Frauke Schödel

Supersilylated tetraphosphene derivatives M2[t-Bu3SiPPPPSi-t-Bu3] (M = Li, Na, Rb, Cs) and Ba[t-Bu3SiPPPPSi-t-Bu3]: reactivity and cis-trans isomerization.

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.

Disupersilylperoxo Radical Anion [tBu3SiOOSitBu3]⋅−: An Intermediate of Supersilanide Oxidation

In the oxidative process of the supersilanide anion [SitBu3 ](-) , radical species are generated. The continuous wave (cw)-EPR spectrum of the reaction solution of Na[SitBu3 ] with O2 revealed a signal, which could be characterized as disupersilylperoxo radical anion [tBu3 SiOOSitBu3 ](⋅-) affected by sodium ions though ion-pair formation. A mechanism is suggested for the oxidative process of supersilanide, which in a further step can be helpful in a better understanding of the oxidation process of isoelectronic phosphanes.

Eine elektrochemische und strukturelle Studie an den Eisensilylamiden Fe[N(SiMe3)2]2 und Fe[N(SiMe3)2]3 / An Electrochemical and Structural Study of the Iron Silylamides Fe[N(SiMe3)2]2 and Fe[N(SiMe3)2]3

The bis(trimethyl)silylamido complex Na(THF){Fe[N(SiMe3)2]3} and the disilane tBu3SiSitBu3 were obtained from the reaction of Fe[N(SiMe3)2]3 with the sodium silanide Na(THF)2[SitBu3] in a mixture of benzene and THF. Single crystals of Na(THF){Fe[N(SiMe3)2]3} suitable for X-ray diffraction were grown from the reaction solution at ambient temperature (orthorhombic, C2221, Z = 4). The solid-state structure features a contact-ion pair with two short N-Na contacts. The THF adducts {M(THF)2[N(SiMe3)2]2} reacted with 2,2´-bipyridine to give the corresponding complexes {M(2,2´bipy)[N(SiMe3)2]2} (M= Mn; Fe). Their structures (M= Fe: orthorhombic, Pca21, Z = 8; M = Mn: orthorhombic, Pbca, Z = 8) feature monomeric units. The cyclic voltammogram of Fe[N(SiMe3)2]3 revealed a reversible redox transition with the potential of -0;523 V (E½), which was assigned to the Fe(III)[N(SiMe3)2]3 → Fe(II)[N(SiMe3)2]-3 redox transition, whereas the compounds {Fe(THF)2[N(SiMe3)2]2} (Eox = -0;379 V) and {Fe(2,2´bipy)[N(SiMe3)2]2} (Eox = -0;436 V) featured irreversible oxidation waves. The related manganese bis(trimethylsilyl)amido complexes {Mn(THF)2[N(SiMe3)2]2} (Eox = -0;458 V) and {Mn(2,2´bipy)[N(SiMe3)2]2} (Eox = -0513 V) also underwent irreversibile electron transfer processes. Graphical Abstract Eine elektrochemische und strukturelle Studie an den Eisensilylamiden Fe[N(SiMe3)2]2 und Fe[N(SiMe3)2]3 / An Electrochemical and Structural Study of the Iron Silylamides Fe[N(SiMe3)2]2 and Fe[N(SiMe3)2]3

Tetra-n-butyl­ammonium tetra­kis(penta­fluoro­phen­yl)borate

In the title compound, C16H36N+·C24BF20−, the geometric parameters do not show any unusual values. The four n-butyl chains adopt an all-trans conformation.

Tetra-n-butyl­ammonium hexa­fluoro­phosphate

The structure of the title compound, C16H36N+·PF6−, has been reported previously by Angaridis, Cotton & Petrukhina [Inorg. Chim. Acta (2001), 324, 318–323]. However, these authors found the PF6− ion to be heavily disordered and they did not publish any coordinates. We present here a redetermination of this structure, based on new intensity data and exhibiting no disorder.

Synthesis and properties of 1,3-Bis(2,6-diisopropylphenyl)-2-(trimethylstannyl)- 2,3-dihydro-1H-1,3,2-diazaborole

Abstract The diazaborole Me3Sn–B{N(Dipp)CH}2 (1; B{N(Dipp)CH}2=N,N′-bis(2,6-diisopropylphenyl)-2,3-dihydro-1H-1,3,2-diazaborolyl) was prepared by the reaction of Me3SnCl with one equivalent of Li[B{N(Dipp)CH}2]. Single crystals of 1 were obtained from hexane (triclinic space group P1̅). The diazaborole 1 was mono-deprotonated at the heterocycle upon treatment with Li[Me] to give product 2. In contrast to Li[B{N(Dipp)CH}2] which reacted with P4 to give the tetraphosphenediide Li2[{HC(Dipp)N}2B–P(1)P(2)P(3)P(4)–B{N(Dipp)CH}2] (3; δP=364.5, –29.4; 1JP(2),P(3)=–509.8 Hz, 1JP(1),P(2)=–434.3 Hz, 2JP(1),P(3)=–3.7 Hz, 3JP(1),P(4)=178.9 Hz) and the triphosphenide Li[{HC(Dipp)N}2B–PPP–B{N(Dipp)CH}2] (δP=665.1, 175.4; 1JP,P=500 Hz), the stannyl derivative 1 did not activate white phosphorus. The reaction of 1 with GaCl3 yielded either Me2ClSn–B{N(Dipp)CH}2 (4) or MeCl2Sn–B{N(Dipp)CH}2 (5) depending on the molar ratio of the reactants. The monochlorinated diazaborole Me2ClSn–B{N(Dipp)CH}2 was also obtained by the reaction of 1 with AsCl3.

Activation of P4 by Li[SitBu3]: generation of lithium bis(supersilyl)heptaphosphanortricyclanide Li[P7(SitBu3)2]

Abstract Treatment of P4 with one equivalent of Li[SitBu3] leads to the formation of a number of oligo-phosphanes and -phosphides, e.g. the bicyclo[1.1.0]tetraphosphane P4(SitBu3)2, the heptaphosphanortricyclane P7(SitBu3)3, the tetraphosphides Li3[P(PSitBu3)3] (Li3[2a]), and the pentaphosphacyclopentadienide Li[P5]. From this reaction we could isolate single crystals of Li3[2a]. However, this reaction took another course in the presence of Li[OSitBu3]. When P4 was treated with one equivalent of Li[SitBu3] in the presence of Li[OSitBu3], the heptaphosphanortricyclanide Li[P7(SitBu3)2] (Li[8a]) was formed. Single crystals of the cluster {Li4(C6H6)(OSitBu3)[8a]3}·C6H6 (orthorhombic, space group Pca21) were isolated from the reaction mixture at ambient temperature. This cluster compound consists of three chiral Li[P7(SitBu3)2] units, one silanolate Li[OSitBu3], and one benzene molecule. We further investigated the degradation reaction of the bicyclo[1.1.0]tetraphosphane P4(SitBu3)2. After heating a benzene solution to 60 °C for 24 h, we found 100 % conversion of P4(SitBu3)2, and P7(SitBu3)3 (monoclinic, space group P21/c) and tBu3SiPH2 were formed.

Crystal structure and thermal decomposition of the Silanimine tBu2Si=N-SitBu3·thf

Abstract The thf-complexed silanimine tBu2Si=N–Sit- Bu3·thf (1(thf); monoclinic, space group C2/c) was prepared by the reaction of 1 equivalent of tBu2SiClN3 with 1 equivalent of Na[SitBu3] in Bu2O and subsequent addition of thf. By heating a benzene solution over a period of 11 d –140 °C, 1(thf) slowly released the thf donor to form the uncomplexed silanimine 1. However, under these conditions the silanimine 1 is unstable and is thermolized to give the ene reaction product of 1 with isobutene, H2C=C(CH2SitBu2–NH–SitBu3)2. By contrast, the thermolysis reaction of Me2Si=N–SitBu3·thf yielded the silanimine dimer (Me2SiNSitBu3)2 in 51 % and the vinyl ether Me2Si(OCH=CH2)NHSitBu3 in 49 % yield.

Untersuchungen zur Reaktivität des Lithiumphosphanids Li[PtBu2] gegenüber GaCl3 / Investigations of the Reactivity of the Lithiumphosphanide Li[PtBu2] towards GaCl3

Single crystals suitable for X-ray diffraction of (tBu2P)3Ga (monoclinic, space group Cc) were obtained from GaCl3 and two equivalents of Li[PtBu2] at room temperature in benzene. The phosphanylgallane (tBu2P)3Ga was also produced via a one-pot approach by reaction of GaCl3 with three or more than three equivalents of Li[PtBu2]. However, treatment of one equivalent of GaCl3 with one equivalent of Li[PtBu2] and subsequent protolysis yielded [tBu2PH2][tBu2P(GaCl3)2 - Li(Cl3Ga)2PtBu2]. Single crystals of this phosphonium salt (monoclinic, space group Cc) were obtained from benzene at room temperature. Graphical Abstract Untersuchungen zur Reaktivität des Lithiumphosphanids Li[PtBu2] gegenüber GaCl3 / Investigations of the Reactivity of the Lithiumphosphanide Li[PtBu2] towards GaCl3

Supersilylated Tetrachlorodigermane (tBu3Si)Cl2GeGeCl2(SitBu3) and Trigermoxetane (tBu3Si)3Ge3Cl3O

In contrast to the tetrachlorodigermane (tBu3Si)Cl2Ge-GeCl2(SitBu3), the cis,transcyclotrigermane (tBu3SiGeCl)3 is sensitive to oxygen. Its treatment with O2 at ambient temperature leads to the trigermoxetane (tBu3Si)3Ge3Cl3O. According to an X-ray structure analysis of single crystals consisting of cocrystallized (tBu3Si)3Ge3Cl3O and (tBu3Si)Cl2Ge-GeCl2(SitBu3) the trigermaoxetane contains an almost planar Ge3O-ring while the tetrachlorodigermane (tBu3Si)Cl2Ge- GeCl2(SitBu3) possesses a Si-Ge-Ge-Si chain which is exactly all trans