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.