Dimethylerdmetall‐Heterocyclen als Derivate trimethylsilylierter, ‐germylierter und ‐stannylierter Phosphane und Arsane – Synthesen,Spektren und Strukturen

Dimethyl Earth‐Metal Heterocycles – Derivatives of Trimethyl‐silylated, ‐germylated, and ‐stannylated Phosphanes and Arsanes – Syntheses, Spectra, and Structures The organo earth‐metal heterocycles [Me₂M^III–E(M^IVMe₃)₂]_n with M^III = Al, Ga, In; E = P, As; M^IV = Si, Ge, Sn and n = 2, 3 (Me = CH₃) have been prepared from the dimethyl metal compounds Me₂M^IIIX (X = Me, H, Cl, OMe, OPh) and the pnicogen derivatives H_nE(M^IVMe₃)_3–n (n = 0, 1) according to known preparation methods. The mass, ¹H, ¹³C, ³¹P, ²⁹Si, ¹¹⁹Sn nmr, as well as the ir and Raman spectra have been discussed comparatively; selected representatives are characterized by X‐ray structure analyses. The dimeric species with four‐membered (E–M^III)₂ rings are isotypic and crystallize in the triclinic space group P1, the trimer [Me₂In–P(SnMe₃)₂]₃ with a strongly puckered (In–P)₃‐ring skeleton crystallizes with two formula units per cell in the same centrosymmetric triclinic space group.     

β-SrNH und β-SrND – Synthese und Kristallstrukturbestimmung mittels Röntgen- und Neutronenbeugung an Pulvern

β-SrNH and β-SrND – Synthesis and Crystal Structure Determination by X-Ray and Neutron Powder Diffraction By reaction of strontium with NH₃ in a flow tube at 750 °C a novel modification of strontium imide, β-SrNH, was obtained as a dark yellow powder. According to X-ray powder diffractometry und crystal structure determination by direct methods β-SrNH and β-SrND adopt a highly distorted variant of the NaCl type of structure (Pnma, a = 757.70(1), b = 392.260(4), c = 569.652(9) pm, Z = 4, wR_p = 0.098, R_p = 0.075, R_F = 0.044). Temperature dependent neutron powder diffraction of β-SrND revealed the position of the D atoms which in contrast to α-SrND are crystallographically ordered. At higher temperatures β-SrNH transforms to α-SrNH.     

Synthese und Charakterisierung von 2‐O‐funktionalisierten Ethylrhodoximen und ‐cobaloximen

Synthesis and Characterization of 2‐O‐Functionalized Ethylrhodoximes and ‐cobaloximes 2‐Hydroxyethylrhodoxime and ‐cobaloxime complexes L—[M]—CH₂CH₂OH (M = Rh, L = PPh₃, 1 ; M = Co, L = py, 2 ; abbr.: L—[M] = [M(dmgH)₂L] (dmgH₂ = dimethylglyoxime, L = axial base) were obtained by reaction of L—[M]^— (prepared by reduction of L—[M]—Cl with NaBH₄ in methanolic KOH) with BrCH₂CH₂OH. H₂O—[Rh]^—, prepared by reduction of H[RhCl₂(dmgH)₂] with NaBH₄ in methanolic KOH, reacted with BrCH₂CH₂OH followed by addition of pyridine yielding py—[Rh]—CH₂CH₂OH ( 3 ). Complexes 1 and 3 were found to react with (Me₃Si)₂NH forming 2‐(trimethylsilyloxy)ethylrhodoximes L—[Rh]—CH₂CH₂OSiMe₃ (L = PPh₃, 4 ; L = py, 5 ). Treatment of complex 1 with acetic anhydride resulted in formation of the 2‐(acet oxy)ethyl complex Ph₃P—[Rh]—CH₂CH₂OAc ( 6 ). All complexes 1 — 6 were isolated in good yields (55—71 %). Their identities were confirmed by NMR spectroscopic investigations ( 1 — 6 : ¹H, ¹³C; 1 , 4 , 6 : ³¹P) and for [Rh(CH₂CH₂OH)(dmgH)₂(PPh₃)]·CHCl₃·1/2H₂O ( 1 ·CHCl₃·1/2H₂O) and py—[Rh]—CH₂CH₂OSiMe₃ ( 5 ) by X‐ray diffraction analyses, too. In both molecules the rhodium atoms are distorted octahedrally coordinated with triphenylphosphine and the organo ligands (CH₂CH₂OH and CH₂CH₂OSiMe₃, respectively) in mutual trans position. Solutions of 1 in dmf decomposed within several weeks yielding a hydroxyrhodoxime complex “Ph₃P—[Rh]—OH”. X‐ray diffraction analysis exhibited that crystals of this complex have the composition [{Rh(dmg)(dmgH) (H₂O)(PPh₃)}₂]·4dmf ( 7 ) consisting of centrosymmetrical dimers. The rhodium atom is distorted octahedrally coordinated. Axial ligands are PPh₃ and H₂O. One of the two dimethylglyoximato ligands is doubly deprotonated. Thus, only one intramolecular O—H···O hydrogen bridge (O···O 2.447(9)Å) is formed in the equatorial plane. The other two oxygen atoms of dmgH^— and dmg^2—, respectively, act as hydrogen acceptors each forming a strong (intermolecular) O···H′—O′ hydrogen bridge to the H′₂O′ ligand of the other molecule (O···O′ 2.58(2)/2.57(2)Å).     

Poly- und spirocyclische Silylhydrazone – Synthese und Molekülstrukturen

Poly- and Spirocyclic Silylhydrazones — Synthesis and Molecular Structures Bulky aminotrifluorosilanes react with lithiated dimethylketone-hydrazone to give 1,2-diaza-3-sila-5-cyclopentenes — DSCP — ( 1, 2 ). The 4-silylated ( 3–5, 8–15 ) and siloxysilyl-substituted ( 17, 18 ) rings eliminate no halosilane or siloxane thermally. Lithiated 2 dimerises with LiF elimination to give the (2+2)cycloadduct of a 1,2-diaza-3-sila-3,5-cyclopentadiene ( 6 ). Lithiated DSCP reacts with MeSiF₂N(CMe₃)SiMe₂CMe₃ via a nucleophilic 1,3-methanide ion migration to form LiF and the spirocyclic compound 18 . A compound with spirocyclic silicon ( 21 ) is formed in the reaction of bis(1,2-diaza-3-sila-5-cyclopenten-4-yl)difluorosilane ( 19 ) and the lithium salt of dimethyl-ketone-tert-butylhydrazone. The crystal structures of 6 and 21 are reported.     

Synthese und Kristallstrukturen von 1,1,3,3‐Tetramethylimidazolinium‐dichlorid und 1,1,4‐Trimethylpiperazinium‐chlorid

Synthesis and Crystal Structures of 1,1,3,3‐Tetramethylimidazolinium Dichloride and 1,1,4‐Trimethylpiperazinium Chloride Single crystals of 1,1,3,3‐tetramethylimidazolinium dichloride ( 1 ) and 1,1,4‐trimethylpiperazinium chloride ( 2 ) were obtained by reaction of CH₂Cl₂ with tetramethylethylenediamine (TMEDA) and NNN′N″N″‐pentamethyldiethylenetriamine (PMDETA), respectively. Both compounds are characterized by single crystal X‐ray diffraction and by IR spectroscopy. 1: [C₇H₁₈N₂]Cl₂, space group P2₁/c, Z = 4, lattice dimensions at 193(2) K: a = 821.97(11), b = 1130.38(8), c = 1143.08(13) pm, β = 100.348(15)°, R₁ = 0.0271. The C₇N₂ heterocyclic ring has envelope conformation like other salts with this dication. 2: [C₇H₁₇N₂]Cl, space group P2₁2₁2₁, Z = 4, lattice dimensions at 100(2) K: a = 1030.37(8), b = 1036.55(6), c = 831.39(4) pm, R₁ = 0.0180. Although the heterocyclic mono‐cation is without site symmetry in the crystal, its molecular symmetry is close to C_s, forming chair conformation of the C₄N₂ six‐membered ring.     

Homo- und heteroleptische Zinkarsanide — Synthese und Struktur

Homo- and Heteroleptic Zinc Arsanides — Syntheses and Structure Bis(trimethylsilyl)arsane reacts with dialkylzinc ZnR₂ (R = Me, Et, CH₂SiMe₃) in the stoichiometric ratio of 1 : 1 in hydrocarbons to the heteroleptic alkyl zink bis(trimethylsilyl)arsanides. The steric demand of the alkyl substituent enforces the oligomerisation degree of two or three. Diethylzinc and two equivalents of HAs(SiMe₃)₂ yield dimeric zinc bis[bis(trimethylsilyl)arsanide]. Methyl zinc bis(trimethylsilyl)arsanide crystallizes as a trimer with a six-membered Zn₃As₃-cycle in the twist-boat conformation {orthorhombic, P2₁2₁2₁, a = 1 015.3(1), b = 1 887.6(4), c = 2 272.9(4) pm, Z = 4}. The molecule of ethyl zinc bis(trimethylsilyl)arsanide is built similar in the solid state {monoclinic, P2₁/n, a = 1 220.2(4), b = 1 889.0(6), c = 1 968.5(6) pm, β = 90.24(1)°, Z = 4}. However, zinc bis[bis(trimethylsilyl)arsanide] separates due to the steric demand of the terminal (Me₃Si)₂As-ligand as a dimer in the triclinic space group P1 {a = 967.8(2), b = 1 088.5(2), c = 1 238.1(2) pm, α = 92.41(1), β = 105.20(1), γ = 105.05(1)°, Z = 2}. The endocyclic zinc-arsenic distances vary only slightly around 248 pm, but the exocyclic one is with a value of 238 pm drastically shorter. The Zn? C bond lengths with values around 197 pm lie in the characteristic region for zinc with the coordination number of three.     

Γ-Lakton-cis-anellierung an Δ2- und Δ3- Cholesten

γ-Lactone-cis-annulation to Δ²- and Δ³- Cholestene. From Δ²- and Δ³- cholestene the γ-lactones 11a , 11b , 12a , and 12b are synthesized through the dibromocarbene adducts 3 and 4 , the bromohydrines 5 and 6 , the oxapiropentanes 7 and 8 , and the cyclobutanones 9a , 9b and 10a , 10b , respectively. The ¹³C-NMR.-spectra of 1–8 and 11 as well as the ORD.-spectra of the cyclobutanones 9 and 10 are reported.     

Aminocarbonylthioformiate – Darstellung und Reaktionen

Aminocarbonylthioformates — Preparation and Reactivity Sodium aminocarbonylthioformate NaSCOCONH₂ (II) is obtained by reaction of sodium cyanodithioformate with acetone in presence of a secondary amine and water. II permits to produce the acid HSCOCONH₂ · H₂O (IX) and salts M^II(SCOCONH₂)₂ · 2H₂O. In basic aqueous solutions hydrolysis of II to oxaminate and oxalate, respectively, takes place, an excess of aqueous ammonia leads to amidino formic acid. In organic solvents the reaction of IX with N-bases yields stable ammonium salts. The results of i.r. spectroscopic and thermogravimetric measurements are discussed.     

Cyanohydrazonothioformiate – Darstellung und Reaktionen

Cyanohydrazonothioformate — Preparation and Reactions Sodiumcyanohydrazonothioformate-monohydrate NaSC(CN)NNH₂ · H₂O is obtained by reaction of sodiumcyanodithioformate with hydrazine. The new compound forms S-organosubstituted derivatives. Reaction with bivalent metal cations lead to coordination compounds M^II(SC(CN)NNH₂)₂ · 2H₂O, which subjected the facile reaction with carbonyl compounds yield alkylidenehydrazonocyanothioformates M^II(SC(CN)NNCRR¹)₂. The results of i.r. spectroscopic and thermogravimetric measurements are reported.