Synthesis, spectroscopic and X-ray crystallographic properties of manganese compounds of keto- and enol-coordinated di-2-pyridyl ketone benzoyl hydrazone (dpkbh). Reactions of [Mn(CO) 5 Br] with dpkbh

Crystallization of fac -[Mn I (CO) 3 (κ 2 -N py ,N im -dpkbh)Br]·H 2 O from dmso or CH 3 CN produced dark red crystals of [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ]·nX (X = dmso, n = 1 and X = H 2 O, n = 0.22).

This is in contrast to the reaction of [Re(CO) 5 Cl] with dpkbh in refluxing toluene to form fac -[Re I (CO) 3 (κ 2 -,N py ,N py -dpkbh)Cl] which can be crystallized from CH 3 CN, dmso or dmf to form fac -[Re I (CO) 3 (κ 2 -,N py ,N py -dpkbh)Cl]·nX (X = CH 3 CN, n = 0 and solvate = dmso or dmf, n = 1). Infrared spectral measurements are consistent with keto coordination of dpkbh to Mn(I) in fac -[Mn I (CO) 3 (κ 2 -N py ,N im -dpkbh)Br]·H 2 O and Mn(II) in [Mn II Br 2 (κ 3 -N py ,N im ,O-dpkbh)] plus enol coordination of the amide-deprotonated dpkbh, to the Mn(II) center in [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ]·0.5H 2 O. Electronic absorption spectral measurements in non-aqueous solvents indicate sensitivity of fac -[Mn I (CO) 3 (κ 2 -N py ,N im -dpkbh)Br]·H 2 O and [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ]·0.5H 2 O to changes in their outer-shell environments.