Nitrosyl complexes of rhenium. 3. The synthesis and substitution reactions of [ReH(CH3OH)(NO)(PPh3)3]ClO4 derived from the reaction of ReH2(NO)(PPh3)3 with HClO4. Members of the series ReHX(NO)(PPh3)3

Abstract

ReH2(NO)(PPh3)3 reacts with alcoholic HClO4 to yield the solvated cation, [ReH(ROH)(NO)(PPh3)3]ClO4 (R = CH3, C2H5) which can be isolated as an explosive solid (R = CH3 only). In the solid state, the perchlorate counter ion is hydrogen bound to the ligated alcohol, as observed for [ReH(CH3OH)(CO)(NO)(PPh3)2]ClO4. This latter complex also results from the reaction of [ReH(CH3OH)(NO)(PPh3)3]ClO4 with CO under ambient conditions. On reaction with p-tolylisocyanide (RNC), however, substitution is also accompanied by dihydrogen elimination to give [Re(OR)(NO)(CNR)2(PPh3)2]ClO4, irrespective of the mole ratio of the reactants. In contrast, [ReH(CH3OH)(NO)(PPh3)3]ClO4 reacts with coordinating anions with loss of methanol to give air-sensitive ReHX(NO)(PPh3)3 (X = OCH3, F, Cl, Br, I, N3, NCO, SCN), of which only those with X = Cl, Br, N3 were characterized in solution. The compounds ReHX(NO)(PPh3)3 are similar to their osmium analogues in having a labile third phosphine. Thus, reaction with neutral ligands such as CO or RNC leads to the series of neutral rhenium hydrido nitrosyls ReHX(L)(NO)(PPh3)2. Prior to this work, the only known examples from this series were those with L = CO, X = H, F, OCH3. Interestingly, the isomer of ReHF(CO)(NO)(PPh3)2 isolated in this work differs from that previously isolated (from the reaction of [ReF(CO)(NO)(PPh3)3]+ with [Formula: see text]) in having F trans to NO. All structural assignments have been made on the basis of elemental analyses, infrared spectroscopy, 1H and 31P nmr spectroscopy and deuteration studies, where appropriate. Keywords: hydrido, nytrosyl, rhenium, complexes.