factor of 7. This shows that solution-based silicon is a highly promising candidate for industrial-grade applications of solutionbased semiconductors. Evaluation of Precursors NPS and CPSIn literature, most groups reporting silicon fi lms fabricated from a liquid precursor use a cyclic hydridosilane, namely cyclopentasilane (CPS). We decided to use a branched molecule instead, namely neopentasilane (NPS). The molecular structures of CPS and NPS, as well as the process charts for obtaining solid amorphous silicon (a-Si) layers, are shown in Figure 1 . We characterized the NPS used in our process chain by NMR and by mass spectroscopy, showing the expected fi ngerprints mentioned in literature. [ 4 ] Employing NPS over CPS yields major advantages in processing effi ciency as well as in material quality. In general, branched molecules have a considerably better solubility in organic solvents, because the branches act as spacers, preventing strong interactions between the molecules and enabling better intercalation of solvent molecules. [ 5 ] The NPS material is therefore better soluble than CPS, which leads to improved fi lm homogeneity and uniformity. Moreover, in NMR measurements, we found that the NPS-oligomer bears 70% SiH 3 end groups, in contrast to 1.0% for the CPS-oligomer. Such end groups facilitate the cross-linking of the material to a solid network. Since this process is responsible for the formation of silicon-silicon bonds, we expect a positive effect on the coordination of silicon atoms, resulting in less dangling bonds and improved electronic properties. Until now, we have however not been able to demonstrate differences in nanoscopic amorphous silicon structure between CPS and NPS.Another major advantage of employing NPS instead of CPS lies in the differences in material synthesis. The synthesis of the CPS monomer involves a coupling reaction and subsequent chlorination of diphenyldichlorosilane to obtain decachlorocyclopentasilane. This process produces a large amount of various by-products, which are diffi cult to separate and recycle. However, in the synthesis of NPS, we use catalytic rearrangement of octachlorotrisilane to obtain dodecachloroneopentasilane,

The chloro-bridged interpnictogen compounds [tBu₂PhSiE{BiClCH(SiMe₃)₂}₂] (E = P (4), As (5)) can be synthesized by the reaction of [tBu₂PhSiELi₂] (E = P (2), As (3)) with (Me₃Si)₂CHBiCl₂ in a molar ratio of 1 : 2. The reaction of iPr₃SiAs(SiMe₃)₂ with (Me₃Si)₂CHBiCl₂ yields the analogous compound [iPr₃SiAs{BiClCH(SiMe₃)₂}₂] (6) as well as the diarsine species [As{BiClCH(SiMe₃)₂}₂]₂ (7). Preparation of 7 is also possible in the reaction of As(SiMe₃)₃ with (Me₃Si)₂CHBiCl₂. Starting from (Me₃Si)₃SiTeSiMe₃, the Bi/Te compounds [{(Me₃Si)₃SiTe}₂BiR] (R = CH(SiMe₃)₂ (8), C(SiMe₃)₃ (9)) are obtained by the reaction with RBiCl₂ (R = CH(SiMe₃)₂, C(SiMe₃)₃ (1)). The intermediate and final products are characterized by multinuclear NMR spectroscopy and IR spectroscopy. Furthermore, crystal structures determined by X-ray diffraction are described for compounds 1 and 3-9.

The 1,2-diphosphanyldisilane iPr 4 Si 2 (PH 2 ) 2 (1) was obtained from the reaction of iPr 4 Si 2 Cl 2 with [Li(dme)PH 2 ]. Whereas reactions of [Li(dme)PH 2 ] with the 1,3-dichlortrisilane iPr 6 Si 3 Cl 2 and the 1,5-dichlortrisiloxane tBu 2 Si(OSiiPr 2 Cl) 2 yield the cyclic compounds (iPr 2 Si) 3 PH (2) and tBu 2 Si(OSiiPr 2 ) 2 PH (3). The reaction of 1 with AlEt 3 produced the polycyclic compound [iPr 4 Si 2 {P(H)AlEt 2 }{PAlEt}] 2 (4), by reactions of 2 and 3 with 2199 nBuLi the tricyclic compounds [(iPr 2 Si) 3 PLi(dme)] 2 (5) and [tBu 2 Si(OSiiPr 2 ) 2 PLi(Et 2 O)] 2 ·C 7 H 8 (7) were obtained. Reactions of these lithium compounds with Me 3 SiCl produced the tertiary, cyclic silylphosphanes (iPr 2 Si) 3 PSiMe 3 (6) and tBu 2 Si(OSiiPr 2 ) 2 PSiMe 3 (8).iPr 6 Si 3 PH (2) und tBu 2 Si(OSiiPr 2 ) 2 PH (3) berichten. Sie wurden bei den Versuchen erhalten Verbindungen der Typen D und E darzustellen. Darüber hinaus werden Reaktionen der Verbindungen 1Ϫ3 mit AlEt 3 bzw. nBuLi vorgestellt.Schema 1 Diphosphanylsilane und -siloxane

The heterocubane-like molecules [tBu 2 PhSiESn] 4 (E = P (2), As (3)) and [(Me 3 Si) 3 SiPM] 4 (M = Sn (4), Pb (5)) were obtained by the reaction of primary silyl phosphines or -arsines with M{N(SiMe 3 ) 2 } 2 . Likewise, the reactions of the miscellaneously substituted arsine (Me 3 Si) 3 SiAs(SiMe 3 ) 2 (1) with MCl 2 yielded the heterocu-

The first structurally characterised lead(II) antimony compound with a chemical bond between lead and antimony, [Pb(4)(SbSiiPr(3))(6)] (3), was obtained by the reaction of iPr(3)SiSb-(SiMe(3))(2) with PbCl(2) in Et(2)O at 0 degrees C. The Pb(4)Sb(6) cage structure can be described as a Pb(4)Sb(4) heterocube where two SbSiiPr(3) edges are replaced by (SbSiiPr(3))(2). The average Pb-Sb bond length is 297.7 pm. The heterocubane compounds [PbESi-tBu(2)Ph](4) (E = P, As) were obtained from the reactions of Pb{N(SiMe(3))(2)}(2) with tBu(2)PhSiEH(2).