Electro‐ and Magnetocommunication in [5,5]Ditrovacenyls, [(η⁷‐C₇H₇)V(η⁵‐C₅H₄‐X‐η⁵‐C₅H₄)V(η⁷‐C₇H₇)], Mediated by the Spacers X=(Z)CHCH, (E)CHCH, >CCH₂, CH₂CH₂, and CH₂

Abstract

Five new paramagnetic dinuclear complexes containing [5]trovacenyl groups, (eta7-C7H7)V(eta5-C5H4-), have been prepared and characterized, including by single-crystal X-ray diffraction. As intervening spacers, ethenediyl units in the geminal and vicinal (Z)- and (E)-bridging modes as well as methanediyl and ethanediyl units have been included with the aim of studying their propensity to transmit electric and magnetic information. It is found that redox splitting of consecutive electron-transfer steps is resolved for reduction (0-->1- -->2-) only, unsaturation of the C2 bridge not being requisite, since the -CH2CH2- spacer also gives rise to a small redox splitting. Magnetic communication is quantified in terms of the exchange coupling constant J, accessible from the EPR hyperfine pattern in solution and from magnetic susceptometry in the solid state. The results obtained from these methods generally differ; this fact is not surprising in view of conformational differences in the respective states of aggregation. It is concluded that orientation-dependent mechanisms of spin-spin interactions (pi-orbital overlap, hyperconjugation) contribute extensively although, as implied by sizeable J values for -CH2- and -C2H4- linked di[5]trovacenyl groups, coupling mediated by the sigma-orbital chain must also be considered.

Cycloheptatrienyl Zirconium Sandwich Complexes with Lewis Basic Phospholyl Ligands (Phosphatrozircenes): Synthesis, Structure, Bonding and Coordination Chemistry

“…[12] Alternatively, the cyclopentadienyl system can also be extended by one or more CH units. Following extensive studies by Green and Ng in the 1990s, [13] independent reports from the groups of Braunschweig, [14] Elschenbroich, [15] Girolami [16] and Tamm [17] have recently revitalised interest in early-transition-metal complexes containing the cycloheptatrienyl (Cht) ligand. Our group has especially focused on Group 4 Cht-Cp sandwich complexes, [18] in which-based on experimental and theoretical results-a formal + 4 oxidation state can be assigned to the metal atom, implying that the C 7 H 7 ligand is best considered as a trianion.…”

A journey into the electrochemistry of vanadium compounds

“…Successively, [5]trovacenyl units were connected with different spacers: boron [244], silicon [245] and tin [246], a carbonyl group [247], methylene, ethylene and various groups with double bonds [248], triple bonds and extensively conjugated triple bonds [249] to the most recent, octamethylferrocene-1,1 -diyl [250]. Up to four [5]-trovacenyl groups were assembled into a benzene ring [251].…”

Fulvalenediyl-bridged heterobimetallic complexes consisting of sandwich and half-sandwich compounds with early–late transition metals

“…In 4a the iron and titanium atoms are separated by 5.3076(8) Å and are connected exo to the p-faces of a common pconjugated hydrocarbyl ligand. Such arrangements are known to support magnetic and electronic interactions between the bridged sites as, for example, in biferrocenes [8], bis(trovacenes) [9], fulvalenediyl-bridged dimanganese and chromium complexes [10] or binickelocenes, -cobaltocenes and -vanadocenes [11]. Hence, complex 4a was exemplarily studied to obtain information about possible metal-metal (Fe(II)-Ti(IV) cooperative effects.…”