Chemie polyfunktioneller Molekäle, 130. Mitt. [1]: Rubidium- und Cäsium-bis(diphenylphosphanyl)amid – Synthesen, (18-Krone-6)-Komplexe, Spaltprodukte, Kristallstrukturen und Festkörper-NMR-Spektren

Abstract

The metalation of bis(diphenylphosphanyl)amine, HN(PPh 2 ) 2 (5), with RbOtBu in the presence of N,N,N H ,N HH ,N HH -pentamethyldiethylenetriamine (PMDTA (3)) in toluene surprisingly affords the nearly PMDTA free RbN(PPh 2 ) 2 (6a). Recrystallization of 6a from tetrahydrofuran (THF) yields RbN(PPh 2 ) 2 Á 0.5 THF (6b). Compounds 6a, b crystallize in thin needles; however, these are not suitable for X-ray structure analyses. The reactions of 5 with MOtBu (M Rb, Cs) in the presence of 18-crown-6 in toluene yield the monomeric, pale yellow rubidium and caesium complexes [Rb(18-crown-6)(N(PPh 2 ) 2 )] (7) and [Cs(18-crown-6)(N(PPh 2 ) 2 )] (8), respectively. Allowing to stand a solution of 8 in THF for three months at 20 C results in a cleavage product of 8. This is identi®ed as the dimeric yellow complex [(Cs(18-crown-6)) 2 ("-N=P(H)Ph 2 ) 2 ] Á THF (9). The source of the hydrogen atom in the bridging phosphorane iminate anion [ a a n n N=P(H)Ph 2 ] À is uncertain. Compounds 7±9 are structurally characterized by X-ray analyses. These reveal that [N(PPh 2 ) 2 ] À acts as P-ligating chelate in 7, whereas it coordinates the Cs as N-donor as well as 2 C-donor with one phenyl group in 8. No phosphorus coordination is observed in 8. The two caesium cations in 9 are two-fold N-bridged by [ a a n n N=P(H)Ph 2 ] À . The coordination sphere of each caesium atom is completed by a 18-crown-6 ligand. The solid state 13 C NMR spectrum of 8 reveals dynamic phenomena (rotation of the 18-crown-6 ligand). In the solid state 31 P spectrum of 8, 31 P, 31 P±J-coupling is observed between the chemically non-equivalent phosphorus sites (J 390 Hz).

Structural, Spectroscopic, and Computational Analysis of Heterometallic Thorium Phosphinidiide Complexes

“…Complex 3 is the only compound in which the alkali metal does not have an interaction with an arene ring of the mesityl, which may be the reason why it is an outlier, because the alkali metal–phosphinidiide bond lengths of 2.881(2), 3.2297(16), 3.5586(9), and 3.6467(14) Å are consistent with their respective effective nuclear charge. There are few compounds containing Rb–P − and Cs–P ,,− ,− bonds, with the M–P distances ranging from ∼3.32 to 3.57 (for Rb) Å and from ∼3.42 to 3.81 Å (for Cs), which encompass the distances observed in 4 and 5 .…”