Amphiphilic block copolymers containing phosphine moieties in the main chain are employed as macromolecular ligands for gold(I). The sequential living anionic copolymerization of isoprene (I) and the phosphaalkene, MesP CPh2 (Mes = 2,4,6-trimethylphenyl) affords the block copolymer [PI]404-b-[MesP-CPh2]32 (1a). The incorporation of gold(I) moieties into this functional copolymer is accomplished by treating 1 with THT.AuCl (THT = tetrahydrothiophene) which affords [PI]404-b-[MesP(AuCl)-CPh2]32 (2a). Remarkably, dissolution of gold-functionalized 2 in n-heptane, a block-selective solvent for isoprene, affords spherical micelles with gold(I)-rich cores. Micelles were examined by transmission electron microscopy (TEM) and dynamic light scattering (DLS). We also prepared two additional copolymers with longer phosphine blocks and shorter PI segments: [PI]222-b-[MesP(AuCl)-CPh2]77 (2b) and [PI]164-b-[MesP(AuCl)-CPh2]85 (2c). When assembled in isoprene-selective solvents, 2b forms wormlike structures and 2c, with the longest phosphine block, forms fascinating micron sized intertwined wormlike structures. This represents a new method to control the shape and size of gold(I) nanostructures.
The synthesis of (SiMe3)3SiPH2 (1) (further on denoted as hypersilylphosphane, HypPH2) was achieved by two methods: by the reaction of (SiMe3)3Si(OSO2CF3) with PH3, and alternatively, by the reaction of NaPH2 with (SiMe3)3SiCl (hypersilylchloride). The latter reaction also afforded bis(hypersilyl)phosphane Hyp2PH (2). By the reaction of 1 and known hypersilylbis(trimethylsilyl)phosphane (3) with tBuOK, the novel hypersilylphosphanides HypPHK (4) and Hyp(SiMe3)PK (5) were prepared. Compound 1 also reacted with nBuLi to form HypPHLi (6) and HypPLi2 (7). Furthermore, 3 reacted with hexachloroethane and 1,2‐dibromotetrachloroethane to give HypPCl(SiMe3) (8) and HypPBr(SiMe3) (9) as well as HypPCl2 (10) and HypPBr2 (11). Compounds 4 and 5 reacted smoothly with 1,2‐dibromoethane to give diphosphane HypHPPHHyp (12) as a mixture of the meso‐ and rac‐d,l‐diastereomers and Hyp(SiMe3)PP(SiMe3)Hyp (13) as the d,l‐modification only. By reducing the known compound tBuHypPCl with potassium, the d,l‐modification of tBuHypPPHyptBu (14) was obtained. All compounds were characterized by 29Si‐ and 31P NMR spectroscopy and elemental analyses with the exception of the phosphanides which were characterized spectroscopically only. The crystal structures of 3 and 4 and of diphosphanes 10, 11 and 13 are reported. From temperature‐dependent 31P NMR experiments, the coalescence temperature for the meso↔d,l interconversion of 12 was determined at 110 °C and gave an inversion barrier of roughly 69.4 kJ mol–1, which is corroborated by results of ab initio calculations at the B3LYP/6‐31G(d) level. Two diastereomeric inversion transition structures for diphosphanes R–PH–PH–R with either a syn or an anti arrangement of the P–H bond and the phosphorus lone pair of electrons could be located; bulky substituents seem to prefer the anti arrangement.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Three new nortricyclic P 7 R 3 derivatives with R = (SiMe 3 ) 2 -MeSi-(2), (SiMe 3 ) 2 PhSi-(3), and cyclo-Si 6 Me 11 -(4) were synthesized from red phosphorus, sodium/potassium alloy, and a chlorooligosilane, and their structures were elucidated with X-ray diffraction. Reactions of 2 and 3 and of tri(hypersilyl)heptaphosphane 1 [hypersilyl = (SiMe 3 ) 3 Si-] with KOtBu and LiOtBu were performed, which led to different results depending on the size of the substituent. With KOtBu, Si-P bonds were cleaved in 2 and 3, and the mono-and dianions [ 18-crown-6]+ salt of 2b suitable for X-ray diffraction could be grown successfully. Compound 1 reacted in an unprecedented way with KOtBu at -60°C. An Si-Si bond was cleaved, and a transient silyl anion formed, which immediately rearranged into a transient heptaphosphanide anion [Hyp 2 P 7 ] -(1a) under expulsion of bis(trimethylsilyl)silylene.
Keywords: Ab initio calculations / Carbene homologues / Phosphanes / SiliconThe reaction of hypersilyl(trimethylsilyl)chlorophosphane (SiMe 3 ) 3 SiP(SiMe 3 )Cl (1) with tBuOK in THF at -60°C proceeds by Si-P bond cleavage of the trimethylsilyl group and formation of tBuOSiMe 3 /KCl and bis(hypersilyl)phosphanylidene. The phosphanylidene dimerizes to form bis(hypersilyl)diphosphene (2) in excellent yields (Ն95%). X-ray diffraction experiments reveal the simultaneous presence of two rotamers in the solid state that differ in their SiSiPP torsion angles. Ab initio calculations for the parent diphosphene (SiH 3 ) 3 SiP=PSi(SiH 3 ) 3 at the DFT/6-31+G(d) level predict an energy difference of 2.3 kJ mol -1 . A cis arrangement of the two Si(SiH 3 ) 3 groups raises the energy by about 45 kJ mol -1 . In the UV/Vis spectrum the n Ǟ π* excitation is observed at 622 nm, which is in excellent agreement with the ab initio results. In the Raman spectrum, the P=P stretching vibration is easily identified as a strong line at 591 cm -1 . When a solution of 1 in THF is added to a solution of KOtBu in THF, maintaining an excess of KOtBu during the reaction,
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