Non-symmetrically substituted ruthenocenes: synthesis, structures, and bond nature. Electronic effects of substituents in ruthenocene

Abstract

Non symmetrically substituted ruthenocenes CpRuCp´ (Cp´ = C 5 H 4 CHO (1a), C 5 H 4 COMe (1b), C 5 H 4 SiMe 3 (1c), 1,3 C 5 H 3 (SiMe 3 ) 2 (1d), and Cp* (1e)) were synthesized in high yields by the reaction of [CpRu(MeCN) 3 ] + with cyclopentadienide anions. The structures of complexes 1a,b,d were determined by X ray diffraction analysis. According to the energy partition analysis data, donor substituents strengthen the interaction between the [RuCp] + and Cp´-fragments, whereas acceptor substituents weaken the interaction. This bond is predo minantly electrostatic (56-59%). Based on the calculated electrostatic potentials at the ruthe nium nucleus, it is shown that the donor ability of the substituents decreases in the following order: NMe 2 > NH 2 > OMe > Me  OH > Rc > Fc  Allyl  H > SiMe 3 > CH=CH 2  Ph > PH 2 > > SH  F > SiH 3  CCH > Cl > Br  I  COOMe > COOH > COMe > CF 3 > CHO > CN > NO 2 .

Electron‐Deficient Imidazolium Substituted Cp Ligands and their Ru Complexes

“…To quantify the influence of our new ligands on the metal center, we decided to synthesize their respective mixed Cp*Ru‐complexes and compare their redox potential with the mixed ruthenocene [RuCp*Cp] ( 15 ). The synthesis of the literature known complex starts from [Ru(CH 3 CN) 3 Cp](PF 6 ) using LiCp* [29] and involves a low reaction temperature (−78 °C) and 14 h reaction time in total. However, we obtained a higher yield and comparable purity, when we started from [Ru(CH 3 CN) 3 Cp*](PF 6 ) and LiCp (see Scheme 7) in acetonitrile as solvent and ran the reaction at room temperature for 10 min.…”

“…J HH = 7.0 Hz, 4H,N CH 2 ), 3.66 (s, 6H,N CH 3 ), 2.30 (s, 6H,C CH 3 ), 1.98 (tq, 4H, 3 J HH = 7.4 Hz, 3 J HH = 7.0 Hz, CH 2 ), 1.01 (t, 6H, 3 J HH = 7.4 Hz, CH 3 ). 13 Modified synthesis of 1,2,3,4,5-pentamethylruthenocene (15): [29,53] To as uspension of LiCp (15.0 mg, 208 mmol, 1.05 equiv) in 2mLo f acetonitrile as olution of [Ru(CH 3 CN) 3 Cp*](PF 6 )( 100 mg, 198 mmol, 1equiv) in 1mLo fa cetonitrile was added under stirring. After 10 min, the solvent of the formed solution was removed in vacuo, and the residue extracted three times with 3mLp entane.…”

“…NMR data match with those from literature. [29] Synthesis of 1-(1,3,4,5-tetramethylimidazolium)-1',2',3',4',5'-pentamethylruthenocene hexafluorophosphate (16):T oasuspension of 2 (29.9 mg, 159 mmol, 1equiv) in 0.75 mL of acetonitrile as olution of [Ru(CH 3 CN) 3 Cp*](PF 6 )( 80.0 mg, 159 mmol, 1equiv) in 0.75 mL of acetonitrile was added under stirring. The suspension turned yellow and the solid dissolved after 30 min.…”

X-ray structure analysis of symmetrically substituted 1,1′-diformylruthenocene

“…Different types of substituents on the Cp ring often result in significant changes in the reactivity and properties of ruthenocene as a result of the electronic and steric factors that influence the molecular entity. In general, ferrocene (Fc) and its heavier analogue ruthenocene (Rc) have similar structures (Muratov et al, 2014). The molecular structures of formyl ferrocene, 1,1 0 -diformyl ferrocene and formyl ruthenocene are known in the literature (Braga et al, 1999;Muratov et al, 2014).…”

“…In general, ferrocene (Fc) and its heavier analogue ruthenocene (Rc) have similar structures (Muratov et al, 2014). The molecular structures of formyl ferrocene, 1,1 0 -diformyl ferrocene and formyl ruthenocene are known in the literature (Braga et al, 1999;Muratov et al, 2014). The structures of 1,1 0 -disubstituted ferrocenes containing carboxylic or carbonyl groups have the potential to form a large number of intermolecular interactions, building blocks in two or three dimensions, and to mould the intermolecular hydrogen bonds and CO networks to achieve highly organized superstructures (Braga & Grepioni, 1997).…”