A COMPARATIVE-STUDY OF THE REACTIVITY OF MN(NO)(2)L(2)H AND MN(CO)(3)L(2)H COMPLEXES (L=PHOSPHORUS DONOR)

Mn(NO)(2)L(2)H complexes [L = PMe(3) 1a, PEt(3) 1b, P(OMe)(3) 1c, P(OE t)(3) 1d, P(OiPr)(3) 1e] have been prepared by the reaction of the cor responding Mn(NO)(2)L(2)Br compounds with NaBH4 in ethanol. The reacti vity of 1a and 1b is compared to that of Mn(CO)(3)L(2)H species (L = P Me(3) 2a, L = PEt(3) 2b). Compound 1b reacts with weak acids like PhOH , (CF3)(2)CHOH and CH3COOH to yield Mn(NO)(2)(PEt(3))(2)X complexes [X = OPh 3a, OCH(CF3)(2) 3b OC(O)CH3 3c] and H-2. Compound 2b does not u ndergo reaction with these acids. At room temperature in toluene 1a, b undergo facile CO2 insertion processes, while 2a, b do not show this reactivity even under more rigorous reation conditions. From 1a, b and CO2 formato complexes Mn(NO)(2)L(2)[OC(O)H] (L = PMe(3) 4a, L = PEt(3 ) 4c) are obtained. The reaction of 1b with salicylaldehyde in toluene proceeds with the formation of a -phenoxy]dinitrosylbis(triethylphosp hane)manganese complex 5b, which exchanges the phenoxy ligand in the p resence of excess of salicylaldehyde to give phenoxy)-dinitrosylbis(tr iethylphosphane)manganese (6b) and alpha,2-dihydroxytoluene. p-Hydroxy benzaldehyde, vanilline, and 4-hydroxy-3,5-dimethoxybenzaldehyde and 1 b also afford phenoxy derivatives Mn(NO)(2)(PEt(3))(2)(OAr) [Ar = p-OC 6H4-CHO 7a; OC6H3-2-OCH3-4-CHO 7b; OC6H2-2,6-(OCH3)(2)-4-CHO 7c] and H -2. Compounds 2a, b do not react with any of these hydroxybenzaldehyde s. Compounds 1a, b have been converted into Mn(NO)(2)L(2)[(Z)-C(COOR') =C(R)H] species (L = PMe(3), R = H, R' = Me 8a; L = PEt(3), R = H, R' = Me 8b; L = PMe(3) R, R' = Me 9a; L = PMe(3), R = Ph, R' = Et 10a; L = PMe(3), R = COOMe, R' = Me 11a; L = PEt(3), R = COOMe, R' = Me 11b) in the presence of alkyl propiolates RC drop CCOOR' (R = H, Me, Ph, CO OMe; R' = Me, Et). Similarly, but under rigorous conditions, insertion of RC drop CCOOMe (R = H, COOMe) into 2a, b occurs and alpha metalati on products Mn(CO)(3)(PMe(3))(2)[(Z)-C(COOMe)=CHR] (L = PMe(3), R = H 12a; L = PEt(3), R = H 12b; L = PMe(3), R = COOMe 13a; L = PEt(3), R = COOMe 13b) are formed. In the case of the methyl propiolate insertion into 2 a, 10% of an additional beta-metalation compound Mn(CO)(3)(PMe (3))(2)[(Z)-CH=CH(COOMe)] (12c) have been detected spectroscopically. Compounds 11b and 13a, b have been transformed into manganacyclic comp les Mn[C(COOMe)=CH(COOME)]-(NO)(2)(PEt(3))(2) (14b) and MN[C(COOMe)=CH (COOMe)]-(CO)(2)L(2) (L = PMe(3) 15a; L = PEt(3), CO 15b; L = PEt(3) 1 5c). Compound 15c has been identified spectroscopically, and 1a, 8a, a nd 9a have been characterized by X-ray structure determinations.