Reactivity of the Inversely Polarized Phosphaalkenes RP=C(NMe2)2 (R=tBu, Me3Si, H) towards Arylcarbene Complexes [(CO)5M=C(OEt)Ar] (Ar=Ph, M=Cr, W; Ar=2-MeC6H4, 2-MeOC6H4, M=W)

Abstract

The reaction of the arylated Fischer carbene complexes [(CO)5M=C(OEt)Ar] (Ar=Ph; M = Cr, W; 2-MeC6H4; 2-MeOC6H; M = W) with the phosphaalkenes RP=C(NMe2), (R=tBu, SiMe3) afforded the novel phosphaalkene complexes [[RP=C(OEt)Ar]M(CO)5] in addition to the compounds [(RP=C(NMe2)2]M(CO)5]. Only in the case of the R = SiMe3 (E/Z) mixtures of the metathesis products were obtained. The bis(dimethylamino)methylene unit of the phosphaalkene precursor was incorporated in olefins of the type (Me2N)2C=C(OEt)(Ar). Treatment of [(CO)5W=C(OEt)(2-MeOC6H4)] with HP=C(NMe2)2 gave rise to the formation of an E/Z mixture of [[(Me2N)2CH-P=C(OEt)(2-MeOC6H4)]W(CO)5] the organophosphorus ligand of which formally results from a combination of the carbene ligand and the phosphanediyl [P-CH(NMe2)2]. The reactions reported here strongly depend on an inverse distribution of alpha-electron density in the phosphaalkene precursors (Pdelta Cdelta+), which renders these molecules powerfu] nucleophiles.

Transition‐Metal Carbonyl Complexes and Electron‐Donating Properties of N‐Heterocyclic‐Carbene–Phosphinidene Adducts

“…In agreement with the results obtained for the rhodium(I) complex 2 (vide supra), the stronger electron‐donating properties of the carbene–phosphinidenes 1a – 1c in comparison with those of phosphine and NHC ligands is confirmed by the observation of consistently lower CO stretching frequencies. Furthermore, these values agree well with those reported for complexes containing related polarized phosphaalkenes, for example, [{ t BuP=C(NMe 2 ) 2 }W(CO) 5 ] . Finally, it should be noted that the CO stretching frequencies of 4a and 4b as well as those of 5a and 5b are very similar; therefore, 1a and 1b have similar donor properties, whereas the higher values for 4c indicate a slightly reduced donating ability of the mesityl derivative 1c .…”

“…This resembles the observation reported for the iron tetracarbonyl complex [(IPr* · PH)Fe(CO) 4 ] (vide supra, δ = –96.4 ppm, 1 J P,H = 208 Hz) . Similarly, shifts to higher field are also observed for the 31 P NMR resonances of 4b , 4c , and 5b upon the metal coordination of 1b and 1c , as was also reported for related W(CO) 5 complexes of inversely polarized phosphaalkenes such as [{ t BuP=C(NMe 2 ) 2 }W(CO) 5 ] ( δ = –25.1, 1 J P,W = 154 Hz) . Strikingly, the opposite trend is usually found for phosphine complexes of the type [(R 3 P)W(CO) 5 ], which exhibit shifts of ca.…”

Facile rotation around a silicon–phosphorus double bond enabled through coordination to tungsten

“…7c The angles around phosphorus are nearly 1201 and the torsion angle Si2-Si1-P1-W1 amounts to 175.131 establishing the Z 1 -coordination of the SiQP bond to tungsten. The P1-W1 bond length (2.6265(18) Å) is longer than in phosphaalkene tungsten complexes (2.51-2.54 Å) 9 and closer to that of the (phosphoranylidenephosphine)penta-carbonyltungsten complex (2.603(1) Å). 8b DFT calculations were utilized to understand the molecular structure of (Z)-2.…”

Synthesis and Structure of the First η3‐1,2‐Diphosphaallyl Complexes [(η5‐C5H5)(CO)2M{η3‐RPPC(SiMe3)2}] (M = Mo, R = tBu, Cy; M = W, R = tBu) from [(η5‐C5H5)(CO)2M=P=C(SiMe3)2] (M = Mo, W) and Inversely Polarized Phosphaalkenes RP=C(NMe2)2 (R = tBu, Cy)

“…Reaction of the phosphavinylidene complex [(η 5 ‐C 5 H 5 )(CO) 2 Mo=P=C(SiMe 3 ) 2 ] ( 2 )5 with an equimolar amount of phosphaalkene t BuP=C(NMe 2 ) 2 ( 1a )4b in toluene in the range of –30 °C to room temperature afforded the yellow complex 3a , which was purified by column chromatography on silica (31 % yield). The air‐ and moisture‐sensitive compound is soluble in saturated hydrocarbons, ethereal and aromatic solvents (see Scheme ).…”

“…Solvents were vigorously dried with an appropriate drying agent and freshly distilled under N 2 before use. The following compounds were prepared according to literature procedures: [Cp(CO) 2 M=P=C(SiMe 3 ) 2 ] M = Mo ( 2 ); M = W ( 5 ),5 t BuP=C(NMe 2 ) 2 ( 1a ),4b HP=C(NMe 2 ) 2 ( 1c );13 CyPH(SiMe 3 ),17 [(Me 2 N) 2 CSMe]I 18. IR spectra: Bruker FT‐IR VECTOR 22.…”