Oxidative decarbonylation of Mo(CO)6 with [–Se(Se)P(Oi-Pr)2]2 generates the mixed-valent tetranuclear cluster Mo4(μ3-Se)4[Se2P(Oi-Pr)2]6 and a cationic trinuclear cluster [Mo3(μ3-Se)(μ2-Se2)3{Se2P(Oi- Pr)2}3]+

Oxidative decarbonylation of Mo(CO)6 with [–Se(Se)P(Oi-Pr)2]2 yielded a novel tetranuclear, mixed-valent (MoIII/IV) Mo4(μ3-Se)4[Se2P(Oi-Pr)2]6 cluster 1 (dark brown), and a trinuclear, [Mo3(μ3-Se)(μ2-Se2)3{Se2P(Oi- Pr)2}3][Se2P(Oi-Pr)2] cluster 2a (orange).The uncoordinated Se2P(Oi-Pr)2anion of 2a was replaced by halide anions to yield [Mo3(μ3-Se)(μ2-Se2)3{Se2P(Oi- Pr)2}3](X) (X = Cl, 2b; Br, 2c; I, 2d) via the anion exchange reactions.In cluster 1, each Mo atom is bonded to two Se atoms from one chelating dsep (dsep = diselenophosphates) ligand, one Se from bridging dsep and to three, triply bridging μ3-Se atoms with Mo–μ3-Se bond distances, 2.4580–2.503 Å, and Mo–(1η-Se) bond distances, 2.691–2.729 Å.The cyclic voltammogram of 1 reveals one quasi-reversible one-electron oxidation wave (E1/2 = 0.67 V), corresponding to the formation of the Mo4Se47+ state, and two quasi-reversible one-electron reduction waves (E1/2 = −0.23 and −1.09 V), suggesting the formation of Mo4Se45+ andMo4Se44+ cores. In cluster cation, 2, three Mo atoms form an equilateral triangle which is capped by a μ3-Se2− anion, and each Mo atom is further coordinated to two μ2-Se22- ligands and a chelated dsep ligand. Interestingly, clusters 2a–2d exhibited unusual, intermolecular Se⋯Se interactions to produce infinite chains. All “sandwiched” halides are attached to three Seax atoms of one Mo3 unit and one Seeq atom of the neighboring unit in clusters 2b–2d and these distances are far shorter than the sum of the van der Waals radii.

Both tetranuclear cluster Mo4(μ3- Se)4[Se2P(Oi-Pr)2]6 (1) and cationic, trinuclear cluster [Mo3(μ3-Se) (μ-Se2)3{Se2P(Oi-Pr)2}3]+ (2) were obtained in an one-pot reaction via Se transfer in the oxidative decarbonylation of Mo(CO)6 with [–Se(Se)P(Oi-Pr)2]2.While cluster 1 is the first [Mo4(μ3-Se)4] cubane core with outer selenium-donor ligands, the cluster 2 displays unusual, intermolecular Se⋯Se contacts to produce infinite chains.In addition, the “sandwiched” halide anion is attached to three, electrophilic Seax atoms of one Mo3 unit and one Seeq atom of the neighboring unit and these distances are far shorter than the sum of the van der Waals radii.Figure optionsDownload as PowerPoint slide