A Comparative Study of the Reactivity of Mn(no)₂L₂H and Mn(CO)₃L₂H Complexes (L = Phosphorus Donor)

Mn(NO) 2 L 2 H complexes [L = PMe 3 1a , PEt 3 1b , P(OMe) 3 1c , P(OEt) 3 1d , P(O i Pr) 3 1e ] have been prepared by the reaction of the corresponding Mn(NO) 2 L 2 Br compounds with NaBH 4 in ethanol. The reactivity of 1a and 1b is compared to that of Mn(CO) 3 L 2 H species (L = PMe 3 2a , L = PEt 3 2b ). Compound 1b reacts with weak acids like PhOH, (CF 3 ) 2 CHOH and CH 3 COOH to yield Mn(NO) 2 (PEt 3 ) 2 X complexes [X = OPh 3a , OCH(CF 3 ) 2 3b , OC(O)CH 3 3c ] and H 2 . Compound 2b does not undergo reaction with these acids. At room temperature in toluene 1a , b undergo facile CO 2 insertion processes, while 2a , b do not show this reactivity even under more rigorous reaction conditions. From 1a , b and CO 2 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 [2‐(hydroxymethyl)‐phenoxy]dinitrosylbis(triethylphosphane) manganese complex 5b , which exchanges the phenoxy ligand in the presence of excess of salicylaldehyde to give (2‐formylphenoxy)‐dinitrosylbis(triethylphosphane)manganese ( 6b ) and α,2‐dihydroxytoluene. p ‐Hydroxybenzaldehyde, vanilline, and 4‐hydroxy‐3,5‐dimethoxybenzaldehyde and 1b also afford phenoxy derivatives Mn(NO) 2 (PEt 3 ) 2 (OAr) [Ar = p ‐OC 6 H 4 ‐CHO 7a ; OC 6 H 3 ‐2‐OCH 3 ‐4‐CHO 7b ; OC 6 H 2 ‐2,6‐(OCH 3 ) 2 ‐4‐CHO 7c ] and H 2 . Compounds 2a , b do not react with any of these hydroxybenzaldehydes. 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≡CCOOMe (R = H, Me, Ph, COOMe; R′ = Me, Et). Similarly, but under more rigorous conditions, insertion of RC≡CCOOMe (R = H, COOMe) into 2a , b occurs and α metalation 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 2a , 10% of an additional β‐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 complexes 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 15c ). Compound 15c has been identified spectroscopically, and 1a , 8a , and 9a have been characterized by X‐ray structure determinations.