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Interaction of dialkyl disulfides with C-N,N-dimethylaminomethylene-P-phenylphosphine 1a results in the complete cleavage of the P=C double bond and formation of S,S-dialkylphenyldithiophosphonites. Ethyl sulfenylchlorides undergoes dehydrochlorination by 1a, while phenyl sulfenylchloride cleaves the P=C bond in C-N,N-dialkylaminosubstituted phosphaalkenes with the predominant formation of either PhP(SPh)2 6 or PhP(SPh)CI 7 depending on the phosphaalkene used and reaction conditions.

Vibrational spectra of (CH3O)nSbCl5-n. n = 1: 1; n = 2: 2: n = 3: 3: n = 4: 4; n = 5: 5; have been recorded. According to ir and Raman data 1-5 are centrosymmetrical bridged dimers. The Raman spectra of 3-5 exhibit v(Sb-O) doublets of terminal CH3O at 530-541 and 550-570 cm-1; vibrations of the 4-membered Sb2O2 ring, observed in the 500-517 cm-1 region of the ir spectra of 1-5, are absent. The v(C-O) bands of bridged and terminal CH3O are shifted to higher wave numbers (60 and 31 cm-1, respectively) in the series 1 → 5. The stability of the dimers increases in the series 1 < 2 < 3 < 4 << 5. At 100-120°C and in CH3CN solutions dimers of 1-3 dissociate to monomers (v(Sb-O) 537-540 cm-1, ir data). The monochloride, 4, is partially dissociated in CH3CN. On solution of the tetrachloride, 1, in benzene a dimer-monomer equilibrium has been observed, with the dimeric form being predominant.

The structure of dimers [Cl5-nSb(OCH3)n]2 with n = 1-5 and their polyhedral stereoisomery have been studied on the basis of 1H nmr data. It has been shown that in the case of n = 1 only one nondegenerate dimeric structure and with n = 5 only a single 25-fold degenerated structure formed by two tetragonal bipyramids are formed. The complicated spectra of compounds with n = 2, 3 and 4 may be explained as a superposition of resonance lines from different isomeric structures. In these structures the tetragonal-bipyramidal moieties have OCH3 groups at different apical and equatorial positions. Solvent effects and temperature dependencies of spectra are discussed qualitatively.

A new type of phosphorotropic tautomerism for a series of five membered monocyclic phosphoranes with an acyl group in position 4 (1a, 4a-c, 5a-c, 6a, 7a) has been discovered and studied. An equilibrium of two tautomeric forms with a pentacoordinated phosphorus atom (Schemes 2, 3, 4) is likely to occur via an intermediate acylic zwitterion. The values of chemical shifts 31P for the compounds studied have been shown to be unchanged in the range of temperatures from 203 K to 383 K. Activation parameters of the tautomeric rearrangement have been determined by means of NMR (1H and 13C) spectroscopy. The proposed schemes of the tautomeric processes have been confirmed by a comparison of the temperature changes in the 13C- and 31P-NMR spectra of phosphoranes 6a, 7a and related bipolar ions 6b and 7b.

The crystal and molecular structure of 2-[1',2';3',4'-bis-O-(N-dimethylamidothionophosphate)-D-arabinotetraoxybutyl]quinoxaline, C16H21N4P2S2O4, and its absolute configuration have been determined by an X-ray study. One of the dioxaphospholane rings has an envelope conformation, the other is in a twist conformation. The quinoxaline ring is planar.

The crystal and molecular structure of 2-0-[bis(diethylamido)thionophosphate]-3,4-0,0-(diethylamidothionophosphate)-1,6-anhydro-β-D-glucopyranose, C18H37N3P2O5S2, and its absolute configuration have been determined by an X-ray study. The pyranose ring has a twist-boat conformation; both five-membered rings are in a twisted envelope conformation. A considerable dispersion of the C-C bond lengths in the pyranose ring can be attributed to its strong conformational distortion.

Structures, energies, and electronic properties of H2PCH=CHBH2 (1) have been studied with ab initio molecular orbital theory by using STO-3G and 3-21G (d(P)) basis sets. The Z-1 isomer with the perpendicular arrangement of BH2 group is less stable than Z-1 and E-1 ones with the planar orientation of BH2 group. The short P-B contact of the former is obtained only at STO-3G level. It's bond critical point data, binding energy, localized molecular orbital suggest the presence of weak covalent bonding between the phosphorus and boron atom.

In the course of the last 20 years the λ3σ2- and λ3σ2As-Chemistry has progressed rapidly. Compounds, containing λ3P- and σ3As-(p-p)π-bonds, considered before to be unstable have become the basis of a new and extremely interesting branch of chemistry. Cycloadditions to the P=C and As=C-bonds are developing rapidly at the present time. Many new types of compounds have been obtained and many rearrangements have been discovered, which are presented and discussed in this compilation.Die Chemie der λ3σ2-Phosphor und λ3σ2-Arsen-Verbindungen befindet sich seit etwa 20 Jahren in stürmischer Entwicklung. Verbindungen dieser Elemente mit pπ-pπ-Mehrfachbindungen, die früher als unbeständig galten, können isoliert und untersucht werden. Zur Zeit stehen Cycloadditionen an die Mehrfachbindungen im Vordergrund des Interesses. Neue Verbindungstypen wurden erhalten und zahlreiche Umlagerungen und Folgereaktionen beobachtet, deren Besonderheiten in der vorliegenden übersicht behandelt werden.

The 13C and dynamic 1H NMR spectroscopy were employed to derive spectral tests for conformational studies of eight-membered phosphorus (PIII and PIV) containing heterocycles: 4,5; 7,8-dibenzo-(I) and dinaphto-(II) 1,3,2-dioxaphosphocines. Passing from series (I) to (II) causes a dramatic change in the shift difference of methylene protons at C-6. The geminal 2J(HH) and long-range 5J(PH) spin-spin couplings are determined by the ring structure. The latter is also influenced by the phosphorus valence state and the orientation of substituents at phosphorus. Fairly definite stereo-chemical assignments can be made using the nJ(31P13C) couplings with n of 2 to 5.

The dipole moments and polarizability ellipsoids of phosphorus-containing bonds in 2,6,7-trimethyl-4-methyl-2,6,7-triaza-1-phosphaicyclo[2.2.2]octane (3) and its 1-oxide (4) and 1-sulfide (5) and in 2-dimethylamino-1,3,2-dioxaphosphorinane (2) have been determined from dipole moment, Kerr effect and depolarization of Rayleigh scattering measurements. The conformational rigidity of bicyclic compounds such as (3-5) as well as of several 2-oxo-2R-4,6-dimethyl-1,3,2-dioxaphosphorinanes are utilized in considering the implications of assuming that the component moments are primarily directed along the phosphoryl bond.

Unlike of the Cu(II) catalysed thermal decomposition of 2-diazo-I,3-dicarbonyl compounds(I) in dialkyl phosphites that results in the formation of 2-phosphono-I,3-dicarbonyl compounds (II,X_C)I, the photosensitized process affords also thiophosphono analogs of the latter (II,X_S) while carried out in dialkyl thio-phosphites. Since there are no P-H insertion products(II) formed on the direct photolysis of I it seems reasonable to suggest that it is the triplet carbene as intermediate that is needed for their formation. Yields of II, which proved to be rather photosensitive, are found to depend substantially on the reaction time. The tendency of II to enolization deecreases with replacement of P-O for P-S group.

The effect of the nature of planar fragments and substituents located at tri- and tetracoordinated phosphorus atom the conformational behavior of 8-membered cyclic systems are established. 4,5,7,8-Dibenzo- and dinaphto-1,3,2-dioxaphophocines with variable exocyclic substituents are considered by means of different physical methods (dynamic NMR spectroscopy 1H, 13C, 31P, dipole moment, Kerr effect). The classification and quantitative description of the conformations (ring atoms coordinates, Cremer-Pople parameters and torsion angles) was carried out using the Cremer-Pople and Palyulin-Zefirov approach. In this way the following set of four canonical conformations of 8-membered rings with two planar fragments is defined: boat-chair (BC), boat-boat (BB), boat (B) and twist-boat (TB). A tendency toward the equilibrium existence of BC and/or BC and B-forms is found for 4,5,7,8-dibenzo-derivatives and of B-forms for its 4,5,7,8-dinaphto-analogues.