Phosphite complexes of rhenium

This is, as expected, the rarest oxidation state as far as non-organometallic complexes of rhenium are concerned. The dirhenium phosphite complex Re2[P(OMe)3]10 has been prepared12,13 in low yield by several methods, viz. the potassium-potassium iodide reduction of ReOCl3(py)2 or an ReCLj-pyridine complex, followed by treatment with trimethyl phosphite. This yellow complex displays a 31P H) NMR spectrum that appears as a first order AB4 pattern, and is isoelectronic with Re2(CO)l0. It reacts with H2 upon photolysis in THF solution to produce hydridorhenium(III) and other species.13 The related triphenyl phosphite derivative Re2[P(OPh)3]l0 has been described14 as a product of the reaction between ReH3(PPh3)4 and P(OPh)3. 

The coordination chemistry of the hydrido/phosphine rhenium complexes can be extended to phosphonite and phosphite complexes. This has been demonstrated for monodentate ligands such as P(OEt)3, P(OCH2)3CEt and PPhtORE (R = Me, Et, Pri),2S8779,809,iii8 chelating phos-... 

Phosphites, in comparison with phosphines, tend to give lower oxidation state complexes [Re2 P(OR)3 io], [ReH P(OR)3 s], and [ReH3 P(OR)3 4]. Much of the chemistry of Re involves carbonyl complexes (see Rhenium Organometallic Chemistry). 

Discussions have appeared of the photochemistry of some rhenium phosphite complexes such as trans. msi. ReCl3py2[P(OEt3) ],... 

The rhenium compound 10 is rather unreactive. Carbonylation (100°C, 200 atm) gives Cp Re(CO)3, while treatment with I2 affords Cp Re(CO)2-(I)2. It does not react with ethyne, diazomethane, or phosphines under conditions where other dimetal complexes with multiple MM bonds do so (78). The manganese complex 8, also somewhat unreactive, reacts with phosphites by Mn=Mn cleavage. In the case of P(OEt)3 the two products Cp Mn(CO)2[P(OEt)3] and CpMn(CO)[P(OEt)3]2 form in a 1 1 ratio (51). 

---