Solvent-Mediated Central Metals Transformation from a Tetranuclear Ni<sup>II</sup> Cage to a Decanuclear Cu<sup>II</sup> “Pocket”

When a well-designed tetranuclear Ni<sup>II</sup> cage [Ni<sub>4</sub>(bppdca)<sub>2</sub>(H<sub>2</sub>bppdca)<sub>4</sub>(SO<sub>4</sub>)<sub>2</sub>(H<sub>2</sub>O)<sub>6</sub>]·H<sub>2</sub>O·CH<sub>3</sub>OH (<b>1</b>; H<sub>2</sub>bppdca = <i>N</i>,<i>N</i>′-bis(pyridin-3-yl)-2,6-pyridinedicarbox-amide) was immersed into the methanol solution of CuSO<sub>4</sub>, a novel decanuclear Cu<sup>II</sup> complex [Cu<sub>10</sub>(H<sub>2</sub>bppdca)<sub>4</sub>(SO<sub>4</sub>)<sub>8</sub>(μ<sub>3</sub>OH)<sub>4</sub>(CH<sub>3</sub>OH)(H<sub>2</sub>O)<sub>4</sub>]·11H<sub>2</sub>O·2CH<sub>3</sub>OH (<b>2</b>) would be obtained through central metals transformation. We propose that the transformation is a recurrent dissolving−exchange−crystallization process with a solvent-mediated mechanism confirmed by visual evidence. Direct reaction of H<sub>2</sub>bppdca and CuSO<sub>4</sub> in the absence of <b>1</b> affords different products.