Preparations and structures of (η6-arene)ruthenium(II) complexes bearing 1,1′-bis(diphenylphosphinomethyl)ferrocene or 1,1′-bis(diphenylphosphino)ferrocene

Beyond phosphorus: synthesis, reactivity, coordination behaviour and catalytic properties of 1,1'-bis(diphenylstibino)ferrocene

Compared to their widely studied phosphine counterparts, ferrocene stibines have received only marginal attention thus far. This paper describes the synthesis of 1,1'-bis(diphenylstibino)ferrocene (1*), which is an antimony analogue of the ubiquitous dppf, and our investigations into the reactivity and coordination behaviour of this compound. Thus, distibine 1 was oxidised to stiboranes fc(SbPh₂X₂)₂ (X = Cl, 2*; F, 6*; fc = ferrocene-1,1'-diyl) and to stibine-stiborane Ph₂SbfcSbPh₂F₂ (5*). Compounds 2 and 6 were easily hydrolysed to produce ferrocenophanes fc[SbPh₂XOSbPh₂X] (X = Cl, 3*; F, 7*). Removing the halogen from 3 with silver(I) salts afforded the corresponding ferrocenophanes with O-bound oxyanions, fc[SbPh₂ZOSbPh₂Z] (Z = NO₃, 4a*; ClO₄, 4b*), which were alternatively prepared from 2 and also converted back to 2 by adding a chloride source. Through investigations into the coordination behaviour of distibine 1, the following compounds were isolated and characterised: [(μ-ClO₄)₂{Ag(1-κ²Sb,Sb')}₂] (8*), [Ag(1-κ²Sb,Sb')₂]X (X = ClO₄, 9a; SbF₆, 9b*), [(μ(Sb,Sb')-1){(arene)MCl₂}₂] (10*, 11*) and [(arene)MCl(1-κ²Sb,Sb')][PF₆] (12*, 13*; 10, 12: M/arene = Ru/η⁶-p-cymene, 11, 13; Rh/η⁵-C₅Me₅), [(η⁵-C₅Me₅)RuCl(1-κ²Sb,Sb')] (14), [MCl₂(1-κ²Sb,Sb')] (M = Pd, 15*; Pt, 16*), [Pd(1-κ²Sb,Sb')₂]X₂ (X = BF₄, 17a; SbF₆, 17b*), [Pd(η²-ma)(1-κ²Sb,Sb')] (18*; ma = maleic anhydride), [(μ(Sb,Sb')-1)(AuCl)₂] (19*), and [Au(1-κ²Sb,Sb')₂]X (X = AuCl₂, 20a*; SbF₆, 20b*). Inspection of the structural parameters suggested that complexes featuring 1 exhibit less sterically strained structures than their dppf analogues due to longer M-Sb and Sb-C bonds, which reduce crowding around the ligated metal centre. Cyclic voltammetry and DFT calculations revealed that the primary electrochemical oxidation of 1 is reversible and occurs at the ferrocene unit. Based on preliminary catalytic tests in Suzuki-Miyaura biaryl coupling, Pd-1 complexes exhibited a lower efficiency than their respective Pd-dppf analogues. (An asterisk indicates that the crystal structure has been determined.).

Synthesis, coordination behavior, and catalytic properties of dppf congeners with an inserted carbonyl moiety

Dppf-type ligands, desymmetrized by an inserted carbonyl group coordinate Pd(ii) and Pd(0). Among the air-stable Pd(0) complexes, the compound containing the least electron-donating ligand gives the best catalytic results in the Stille reaction.

Heterodimetallic compounds assembled from ferrocenedicarboxylato and ferrocenecarboxylato ligands

Heteropolynuclear organometallic compounds have been constructed by using two kinds of ferrocene-based ligands, 1,1'-ferrocenedicarboxylic acid (H(2)L(1)) and ferrocenecarboxylic acid (HL(2)). Reactions the ligand H(2)L(1) with copper(II) and nickel(II) salts, in the presence of pyridine, give a tetranuclear Cu(2)Fe(2) mixed-metallic box Cu(2)L(1)(2)(Py)(2)(DMF)(2)(H(2)O)(2) (1) and a tetranuclear heterobimetallic helix Ni(2)L(1)(2)(Py)(4)(H(2)O) (2), respectively. In these complexes, the ferrocene moieties show cisoid conformations which lead to the formation of the finite coordination geometry, i.e. to molecular complexes. Interactions of the ligand H(2)L(1) with lanthanide ions afford two-dimensional networks [La(2)L(1)(3)(CH(3)OH)(4)]( infinity ) (3), [Eu(2)L(1)(3)(H(2)O)(5)]( infinity ) (4), and [Gd(2)L(1)(3)(CH(3)OH)(2)(H(2)O)(3)]( infinity ) (5), respectively, in which transoid conformations of the ferrocene moiety provide opportunities to form infinite 2-D networks. It is suggested that the conformational freedom of the ferrocene moiety makes the ligand L(1) display different conformations and coordination modes in these complexes. In addition, the pi.pi interactions related to the ferrocene moieties were also found to stabilize the supramolecular architectures in the solid state. As a comparison, reaction of lanthanide ions with the ligand HL(2) resulted in three isostructural heterodinuclear windmill-shaped compounds Ln(2)L(2)(6)(CH(3)OH)(2)(H(2)O)(5) [Ln = La (6), Eu (7), and Gd (8)] by simply diffusing the solutions of lanthanide ions into the mixture of HL(2) and NaOH, respectively. Electrochemical properties of the ferrocene-containing complexes 1-8 are also investigated in the solution or solid state.