Synthesis of Novel Heterotetrametallic (d6-d10-d8) Polyalkynyl Complexes Starting from Heterobimetallic Chloride-Bridged (d6-d8) Compounds

Abstract

The reaction between the half‐sandwich cyclopentadienyl complexes [M(η5‐C5Me5)Cl2(PEt3)] (M = Rh, Ir) and [cis‐M′(C6F5)2(thf)2] (M′ = Pt, Pd; thf = tetrahydrofuran) affords the corresponding chloride‐bridged heterobinuclear Rh,Ir/Pt,Pd complexes [(PEt3)(η5‐C5Me5)M(μ‐Cl)2M′(C6F5)2] (1−4). In contrast, similar reactions with the chloro‐bridged binuclear compounds [{M(η5‐C5Me5)Cl(μ‐Cl)}2] (M = Rh, Ir) lead instead to the unexpected mixed salt complexes {Cp*M(μ‐Cl)3MCp*}2[{(C6F5)2M′(μ‐Cl)}2] (M = Rh, Ir; M′ = Pt, Pd) (5−8) as a result of chloride transfer. The structures of [(PEt3)(η5‐C5Me5)Rh(μ‐Cl)2Pt(C6F5)2] (1) and {Cp*Rh(μ‐Cl)3RhCp*}2[{(C6F5)2Pd(μ‐Cl)}2] (6) have been determined by X‐ray diffraction analyses. The reactivity of the new chloride‐bridged heterobinuclear compounds 1−4 towards the alkynylating agents [M′′(C≡CR)]n (M′′ = Cu, Ag) has also been investigated: a new type of tetranuclear product, [(PEt3)Cp*M(μ‐1κCα:η2‐C≡CPh)2M′′2(μ‐4κCα:η2‐C≡CPh)2Pt(C6F5)2] (M = Rh, Ir; M′′ = Cu, Ag) (9−12), was obtained, and fully characterized in the case of complex [(PEt3)Cp*Rh(μ‐1κCα:η2‐C≡CPh)2Cu2(μ‐4κCα:η2‐C≡CPh)2Pt(C6F5)2] (9).

Copper(I) Alkyne and Alkynide Complexes

“…In these species two different bis­(alkynyl) metal fragments are connected to each other via two copper or two silver atoms. As expected, the Rh and Ir atoms are tetrahedrally coordinated by the cyclopentadienyl ligand, the PEt 3 ligand, and the two σ carbon atoms of the PhCC groups, which act as bridging units between the copper atoms, while Pt possesses a somewhat distorted square planar geometry consisting of four σ carbons, two from the mutually cis-oriented C 6 F 5 units and the other two from the PhCC moieties, the latter of which is π-bonded to copper . Double protonation of [ cis -Pt­(CCPh) 2 (Hdmpz) 2 ] in the presence of M­(I) salts (M = Cu, Ag, Au) afforded discrete hexanuclear [PtM 2 (μ-CCPh) 2 (μ-dmpz) 2 ] 2 ( 68 ; dmpz = dimethylpyrazolate), in which the bis­(alkynyl)­platinum–dmpz building blocks are connected by the four M­(I) ions and are stabilized by PhCC and dmpz bridging ligands (Figure ) .…”

“…The platinum–alkynyl units are typical for μ 2 -η 2 (σ,π) alkynyl bridging motifs. − The intermetallic Pt···Cu (2.944(1)–3.179(1) Å) and Cu···Cu distances (3.036(1) Å) indicate that no metal–metal contacts exist. Copper­(I) and silver­(I) ions are also in a position to span bis­(alkynyl) rhodium­(III) and/or iridium­(III) and/or platinum­(II) ions, as verified in [(M­(PEt 3 )­(η 5 -C 5 Me 5 )­(μ-1 κC α :η 2 -CCPh) 2 )­M′ 2 (Pt­(C 6 F 5 ) 2 (μ-4 κC α :η 2 -CCPh) 2 )] (M = Rh, M′ = Cu; M = Rh, M′ = Ag; M = Ir, M′ = Cu; M = Ir, M′ = Ag) . In these species two different bis­(alkynyl) metal fragments are connected to each other via two copper or two silver atoms.…”

Boron Functionalization and Unusual B–C Bond Activation in Rhodium(III) and Iridium(III) Complexes with Diphenylbis(pyrazolylborate) Ligands (Ph2Bp)

“…The dimeric chloro-bridged complexes [{M(η 5 -Cp*)(μ-Cl)Cl} 2 ] (M = Rh, Ir) have been extensively used as starting materials for a wide number of organometallic complexes that have found applications in several fields . These complexes undergo a rich variety of chemistry through chloro bridge cleavage reactions, leading to the formation of interesting neutral and cationic mononuclear complexes . In addition, rhodium(III) and iridium(III) complexes containing scorpionate ligands have recently attracted considerable attention because of their ability to activate the aliphatic and aromatic C–H bonds of hydrocarbons and other substrates …”

Ring-opening reactions induced by gold(i) of five- and four-coordinate palladium(ii) and platinum(ii) complexes containing tripodal or linear polyphosphines

“…1 The choice of supporting ligands such as linear polyphosphines, carboxylates and bridging dithiolates, sulfides and chlorides afforded a variety of compounds containing heterobimetallic centres. [2][3][4][5][6][7][8] Diphosphines or aminophosphines, 2-4 were the most commonly supported phosphine ligands used with the works on triphosphines being more limited. 9 On the other hand, due to the prevention to dissociation of chelating polyphosphines, 10 the reactions between two mononuclear species, one of them involving a diphosphine, to give bimetallic derivatives usually proceeds without any chelate ring-opening process.…”