Diphosphine, tetramethyl

P2S2C4Hi2, Diphosphine, tetramethyl-, disulfide, hazards in preparation of, 23 199 PjS4ZnC7 H60, Zincate(U), tet-rakis(benzenethiolato)-, bis(tetraphenylphosphonium), 21 25 P OujThW, Thorate(lV),... 

The crystal structures of a number of diphosphine disulphides (121) and (122) show a remarkable constancy in the bond lengths. Two types of molecule are observed in the crystal of the tetramethyl compound (121, X = Y = Me). The crystal structure of triphenylphosphine oxide (P—C 176 pm, P—O 164 pm) varies little from that observed in the uranium oxide complexes, and does not confirm P—O bond lengthening in complexes, as indicated by vp=.o (see Section 3C). 

Miscellaneous. Nucleophilic attack of dimethylphosphine (or tetramethyl-diphosphine) occurs at the terminal olefinic carbon of hexafluoropropene to give a mixture of cis- and trani -dimethylpentafluoropropenylphosphines (66) in proportions which depend on the reaction conditions.66 The products do not arise by dehydro-fluorination of a 1 1 adduct. 

A further illustration has appeared28 of the reactivity of simple a-keto-alkyldi-phenylphosphine oxides (31) towards addition reactions, as outlined in Scheme 5. In the same paper, alkylation of chloro(di-t-butyl)phosphine (32) by alkyl benzoates is described 28 see Chapter 3 for details. A similar acylation reaction of tetramethyl-diphosphine disulphide (33) has been described, although the acetylphosphine sulphide (34) was not isolated.29... 

More recently, examination of the cycloisomerization of l,l,2,2-tetramethyl-l,2-divinyldisilane 130 in the presence of a ruthenium-diphosphine complex <2005JOM3451>, ruthenium-DPPE, revealed a selective catalysis and l,l,2,3,3-pentamethyl-l,3-disilacyclopent-4-ene 132 was isolated as the major product, in addition to 131 (DPPE = bis(diphenylphosphino)ethane Equation 22). 

The drying of impure ethers can produce a violent explosion. Further information about this hazard may be found in Inorganic Syntheses, Volume 12, p. 317. A hazard associated with the synthesis of tetramethyl-diphosphine disulfide [ Inorg. Synth., 15, 186 (1974)] is cited in Inorganic Syntheses, Volume 23, p. 199. 

Fig. 9.2. Newman projections of major calculated conformations (X-ray data for 5). a 1,1,2,2-tetramethyl ethane and disilane relation sc to p = 2 1 b 1,1,2,2-tetra-rert-butyl ethane and disilane c 1,1,2,2-tetra-cyclohexyl ethane, disilane and diphosphine...

This reaction has been modified by the activation of the ortho-hcnzylic proton with ruthenium complexing to tetramethyl ethylene diphosphine. In addition, the o-alkynyl phenylisocyanide has been converted into indolene or indole derivatives via radical initiated cyclization. ... 

Diphosphines and diarsines are readily oxidized in air, the tetramethyl compounds being spontaneously inflammable. The P—P or As—As bond is readily cleaved by a variety of reagents. Some of these reactions are exemplified by tetraphenyldiarsine. 

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