To cite this article: Mohammed Bakir & Rebecca Conry (2016): Synthesis, spectroscopic and Xray 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, Journal of Coordination Chemistry, ABSTRACT Reactions between [Mn(CO) 5 Br] and dpkbh in low boiling solvents in air gave fac-[Mn I (CO) 3 (κ 2 -N py ,N im -dpkbh)Br]·H 2 O, [Mn II Br 2 (κ 3 -N py ,N im ,O-dpkbh)], and [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ]·0.5H 2 O (N im = imine nitrogen and N py = pyridyl nitrogen). 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 ,Odpkbh-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 ,Odpkbh-H) 2 ]·0.5H 2 O. Electronic absorption spectral measurements in nonaqueous 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 outershell environments. X-ray crystallographic analyses elucidated the identities of [Mn II Br 2 (κ 3 -N py ,N im ,O-dpkbh)] and [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ]·nX and divulged weaker coordination of [dpkbh] to Mn(II) in [Mn II Br 2 (κ 3 -N py ,N im ,Odpkbh)] and stronger coordination of [dpkbh-H] − to Mn(II) in [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ]·0.22H 2 O. Low-temperature X-ray structural analyses were employed to account for the disorder in the structure of [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ] and the short NH bond distance observed in the structure of [Mn II Br 2 (κ 3 -N py ,N im ,O-dpkbh)]. A PLATON SQUEEZE treatment was invoked to account for the fractional occupancy of lattice water in the structure of [Mn II (κ 3 -N py ,N im ,O-dpkbh-H) 2 ].
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