Synthesis and Theoretical Investigation of Diphosphastannylenes

Abstract

The factors affecting the stabilization of diphosphastannylenes, such as substituent size, steric demand, and type of substituent (aryl, alkyl, silyl) were investigated via a comprehensive DFT and experimental investigation. The influence of various substituents (H, Me, t Bu, Ph, TMS, Hyp = (Si(SiMe 3 ) 3 )) on the pyramidalization of the phosphorus centers and cone angle determination of those substituents were carried out. Through these considerations, ligand systems capable of isolating a stable Sn(II) species were determined. Synthetic work led to the isolation of dimeric supermesityl(trimethylsily)phosphanides, 2,4,6-tris(t-butyl)phenyl trimethylsilyl lithium phosphanide, 2,4,6-tris(t-butyl)phenyl trimethylsilyl potassium phosphanide, and one hypersilylphosphanide [HypP(SiMe 3 )-K•DME]. In addition to that, a novel monomeric diphosphastannylene [HypP(SiMe 3 )] 2 Sn was isolated as well as confirmed by experimental and calculated NMR data and single crystal X-ray analysis.

Low‐Valent Group 14 Phosphinidenide Complexes [({SIDipp}P)2M] Exhibit P–M pπ–pπ Interaction (M=Ge, Sn, Pb)

“…Furthermore, the group of Flock examined the effects that stabilize diphosphastannylenes by means of theoretical as well as experimental investigations leading to the presumption that the formation of a Sn=P double bond is less important regarding molecular stabilization. They draw the conclusion that steric shielding is the important driving force for the planarization of the phosphorus atom . In our previous work, we were able to show the possibility of the synthesis of main‐group phosphinidenide compounds through salt elimination reaction using the deprotonated compound (SIMes)PK (SIMes=1,3‐bis(2,4,6‐trimethylphenyl)imidazolidine‐2‐ylidene) as a precursor …”

“…They draw the conclusion that steric shielding is the important driving force for the planarization of the phosphorus atom. [32] In our previous work, we were able to show the possibility of the synthesis of main-group phosphinidenide compounds through salt elimination reaction using the deprotonated compound (SIMes)PK (SIMes = 1,3bis(2,4,6-trimethylphenyl)imidazolidine-2-ylidene) as a precursor. [2][3][4][5] However, reactions between (SIMes)PK and (SIMes)MX 2 (M = Ge, Sn, Pb; X = Cl or Br) yielded not the expected NHC-stabilized phosphinidenide substituted tetrylenes.…”

How Can One Controllably Use of Natural ΔpH in Polyelectrolyte Multilayers?

“…Another interesting question is the mobility of associ ated water molecules in the multilayers. [1a] Schwartz and Schönhoff [23] analyzed 1 H spin relaxation by NMR for the investigation of the hydration of multilayers. The multilayers were formed by alternating adsorption of PSS and PAH.…”

“…On contrast, deposi tion of a strong PSS led to a decrease in 1 H spin relaxation rate and thus to a decrease in water mobility due to reduction in dynamic of bounded water molecules or to a decrease of the amount of water in the multilayers. [23] Choudhury and Roy [22] calculated the relaxation time for the hydrogen bounded water molecules and water molecules, that were clustered due to hydrophobic interactions with polymer backbones. It was found, that for both water fractions the relax ation time of water molecules increased, when the polymer was protonated.…”

P–Ge/Sn π Interactions Versus Arene···Ge/Sn Contacts for the Stabilization of Diphosphatetrylenes, (R2P)2E (E = Ge, Sn)

“…While diaminocarbenes and their heavier group 14 analogues (diaminotetrylenes (R 2 N) 2 E; E = Si, Ge, Sn, Pb) are well-known, the chemistry of the corresponding phosphorus-substituted species (diphosphacarbenes (R 2 P) 2 C and diphosphatetrylenes (R 2 P) 2 E) is much less well developed. − This may chiefly be attributed to the large barrier to planarization of phosphorus compared to nitrogen (for comparison, the inversion barriers of NH 3 and PH 3 are approximately 25 and 150 kJ mol –1 , respectively), which inhibits π overlap between the phosphorus lone pair(s) and the vacant p-orbital at the tetrel center, barring one of the primary means of stabilization of these species. Nonetheless, a small number of diphosphacarbenes and an increasing number of diphosphatetrylenes have been reported. − While the known diphosphacarbenes exhibit near-planar phosphorus centers (and consequent PC π-overlap), the corresponding diphosphatetrylenes are typically isolated as dimers containing a P 2 E 2 core ( A ) or else as monomers containing pyramidal phosphorus centers ( B ), − which do not exhibit any tendency toward PE π interactions; until recently, diphosphatetrylenes containing a planar phosphorus center ( C ) were unknown (Chart ).…”