Zdirad Zak

Lithium-bis(silyl)hydrazide, Tris(silyl)hydrazine und 1,2-Diaza-3,5-disilacyclopentane

Abstract Bis(trimethylsilyl) hydrazine reacts with n -BuLi in tetrahydrofuran to give a dimeric lithium derivative consisting of a N -lithium- N ′, N ′-bis(trimethylsilyl)hydrazide and a N , N ′-dilithium- N , N ′-bis(trimethylsilyl)hydrazide unit. Tris(silyl)hydrazines and 1,2-diaza-3,5-disilacyclopentanes are obtained in reactions of lithiated bis(silyl)hydrazines with halogensilanes. Reaction mechanisms and crystal structures are discussed.

Stereospecific Formation of Dinuclear Vanadium(V) Tartrato Complexes

The first dinuclear nonperoxido tartrato complexes of vanadium(V), (NMe(4))(2)[V(2)O(4)((2R,3R)-H(2)tart)(2)] x 6 H(2)O (1), (NMe(4))(2)[V(2)O(2)((2R,3R)-tart)((2S,3S)-tart)] (2), (NEt(4))(2)[V(2)O(2)((2R,3R)-tart)((2S,3S)-tart)] (3) (tart = tartrato(4-) = C(4)H(2)O(6)(4-)) have been prepared from water-ethanol medium and characterized by X-ray structure analysis and spectral methods. The formation of the complexes has been found to be stereospecific; the composition and structure of anions containing one or both enantiomers of the ligand are profoundly different. The structure of anions in 1-3 also differs significantly from the structure of other dinuclear vanadium(V) alpha-hydroxycarboxylato complexes, but, interestingly, the geometry of the [V(2)O(2)((2R,3R)-tart)((2S,3S)-tart)](2-) ion resembles the structure of the [(VO)(2)((2R,3R)-tart)((2S,3S)-tart)](4-) ion which has a vanadium(IV) center. Using Raman and (51)V NMR spectroscopy the solvent dependent mutual transformations of [V(4)O(8)((2R,3R)-tart)(2)](4-) (V(4)L(2)-RR), [V(4)O(8)((2S,3S)-tart)(2)](4-) (V(4)L(2)-SS), [V(2)O(4)((2R,3R)-H(2)tart)(2)](2-) (V(2)L(2)-RR), [V(2)O(4)((2S,3S)-H(2)tart)(2)](2-) (V(2)L(2)-SS), and [V(2)O(2)((2R,3R)-tart)((2S,3S)-tart)](2-) (V(2)L(2)-rac) have been established. In aqueous solution the following reactions take place; 2 V(2)L(2)-rac --> V(2)L(2)-RR + V(2)L(2)-SS followed by partial decomposition, V(2)L(2)-RR --> V(4)L(2)-RR + 2 L (V(2)L(2)-SS --> V(4)L(2)-SS + 2 L). On the other hand V(2)L(2)-rac is stable in CH(3)CN solution while V(2)L(2)-RR (V(2)L(2)-SS) decomposes into several species.

Taming the Oxidative Power of SeO3 in 1,4-Dioxane, Isolation of Two New Isomers of Mixed-Valence Selenium Oxides, and Two Unprecedented Cyclic Esters of Selenic Acid

The reaction of (SeO3)4 with 1,4-dioxane (diox, dioxane) with or without diluting solvent led to the isolation of the unprecedented esters of selenic acid-1,2-ethyl selenate (CH2O)2SeO2 and the glyoxal diselenate O2Se[(OCHO)2]SeO2. It was possible to isolate an unknown dimeric form of Se2O5 (Se4O10·(diox)2) and a geometrical isomer of the mixed-valence oxide trans-Se3O7, both stabilized by dioxane. The dioxane adduct of monomeric selenium trioxide SeO3·diox was obtained from the reaction of (SeO3)4 with dioxane in liquid SO2. The reaction mechanism for the formation of these compounds was elucidated, and the molecular structure of the unstable form of the selenium trioxide was determined, consisting in a trimeric arrangement (SeO3)3.

New polyheteroatomic cyclic molecules containing elements of the 13.-16. group

During studies of the reactions of ─N(H)SiMe 3 and ─N(Me)SiMe 3 derivatives of Cl 3 PNSO 2 Cl with acetonitrile and BCl 3 we have obtained six-membered polyheteroatomic cycles ⌈P(Cl 2 )NSO 2 (Cl)N(H) C(Me)N⌉ and ⌈P(Cl 2 )NS(O)(Cl)OB(Cl 2 )N(Me)⌉.1, 2 In the system Ph 2 PCl 3 , H 2 NSO 2 Cl and HN(SiMe 3 ) 2 we have identified and isolated several P─N─S cycles, e.g. the reaction of Ph 2 PCl 3 with H 2 NSO 2 Cl gives Ph 2 ClPNSO 2 Cl3 which with HN(SiMe 3 ) 2 reacts to ⌈S(O 2 )N(H)P(Ph) 2 N(H)SO 2 N(H)P(Ph) 2 N(H)⌉, ⌈S(O 2 )N(H)S(O 2 )N(H)P(Ph) 2 N(H)P(Ph) 2 N(H)⌉ and ⌈[S(O 2 )N(H) P(Ph) 2 NP(Ph) 2 N(H)]+⌉ Cl−; Ph 2 PCl 3 with HN(SiMe 3 ) 2 gives N[P(Ph) 2 N(H)SiMe 3 ] 2 + Cl−, and H 2 NSO 2 Cl with HN(SiMe 3 ) 2 leads to SO 2 (NHSiMe 3 ) 2 . The reaction of Ph 2 PCl 3 with HN(SiMe 3 ) 2 gives N(P(Ph) 2 NHSiMe 3 ) 2 Cl in a very good yield which was further used to syntheses of metal-containing heterocycles. By the reaction of N[P(Ph) 2 N(H)SiMe 3 ] 2 +Cl− with some covalent halogenides we have obtained six-membered heterocycles containing B, As, In, and Sn. The same cyclic compounds can also obtained by the reaction of N[P(Ph 2 )NH 2 ] 2 +Cl− or HN(P(R 2 )N(H)SiMe 3 ) 2 with covalent halogenides.4−6 However, the synthetic route via N[P(Ph) 2 NHSiMe 3 ] 2 +Cl− is more convenient and gives the compounds in almost quantitative yields. The identity of all compounds was unambiguously establised by their X-ray structure determination.

The reaction of P3N3Cl5NH2 with SOCl2: the crystal structures of P3N3Cl5NSO and Cl5N3P3OP3N3Cl5

Abstract Depending on reaction conditions, the reaction of P3N3Cl5NH2 with SOCl2 gives four compounds: P3N3Cl5NSO, P3N3Cl5NSNP3N3Cl5, P3N3Cl5NSCl2 and P3N3Cl5OP3N3Cl5. The reaction course and the composition of the reaction mixture can be easily monitored by 31P NMR spectroscopy. P3N3Cl5NSO and P3N3Cl5OP3N3Cl5 were isolated in the form of single crystals and their structures have been determined by X-ray structure analysis. The vibrational spectra of P3N3Cl5NSO, P3N3Cl5NSNP3N3Cl5 and P3N3Cl5NSCl2 are also briefly discussed.