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A new way of M−Cl bond activation (M = Si, P, Au fragments) is reported. It consists on the 1,2-addition of M−Cl containing species on the Zr−N bond of azazirconaindene complexes. Unprecedented imino gold complexes incorporating two electron-deficient metallic centers (Au, Zr) have been prepared.

The reaction of bis(phosphinoyl) diselenides R1R2P(O)Se–SeP(O)R1R21 with P(III) compounds has been investigated and its mechanistic features have been elucidated by variable temperature 31P NMR spectroscopy. These studies show that in most cases phosphonium intermediates 7, 13 and 10, 16 are involved. In the case when ligands on P(III) increase the stability of the five-coordinate structure, a phosphorane intermediate is observed. In the isomerization 7→10 and 13→16 the pathway of decomposition (deselenization, deoxygenation or dealkylation) to give stable end products is influenced by electronic and steric factors.

A series of new unstable tris(bidentate) hexacoordinated phosphorus compounds 1 with 1,3,2-dioxaphosphorinane rings was prepared and studied by NMR and X-ray crystallography. The X-ray crystal structures showed that the 1,3,2-dioxaphosphorinane ring adopts different conformations depending on the number and size of substituents at the carbon atom C14. Substituents are deployed around the phosphorus atom in a slightly deformed octahedral structure. Deviations in bond lengths around the phosphorus atom depend on the character of the bonds and the distribution of the negative charge. (1)H and (13)C NMR measurements showed that in solution the flexibility of 1,3,2-dioxaphosphorinane ring depends on the size of substituents at the carbon C14.

Selective reductions of PO, PS, >CC

Reaction between oxophosphoranesulfenyl chloride 1(R = R′= EtO) and o-phenylene neopentyl phosphite 4 takes predominantly the deoxygenation course, yielding the phosphorochloridothioate 7 and the phosphate 8. Formation of minor products 5 and 6 corresponding to the desulfurization pathway, and low-temperature 31P NMR observations, are rationalized by proposing phosphoranephosphonium equilibria which are shifted towards phosphorane structures 9, 13, 11. These results supplement our earlier studies on desulfurization and deoxygenation of compound 1 with tricoordinate phosphorus compounds and add new evidence for phosphonium–phosphorane equilibria.

Thioxaphosphoranesulfenyl bromide 1 reacts with various aliphatic alkenes to give the corresponding adducts 3. These species can be reacted with tetrabutylammonium fluoride trihydrate (TBAF·3H2O) at room temperature to give the episulfides 4 in satisfactory yield. The great affinity of fluoride to phosphorus is claimed to be the driving force in the formation of the s-bromo thiolate ion 6 which gives ring closure.

Selective reductions of PO, PS, >CC

A series of new unstable tris(bidentate) hexacoordinated phosphorus compounds 1 with 1,3,2-dioxaphosphorinane rings was prepared and studied by NMR and X-ray crystallography. The X-ray crystal stru...

The reaction of oxophosphoranesulfenyl chlorides RR'P(O)SCl 2 with P III compounds has been investigated. Its mechanistic features have been elucidated by variable-temperature 31 P NMR spectroscopy and stereochemical changes at P IV and P III phosphorus centers. These studies show that in all cases phosphonium intermediates containing the sulfur bridge>P(O)-S-P

The interaction of 1,2-aIkadienephosphonic derivatives with phosphorus containing pseudohalogenes affords 2,5-dihydro-1,2-oxaphospholene derivatives. The structure of the new compounds is determined by NMR and IR spectroscopy.

The zirconaindane phospholane 3 reacts either with PhSbCl 2 or Me 2 SnCl 2 to give tricyclic systems incorporating phosphorus, antimony or tin; the same reaction involving 3 and R 2 PCl (R = Ph, Et) leads to acyclic–cyclic diphosphanes.

The reaction of acyclic oxophosphoranesulphenyl chlorides, with phosphorus trichloride has been found to give thiophosphoryl chlorides, and phosphoryl oxychloride—the products of the exclusive deoxygenation of sulphenyl chloride. Optically active phosphonochloridothionates and phosphorochloridothionates in a high state of optical purity have been obtained with inversion of configuration from optically active sulphenyl chlorides and phosphorus trichloride. It has been shown, however, that cyclic oxophosphoranesulphenyl chlorides undergo simultaneous desulphurisation and deoxygenation when treated with phosphorus trichloride. Using cis- and trans-isomers of 2-chlorothio-4-methyl-1,3,2-dioxaphosphorinan-2-one it has been demonstrated that deoxygenation is accompanied by inversion, whereas desulphurisation occurs with retention at phosphorus. The mechanism of the title reaction is discussed.

Efficient, general synthesis of oxophosphoranesulphenyl chlorides ABP(O)SCl 2 based on the reaction of phosphorus trimethylsilylthionoesters ABP(S)OSiMe3 7 with chlorinating agents is described.

The reaction of the individual diastereoisomeric cyclic phosphorothioates 2a , 2b in the trans-2,4,7-trioxa-3-phosphabicyclo (4.4.0) decane and 4a , 4b in the trans-2,4,7-trioxa-3-phosphabicyclo (4.3.0) nonane series with sulphuryl chloride affords the corresponding sulphenyl chlorides 5a , 5b , 6a , 6b with retention of the configuration of the phosphorus atom. The reaction of the latter with phosphorus trichloride leads stereospecifically to the chlorophosphates 7a , 7b , 8a and 8b with full retention of configuration at phosphorus.

The selectivity of sulphur, selenium and oxygen removal from pseudohalogens: phosphorus disulphides 1 and 2, diselenides 3 and oxophosphoranesulphenyl chlorides 4 has been investigated. A mechanistic rationalization is proposed to account for sulphur (selenium)/oxygen extrusion variation as a function of substrates structure and reaction conditions.

Synthesis and stereochemistry of several new six-coordinate organophosphorus compounds are discussed.

The results of stereochemical and product studies on the chlorination of phosphorus thionesters are rationalized in terms of phosphonium and five-co-ordinate intermediates which in the case of thionophos-phonates and cyclic five-membered thionophosphates undergo nucleophilic ligand exchange.xs

Direct evidence by 31P-n.m.r. spectroscopy is presented for the formation of a five-co-ordinate intermediate in the Arbuzov reaction of tervalent phosphorus esters with elemental chlorine or elemental bromine and benzenesulphenyl chloride.

The ratio of desulphurisation to deoxygenation of oxophosphoranesulphenyl chlorides, >P(O)SCI, by trivalent phosphorus compounds depends on the nature of the PIII compounds and is accompanied by inversion of configuration at the chiral phosphorus atom of the sulphenyl chloride.

Monocyclic chlorophosphoranes 1 and 2 have been used as models for investigations of nucleophilic displacement reactions at the pentacoordinate phosphorus atom. The chlorine ligands of 1 and 2 can be exchanged by nucleophiles under very mild conditions. The synthesis of the pentacoordinate phosphorus systems 4 and 5 via the reactions of 1 and 2 with a variety of nucleophiles is demonstrated. Special attention is paid to the reactions of chlorophosphoranes with such nucleophiles as organic phosphorus acids and thiocyanates.

Synthesis and stereochemistry of several new six-coordinate organophosphorus compounds are discussed.

Direct evidence by 31P-n.m.r. spectroscopy is presented for the formation of a five-co-ordinate intermediate in the Arbuzov reaction of tervalent phosphorus esters with elemental chlorine or elemental bromine and benzenesulphenyl chloride.

Cyclic phosphorus esters and amides in the 1,3,2-dioxaphosphorinane-2-one series are usually obtained by the condensation of a diol with a suitable phosphorus oxyhalide. In the case of dissymetric diols the formation of two diastereoisomeric products, epimeric at phosphorus, can be expected. This procedure failed or proceeded with low yields when applied to the preparation of cyclic phosphates which would lead to the formation of sterically strained dioxaphosphorinane ring.1

Our recent work on ligand exchange in chlorophosphonium salts and chloro-phosphoranes as well as on the reactions of phosphorus pseudohalogens with PIII compounds resulted in the novel methods for the synthesis of various phosphorus and carboxylic acids anhydrides.