Supersilylated Tetraphosphene Derivatives M₂[t-Bu₃SiPPPPSi-t-Bu₃] (M = Li, Na, Rb, Cs) and Ba[t-Bu₃SiPPPPSi-t-Bu₃]: Reactivity and Cis−Trans Isomerization

Abstract

The tetraphosphenediides M2[t-Bu3SiPPPPSi-t-Bu3] (M = Li, Na, K) were accessible by the reaction of P4 with the silanides M[Si-t-Bu3] (M = Li, Na, K), whereas M2[t-Bu3SiPPPPSi-t-Bu3] (M = Rb, Cs) were obtained from the reaction of RbCl and CsF with Na2[t-Bu3SiPPPPSi-t-Bu3]. 31P NMR experiments revealed that, in tetrahydrofuran, Na2[t-Bu3SiPPPPSi-t-Bu3] adopts a cis configuration. However, treatment of Na2[t-Bu3SiPPPPSi-t-Bu3] with 18-crown-6 led to the formation of [Na(18-crown-6)(thf)2]2[t-Bu3SiPPPPSi-t-Bu3] that possesses a trans configuration in the solid state. The ion-separated tetraphosphenediide [Na(18-crown-6)(thf)2]2[t-Bu3SiPPPPSi-t-Bu3] was analyzed using X-ray crystallography (monoclinic, space group P2(1)/n). The reaction of Na2[t-Bu3SiPPPPSi-t-Bu3] with BaI2 gave, conveniently, the corresponding barium derivative Ba[t-Bu3SiPPPPSi-t-Bu3]. However, addition of AuI to the tetraphosphenediide Na2[t-Bu3SiPPPPSi-t-Bu3] yielded 1,3-diiodo-2,4-disupersilyl-cyclotetraphosphane (monoclinic, space group C2/c), which is an isomer of disupersilylated diiodotetraphosphene. A further isomeric derivative of disupersilylated tetraphosphene, the 3,5-disupersilyl-2,2-di-tert-butyl-2-stanna-bicyclo[2.1.0(1,4)]pentaphosphane, which possesses a phosphanylcyclotriphosphane structure, was obtained by the reaction of Na2[t-Bu3SiPPPPSi-t-Bu3] with t-Bu2SnCl2. Calculations revealed that the acyclic cis and trans isomers of the dianions [HPPPPH]2- and [H3SiPPPPSiH3]2- are thermodynamically more stable than the cyclic isomers with a phosphanylcyclotriphosphane or a cyclotetraphosphane structure. However, the neutral cyclic isomers of H4P4 and H2(H3Si)2P4 represent more stable structures than the cis- and trans-tetraphosphenes H2P-P=P-PH2 and (H3Si)HP-P=P-PH(SiH3), respectively. In addition, the molecular orbitals (MOs) of the silylated cis- and trans-tetraphosphene dianions of [H3SiPPPPSiH3]2-, which are comparable with those of the ion-separated supersilylated tetraphosphenediide [t-Bu3SiPPPPSi-t-Bu3]2-, show the highest occupied antibonding pi*MO (HOMO). The HOMO is represented by the (p(z)-p(z)+p(z)-p(z)) pi* MO.

Dimers and Trimers of Diphosphenes: A Wealth of Cyclo‐Phosphanes

“…These values compare nicely with the NMR shifts and coupling constants previously reported for 3 a (À14.8 ppm, 120.5 ppm; À244 Hz) and 3 b (À34.9 ppm, 149.0 ppm; À227 Hz). [17,18] All attempts to crystallize and subsequently isolate 10 failed. Instead, the constitutionally isomeric cyclo-tetraphosphane 11 ( Figure 2) was isolated in moderate yield from saturated solutions.…”

“…PSitBu 3 )] 2 (3 b), which was obtained by reaction of the tetraphosphenediide Na 2 [tBu 3 SiPPPPSitBu 3 ] (4 a) with AuI, was fully characterized, including single crystal structure elucidation. [18] Upon treatment with iodine, the similar tetraphosphenediide Tl 2 [Ter'PPPPTer'] (4 b, Ter' = 2,6-(2,6-diisopropylphenyl)phenyl) gave the bicyclotetraphosphane Ter'P 4 Ter' (5 a), which can be regarded as the formal reduction product of [XP(m-PTer')] 2 . [19] Concerning halogen-substituted diphosphenes, the formal monomers of the discussed cyclo-tetraphosphanes, the only reported example is Mes*PPCl (6), which was proposed to be the labile intermediate of the reaction of Mes*PPN(iPr) 2 (7) with various organolithium compounds (RLi) in the presence of HCl, leading to differently substituted diphosphenes of the type Mes*PPR.…”

The atomic level mechanism of white phosphorous demolition by di-iodine

“…No other example of this is instead present in the CCDC, 29 which in no case has a P 4 ring with only halogen substituents, but at most two of them in the species P 4 I 2 (SiR 3 ) 2 . 41 Since other structures feature pairs of trans-diagonal organo-substituents on the same side of the P 4 ring, we computationally tested such a stereochemistry also for (PI) 4 . Hence, the corresponding species 3′ in Fig.…”

Anorganische Chemie 2009

“…Die Umsetzung von P4 mit Phosphanylkationen (Ph2P+) eignet sich dazu, kationische Käfige des Typs [Ph2P5]+, [Ph4P6]2+ und [Ph6P7]3+ zu erzeugen 1_30. Setzt man P4 jedoch mit Silaniden des Typs M(SitBu3)2 (M = Li, Na, K) um, so erhält man offenkettige Bis(silyl)tetraphosphenide vom Typ M2[tBu3SiPPPPSitBu3] 1_31…”