[Ni₂₃Se₁₂(PEt₃)₁₃] Revisited: Isolation and Characterization of [Ni₂₃Se₁₂Cl₃(PEt₃)₁₀]

Abstract

The reaction of [Ni(1,5-COD) 2 ] (1.0 equiv), PEt 3 (0.04 equiv), SePEt 3 (0.52 equiv), and [NiCl 2 (PEt 3 ) 2 ] (0.07 equiv) in a mixture of toluene and THF results in the formation of [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ] (1), which can be isolated in moderate yield after workup. Complex 1 was characterized by NMR spectroscopy, ESI-MS, and X-ray crystallography. This open-shell nanocluster features a central [Ni 13 ] 7+ anticuboctahedral kernel, which is encapsulated by a [Ni 10 (μ-Se) 9 Cl 3 ] − shell, along with ten PEt 3 ligands and three (μ 4 -Se) 2− ligands. On the basis of our spectroscopic and crystallographic analysis, coupled with in situ spectroscopic monitoring, we believe that the previously reported nanocluster, [Ni 23 Se 12 (PEt 3 ) 13 ], is actually better formulated as [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ].

[Ni30S16(PEt3)11]: an open-shell nickel sulfide nanocluster with a “metal-like” core

“…Similar “[ cyclo -{Ni(μ-E)(PEt 3 )} 3 ]” units are found in [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ]. 20 The addition of these three capping units brings the total metal nuclearity to 30 ( Fig. 1E and F ).…”

“…30 For further comparison, the average Ni-S distance in b-NiS is 2.31 Å, 36 whereas the Ni-S distances in Ni 3 S 2 are 2.2914(5) and 2.2534(5) Å. 37 20,30,33 The average Ni oxidation state in 1 is 1.067, making it among the most reduced Ni chalcogenide clusters yet isolated, and highlighting its high "metal-like" character. For comparison, and 1.17, respectively.…”

“…For comparison, only two other reported Ni nanoclusters feature compact “metal-like” cores, namely, [Ni 21 Se 14 (PEt 2 Ph) 12 ] and [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ], which each have just one fcc and hcp Ni 13 “kernel”, respectively. 20,33 This paucity of examples lies in stark contrast to the broad landscape of “metal-like” structures observed for Ag and Au. Indeed, over 250+ high-nuclearity, low-valent group 11 APNCs have been structurally characterized over the last 10 years.…”

“…Intriguingly, [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ] also features fcc packing of its central Ni 13 core. 20,21 While its electronic structure is not entirely understood, we propose that its paramagnetism is related to this metal-like core structure. Moreover, we hypothesize that larger nickel chalcogenide APNCs will feature greater structural similarity to bulk Ni, potentially resulting in the emergence of superparamagnetic or ferromagnetic behaviour.…”

“…[16][17][18] Similarly, the mixed-metal cluster [NBu 4 ] 4 [Ni 16 Pd 16 (CO) 40 ], features a J ¼ 2 ground state. 19 In addition, we recently reported the isolation of [Ni 23 Se 12 Cl 3 (PEt 3 ) 10 ], [20][21][22] which features an S ¼ 3/2 ground state according to an Evans' method determination. Also notable are calculations of [Ni 44 (CO) 48 ] 6À , [23][24][25] which predict an open shell ground state.…”