Tris(3,5‐dimethylpyrazolyl)methane‐Based Heterobimetallic Complexes that Contain Zn and CdTransition‐Metal Bonds: Synthesis, Structures, and Quantum Chemical Calculations

Abstract

Reactions of the tris(3,5-dimethylpyrazolyl)methanide amido complexes [M'{C(3,5-Me2 pz)3 }{N(SiMe3 )2 }] (M'=Mg (1 a), Zn (1 b), Cd (1 c); 3,5-Me2 pz=3,5-dimethylpyrazolyl) with two equivalents of the acidic Group 6 cyclopentadienyl (Cp) tricarbonyl hydrides [MCp(CO)3 H] (M=Cr (2 a), Mo (2 b)) gave different types of heterobimetallic complex. In each case, two reactions took place, namely the conversion of the tris(3,5-dimethylpyrazolyl)methanide ligand (Tpmd*) into the -methane derivative (Tpm*) and the reaction of the acidic hydride M = H bond with the M' = N(SiMe3 )2 moiety. The latter produces HN(SiMe3 )2 as a byproduct. The Group 2 representatives [Mg(Tpm*){MCp(CO)3 }2 (thf)] (3 a/b) form isocarbonyl bridges between the magnesium and chromium/molybdenum centres, whereas direct metal-metal bonds are formed in the case of the ions [Zn(Tpm*){MCp(CO)3 }](+) (4 a/b; [MCp(CO)3 ](-) as the counteranion) and [Cd(Tpm*){MCp(CO)3 }(thf)](+) (5 a/b; [Cd{MCp(CO)3 }3 ](-) as the counteranion). Complexes 4 a and 5 a/b are the first complexes that contain Zn - Cr, Cd - Cr, and Cd - Mo bonds (bond lengths 251.6, 269.8, and 278.9 pm, respectively). Quantum chemical calculations on 4 a/b* (and also on 5 a/b*) provide evidence for an interaction between the metal atoms.

A theoretical study of the bonding capabilities of the zinc‐zinc double bond

“…Concerning computed MZn distances, they compare well with experimental values found by X‐ray methods. For instance, the ZnCr bond distances of 2.569 and 2.529 Å are close to the value of 2.516(1) Å determined in the cation [(Tp*)Zn{CrCp(CO) 3 }] + that showed an unsupported CrZn bond . The computed ZnFe length of 2.401 Å is identical to that found in [(py) 3 ZnFe(CO) 4 ] complex (2.4017(3) Å) and similar to other complexes containing this FeZn bond without bridging coligands .…”

Generalized Kohn‐Sham energy decomposition analysis and its applications

“…Metal‐ligand interactions play important roles in nanocrystals, molecular recognition, drug design, metalloprotein chemistry, and so on. Both GKS‐EDA and LMO‐EDA have been employed in the interpretations of various metal‐ligand interactions, which are not trivial tasks due to the inherent complexity of the arrangement of electrons in d‐ and f‐metal‐atom orbitals coupled with the various ligands.…”

Synthesis and Characterization of Heterobimetallic Tantalum–Rhodium and Tantalum–Iridium Complexes Connected by a Tantalacyclopentadiene Fragment

“…Among them, heterobimetallic complexes containing early‐ and late‐transition metals (early‐late heterobimetallic complexes, ELHBs) have attracted special interest because they provide vastly different reaction sites that comprised of a hard Lewis acidic early‐transition metal and a soft Lewis basic late‐transition metal, respectively. [2] In addition, the unique nature of ELHBs is highlighted to the covalent bonding[3] and dative bonding[3c][4] character of the metal–metal interaction in ELHBs, and the metal–metal interaction has been widely applied for activating small molecules. [3i][4e – o][5] Such ELHBs involving a metal–metal interaction were categorized into two types of structures: one is a metal–metal bond without any bridging ligand, while the other is a ligand‐bridged metal–metal bonded structure.…”

“…[3d – h][4p][5d – f][6] Similar heterobimetallic complexes are also prepared by the treatment of late‐transition‐metal hydride complexes and amidometal complexes of early‐transition metals via amine elimination reactions. [3j][3k] These nonbridged heterobimetallic complexes can be fragmented into two monometallic complexes upon reaction with external substrates. In contrast, ligand‐supported early‐ and late‐heterobimetallic complexes are much more attractive because the metal–metal interaction or the proximity of the two metal centers is maintained, leading to unique reactivity.…”