Abstract
A series of heterobimetallic d10−d8 complexes, [AuIM′(R1)2(R2)2] (M′ = PtII, AuIII; R1 = CN−, C≡CH−; R2 = PH2CH2PH2, CH2PH2CH2−), were explored using ab initio methods and time-dependent density functional theory (TD-DFT). In the ground states, d10−d8 distances were calculated at 2.88−3.00 Å with associated vibrational frequencies of 102−114 cm−1 by the MP2 method; energies of metallophilic interactions were estimated to be in the range 11.0−18.2 and 7.03−9.14 kcal/mol at the MP2 and CCSD levels, respectively. With the reference complex [AuIPtII(CN)2(PH2CH2PH2)2]+ (1), the variation of the d8 heterometal (M′), the coordination environment of the d8 metal (R1), and the bridging ligand (R2) changes the electronic structures and thus further tunes the electronic spectroscopy of these complexes. The known experimental absorption spectra were well reproduced by the present TD-DFT calculations. Upon excitation, UMP2 revealed the metal−metal interactions in their triplet excited states were strengthened. The corresponding phosphorescent emissions were attributed to the combination of metal-centered (MC) transition, metal-to-metal charge transfer (MM′CT), and ligand-to-metal charge transfer (LMCT). The MC and MM′CT transitions are responsible for the excited metal−metal contraction. The contraction in the AuI−AuIII complex is larger than that in corresponding AuI−PtII complex due to greater participation of MM′CT transitions.
Published Version
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