Phosphanes, primary clusters

Reviews covering the chemistry of group 2 metal complexes with phosphorus-stabilized carbanions,279 and of molecular clusters of magnesium dimetallated primary phosphanes, are available.2 u Magnesium phosphanes remain rare compounds.281 Lithiation of bromide 98 with BuLi in the presence of tmeda in pentane produces a lithium phosphine dimer subsequent treatment with MgCl2 in EtzO gives the phosphane 99 in 69% overall yield (Equation (19)). The centrosymmetric 99 has Mg-C = 2.217 A Mg-P = 2.77 A (av.).282... 

Molecular Clusters of Dimetalated Primary Phosphanes and Arsanes Matthias Driess... 

MOLECULAR CLUSTERS OF DIMETALATED PRIMARY PHOSPHANES AND ARSANES... 

Dilithiated primary phosphanes could only be isolated in a reproducible crystalline form if the lithiation of the phosphane with BuLi (ratio of 1 2) in toluene was carried out in the presence of a trace amount of LiOH (3). This is evident by the respective transformation of the silylphosphanes 1, which furnished, depending on the steric demand of the silyl group, a dodecameric or a octameric associate (Scheme 1). Thus, reaction of la with BuLi in the molar ratio of 1 2 led to the globular, Li20-filled cluster 5a, whereas metalation of the bulkier substituted phosphane lb gave the Li20-filled octamer 5b. 

Reaction of the primary phosphane Bu3SiPH2 If with MgBu2 furnishes the solvent-free hexameric cluster 17 (Eq. 10) (47). Yellow crystals, have been isolated in 39% yield, which are thermochromic. The NMR spectrum, especially the 31P NMR signal at S = -263.8, suggested that the molecule prefers a high symmetry or dissociates rapidly on the NMR time scale. Since 15 is highly soluble in aromatic hydrocarbons even at low temperature and free of metal oxide, it can thus be regarded as a valuable source of phosphandiide, that is, for nucleophilic RP2 transfer reactions. 

A series of metal-rich, coin-metal containing phosphanediyl clusters (phosphandiides) with additional terminal donor ligands (i.e., triorga-nophosphanes) have been prepared only one example of a donor-free dicopper phosphandiide has been reported up to now (37, 38). Thus, the neutral cluster 16 has been prepared by the reaction of the primary phosphane la with CuOfBu in toluene at 60°C and has been isolated in 81% yield in the form of dark red crystals that are only sparingly soluble (39) ... 

M. Driess, Molecular clusters of dimetallated primary phosphanes—, Adv. Inorg. Chem., 50, 235,... 

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