Bidentate diphosphines dppm

Coordination of an additional metallic fragment to a free donor atom of a bidentate diphosphine, dppm [172, 175], (PPh2)2C=CH2 (vinylidenebis(diphenylpho-... 

Bidentate diphosphines, such as bis(diphenylphosphino)methane (dppm) [242— 244], l,2-bis(diphenylphosphino)ethane (dppe) [245], l,2-bis(hydroxymethylpho-sphinojethane (hmpe) [246], l,2-bis(dicydohexyphosphine)ethane (dcype) [247] or bis(diphenylphosphino)isopropane (dppip) [248] build structures of stoichiometry [Au2(P P)2]2+ such as those shown in Figure 2.45. The crystal structure of [Au2(dmpe)2]X2-nH20 (dmpe = l,2-bis(dimethylphosphino)ethane X = Cl, n = 2 Br, = 1.5) consist of polymeric chains anion/water molecule/cation/anion/cat-ion/anion/water molecule [249]. 

Rather different products result from the use of diphosphines, for example dppe requires two equivalents of peroxide dimer and yields the asymmetric dimer ( BU2Ga) ()l-OBu ) ( i-OOBu ) (GaBu2 ) and dppe02. In contrast, dppm yields not the phosphine oxide but (46), in which deprotonated dppm02 acts as a bidentate ligand analogous to a p-diketonate. 

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