Mixed‐Valent Selenium Ligands in the Uncharged Iridium Complexes [Ir₄Se₁₀Br₁₆] and [Ir₆Se₈Cl₃₀]

Abstract

The reaction of Ir with Se and SeBr 4 at 200°C yields shiny vermillion slate-like crystals of the new compound Ir 4 Se 10 Br 16 . Single-crystal X-ray diffraction revealed an orthorhombic unit cell, space group Pccn, with lattice parameters a = 1515.0(1) pm, b = 1534.4(1) pm, and c = 1514.5(1) pm at 296(1) K. The crystal structure consists of uncharged tetranuclear iridium complexes [Ir 4 Se 10 Br 16 ] with C 2 symmetry. In the [(Ir 3+ ) 4 (μ 4 -η 2 -Se 2 2-) 2 (μ-η Se -[SeBr] -) 2 (η Se -SeBr 2 ) 4 (μ-Br -) 2 (Br -) 4 ] complex, each of the iridium atoms is coordinated octahedrally by four selenium and two bromine atoms. Selenium adopts three different oxidation states: -I in the fourfold-bonded diselenide dumbbell, Ϯ0 in the bridging [a]

Bridging Nonaselenium Ring in [Se9(IrBr3)2], and Three Modifications of the Mononuclear Complex [IrBr3(SeBr2)3]

“…[1][2][3] The three modifications a-facIrBr 3 (SeBr 2 ) 3 , m-fac-IrBr 3 (SeBr 2 ) 3 , and mer-IrBr 3 (SeBr 2 ) 3 comprise only terminal selenium and halogen ligands, which differ by configuration. The modifications seem to be almost equally stable.…”

“…With additional selenium, diverse ternary iridium coordination compounds can be isolated. These are, in the order of increasing nuclearity, [Se 9 (IrCl 3 ) 2 ], [1] [Ir 4 Se 10 Br 16 ], [Ir 6 Se 8 Cl 30 ], [2] [Ir 8 Se 28 Br 14 ], [3] and [Ir 8 Se 40 Br 10 ] [1] (Figure 1). Remarkable features are uncharged selenium rings, oligoselenide chains, and SeX -(X = Cl, Br) dumbbells, all of them acting as bridging ligands.…”