Reactivity of Molybdenum and Rhenium Hydroxo Carbonyl Complexes toward Organic Electrophiles

LUCIANO CUESTA; DARÍO C. GERBINO; EVA HEVIA; DOLORES MORALES; M. ELENA NAVARRO CLEMENTE; JULIO PÉREZ; LUCIA RIERA; VÍCTOR RIERA; DANIEL MIGUEL; IGNACIO DEL RÍO

CHEMISTRY-A EUROPEAN JOURNAL

Wiley-VCH Verlag GmbH & Co. KgaA

Lugar: Weinheim; Año: 2004 vol. 10 p. 1765 - 1777

0947-6539

Abstract The hydroxo compounds [Re(OH)(CO)3(NN)] (NN=bipy, 2 a; Me2bipy, 2 b) were prepared in a biphasic H2O/CH2Cl2 medium by reaction of [Re(OTf)(CO)3(NN)] with KOH. In contrast, when anhydrous CH2Cl2 was used, the binuclear hydroxo-bridged compound [{Re(CO)3(bipy)}2(-OH)]OTf (3-OTf) was obtained. Compound [Re(OH)(CO)3(Me2bipy)] (2 b) reacted with phenyl acetate or vinyl acetate to afford [Re(OAc)(CO)3(Me2bipy)] (4) and phenol or acetaldehyde, respectively. The reactions of [Mo(OH)(3-C3H4Me-2)(CO)2(phen)] (1), 2 a, and 2 b toward several unsaturated organic electrophiles were studied. The reaction of 1 with (p-tolyl)isocyanate afforded an adduct of N,N-di(p-tolyl)urea and the carbonato-bridged compound [{Mo(3-C3H4Me-2)(CO)2(phen)}2(-1(O),1(O)-CO3)] (5). In contrast, the reaction of 2 a with phenylisocyanate afforded [Re(OC(O)NHPh)(CO)3(bipy)] (6); this results from formal PhNCO insertion into the OH bond. On the other hand, compounds [Mo[SC(O)NH(p-tolyl)](3-C3H4Me-2)(CO)2(phen)] (7), [Re[SC(O)NH(p-tolyl)](CO)3(Me2bipy)] (8 a), and [Re[SC(O)NHEt](CO)3(Me2bipy)] (8 b) were obtained by reaction of 1 or 2 b with the corresponding alkyl or aryl isothiocyanates. In those cases, RNCS was inserted into the MO bond. The reactions of 1, 2 a, and 2 b with dimethylacetylenedicarboxylate (DMAD) gave the complexes [Mo[C(OH)C(CO2Me)C(CO2Me)O](3-C3H4Me-2)(CO)(phen)] (9) and [Re[C(OH)C(CO2Me)C(CO2Me)O](CO)2(NN)] (NN=bipy, 10 a; Me2bipy, 10 b). The molecules of these compounds contain five-membered metallacycles that are the result of coupling between the hydroxo ligand, DMAD, and one of the CO ligands. The new compounds were characterized by a combination of IR and NMR spectroscopy, and for [{Re(CO)3(bipy)}2(-OH)]BF4 (3-BF4), 4, 5, 6, 7, 8 b, 9, and 10 b, also by means of single-crystal X-ray diffraction.