The abstraction of the Lewis acid from [W(CO)5(PH2BH2⋅NMe3)] (1) by an excess of P(OMe3)3 leads to the quantitative formation of the first Lewis base stabilized monomeric parent compound of phosphanylborane [H2PBH2⋅NMe3] 2. Density functional theory (DFT) calculations have shown a low energetic difference between the crystallographically determined antiperiplanar arrangement of the lone pair and the trimethylamine group relative to the PB core and the synperiplanar conformation. Subsequent reactions with the main-group Lewis acid BH3 as well as with an [Fe(CO)4] unit as a transition-metal Lewis acid led to the formation of [(BH3)PH2BH2⋅NMe3] (3), containing a central H3BPH2BH2 unit, and [Fe(CO)4(PH2BH2⋅NMe3)] (4), respectively. In oxidation processes with O2, Me3NO, elemental sulfur, and selenium, the boranylphosphine chalcogenides [H2P(Q)BH2⋅NMe3] (Q = S 5 b; Se 5 c) as well as the novel boranyl phosphonic acid [(HO)2P(O)BH2⋅NMe3] (6 a) are formed. All products have been characterized by spectroscopic as well as by single-crystal X-ray structure analysis.

Lewis Base Stabilized Phosphanylborane

A theoretical study has been carried out on 31P NMR chemical shifts in the phosphine-substituted metal carbonyls of the type M(CO)5PR3 (M = Cr and Mo; R = H, CH3, C6H5, F, and Cl) as well as the 95Mo NMR chemical shift of Mo(CO)5P(C6H5)3 and Mo(CO)5PX3 (X = F and Cl). The study was based on density functional theory (DFT) and gauge-including atomic orbitals (GIAO). The calculated chemical shifts and the components of the chemical shift tensor are in good agreement with the available experimental data. The coordination chemical shift expressed as the difference in the isotropic shifts Δδ = δΜ(CO)5PR3 − δPR3 between PR3 as a ligand, δM(CO)5PR3, and free PR3, was analyzed in detail. It was shown that the paramagnetic coupling between the π orbitals of the complexed PR3 ligand πPR3 and the dσ metal-based LUMO of the M(CO)5PR3 complex has a positive contribution to the coordination chemical shift, Δδ, whereas the paramagnetic couplings between σPR3 and π*PR3 as well as πPR3 and π*PR3 of the complexed ligand ha...

A theoretical study of 31p and 95mo nmr chemical shifts in m(co)5pr3 (m = cr, mo; r = h, ch3, c6h5, f, and cl) based on density functional theory and gauge-including atomic orbitals

2D NMR applied to dynamic stereochemical problems

The ligand precursors P(CH2NH-3,5-(CF3)2C6H3)3 (1a), P(CH2NHPh)3 (1b), and P(CH2NH-3,5-Me2C6H3)3 (1c), react with the reagents Ti(NMe2)4 and tBuNTa(NEt2)3 to generate metal complexes of the type P(CH2NArR)3TiNMe2 (2a−c) and P(CH2NArR)3TaNtBu (3a−c) (where ArR = 3,5-(CF3)2C6H3, Ph, and 3,5-Me2C6H3). Due to ring strain, the phosphine lone pair cannot chelate and is available to bind a second metal, and this feature can be utilized to synthesize heterometallic polynuclear complexes. The 31P chemical shifts observed upon complexation of the early transition metals to the amido donors are large and in the opposite direction expected for the increased C−P−C bond angles in these complexes; these unusual shifts are due to P−Ti and P−Ta distances that are significantly shorter than the sum of van der Waals radii. The reaction of 2c with Ni(CO)4 produces at first the bimetallic complex (CO)3Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2] (4c), which gradually converts to the trimetallic complex (CO)2Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2]2 ...

Diligating tripodal amido-phosphine ligands: the effect of a proximal antipodal early transition metal on phosphine donor ability in a building block for heterometallic complexes.

(CO)5CrC(OCH3)CH3 reagiert thermisch bei Temperaturen von 60–80°C, aber auch photochemisch bei Raumtemperatur mit tertiaren Arsinen und Stibinen YR3(Y = As, Sb; R = CH3, C2H5, C6H5,c-C6H11) hauptsachlich unter CO-Abspaltung zu cis- und trans-Tetracarbonyl(carben)-Komplexen. Die Umsetzung mit tertiaren Bismutinen verlauft dagegen nicht mehr unter CO-Substitution. In einigen Fallen (R = CH3, C2H2, c-C6H11) lassen sich aber Pentacarbonyl(bismutin)-Komplexe isolieren. Die IR-, 1H-NMR-, 13C-NMR- und Massenspektren der neuen Verbindungen, sowie das Isomerisierungsverhalten der cis-bzw, trans-Tetracarbonyl-(carben)-Komplexe werden diskutiert.



Transition metal Carbene Complexes, LXXXIV: Synthesis and Isomerisation of Arsine- and Stibine-substituted cis and trans- Tetracarbonyl (carbene)Complexes and Syntheses of Pentacarbonyl (trialkylbismuthine)Complexes of Chromium(0)



(CO)5CrC(OCH3)CH3 reacts thermally in the temperature range of 60-−80°C as well as photochemically at room temperature with arsines and stibines YR3 (Y = As, Sb; R = CH3, C2H5, C6H5c-C6H11 mainly under splitting off of a CO-group to give cis and trans-tetracarbonyl (carbene) complexes. Tertiary bismuthines, however, do not react under CO-substitution. In some cases (R = CH3, C2H5, c-C6H11) pentacarbonyl(bismuthine) complexes can be isolated. I. r., 1H n. m. r., 13C n. m. r., and mass spectra of the new compounds as well as the isomerisation of the cis-and trans-tetracarbonyl(carbene)complexes are discussed.

Übergangsmetall-Carben-Komplexe, LXXXIV: Synthese und Isomerisierung von arsin- und stibinsubstituierten cis und trans-Tetracarbonyl(carben)-Komplexen und Darstellung von Pentacarbonyl(trialkylbismutin)-Komplexen von Chrom(0)

R. Mathieu

Papers

Phosphorus-31 nuclear magnetic resonance study of trivalent phosphorus derivatives of metal carbonyls

Phosphor-31-kernmagnetische resonanz von carbonylmetallkomplexen mit phosphor(iii)-liganden