Structures and bonding of homoleptic bis(2,3-dihydro-1,3-diborole) complexes of nickel and platinum

• Homoleptic sandwich complexes [M12] (M = Ni, Pt; 1 = 2,3-dihydro-1,3-diborole) are described.
• X-ray crystal structure analyses reveal different coordination modes for M = Ni (18 VE) and Pt (14 VE).
• DFT MO calculations of [M12] are presented.

Homoleptic metal complexes of the boron heterocycle 2,3-dihydro-1,3-diborole {(R1C)2(R2B)2R3(H)C} 1 are described. X-Ray crystal structure determinations of two nickel and platinum derivatives are presented. In the nickel complex [Ni(1d)2] 6d (R1 = R2 = R3 = Et) the essentially coplanar heterocycles attain a pentahapto coordination mode with a gauche orientation with respect to one another. An 18 VE count is attained. In contrast, in the 14 VE platinum complex [Pt(1a)2] 4a (R1 = R2 = Et, R3 = Me) the ligands are strongly folded and adopt a tetrahapto coordination. The molecule is centrosymmetric in the crystalline state. DFT MO calculations are presented to establish the relative stabilities of these coordination modes for nickel and platinum, respectively.

In the homoleptic sandwich complexes [M12] (M = Ni, Pt) two different coordination modes are adopted by the boron heterocycle 2,3-dihydro-1,3-diborole 1, resulting in an 18 valence electron count for M = Ni whilst only 14 valence electrons are reached for M = Pt.Figure optionsDownload as PowerPoint slide