This
work provides a facile access to a series of triangular [Zn2M] (M = group 10 and 11 metals) clusters. Treatment of Zn–Zn-bonded
compounds [LZn–ZnL] (L = CH3C(2,6-
i
Pr2C6H3N)CHC(CH3)(NCH2CH2PR2); R = Ph,
i
Pr)
with zero-valent transition-metal reagents selectively afforded the
corresponding triangular clusters [Zn2M], where M = Ni(0),
Pd(0), and Pt(0). Notably, the isoelectronic triangular clusters [Zn2M]+, where M = Ag(I) and Cu(I), could also be obtained
by reactions of [LZn–ZnL] with AgOTf and CuOTf, respectively.
The [Zn2Ag]+ complex containing elusive Zn–Ag
bonds was investigated by density functional theory analysis, showing
a 3c–2e bonding feature in the metallic ring. The electrochemical
behaviors of [Zn2M] complexes were examined and revealed
the donation of electron density from the Zn–Zn σ-bond
to the metal centers. Reaction of the [Zn2Ni] complex with
isocyanide gave heterometallic species by coordination of isocyanide
to the nickel center, keeping the trimetallic ring core structure
intact. In contrast, the Zn–Zn bond was rapidly cleaved upon
treatment of the [Zn2Ni] complex with dihydrogen or phenyl
acetylene, generating the hydride- or acetylide-bridged heterotrimetallic
complex.