UNEXPECTED FORMATION OF HYDRIDO-HYDROXY DERIVATIVES AS DIRECT PRODUCTS IN THE REACTIONS OF THE UNSATURATED DIHYDRIDES [MN2(MU-H)2(CO)6(MU-L-L)] (L-L = PH2PCH2PPH2, (ETO)2POP(OET)2) WITH CARBON-DIOXIDE

The unsaturated dihydrides [Mn2(mu-H)2(CO)6(mu-L-L)] (L-L = Ph2PCH2PPh2, dppm, 1; (EtO)2POP(OEt)2, tedip, 2) react with carbon dioxide (at 50 atm) or with formic acid to yield not only the expected hydridoformate complexes [Mn2(mu-H)(mu-O2CH)(CO)6(mu-L-L)] (L-L = dppm, 3a; tedip, 3b) but also the hydridohydroxo-derivatives [Mn2(mu-H)(mu-OH)(CO)6(mu-L-L)] (L-L = dppm, 4a; tedip, 4b). The complexes 4 do not seem to arise from decomposition of 3 or to be products of the reaction of 1 and 2 with water. The hydrides 1 and 2 also react under mild conditions with several heterocumulenes (cyclohexylisocyanate, dicyclohexylcarbodiimide and trimethylsilylazide) to afford [Mn2(mu-H){mu-OC(H) = NCy}(CO)6(mu-tedip)] (5), [Mn2(mu-H)(mu-CyNC(H)NCy}(CO)6(mu-L-L)] (L-L = dppm, 6a; tedip, 6b) and [Mn2(mu-H)(mu-N3)(CO)6(mu-L-L)] (L-L = dppm, 7a: tedip, 7b), respectively.