Molybdenum complexes bidentate phosphines

Simple chiral phosphines have already been mentioned (Section 3.1.3) and the macrocycle enantiomers are discussed below (Section 4.6). Current research in this area is concentrated on bidentate chiral phosphines, such as the ligands (24)-(27). Although their transition metal complexes are normally used for stereospecific synthesis, Whitmire and coworkers used the molybdenum complexes to resolve their racemic bisphosphines via flash chromatography. The phosphines were decomplexed by reductive cleavage at low temperatures (-78 °C) using sodium naphthalenide (Scheme 1). 

The unsymmetrical Mo=Mo (2.235 A) complex [Mo2(OPr )4(CH2Ph)2(PMe3)] has one molybdenum bonded to benzyl gronps and one PMe3 ligand.2" 6.247 With the bidentate phosphine (Me2P)2CH2 (dmpm) the symmetrical dimer... 

Fig. 6 Molybdenum and tungsten complexes featuring metallocene-derived bidentate phosphine ligands, which form NH3 on protonolysis. ...

Hidai and Chatt thoroughly studied the reactivity of molybdenum and tungsten dinitrogen complexes with various phosphine hgands such as the bidentate derivatives dppe (where dppe = Ph2PCH2CH2PPh2) or depe (where depe =Et2PCH2CH2PEt2) for synthetic dinitrogen fixation. 

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