Gold(I) Chloride Complexes of Polyphosphine Ligands with Electron-Rich Arene Spacer: Gold–Arene Interactions

The reactions of Au­(tht)Cl (tht = tetrahydrothiophene)
with the electron-rich-arene-spacer-containing polyphosphine ligands N,N′-bis­((diphenylphosphino)­methyl)­benzene-1,4-diamine
(Dpba), N,N′-bis­((diphenylphosphino)­methyl)­naphthalene-1,5-diamine
(Dpna), N,N,N′,N′- tetrakis­((diphenylphosphino)­methyl)­benzene-1,4-diamine
(Pbaa), N,N,N′,N′-tetrakis­((diphenylphosphino)­methyl)­naphthalene-1,5-diamine
(Pnaa), and N,N,N′,N′-tetrakis­((diphenylphosphino)­methyl)­biphenyl-4,4′-diamine
(Pbbaa) lead to [Dpba­(AuCl)2] (1), [Dpna­(AuCl)2] (2), [Pnaa­(AuCl)4] (3), [Pbbaa­(AuCl)4 (4). and [Pbaa­(AuCl)4] (5), which are characterized by 1H and 31P NMR, IR, elemental analysis, and X-ray crystal
structure analysis. These complexes exhibit weak Au–arene interactions
with the electron-rich arene spacer, while the Au–arene interactions
are modified by a combination of electronic and steric effects from
the ligands. Different from monomeric complexes 1, 2, 3, and 4, complex 5 in the solid state exhibits a centrosymmetric trimeric unit that
is constructed by intermolecular Au···Au interactions
between the central molecule and the two symmetry-related terminal
molecules and in which the conformation of the central molecule is
different from that of the two symmetric terminal molecules. On the
basis of the Kochi’s geometric criteria and the crystal structural
parameters relating to Au–arene interactions, the Au···Carene contacts in 3 and 4 feature
nearly η2-arene interactions, while
the Au···Carene contacts in 5 can be described as η1-arene interactions, and
the Au···Carene contacts in 1 and 2 are very weak due to intermolecular N–H···Cl
interactions.