Heterobimetallic Complexes of Rhodium Dibenzotetramethylaza[14]annulene [(tmtaa)Rh-M]: Formation, Structures, and Bond Dissociation Energetics

Abstract

A rhodium(II) Dibenzotetramethylaza[14]annulene dimer ([(tmtaa)Rh]2) undergoes metathesis reactions with [CpCr-(CO)3]2, [CpMo(CO)3]2, [CpFe(CO)2]2, [Co(CO)4]2, and [Mn-(CO)5]2 to form (tmtaa)Rh-M complexes (M = CrCp(CO)3, MoCp(CO)3, FeCp(CO)2, Co(CO)4, or Mn(CO)5). Molecular structures were determined for (tmtaa)Rh-FeCp(CO)2, (tmtaa)Rh-Co(μ-CO)(CO)3, and (tmtaa)Rh-Mn(CO)5 by X-ray diffraction. Equilibrium constants measured for the metathesis reactions permit the estimation of several (tmtaa)Rh-M bond dissociation enthalpies (Rh—Cr = 19 kcal mol−1, Rh—Mo = 25 kcal mol−1, and Rh—Fe = 27). Reactivities of the bimetallic complexes with synthesis gas to form (tmtaa)Rh-C(O)H and M-H are surveyed.

CoIII–Carbene Radical Approach to Substituted 1H-Indenes

“…This is in sharp contrast to the synthesis of porphyrin complexes, which is in general work-intensive, low yielding, time-consuming and produces large amounts of unwanted side products, thus demanding elaborate (column chromatographic) purification steps. The MeTAA ligand has similar bonding properties as a porphyrin, which reflects in its ability to bind a variety of transition metals. , However, there are also some differences which likely explain its increased reactivity as compared to [Co­(TPP)]. While porphyrins have an aromatic (4 n + 2) delocalized π-cloud, MeTAA is Hückel antiaromatic (4 n ), which increases the flexibility of the ligand.…”

Synthesis, functionalization and coordination chemistry of dibenzotetraaza[14]annulenes

“…Wayland et al [47][48][49] discovered a set of versatile reactions between rhodium and DBTAA. The dimeric rhodium(II) complex 14 was synthesized by refluxing rhodium(II) acetate with 2a in toluene (Scheme 6) [47].…”

“…Interestingly, the X-ray crystallographic analysis of 18 (Figure 5) shows the presence of a semibridging carbonyl ligand between the Rh(II)−Co single bond, which occurs due to the donation of the rhodium dπ orbital into the CO π* orbital. Complex 19 can also be prepared by the simple mixing of 14 with [Mn(CO)5]2 under similar conditions as for the preparation of 17 and 18 [49]. of cyclooctadiene with two CO ligands afforded the highly hygroscopic tetracarbonyl complex 24 in good yield.…”

Activation of C–H, N–H, and O–H Bonds via Proton-Coupled Electron Transfer to a Mn(III) Complex of Redox-Noninnocent Octaazacyclotetradecadiene, a Catenated-Nitrogen Macrocyclic Ligand

“…The vast majority of tetrazene complexes exhibit only a single tetrazene ligand, with only a few exceptions to our knowledge where complexes of two tetrazene ligands have been reported. , In this report, we describe a related assembly of a pair of tetrazene units embedded in a macrocyclic ligand around manganese, using as a synthon the disubstituted 1,3-diazidopropane. The result is a novel 1,2,3,4,­8,9,10,11-octa­aza­cyclo­tetra­deca-2,9-diene-1,4,8,11-tetraido macrocycle (OIM) ligand, an octanitrogen topological analogue of the previously reported 2,3,9,10-tetra­aza­cyclo­tetra­deca-1,3-diene macrocycle (TIM), and a redox noninnocent, unsaturated variant of the extensively reported tetra­aza­cyclo­tetra­decane (Cyclam) ligand. − This ligand also represents a more saturated analogue of the tetraazaannulene ligand and derivatives thereof, which has been a focus of our work − and that of others, including examples of manganese chemistry. − We report the synthesis of manganese complexes of OIM, their electronic structures, and PCET reactions via activation of C–H, N–H, and O–H bonds.…”