐c) which were isolated by column chromatography as yellow crystals in 24‐30 % yield. Similarly, phosphenium complexes [(η5‐C5H5)(CO)2M=P(H)tBu] (M = W (6); Mo (8)) were converted into $\rm [(\eta^{5}-C_{5}H_{5})(CO)_{2}\overline {MP({\it t}Bu)P}(H){\it t}Bu]$ (M = W (11); Mo (12)) by the formal abstraction of the phosphanediyl [PtBu] from 1a. Treatment of [(η5‐C5H5)(CO)2W=P(Ph)N(SiMe3)2] (4) with HP=C(NMe2)2 (1d) gave rise to the formation of yellow crystalline $\rm [(\eta^{5}-C_{5}H_{5})(CO)_{2}\overline {W-P(H)-P} (Ph)N(SiMe_{3})_{2}]$ (10). The products were characterized by elemental analyses and spectra (IR, 1H, 13C‐, 31P‐NMR, MS). The molecular structure of compound 10 was elucidated by an X‐ray diffraction analysis.

Rhodium-Catalyzed Isomerization of a Bis(secondary phosphine) to an Unsymmetrical Diphosphine via P–C Cleavage and P–P and C–H Bond Formation

“…The ABXYM 31 P­{ 1 H} NMR spectrum of 9 (toluene- d 8 , Table ) included two signals assigned to the IsMeP group (δ −65.3 (very broad m) and −74.5 (dddd, J P–P = 37, 247, 467, J Rh–P = 118) and the PIs group (δ −118.8 (dddd, J P–P = 21, 94, 482, J Rh–P = 24); −126.8 (dddd, J P–P = 20, 84, 467, J Rh–P = 24)) for the major and minor isomers, respectively. The large J PP values are similar to those in related chelate complexes of the deprotonated diphosphine ligand (R 2 P–PR – ) and are characteristic of the presence of a P–P bond . The new P-Me group in 9 was identified for the major diastereomer by 1 H (δ 1.71, t, J = 7 Hz) and 13 C­{ 1 H} NMR (δ 22.0, d, J = 11 Hz) spectroscopy in toluene- d 8 , while the PH and CH 2 signals of precursor 6 disappeared.…”

Phosphaalkenes R1C(O)–P=C(NMe2)2 (R1=Ph, 4‐EtC6H4): Versatile Reagents for 1,3‐Dipolar Cycloadditions to Phosphenium Complexes [Cp(CO)2M = PPh2] (M = Mo, W)

“…The [M(CO) 2 ] group gives rise to two intense bands in the IR spectra at $\tilde {\nu}$ = 1935–1943 and 1864–1881 cm –1 , which are due to the symmetric and asymmetric CO stretching vibrations. Interestingly, the novel bidentate chelating ligand exhibits a decreased donor capacity relative to the η 2 ‐diphosphanido ligand in complexes of the type [Cp(CO) 2 MPR 1 –PR 2 R 3 ], IV ($\tilde {\nu}$ = 1918–1933; 1837–1849 cm –1 ) 5. The carbonyl vibration of the aryl group in precursor 4 was observed at $\tilde {\nu}$ = 1535 cm –1 , and does not show up in the products any longer, which means that it was involved in a cycloaddition process.…”

“…Transition‐metal‐induced cleavage of inversely polarized phosphaalkenes with concomitant transfer of the phosphanediyl unit on carbene‐ or phosphenium ligands to give η 1 ‐phosphaalkene2 and η 2 ‐diphosphanido complexes5 have previously been described. Here the smooth generation of complexes 4a , b and 6a featuring the chelating 1,4,2‐diphosphaoxabutene‐3‐yl ligand underlines the ability ofphosphaalkenes to act as convenient sources for phosphanediyl units under mild conditions.…”

“…η 3 ‐1,2‐Diphosphaallyl complexes III were obtained from the combination of phosphaalkenes and phosphavinylidene complexes 4. Only recently we disclosed the generation of η 2 ‐diphosphanyl complexes IV by reacting phosphaalkenes and phosphenium complexes5 (Scheme ).…”

Phospha‐ and Arsaalkenes RE=C(NMe2)2 (E = P, As) as Novel Phosphinidene‐ and Arsinidene‐Transfer Reagents

“…Thus it was obvious to also include transition-metal-phosphenium complexes in the investigations on the nucleophilicity and on the phosphinidenetransfer tendency of inversely polarized phosphaalkenes. Phospheniumcomplexes[Cp(CO) 2 phanyl complexes 129a,b,d, 130, 131, and 133 were generated and isolated as crystalline compounds after column chromatography in 24-30 % yield [69] (Scheme 53). The reaction of 126a,b was also conducted with an excess of carbonyl-stabilized phosphaalkenes arylC(O)P=C-(NMe 2 ) 2 (134: aryl = Ph; 135: aryl = 4-EtC 6 H 4 ) in toluene in the range -30°C to room temperature to afford metallophosphaalkenes 136a,b and 137a,b in modest yields (30-46 %) [70] (Scheme 54).…”