Magnesium coordination

The chlorophyll molecule (309) is involved in initiating photosynthesis in green plants and contains magnesium coordinated to a partially reduced porphyrin (namely, a chlorin derivative). Life relies ultimately on the unique redox and electron transfer abilities of the chlorophylls which are necessary for the conversion of light to chemical energy. Chlorophyll mainly absorbs light from the far red region of the spectrum... 

S. Kroeker and J. F. Stebbins, Magnesium coordination environments in glasses and minerals new insight from high-field magnesium-25 MAS NMR. Am. Mineral, 2000,85, 1459-1464. 

DFT calculations indicate that an incoming CO2 displaces a water ligand at magnesium. Coordination of one of the oxygen atoms in CO2 to Mg " bends, and thus polarizes, the central carbon atom which becomes sufficiently electrophilic to attack the Si face (observed experimentally ) of the enediolate C2 atom, which leads to the formation... 

The stereoselectivities in nucleophilic additions to various hexopyran-osid-2-163, -3-164, and -4-ulosesI6S 167 were extensively examined (see Tables II and III). The results in the Grignard reactions in Table III were commonly explained by the approach of the reagent from the sterically favored direction to the magnesium-coordinated conformations (left-hand side in the equilibration formulas), but the concept for the methyl-... 

Chlorophylls contain magnesium coordinated by chlorin groups. These compounds, essential in photosynthesis, will be discussed in Chapter 16. 

A successful approach to exploit the chelating ability of MeMgBr to control addition to the hydrazone 31 was discovered when the Grignard reaction was carried out in toluene solvent. Since toluene is a noncoordinating and nonpolar solvent, the magnesium coordinates with the substrate to activate the hydrazone and control the facial selectivity, as shown. A 94 6 selectivity for Re face attack to give 32 was observed after 1 hr at 20 C. There was no reaction after 48 hr at reflux temperature in THF [50]. 

Figure 12. CheY (PDB file 1CHN). (a) Immediate surroundings of the magnesium ion in the crystal structure of CheY. Note the magnesium-water-carboxylate motif of Figure 7 occurs twice in this magnesium coordination octahedron, (b) Further details of the active site of CheY.

Liu HK, Tsao TH, Zhang YT et al (2009) Microwave synthesis and single-crystal-to-single-crystal transformation of magnesium coordination polymers exhibiting selective gas adsorption and luminescence properties. CrystEngComm 11 1462-1468... 

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