Metal−Metal Interactions in Heterobimetallic d<sup>8</sup>−d<sup>10</sup> Complexes. Structures and Spectroscopic Investigation of [M‘M‘ ‘(<i>μ</i>-dcpm)<sub>2</sub>(CN)<sub>2</sub>]<sup>+</sup> (M‘ = Pt, Pd; M‘ ‘ = Cu, Ag, Au) and Related Complexes by UV−vis Absorption and Resonance Raman Spectroscopy and ab Initio Calculations
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posted on 2003-07-31, 00:00 authored by Bao-Hui Xia, Hong-Xing Zhang, Chi-Ming Che, King-Hung Leung, David Lee Phillips, Nianyong Zhu, Zhong-Yuan ZhouX-ray structural and spectroscopic properties of a series of heterodinuclear d<sup>8</sup>−d<sup>10</sup> metal
complexes [M‘M‘ ‘(<i>μ</i>-dcpm)<sub>2</sub>(CN)<sub>2</sub>]<sup>+</sup> containing d<sup>8</sup> Pt(II), Pd(II), or Ni(II) and d<sup>10</sup> Au(I), Ag(I), or Cu(I) ions
with a dcpm bridging ligand have been studied (dcpm = bis(dicyclohexylphosphino)methane; M‘ = Pt,
M‘ ‘ = Au <b>4</b>, Ag <b>5</b>, Cu, <b>6</b>; M‘ ‘ = Au, M‘ = Pd <b>7</b>, Ni <b>8</b>). X-ray crystal analyses showed that the metal···metal
distances in these heteronuclear metal complexes are shorter than the sum of van der Waals radii of the
M‘ and M‘ ‘ atoms. The UV−vis absorption spectra of <b>4</b><b>−</b><b>6</b> display red-shifted intense absorption bands
from the absorption spectra of the mononuclear <i>trans</i>-[Pt(phosphine)<sub>2</sub>(CN)<sub>2</sub>] and [M‘ ‘(phosphine)<sub>2</sub>]<sup>+</sup> counterparts, attributable to metal−metal interactions. The resonance Raman spectra confirmed assignments of
<sup>1</sup>[<i>n</i>d<sub>σ</sub>*→(<i>n</i> + 1)p<sub>σ</sub>] electronic transitions to the absorption bands at 317 and 331 nm in <b>4</b> and <b>6</b>, respectively.
The results of theoretical calculations at the MP2 level reveal an attractive interaction energy curve for the
skewed [<i>trans</i>-Pt(PH<sub>3</sub>)<sub>2</sub>(CN)<sub>2</sub>−Au(PH<sub>3</sub>)<sub>2</sub><sup>+</sup>] dimer. The interaction energy of Pt(II)−Au(I) was calculated to
be ca. 0.45 ev.
