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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

Synthese der Amide M[N(SiMetBu2)(SitBu3)] (M = Li, Na) durch N2-Eliminierung aus den Triazeniden M[tBu3SiNNNSiMetBu2] (M = Li, Na) / Synthesis of the Amides M[N(SiMetBu2)(SitBu3)] (M = Li, Na) by N2-Elimination Reaction of the Triazenides M[tBu3SiNNNSiMetBu2] (M= Li, Na)

The thermolabile triazenides M[tBu3SiNNNSiMetBu2] (M = Li, Na) are accessible from the reaction of tBu2MeSiN3 with the silanides MSitBu3 (M = Li, Na) at −78 °C in THF. At r. t. N2 elimination from the triazenides M[tBu3SiNNNSiMetBu2] (M = Li, Na) takes place with the formation of M[N(SiMetBu2)(SitBu3)] (M = Li, Na). X-Ray quality crystals of Li(THF)[N(SiMetBu2)(SitBu3)] (orthorhombic, Pna21) are obtained from a benzene solution at ambient temperature. In contrast to the structures of the unsolvated silanides MSitBu3 (M = Li, Na), the THF adduct Li(THF)3SitBu3 is monomeric in the solid state (orthorhombic, Pna21).

Iodido(tri-tert-butyl-phosphane-κP)gold(I).

The AuI atom of the title compound, [AuI(C12H27P)], shows an almost linear coordination, with a P—Au—I angle of 178.52 (3)° [Au—P = 2.2723 (14) Å and Au—I = 2.5626 (6) Å].

The chemical behavior of the silaoxine C22H34OSi3 and silaazetidine C25H43NSi4 towards CO2

Abstract When 4,4a-dihydro-3,3-dimethyl-1-phenyl-4,4-bis(trimethylsilyl)-3H-2-oxa-3-sila-naphthaline (silaoxine C22H34OSi3 (3); orthorhombic, space group Pna21, Z=4) was thermolized in a CO2 atmosphere, the corresponding oxasilacyclobutane (silaoxetane) 5 was quantitatively formed. The [2+2] cycloreversion of the silaoxetane 5 occurred at temperatures higher than 120°C to give exclusively Ph2C=C(SiMe3)2 and (Me2SiO)n. Single crystals of Ph2C=C(SiMe3)2 (6; monoclinic, space group C2/c, Z=8) were isolated from this reaction. When the azasilacyclobutane (silaazetidine) C25H43NSi4 (4; monoclinic, space group P21/n, Z=4) was reacted with an excess of CO2 at 100°C an unknown intermediate was formed along with the benzophenonimine Ph2C=N(SiMe3). The NMR resonances of this intermediate indicates the formation of the β-silalactone (silaoxetanone) C10H24O2Si3 (7). At temperatures higher than 120°C the silaoxetanone 7 decomposed to give (Me3Si)2C=C=O and (Me2SiO)n, respectively.

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 of bis-[1,3-bis-(2,6-diiso-propyl-phen-yl)imidazol-2-yl-idene]silver(I) chloride tetrahydro-furan monosolvate.

In the title compound, the silver atom is coordinated by two 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene ligands, with the imidazole rings inclined to one another by 46.69 (13)°. In the crystal, molecules are linked by trifurcated C—H⋯(Cl,Cl,Cl) hydrogen bonds, forming two-dimensional networks parallel to (010).

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

Thermolysereaktionen der donorfreien Silanimine tBu2Si=N-SiRtBu2 (R = tBu, Ph) / Thermolysis Reactions of Donor-free Silanimines tBu2Si=N-SiRtBu2 (R = tBu, Ph)

The donor-free silanimines tBu2Si=N-SiRtBu2 (R = tBu, Ph), which are prepared from tBu2ClSiN3 and NaSiRtBu2 at −78 ◦C inBu2O, decompose in benzene at room temperature with the formation of isobutene. Products of ene reactions of isobutene and tBu2Si=N-SiRtBu2 (R = tBu, Ph) are formed. X-Ray quality crystals of H2C=C(CH2SitBu2-NH-SiPhtBu2)2 (monoclinic, space group C2/c, Z = 4) were grown from a benzene solution at ambient temperature, whereas single crystals of H2C=C(CH2SitBu2-NH-SitBu3)2 (monoclinic, space group P21, Z = 2) were obtained by recrystallization from THF Graphical Abstract Thermolysereaktionen der donorfreien Silanimine tBu2Si=N-SiRtBu2 (R = tBu, Ph) / Thermolysis Reactions of Donor-free Silanimines tBu2Si=N-SiRtBu2 (R = tBu, Ph)