REACTIONS OF THE POLYHYDRIDE COMPLEX REH7(DPPE) (DPPE=PH(2)PCH(2)CH(2)PPH(2)) WITH PYRIDINE-2-CARBOXYLIC ACID, 1-ISOQUINOLINECARBOXYLIC ACID, 2-HYDROXY-6-METHYLPYRIDINE AND 2-MERCAPTOQUINOLINE - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF 7-COORDINATE MONOHYDRIDO COMPLEXES OF RHENIUM(III)

The thermal reactions of ReH7(dppe) (dppe = Ph(2)PCH(2)CH(2)PPh(2)) wi th pyridine-2-carboxylic acid (Hpic), 1-isoquinolinecarboxylic acid (H isoquin), 2-hydroxy-6-methylpyridine (Hmhp) and 2-mercaptoquinoline (H mq) in refluxing benzene afforded the monohydridorhenium(III) species ReH(L)(2)(dppe) [L = pic (1a), isoquin (1b), mhp (1c), mq (1d)]. While analogous complexes have been prepared previously from ReH7(PPh(3))(2 ) in the case of L = pie, isoquin and mhp, the reactions between ReH7( PPh(3))(2) and the ligands 2-hydroxyquinoline and 2-mercaptoquinoline are dependent on the choice of reaction solvent; the rhenium hydride c omplexes ReH4(L)(PPh(3))(2) (L = hq or mq) and ReH(hq)(2) (PPh(3))(2) have been isolated in a pure state. H-1 and P-31 NMR Spectral measurem ents on the seven-coordinate species 1a-d show that these compounds ar e stereochemically rigid at room temperature. The solution structures are in accord with the solid state structures of 1c and 1d, as determi ned by X-ray crystallography. Copyright (C) 1996 Elsevier Science Ltd