Modular chemistry with aluminum phosphanides: cluster formation of (AlP)n (n=3,6,7), Al4P3, and Al4Li4P6 frameworks

Synthesis and Application of Alkali Metal Antimonide-A New Approach to Antimony Chemistry

Alkali metal dihydrogen-antimonides [M(L)_x SbH₂ ], short: alkali metal antimonides (M=Li, Na, K, Rb, Cs; 1: L=pmdta; 2: L=crown-ether), were prepared from stibine and n-Butyllithium, M(hmds) (hmds=hexamethyldisilazane) or MOtBu, respectively. We developed a generally applicable synthesis route for these compounds and the obtained compounds were examined on their stability depending on the alkali metal and stabilizing additives used, whereby the use of appropriate crown-ethers allowed their isolation and characterization at room temperature. Moreover, the 1,4-dioxane adduct [Na(dioxane)_x SbH₂ ] was the appropriate starting compound for the synthesis of the first primary silylstibane (Me₃ Si)₃ SiSbH₂ (3) which was characterized by NMR and IR spectroscopy. Reaction of 3 with (Dipp₂ NacNac)Ga (Dipp₂ NacNac=HC{C(Me)N(Dipp)}₂ ; Dipp=2,6-iPr₂ C₆ H₃ ) resulted in the formation of (Dipp₂ NacNac)GaH(SbHSi(SiMe₃ )₃ ) (4) which was furthermore characterized by single crystal x-ray diffraction.

Pre-arranged building block approach for the orthogonal synthesis of an unfolded tetrameric organic-inorganic phosphazane macrocycle

Inorganic macrocycles remain challenging synthetic targets due to the limited number of strategies reported for their syntheses. Among these species, large fully inorganic cyclodiphosphazane macrocycles have been experimentally and theoretically highlighted as promising candidates for supramolecular chemistry. In contrast, their hybrid organic-inorganic counterparts are lagging behind due to the lack of synthetic routes capable of controlling the size and topological arrangement (i.e., folded vs unfolded) of the target macrocycle, rendering the synthesis of differently sized macrocycles a tedious screening process. Herein, we report-as a proof-of-concept-the combination of pre-arranged building blocks and a two-step synthetic route to rationally enable access a large unfolded tetrameric macrocycle, which is not accessible via conventional synthetic strategies. The obtained macrocycle hybrid cyclodiphosphazane macrocycle, cis-[μ-P(μ-N^tBu)]₂(μ-p-OC₆H₄C(O)O)]₄[μ-P(μ-N^tBu)]₂ (4), displays an unfolded open-face cavity area of 110.1 Ų. Preliminary theoretical host-guest studies with the dication [MeNC₅H₄]₂²⁺ suggest compound 4 as a viable candidate for the synthesis of hybrid proto-rotaxanes species based on phosphazane building blocks.

Cyclic NHC-stabilized silylphosphinoalanes and -gallanes

The reaction between prestabilized group 13 metal hydrides and primary silylphosphines lead to the formation of rare, butterfly-like folded, four membered rings including free lone pairs on the phosphorus atoms, wherein the Lewis base can readily be substituted by N-heterocyclic carbenes.

Germanium/phosphorus cage compounds with germanium in three different oxidation states

Novel germanium/phosphorus cage compounds with new structural motifs have been synthesized containing germanium in three different oxidation states. The key to obtain this new class of compounds is the use of monolithiated primary phosphine LiHPtBu in the reaction with GeX(2).

Violation of the Isolated Square Rule for Group 13−15 Oligomers: Theoretical Prediction of a New Class of Inorganic Polymers

It is widely thought that the oligomer compounds [RMYR]n (M-group 13, Y-group 15 element) should obey the isolated square rule found for the boron-nitrogen cages. In contrast to these expectations, the needle-shaped oligomers, which violate this rule, are more stable compared to the cage (fullerene-like) oligomers for all MY pairs (M = B, Al, Ga, In; Y = N, P, As). The stability of the needle-shaped clusters improves with increasing oligomerization degree. Thus, the isolated square rule, which is analogous to the isolated pentagon rule widely applied for fullerenes, should not serve as the basis for searches for the most stable structures of the inorganic oligomers. Generation of the needle-shaped oligomers from the group 13 and 15 hydrides is thermodynamically favorable. A synthesis of novel inorganic polymers, formed by fusion of trimeric M3Y3 rings, is expected to be viable.

2,6-Diisopropylphenylphosphane: A new, bulky primary phosphane and its mono- and disilylated Si(CH3)3 and Si(CH3)2-t-Bu derivatives — A synthetic, crystallographic, and dynamic NMR investigation

The bulky primary phosphane 2,6-diisopropylphenylphosphane, DipPH2, has been prepared from 1-bromo-2,6-diisopropylbenzene via the reaction of the Grignard reagent with PCl3. The resulting mixed phosphonous dihalides DipP(Cl,Br)2 are reduced with LiAlH4 to yield the title compound in reasonable yield and on a synthetically useful scale. DipPH2 is also used to prepare the monosilylated derivatives DipPHSi(CH3)3 and DipPH{Si(CH3)2-t-Bu} as well as the disilylated compounds DipP{Si(CH3)3}2 and DipP{Si(CH3)2-t-Bu}2. All products have been fully characterized by IR, mass, and NMR spectroscopy. The crystal structure of DipPH{Si(CH3)2-t-Bu} was determined from single-crystal diffraction data: C18H33PSi, P21/c, Z = 4, a = 8.5768(10), b = 28.104(3), c = 8.1102(4) Å, β = 93.341(3)° (R = 0.0518). Changes in the NMR spectrum of DipPH{Si(CH3)2-t-Bu} were observed over the temperature range 178–380 K. Barrier heights were determined from the peak separation at low temperature and the coalescence points: ΔG‡ [Formula: see text] 40 kJ mol–1 for C(aryl)—P bond rotation and [Formula: see text] 72 kJ mol–1 for pyramidal inversion at phosphorus.Key words: crystal structure, 2,6-diisopropylphenyl, bulky substituents, steric congestion, dynamic NMR, primary phosphane, silyl phosphane.