Structural Diversity in Molecular Nickel Phosphide Carbonyl Nanoclusters

The reaction of [Ni 6 (CO) 12 ] 2- as a [NBu 4 ] + salt in CH 2 Cl 2 with 0.8 equiv of PCl 3 afforded [Ni 14 P 2 (CO) 22 ] 2- . In contrast, the reactions of [Ni 6 (CO) 12 ] 2- as a [NEt 4 ] + salt with 0.4-0.5 equiv of POCl 3 afforded [Ni 22- x P 2 (CO) 29- x ] 4- ( x = 0.84) or [Ni 39 P 3 (CO) 44 ] 6- by using CH 3 CN and thf as a solvent, respectively. Moreover, by using 0.7-0.9 mol of POCl 3 per mole of [NEt 4 ] 2 [Ni 6 (CO) 12 ] both in CH 3 CN and thf, [Ni 23- x P 2 (CO) 30- x ] 4- ( x = 0.82) was obtained together with [Ni 22 P 6 (CO) 30 ] 2- as a side product. [Ni 23- x P 2 (CO) 30- x ] 4- ( x = 0.82) and [Ni 22 P 6 (CO) 30 ] 2- were separated owing to their different solubility in organic solvents. All the new molecular nickel phosphide carbonyl nanoclusters were structurally characterized through single crystal X-ray diffraction (SC-XRD) as [NBu 4 ] 2 [Ni 14 P 2 (CO) 22 ] (two different polymorphs, P 2 1 / n and C 2/ c ), [NEt 4 ] 4 [Ni 23- x P 2 (CO) 30- x ]·CH 3 COCH 3 ·solv ( x = 0.82), [NEt 4 ] 2 [Ni 22 P 6 (CO) 30 ]·2thf, [NEt 4 ] 4 [Ni 22- x P 2 (CO) 29- x ]·2CH 3 COCH 3 ( x = 0.84) and [NEt 4 ] 6 [Ni 39 P 3 (CO) 44 ]·C 6 H 14 ·solv. The metal cores' sizes of these clusters range from 0.59 to 1.10 nm, and their overall dimensions including the CO ligands are 1.16-1.63 nm. In this respect, they are comparable to ultrasmall metal nanoparticles, molecular nanoclusters, or atomically precise metal nanoparticles. The environment of the P atoms within these molecular Ni-P-CO nanoclusters displays a rich diversity, that is, Ni 5 P pentagonal pyramid, Ni 7 P monocapped trigonal prism, Ni 8 P bicapped trigonal prism, Ni 9 P monocapped square antiprism, Ni 10 P sphenocorona, Ni 10 P bicapped square antiprism, and Ni 12 P icosahedron.