NEW RHENIUM COMPLEXES WITH PHOSPHINITE PPH(2)OR OR PHOSPHONITE PPH(OR)(2) (R=ME,ET OR PR-I) LIGANDS - SYNTHESIS AND PROTONATION OF VARIOUS POLYHYDRIDES

The rhenium complexes [ReOCl(3)L(2)] and [ReCl(3)L(3)] [L = PPh(2)OMe, PPh(2)OEt, PPh(2)OPr(i), PPh(OEt)(2) or PPh(OPri)(2)] were prepared b y allowing [ReOCl3(AsPh(3))(2)] to react with the appropriate amount o f phosphinite or phosphonite. Treatment of [ReCl(3)L(3)] with CO and p -MeC(6)H(4)NC afforded the mer-trans-[ReCl(CO)(3)L(2)] and [ReCl2(p-Me C(6)H(4)NC)(4)L]BPh(4) complexes, respectively. Treatment of [ReOCl(3) L(2)] with NaBH4 gave [Re(2)H(8)L(4)], but in the presence of phosphin ite or phosphonite the trihydrides [ReH(3)L(4)] were obtained. Treatme nt of [ReCl(3)L(3)] with NaBH4 gave instead pentahydride complexes [Re H(5)L(3)]. All the multihydrides were characterised as 'classical' spe cies by variable-temperature NMR spectroscopy (H-1 and P-31) and T-1 m easurements. Protonation of [Re(2)H(8)L(4)] and [ReH(3)L(4)] with HBF4 . Et(2)O gave the classical hydride cations [Re(2)H(9)L(4)](+) and [R eH(4)L(4)](+), respectively, while similar treatment of [ReH(5)L(3)] g ave a species formulated as containing an eta(2)-H-2 ligand, [ReH4(eta (2)-H-2)L(3)](+) on the basis of T-1(min) evidence.