Synthese,Struktur und Reaktivität eines 2,4-Diphosphino-1,3-diphospha-2,4-disilacyclobutans

Synthesis, Structure, and Reactivity of a 1,3-Diphosphino-2,4-diphospha-1,3-disilacyclobutane Pentamethylcyclopentadienyltrichlorosilane reacts with Li[Al(PH₂)₄] to give the stable 1,3-diphosphino-2,4-diphospha-1,3-disilacyclobutane 4 . Treatment of 4 with Lithium alkyls affords the Lithium phosphide 5 via regiospecific metalation of a ring phosphorus atom, and reaction with t-Bu₂Hg proceeds via oxidative P? P bond formation to yield the 1,4-disila-2,3,5,6-tetraphospha-bicyclo[2,1,1]-hexane 6 . Cleavage of pentamethylcyclopentadiene is observed during thermolysis of 4 at 200°C. 4–6 were characterised by NMR-spectroscopy, and 4 by an additional crystal structure determination.     

Synthese,Struktur und Reaktivität von Bis(dialkylamino)diphosphanen

Synthesis, Structure, and Reactivity of Bis(dialkylamino)diphosphines Starting with the aminochlorophosphines ⁱPr₂N? PCl₂ 1 and (ⁱPr₂N)₂P? Cl 2 , the synthesis of some new functionalized aminophosphines (ⁱPr₂N)₂P? SiMe₃ 3a , (ⁱPr₂N)₂P? SnMe₃ 3b , (ⁱPr₂N)(DMP)P? Cl 4 , ⁱPr₂N? P(SiMe₃)₂ 5 and ⁱPr₂N? P(SiMe₃)Cl 6 is reported. Reactions of 2 with different phosphides yield the aminodiphosphines (ⁱPr₂N)₂P? P(SiMe₃)₂ 7a , (ⁱPr₂N)₂P? P(SiMe₂^tBu)₂ 7b , (ⁱPr₂N)₂P? PPh₂ 8 and (ⁱPr₂N)₂P? PH₂ 9 . The phosphines 3a/b react with halogenophosphines to the aminohalogenodiphosphines (ⁱPr₂N)₂P? PCl₂ 10 , (ⁱPr₂N)₂P? P^tBuCl 11 and (ⁱPr₂N)₂P? P(NⁱPr₂)Cl 12 . The ambivalente aminophosphine 6 gives the aminotrichlorodiphosphine Cl(ⁱPr₂N)P? PCl₂ 13 after condensation with PCl₃, while the reactions with the corresponding lithiumphosphides yield the aminosilyldiphosphines (ⁱPr₂N)(SiMe₃)P? P(SiMe₃)₂ 14a and (ⁱPr₂N)(SiMe₃)P? P(SiMe₂^tBu)₂ 14b . The aminochlorophosphines 2/4 are reductively coupled with magnesium leading to the symmetrically substituted tetraaminodiphosphines (ⁱPr₂N)₂P? P(ⁱPr₂N)₂ 15a and DMP(ⁱPr₂N)P? P(ⁱPr₂N)DMP 15b . The functionalized aminosilyldiphosphine 7a is treated with methanol to yield the diphosphine (ⁱPr₂N)₂P? PH(SiMe₃) 16 and gives the lithium phosphinophosphide (ⁱPr₂N)₂P? PLi(SiMe₃) 17 after metallation with n-BuLi. The compounds are characterized by their NMR and mass spectra and the ³¹P-NMR values of the diphosphines are discussed according to their substituents. The crystal structures of 7b, 8 and 15b showing significantly differing conformations are presented.     

Bisaminophosphane – Synthese,Struktur und Reaktivität

Bisaminophosphanes – Synthesis, Structure, and Reactivity Different pathways for the synthesis of bis(alkylamino)phosphanes RP(N(H)R′)₂ are described. t‐BuP(N(H)‐ Dipp)₂ (Dipp = 2,6‐i‐Pr₂–C₆H₃) was structurally characterized by single crystal X‐ray diffraction. The reactivity of the compounds was examplarily investigated using t‐BuP(N(H)t‐Bu)₂. Its reaction with Me₃Al and R₂AlH (R = Me, Et, i‐Bu) in 1 : 1 and 1 : 2 stoichiometrie yield monosubstituted compounds of the type t‐BuP(N(H)t‐Bu)(N(AlR₂)t‐Bu).     

Struktur und Reaktivität eines Triazolobenzodiazepin/Oxalylchlorid-Addukts

Structure and Reactivity of a Triazolo-benzodiazepine/Oxalyl Chloride Adduct Reaction of oxalyl chloride with N, N-dimethyl-{8-chloro-6-(0-fluorophenyl)- 4H, 11 H-[1,2,4]triazolo [1,5-α] [1,4]benzodiazepine}-2-carboxamide ( 6a ), the syn-thesis of which is described, leads to the cyclic adduct N, N-dimethyl-{2,12,12-trichloro-13a-(0-fluorophenyl)-11-oxo-10,11,12,13a-tetrahydro-5H, 9H-[1,3]oxazolo [3,2-d] [1,2,4]triazolo [1,5-a] [1,4]benzodiazepine}-7-carboxamide ( 7a ). Upon thermolysis 7a is partly reconverted to the starting diazepine 6a via loss of the elements of oxalyl chloride. Reduction of 7a with sodium borohydride also yields 6a in addition to its dihydro derivative 9 . Energetic treatment of 7a with sodium methoxide leads to the unexpected methoxydiazepines 10a and 10b , and mild treatment of 7a with sodium methoxide to the stereoselective formation of the two precursors of 10 , namely the chloromethoxy derivative 11 and the dimethoxy derivative 12 . Epimerization of 11 followed by nucleophilic substitution gives a mixture of two dimethoxy compounds, 12 and its epimer 14 . The configurational assignments of these derivatives are based upon X-ray analysis of 12 . A possible pathway for this unexpected substitution reaction is proposed.     

Synthese,Struktur und Reaktivität der Erdalkalihydrogensulfate des Mg,Ca, Sr und Ba

Synthesis, Structure, and Reactivity of the Alkaline Earth Hydrogen Sulfates of Mg, Ca, Sr, and Ba The pure compounds of Ba(HSO₄)₂, Sr(HSO₄)₂ and Mg(HSO₄)₂ were prepared and identified as real hydrogensulfates. In contact with moist air Mg(HSO₄)₂ forms the monohydrate Mg(HSO₄)₂ · H₂O which can be dehydrated into Mg(HSO₄)₂ at about 120°C. The hydration of Mg(HSO₄)₂ proceeds crystallographically oriented. The unit cell parameters and the d-values of the new compounds were determined. Ba(HSO₄)₂ and Sr(HSO₄)₂ cristallize orthorhombic, Mg(HSO₄)₂ monoclinic and Mg(HSO₄)₂ · H₂O triclinic. Sr(HSO₄)₂ is isotypic in regard to Ca(HSO₄)₂. The relationship between the crystal structures and the chemical properties of the earth alkaline sulfates are discussed.     

Synthese und ungewöhnliche Reaktivität eines Cyclotrisilans

Reductive coupling of dichlorosilane 1 with magnesium yields the stable, highly moisture sensitive cyclotrisilane 2a. The hydrolysis products, 1,3-siloxanediol 3 and disilane 4 corroborate the proposed structure of 2a. The reaction with typical silylene trapping agents like benzyl, benzophenone or 2,2′-bipyridyl results in cleavage of all three endocyclic bonds of 2a, yielding the formal silylene addition products 8, 9 and 10.