Abstract
The crystal structures of two manganese(I) complexes with ester-substituted bi-pyridine or bi-quinoline supporting ligands are reported, namely, fac-bromido-tricarbon-yl(diethyl 2,2'-bi-pyridine-4,4'-di-carboxyl-ate-κ2 N,N')mangan-ese(I), [MnBr(C16H16N2O4)(CO)3], I, and fac-bromido-tricarbon-yl(diethyl 2,2'-bi-quinoline-4,4'-di-carboxyl-ate-κ2 N,N')manganese(I), [MnBr(C24H20N2O4)(CO)3], II. In both complexes, the manganese(I) atom adopts a distorted octa-hedral coordination sphere defined by three carbonyl C atoms, a Br- anion and two N atoms from the chelating α-di-imine ligand. Both complexes show fac configurations of the carbonyl ligands. In I, the complex mol-ecules are linked by C-H⋯Br hydrogen bonds and aromatic π-π contacts. In II, intra-molecular C-H⋯O hydrogen bonds are present as well as inter-molecular C-H⋯O and C-H⋯Br hydrogen bonds and π-π inter-actions.
Highlights
The crystal structures of two manganese(I) complexes with ester-substituted bipyridine or biquinoline supporting ligands are reported, namely, facbromidotricarbonyl(diethyl 2,20-bipyridine-4,40-dicarboxylate-2N,N0)manganese(I), [MnBr(C16H16N2O4)(CO)3], I, and fac-bromidotricarbonyl(diethyl 2,20-biquinoline-4,40-dicarboxylate-2N,N0)manganese(I), [MnBr(C24H20N2O4)(CO)3], II
The manganese(I) atom adopts a distorted octahedral coordination sphere defined by three carbonyl C atoms, a BrÀ anion and two N atoms from the chelating -diimine ligand
In I, the complex molecules are linked by C—HÁ Á ÁBr hydrogen bonds and aromatic – contacts
Summary
Similar to carbonyl complexes of precious metals, such as ruthenium and rhenium, those with less expensive manganese are attracting attention for their application in CO2 reduction catalysts (Bourrez et al, 2011) and as CO-releasing molecules (CORMs) under external stimuli (Chakraborty et al, 2014a). CORMs using manganese(I) carbonyl complexes controllably release CO by photoirradiation (Motterlini et al, 2002) Considering their application in vivo, photo-CORMs are expected to utilize light at lower energy. Diethyl 2,20-bipyridine4,40-dicarboxylate (debpy) and diethyl 2,20-biquinoline-4,40didicarboxylate (debqn): fac-[MnBr(CO)3(debpy)] (I) and fac-[MnBr(CO)3(debqn)] (II). We successfully compared their crystal structures and photophysical properties. A CT band shift in the visible region was confirmed, depending on the size of the -conjugation system in -diimine ligands. This finding will provide information in the future design of suitable complexes for a variety of photoreactions (Chakraborty et al, 2014b)
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