Gold Complexes with the Selenolate Ligand [2-(Me₂NCH₂)C₆H₄Se]⁻

The reaction of [2-(Me₂NCH₂)C₆H₄Se]M (M = Li, K) with the gold(phosphine) complexes [AuCl(PR₃)] gives the mononuclear gold-selenolate species [Au{SeC₆H₄(CH₂NMe₂)-2}(PPh₃)] (1) or [Au{SeC₆H₄(CH₂NMe₂)-2}(PPh₂py)] (2), respectively. The treatment of the [2-(Me₂NCH₂)C₆H₄Se]M with [Au₂Cl₂(μ-P-P)] [P-P = bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)ethane (dppe), 1,1′-bis(diphenylphosphino)ferrocene (dppf)] derivatives gives complexes with stoichiometry [Au₂{SeC₆H₄(CH₂NMe₂)-2}₂(μ-P-P)] [P-P = dppm (3), dppe (4), or dppf (5)]. These complexes exhibit a different structural framework, that is, 4 crystallizes as a chain polymer with intermolecular aurophilic bonding, while 5 shows an intramolecular Au(I)···Au(I) interaction. The gold(III) derivative Bu₄N[Au(C₆F₅)₃{SeC₆H₄(CH₂NMe₂)-2}] (6) is obtained by reaction of [2-(Me₂NCH₂)C₆H₄Se]K and Bu₄N[AuBr(C₆F₅)₃], in a 1:1 molar ratio. These species exhibit luminescence which probably arises from a mixed ³LMMCT and ³MC excited state. The emission properties in these complexes seem to be useful for structural predictions and lead to the proposal of intermolecular aggregation in the solid state and frozen solution for complexes 1, 2, 3, whose crystal structures have not been elucidated.