Abstract. X-ray single crystal diffraction studies reveal that the nickel complex and cobalt complex are isostructural.In the title crystal structure, the Ni atom lying on ac rystallographic inversion center is six-coordinated by two N,O-bidentate 2-methyl-1H-imidazole-4,5-dicarboxylic acid mono-anionic ligands and two water molecules. As in the Co complex, two coordinated water molecules occupy the apical sites, and the equatorial plane contains two bidentate 2-methyl-1H-imidazole-4,5-dicarboxylic acid mono-anionic ligands. Rich O−H···O, N−H···O and C−H···Ohydrogen bonds link the mononuclear nickel complex into a3 Ds upramolecular structure. The mean distances Ni-Oand Ni-Nof2.0794 Å and 2.0528 Å,respectively, are smaller than that of Co-O(2.1179 Å)and

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Siraitia grosvenorii, an economically important plant species with high medicinal value, is endemic to subtropical China. To determine the population structure and origin of cultivated S. grosvenorii, we examined the variation in three chloroplast DNA regions (trnR-atpA, trnH-psbA, trnL-trnF) and two nuclear gene orthologs (CHS and EDL2) of S. grosvenorii in 130 individuals, selected from 13 wild populations across its natural distribution range, and 21 cultivated accessions using a phylogeographic approach. The results showed non-overlapping distribution of chlorotypes, three distinct chloroplast genetic groups restricted to different mountain ranges, and comparable nuclear diversity among the distinct geographical groups, suggesting the existence of at least three separate refugia. The current phylogeographic patterns of S. grosvenorii probably resulted from long-term survival in multiple refugia and limited expansion. Our results also demonstrated that wild populations in northeastern Guangxi share the same gene pool as cultivated S. grosvenorii accessions, suggesting that the current cultivars originated from wild populations distributed in northeastern Guangxi. The results of this study provide insight into improving the efficiency of S. grosvenorii breeding using a genetic approach, and outline measures for the conservation of its genetic resources.

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