Group 15 elements diphosphines

An alternative preparative route to R2QER acid esters (Q = P, As, Sb, Bi E = S, Se, Te) of interest due to its generally applicability to all the heavier group 15 and 16 elements, is the dismutation reaction between diorganodichalco-genides and tetraorgano-diphosphines, -diarsines, -distibines or -dibismuthines (Equation 17).2... 

As mentioned in Section IV.C, the replacement of boron by its heavier congeners aluminium and gallium markedly affects the coordination behavior of the DPE ligands (E = group 13 element) toward AuCl. In particular, the zwitterionic and neutral forms of the diphosphine-gallane complex 103 were shown to coexist and interconvert in solution.27... 

Termination for names of neutral saturated hydrides of boron and elements of Groups 14 [IVA), 15 [VA), and 16 [VIA] diphosphane [= P2H4, v diphosphine] J... 

The same method was applied to u-difluorobenzene tricarbonylchromium with the aim of obtaining or / o-substituted monophosphines and diphosphines (Scheme 5.10). The first nucleophilic attack provided the desired mono-substituted compound (20) in 97% yield, but no traces of diphosphine borane could be detected, even using excess of phosphide borane. Compound 20 possesses a second stereogenic element (a plane) and it was found to be present as a mixture of separable diastereomers in 60% de. When this compound was reacted with MeMgBr it was found that the large steric hindrance of the phosphine borane group inhibited the second nucleophilic attack and therefore the deprotection of the phosphine was required (Scheme 5.10). 

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