SYNTHESES OF TRIRHENIUM ALKOXIDE CLUSTERS IN THE PRESENCE OF TRIMETHYLPHOSPHINE

The THF adduct of rhenium trichloride, Re-3(mu-Cl)(3)Cl-6(THF)(3), rea cts with trimethylphosphine and NaOPri to give the chloro-hydride Re-3 (mu-OPri)(3)Cl(H)(OPri)(4)(PMe3) and the dimer {Re-3(mu-OPri)(3)Cl(OPr i)(4)}(2)(mu-Cl)(2) in moderate yields. On the basis of spectroscopic studies and an X-ray crystal structure, the hydride ligand in the chlo ro-hydride cluster is proposed to occupy a site trans to Cl and cis to PMe,. The hydride ligand is proposed to originate from isopropoxide P -hydrogen elimination. Ethylene and 2-butyne react with the phosphine- hydride cluster to yield ethyl and 2-butenyl clusters, respectively, a nd sodium isopropoxide reacts to give Re-3(mu-OPri)(3)(H)(OPri)(5)(PMe 3). The latter compound is more conveniently prepared by reacting PMe3 with the homoleptic isopropoxide cluster Re-3(mu-OPri)(3)(OPri)(6), I n contrast, the analogous reaction of PMe3 with the homoleptic neopent oxide cluster Re-3(mu-OCH2Bui)(3)(OCH2Bui)(6) gives a simple phosphine adduct: Re-3(mu-OCH2But)(3)(OCH2But)(6)(PMe3). The reaction of Re-3(m u-Cl)(3)Cl-6(THF)(3) with trimethylphosphine and sodium neopentoxide p roduces the reduced cluster Re-3(mu-Cl)(mu-OCH2But)(2)Cl(OCH2But)(4)(P Me3)(2) in low yield. There are 13 electrons available for Re-Re bondi ng in the reduced cluster but its structure is not significantly diffe rent from similar 12-electron clusters. (C) 1998 Elsevier Science Ltd. All rights reserved.