Thiolate-Bridged Heterodinuclear Manganese–Cobalt Complexes with Bridging Hydride Ligands

Synthesis and structural elucidation of a series of thiolate-bridged
heterobimetallic MnCo complexes are described. Irradiation of [Mn2(CO)10] in the presence of Li[BH3SPh]
followed by room-temperature reaction with [Cp*CoCl]2 (Cp*
= η5-C5Me5) afforded dithiolate-
and hydride-bridged dinuclear heterobimetallic MnCo complex [{(Mn(CO)3}(μ-SPh)2(μ-H){CoCp*}] (1). The solid-state structure of 1 established that the
two metal fragments, {Mn(CO)3} and {Cp*Co}, are linked
by a Mn–Co bond. In addition to 1, the reaction
also yielded half-sandwiched trithiolate-bridged dinuclear MnCo complex
[{Mn(CO)3}(μ-SPh)3(CoCp*)] (2) and a dinuclear heterometal-coordinated diborane analogue [{Mn(CO)3}(μ-η2:η2-SBH3)(μ-H)(CoCp*)] (3). To isolate the Se analogues
of 1–3, a similar reaction was carried out in
the presence of Li[BH3SePh] that led to the formation of
complexes [{(Mn(CO)3}(μ-SePh)2(μ-H)(CoCp*)]
(4), [{Mn(CO)3}(μ-SePh)3(CoCp*)]
(5), and [{Mn(CO)3}(μ-η2:η2-SeBH3)(μ-H)(CoCp*)] (6). All of the complexes were characterized by employing multinuclear
nuclear magnetic resonance and infrared spectroscopies as well as
mass spectrometric techniques. Single-crystal X-ray diffraction analyses
of complexes 1, 2, and 4 helped
to establish the molecular formulations and structural integrity of
these complexes. The bonding interactions present in these di- or
trichalcogenate-bridged dinuclear heterobimetallic complexes were
explicated computationally by density functional theory calculations
that supported the {Mn–H–Co} and Mn–Co bonding
interactions in 1 and 4. The inherent electronic
properties of all of the complexes were demonstrated by ultraviolet–visible
spectroscopy. Furthermore, the critical involvement of the bridging
chalcogenato functionalities was probed via cyclic voltammetry and
complementary spectroelectrochemical studies.