The heteronuclear complex [Pb{HB(pz)3}Au(C6Cl5)2] is a blue emitter in the solid state and displays an unprecedented and unsupported Au(i)···Pb(ii) contact. Ab initio calculations show a very strong metallophilic interaction that is greatly influenced by relativistic effects.

Tetrahedral AuI complexes [L3Au(SnCl3)] (L=PMe3 (1), PMe2Ph (2), PMePh2 (3), and PPh3 (4)) were prepared by treatment of the [(tht)Au(SnCl3)] (tht=tetrahydrothiophene) complex with three equivalents of the corresponding tertiary phosphine. The crystal structures of complexes 1–4 have been determined through X‐ray diffraction studies showing, in all cases, [SnCl3]− fragments covalently bonded to the corresponding [Au(PR3)3]+ units, which leads to a tetrahedral coordination environment for gold. Complexes 3 and 4 show phosphorescence in the solid state at room temperature and 77 K that is largely redshifted relative to the free [Au(PR3)3]+ and [SnCl3]− counterparts. Correlated MP2, SCS‐MP2, and ONIOM MP2/UFF calculations suggest a largely distorted lower triplet excited state (T1) for each model system. The AuP3+ moiety is distorted leading to a T‐shape, whereas the SnCl3− unit is left almost unaltered. Molecular orbital and population analysis suggest that the emission of these tetrahedral AuI complexes arises from a 3MC transition slightly perturbed by the SnCl3− fragment.

Reaction of [AuAgR(EtO)] (R = CClF or CF) with [Pb{HB(pz)}]Cl in a 1:2 molar ratio led to complexes [AuPb{HB(pz)}R] (R = CClF (2) or CF (3)) through transmetalation reactions. The crystal structures of these complexes display unsupported Au(I)···Pb(II) interactions of 3.0954(4) (2) and 3.2778(4) (3) Å, together with one (2) or two (3) F···Pb weak contacts. These intermetallic distances are compared to the shortest one found for the previously reported complex [Pb{HB(pz)}Au(CCl)] (1) of 3.0494(4) (1) Å, showing a clear dependence with the donating properties of the different aurate units. The complexes are emissive in the solid state due to charge transfer transitions associated with the presence of Au(I)···Pb(II) interactions, in which the intermetallic distance plays a crucial role. Density functional theory and time-dependent density functional theory calculations support the assignment of the luminescent properties of the complexes. Ab initio Hartree-Fock and MP2 calculations on model systems of complexes 2 and 3 show the presence of strong Au(I)···Pb(II) closed-shell interactions of an ionic plus dispersive nature together with weak F···Pb contacts of a dispersive origin in the case of complexes 2 and 3.

The structure of the complex [{Pb(HBpz)}{Au(o-CBrF)(HBpz)}] consists of a host-guest heterometallic system built up through a plethora of interactions including electrostatic, metallophilic, H-bonding, AuBr or weak CC or PbBr contacts. Computational studies show that the dispersive interactions are responsible for the attraction of the Pb(ii) cationic moiety within the basket-like trinuclear Au(i) fragment, whereas the ionic component of the interaction placed at the rings produces a molecular clamp.