The donor-free mesityllithium was prepared from the reaction of MesBr with n-BuLi in diethyl ether at -78 degrees C. The solid-state structure of unsupported mesityllithium consists of C(2)Li(2)-rings composed of two LiMes units, which interact with adjacent dimers [LiMes](2), forming a polymeric infinite chain along the crystallographic c-axis (monoclinic space group, P2(1)/n). The structure of donor-free mesityllithium reveals short contacts between the C atoms of the mesityl rings and the lithium atoms of neighbouring [LiMes](2) units. The structure determination of LiMes was performed by X-ray powder diffraction. In addition we have investigated the reaction of LiMes with Me(3)SnCl and P(4) for our understanding of the reactivity of donor-free mesityllithium. The heterogeneous reaction of donor-free mesityllithium with Me(3)SnCl produces conveniently the stannylated mesitylene Me(3)SnMes (triclinic, space group P1). White phosphorus reacts with three equivalents of unsupported mesityllithium in benzene to give Li(3)P(4)Mes(3). In this context it should be noted that a tetraphosphide with an identical LiP-core as in Li(3)P(4)Mes(3) had been formed in the 1:3 reaction of P(4) with the silanide Li[SitBu(3)]. The tetraphosphide Li(3)P(4)Mes(3) was analyzed using X-ray crystallography (monoclinic, space group C2/c).

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

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.

A one-pot synthesis of the tetrasilatetrahedrane (tBu 3 Si) 4 Si 4 was achieved by the reaction of HSiCl 3 and Na[SitBu 3 ]. In this reaction the silane tBu 3 SiH was obtained along with (tBu 3 Si) 4 Si 4 and tBu 3 SiSitBu 3 . The tetrasilatetrahedrane (tBu 3 Si) 4 Si 4 was also obtained via a one-pot approach by treatment of Cl 3 SiSiCl 3 or Cl 3 SiSiCl 2 SiCl 3 with Na-[SitBu 3 ]. In the reaction of HSiCl 3 with Na[SitBu 3 ], two molecules of the tetrasilatetrahedrane (tBu 3 Si) 4 Si 4 crystallize together with one molecule of tBu 3 SiSitBu 3 and one molecule of benzene. Single crystals suitable for X-ray diffraction composed of one molecule of (tBu 3 Si) 4 Si 4 and two molecules of benzene were obtained by recrystallization from benzene.

The caesium triphosphenide Cs[tBu3SiPPPSitBu3] was accessible from the reaction of CsF with the sodium triphosphenide Na[tBu3SiPPPSitBu3] in tetrahydrofuran at room temperature. In contrast to the preparation of tetrahydrofuran-solvated silanides M[SitBu3] (M = Li, Na, K), our efforts to synthesize the caesium silanide Cs[SitBu3] as a tetrahydrofuran complex failed. When tBu3SiBr was treated with an excess of caesium metal in tetrahydrofuran at room temperature, the caesium enolate Cs[OCH=CH2] and the supersilane tBu3SiH formed rather than the silanide Cs[SitBu3]. X-Ray quality crystals of the enolate Cs[OCH=CH2] (orthorhombic, Pnma) were obtained from tetrahydrofuran at ambient temperature. In contrast to the structures of its homologues M[tBu3SiPPPSitBu3] (M = Na, K), the caesium triphosphenide Cs[tBu3SiPPPSitBu3] features a polymer in the solid state (orthorhombic, Cmcm).

The group 13-15 element addition compounds tBu 2 PH·EX 3 (E = B, Al, Ga, In; X = Cl, Br) are accessible from the reaction of tBu 2 PH with the triel halides EX 3 (E = B, Al, Ga, In; X = Cl, Br) at room temperature. The crystal structures of the group 13-15 element addition compounds tBu 2 PH·BBr 3 (monoclinic, P2 1 /c) and tBu 2 PH·EBr 3 (E = B, Al, Ga, In) (monoclinic, P2 1 /n) are described. When the addition compound tBu 2 PH·BBr 3 was treated with one equivalent of LiN(SiMe 3 ) 2 , the reaction led to the formation of the H, 7.13 %. tBu 2 PH·AlCl 3 [1a(Al)]: 1 H NMR (300 MHz, C 6 D 6 ): δ = 1.08 (d, 3 J PH = 14.7 Hz, 18 H, tBu), 3.47 (d, 1 J PH = 324.0 Hz, PH). 13 C{ 1 H} NMR (75.5 MHz, C 6 D 6 ): δ = 30.3 (CCH 3 ), 34.3 (CCH 3 ). 31 P NMR (121.5 MHz, C 6 D 6 ): δ = 10.2 (br. m, 1 J PH = 293.0 Hz). C 8 H 19 AlCl 3 P (279.55): C, 34.37; H, 6.85. Found: C, 32.98; H, 6.16 %. tBu 2 PH·GaCl 3 [1a(Ga)]: 1 H NMR (300 MHz, C 6 D 6 ): δ = 1.03 (d, 3 J PH = 16.9 Hz, 18 H, tBu), 3.98 (d, 1 J PH = 372.3 Hz, PH). 13 C{ 1 H} NMR (75.5 MHz, C 6 D 6 ): δ = 29.3 (d, 2 J PC = 2.3 Hz, CCH 3 ), 34.3 (d, 1 J PC = 18.1 Hz, CCH 3 ). 31 P NMR (121.5 MHz, C 6 D 6 ): δ = 16.3 (br. m, 1 J PH = 376.4 Hz). C 8 H 19 GaCl 3 P (322.29): C, 29.81; H, 5.94. Found: C, 28.94; H, 5.62 %. tBu 2 PH·InCl 3 [1a(In)]: 1 H NMR (300 MHz, C 6 D 6 ): δ = 1.08 (d, 3 J PH = 11.5 Hz, 18 H, tBu), 3.25 (d, 1 J PH = 226.9 Hz, PH). 13 C{ 1 H} NMR (75.5 MHz, C 6 D 6 ): δ = 31.6 (br., CCH 3 ), 33.4 (br., CCH 3 ). 31 P NMR (121.5 MHz, C 6 D 6 ): δ = 22.3 (br. d, 1 J PH = 262.3 Hz). C 8 H 19 InCl 3 P (367.39): C, 26.15; H, 5.21. Found: C, 26.48; H, 5.32 %. Synthesis of tBu 2 PH·EBr 3 (E = B, Al, Ga, In; 1b):A flask was charged with toluene (5 mL) and triel bromides EBr 3 (BBr 3 : 0.343 g, 1.37 mmol; AlBr 3 : 0.180 g, 1.23 mmol; GaBr 3 : 0.240 g, 0.78 mmol; InBr 3 : 0.655 g, 1.85 mmol) to which was added an equimolar amount of tBu 2 PH in toluene (0.1 m solution, B: 13.4 mL; Al: 12.3 mL; Ga: 7.8 mL; In: 18.5 mL) at -78°C. Gas-phase diffusion of pentane into concentrated solutions of the addition compounds yielded colorless Xray quality crystals of tBu 2 PH·EBr 3 (E = B, Al, Ga, In; 1b). tBu 2 PH·BBr 3 [1b(B)]: Yield: 0.456 g (84 %). 1 H NMR (300 MHz, C 6 D 6 ): δ = 1.14 (d, 3 J PH = 14.4 Hz, 18 H, tBu), 4.35 (dm, 1 J PH = tBu 2 PHO·AlCl 3 [2a(Al)]: 1 H NMR (300 MHz, C 6 D 6 ): δ = 0.85 (d, 3 J PH = 17.8 Hz, 18 H, tBu), 5.73 (d, 1 J PH = 433.8 Hz, PH). 13 C{ 1 H} NMR (75.5 MHz, C 6 D 6 ): δ = 25.9 (d, 2 J PC = 2.5 Hz, CCH 3 ), 33.6 (d, 1 J PC = 18.2 Hz, CCH 3 ). 27 P NMR (121.5 MHz, C 6 D 6 ): δ = 79.2 (br. m, 1 J PH = 433.8 Hz). C 8 H 19 AlCl 3 OP (295.55): C, 32.51; H, 6.48. Found: C, 31.78; H, 6.27 %. tBu 2 PHO·GaCl 3 [2a(Ga)]: 1 H NMR (300 MHz, C 6 D 6 ): δ = 0.75 (d, 3 J PH = 14.1 Hz, 18 H, tBu), 5.56 (d, 1 J PH = 430.5 Hz, PH). 13 C{ 1 H} NMR (75.5 MHz, C 6 D 6 ): δ = 25.4 (CCH 3 ), 32.9 (CCH 3 ). 31 P NMR (121.5 MHz, C 6 D 6 ): δ = 79.7 (br. d, 1 J PH = 430.5 Hz). C 8 H 19 GaCl 3 OP (338.29): C, 28.40; H, 5.66. Found: C, 27.43; H, 5.11 %. tBu 2 PH·InCl 3 [1a(I...

The dimeric iron carbonyl [CpFe(CO)(2)](2) and the iodosilanes tBu(2)RSiI were obtained from the reaction of [CpFe(CO)(2)]I with the silanides Na[SiRtBu(2)] (R = Me, tBu) in THF. By the reactions of [CpFe(CO)(2)]I and Na[SiRtBu(2)] (R = Me, tBu) the disilanes tBu(2)RSiSiRtBu(2) (R = Me, tBu) were additionally formed using more than one equivalent of the silanide. In this context it should be noted that reduction of [CpFe(CO)(2)](2) with Na[SitBu(3)] gives the disilanes tBu(3)SiSitBu(3) along with the sodium ferrate [(Na(18-crown-6))(2)Cp][CpFe(CO)(2)]. The potassium analogue [(K(18-crown-6))(2)Cp][CpFe(CO)(2)] (orthorhombic, space group Pmc2(1)), however, could be isolated as a minor product from the reaction of [CpFe(CO)(2)]I with [K(18-crown-6)][PtBu(2)BH(3)]. The reaction of [CpFe(CO)(2)](2) with the potassium benzophenone ketyl radical and subsequent treatment with 18-crown-6 yielded the ferrate [K(18-crown-6)][CpFe(CO)(2)] in THF at room temperature. The crown ether complex [K(18-crown-6)][CpFe(CO)(2)] was analyzed using X-ray crystallography (orthorhombic, space group Pna2(1)) and its thermal behaviour was investigated.

The tricarbonyliron thiolate and selenolate [(OC)3Fe(μ‐ESitBu3)]2 (E = S, Se) were synthesized photochemically from the reaction of 2 equiv. of pentacarbonyliron with the dichalcogenides tBu3Si–E2–SitBu3 (E = S, Se). X‐ray‐quality crystals of the tricarbonyliron thiolate [(OC)3Fe(μ‐SSitBu3)]2 (monoclinic, P21/n) and selenolate [(OC)3Fe(μ‐SeSitBu3)]2 (monoclinic, P21/n) were grown from benzene. The cyclic voltammograms of [(OC)3Fe(μ‐ESitBu3)]2 (E = S, Se, Te) resemble each other. Electrochemical reduction at potential below –2.2 V or reduction of [(OC)3Fe(μ‐ESitBu3)]2 (E = S, Se, Te) with Na or K led to degradation of the complex core with the formation of the chalcogenolates [ESitBu3]– (E = S, Se, Te). The dichalcogenides tBu3Si–E2–SitBu3 (E = Se, Te) are accessible by the reaction of Na[ESitBu3] with oxygen. However, the disulfide tBu3Si–S2–SitBu3 (monoclinic, P21/c) which is used in the synthesis of tricarbonyliron thiolates [(OC)3Fe(μ‐ESitBu3)]2 as starting material, was prepared from S2Cl2 and Na[SitBu3]. Depending on the solvent used for crystallization, the sodium supersilyl chalcogenolates Na[ESitBu3] (E = S, Se) form dimeric or tetrameric structures in the solid state. Single crystals of the dimeric thiolate [Na(thf)2SSitBu3]2 (monoclinic, P21/c) were obtained from thf at –25 °C whereas crystals suitable for X‐ray diffraction of tetrameric chalcogenolates [Na(thf)ESitBu3]4 (E = S, Se) were grown from hexane at –25 °C.