Photochemistry of Cymantrenyl Scorpionates: Formation of a Novel Tritopic Cyclopentadienyl/Scorpionate Hybrid Ligand

Abstract

The ditopic 1,3-cymantrenediyl-bridged scorpionate K2[(OC)3Mn(C5H3(Bpz3)2)] (3) is available in three steps and good yields starting from cymantrene. Its THF adduct [3(THF)2]2 crystallizes in the form of macrocyclic dimers. Reaction of 3 with BrMn(CO)5 gives access to the trinuclear MnI complex [(OC)3Mn(C5H3(Bpz3Mn(CO)3)2)] (4). Irradiation of 3 in CD3CN for 30 min with a high-pressure mercury lamp (λmax = 510 nm) results in the liberation of one CO molecule and intramolecular Mn-pyrazolyl coordination (mono-ansa-complex K2[(OC)2Mn(C5H3(B(μ-pz)pz2)(Bpz3)]; 5). Upon further irradiation, 5 undergoes demetalation, and the free cyclopentadienyl/scorpionate hybrid ligand K2[C5H4(Bpz3)2] (7) can be isolated from the reaction mixture. 7 has been structurally characterized both as a THF adduct (coordination polymer [7a(THF)2]∞) and as a THF/18-crown-6 adduct (dimer [7a(18-c-6)(THF)2]2).

Distortion Pathways of Transition Metal Coordination Polyhedra Induced by Chelating Topology

“…Inspection of the structures with a degree of elongation greater than 20% reveals that they correspond to d 0 , d 5 , and d 10 ions: Cd­(II), − Mn­(II), − Y­(III), , and Ag­(I). , An outlier found among the TpM complexes at S­(OC-6) ≈ 3.8 (Figure b) represents a Cd compound in which the benzyl-1,8-naphthalimide groups hanging from the pivotal carbon atom of TpM introduce severe steric strain that may explain a different distortion mode. It undergoes an elongated Bailar twist of 41% instead, with a very small deviation from that distortion pathway (0.8%).…”

Tricarbonylmanganese(I) and –rhenium(I) Complexes of Imidazol‐Based Phosphane Ligands: Influence of the Substitution Pattern on the CO Release Properties

“…Whereas compounds 1b and 2b with the imidazol-2-ylphosphane ligand liberate approximately 2 mol of CO per mol of complex, in 3b-5b with the coordinated imidazol-4-ylphosphanes, only one molecule of CO per Mn(CO) 3 unit is re- leased, which is also usually found in other complexes LMn(CO) 3 . [46,47] Apparently, the intermediates formed after liberation of the first carbon monoxide have a different reactivity towards further photolytic release of the remaining CO ligands depending on the TIP ligand. The electronic and steric effects that govern this behavior will be the subject of a more detailed study involving time-resolved spectroscopic investigation of 1b-5b and electronic structure calculations on the title compounds and their photoproducts.…”

Third‐Generation Scorpionates [RBpz3]– – How Influential Is the Nondonor Substituent R?

“…The vast majority of tris(pyrazol‐1‐yl)borates still contains a hydrogen atom as substituent R. In some cases, alkyl and aryl substituents (e.g., R = Me, i Pr, n Bu, Ph), have been used, mainly to avoid complications from possible reactions of the BH fragment and to ensure good solubility of the complexes obtained. Moreover, the R group offers the possibility to link two scorpionate moieties together and, thereby, generate oligotopic ligands for the preparation of coordination polymers,, , metal‐containing macrocycles, and multiple‐decker sandwich complexes . Recently, Reger et al elucidated the spin‐state crossover behavior of a series of Fe II complexes [(RBpz 3 ) 2 Fe] (R = substituted aryl) in the solid state.…”