Synthesis and characterization of oligonuclear Naphthalene and Diphosphacyclobutadiene transition metal complexes

This dissertation deals with the synthesis and characterization of oligonuclear transition metal complexes, which contain two different types of bridging ligand: naphthalene (C10H8) and 1,3-diphosphacyclobutadiene P2C2R2, a phospha-organic analogue of cyclobutadiene. Chapter 1 gives a brief introduction into the basic characteristics of polyarene and naphthalene-brigded complexes. Furthermore, the chemistry of metal complexes with diphosphacyclobutadienes is briefly introduced. In chapter 2, the synthesis and the elucidation of the electronic structure of dissymmetrical naphthalene-bridged iron-iron and iron-ruthenium complexes are discussed. Investigations concerning the reactivity of bis(diphosphacyclobutadiene) sandwich anions towards silicon electrophiles are described in chapter 3. The first results of coordination studies of these novel phospha-organometallic building blocks are presented in chapters 3-6

Functionalization of 1,3-diphosphacyclobutadiene cobalt complexes via Si–P bond insertion

We report the synthesis of functionalized 1,3-bis(diphosphacyclobutadiene) complexes via the insertion of carbon-oxygen bonds of ethers, esters, aldehydes and amides into the P-Si bond of silylated complexes. Reactions of [K(tol)(2)][Co(eta(4)-P2C2R2)(2)] [[K(tol)(2)] [1a]: R= tBu, [K(tol)(2)][1b]: R= tPent (=tert-pentyl)] with Me3SiCl afford the trimethylsilyl-substituted derivatives [Co(eta(4)-P2C2R2 SiMe3)(eta(4)-P2C2R2)] (2a,b, R= tBu, tPent). The Me3Si group is connected to a phosphorus atom of one of the 1,3-diphosphacyclobutadiene ligands. 2a,b readily react with organic substrates containing C-O single and C=O double bonds at ambient temperature. [Co(eta(4)-P2C2R2(CH2)(4)OSiMe3)(eta(4)-P2C2R2)] (3a, b) are formed by reaction of 2a, b with traces of THF. They can also be isolated by reacting the THE solvates [K(thf)(2){Co(P(2)C(2)tBu(2))(2)}] ([K(thf)(2)][1a]) and [K(thf)(3){Co(P-2 C(2)tPent(2))(2)}] ([K(thf)(3)][1b]) with Me3SiCl in toluene or THE The adamantyl-substituted complex [Co(eta(4)-P2C2R2(CH2)(4)OSiMe3)(eta(4)-P(2)C(2)Ad(2))] (3c) was prepared analogously from [K(thf)(4){Co(P(2)C(2)Ad(2))(2)}] and Me3SiCl. [K(thf)(2)][1a] reacts cleanly with Ph3SnCl affording [Co(eta(4)-P(2)C(2)tBu(2)SnPh(3))(eta(4)-P2C2Bu2)] (4) in high yield. Reaction of 2a with styrene oxide affords [Co(eta(4)-P(2)C(2)tBu(2)PhC(2)H(3)OSiMe(3))(eta(4)-P(2)C(2)tBu(2))] (5) as a single regioisomer. By contrast, multinuclear NMR spectroscopic studies indicate mixtures of two isomeric insertion products 6/6' and 7/7', respectively, which result from the insertion of 1,2-epoxy-2-methylpropane and 1,2-epoxyoctane.Moreover, these monitoring studies show that reactions of 2a with acyclic ethers afford alkyl substituted complexes such as [Co(eta(4)-P(2)C(2)tBu(2)Et)(eta(4)-P(2)C(2)tBu(2) )] (8) and alkylsilyl ethers. Reaction of 2a with y-butyrolactone gives [Co(eta(4)-P(2)C(2)tBu(2)(CH2)(3)C(O)OSiMe3)(eta(4)-P(2)C(2)tBu(2))] (9) via cleavage of the endocyclic C-O single bond of the lactone. Benzaldehyde and acetone cleanly react with 2a to [Co(eta(4)-P(2)C(2)tBu(2)CH(Ph)OSiMe3)(eta(4)-P(2)C(2)tBu(2))] (10) and [Co(eta(4)-P(2)C(2)tBu(2)CMe(2)OSiMe(3))(eta(4)-P(2)C(2)tBu(2))] (11), while the sterically more demanding ketones 3-pentanone and acetophenone selectively yield the known hydride complex [Co(eta(4)-P(2)C(2)tBu(2))(2)H] (A). Phenyl isocyanate reacts with 2a at elevated temperature to form [Co(eta(4)-P(2)C(2)tBu(2)CON(Ph) SiMe3)(eta(4)-P(2)C(2)tBu(2))] (12) with a functionalizecl eta(3) coordinated ligand. [K(tol)(2)][1a], [K(tol)(2)][1b], 2a, 2b, 3a-c, 4, 5, and 9-12 were isolated and characterized by multinuclear NMR spectroscopy, UV/Vis spectroscopy and elemental analysis. [K(tol)(2)][1b], 2a, 2b, 3c, 4, 5, and 9-12 were additionally characterized by X-ray crystallography

Gold(I) and Silver(I) complexes of diphosphacyclobutadiene cobaltate sandwich anions

The synthesis and structural characterization of the first coordination compounds of bis(diphosphacyclobutadiene) cobaltate anions [M(P2 C2 R2)2]- is described. Reactions of the new potassium salts [K(thf)3{CO(n4-P2C2tPent2)2}] (1) and [K(thf)4{Co(n4-P2C2AD2)2}] (2) with [AuCl(tht)] (tht=tetrahydrothiophene), [AuCl(PPh3)] and Ag[SbF6] afforded the complexes [Au{Co(P2C2tPent2)2}(PME3)2] (3), [Au{CO(P2C2Ad2)2}]x (4), [Ag{Co(P2C2Ad2)2}]x (5), [Au(PME3)4][Au{Co(P2C2Ad2)2}2] (6), [K([18]crown-6)(thf) IND. 2][Au{Co(P2C2Ad2)2}2] (7), and [K([18]crown-6)(thf)2][M{Co(P2C2Ad2)2}2] (8: M=Au 9: M=Ag) in moderate yields. The molecular structures of 2 and 3, and 6–9 were elucidated by X-ray crystallography. Complexes 4–9 were thoroughly characterized by 31 P and 13 C solid state NMR spectroscopy. The complexes [Au{Co(P2C 2Ad2)2}]x (4) and [Ag{Co(P2C2Ad2)2}] x (5) exist as coordination polymers in the solid state. The linking mode between the monomeric units in the polymers is deduced. The soluble complexes 1-3, 6, and 7 were studied by multinuclear 1 H-, 31 P{1 H}-, and 13 C{1 H} NMR spectroscopy in solution. Variable temperature NMR measurements of 3 and 6 in deuterated THF reveal the formation of equilibria between the ionic species [Au(PME3)4] +, [Au(PME3)2] +, [Co(P2C2R2)2] -, and [Au{Co(P2C2R2)2}2]- (R=tPent and Ad).DFG (IRTG1444, WO1496/1-1 to 4-1)Fonds der Chemischen Industrie (FCI)European Phosphorus Sciences Network (PhoSciNet)NRW Forschungsschule “Molecules and Materials

Solid state NMR studies and chemical shift calculations of a gold(I) complex with a diphosphacyclobutadiene cobaltate sandwich anion

The 31P and 13C solid state nuclear magnetic resonance spectra of a neutral gold(I) complex with bis(diphosphacyclobutadiene) cobaltate anions, [Au{Co(P2C2tPent2)2}2(PMe3)2], are reported. Complete 31P resonance assignments have been derived from saturation transfer, radio-frequency driven recoupling (RFDR) and RTOBSY experiments and confirmed further by ab-initio calculations of magnetic shielding tensors by density functional theory, with consideration of relativistic effects. Coordination of the diphosphacyclobutadiene ring with gold(I) results in a high-frequency shift of the 31P signal of the directly coordinated P atom, whereas a low-frequency shift is observed for the P atom at the opposite end of that ring. Based on these results, a previous assignment made for the complex salts [Au(PMe3)4][Au{Co(P2C2Ad2)2}2] and [K(18-crown-6)(thf)2][Au{Co(P2C2Ad2)2}2] (Ad=adamantyl) must be corrected.DFG (SFB858, WO1496/4-1)European Phosphorus Sciences Network (PhoSciNet)Fonds der Chemischen Industrie (FCI)NRW Forschungsschule “Molecules and Materials

Synthesis and Electronic Structure of Dissymmetrical, Naphthalene-Bridged Sandwich Complexes [Cp′Fe(μ‑C₁₀H₈)MCp*]^<i>x</i> (<i>x</i> = 0, +1; M = Fe, Ru; Cp′ = η⁵‑C₅H₂‑1,2,4‑<i>t</i>Bu₃; Cp* = η⁵‑C₅Me₅)

The dissymmetrical naphthalene-bridged complexes [Cp′Fe­(μ-C₁₀H₈)­FeCp*] (<b>3</b>; Cp* = η⁵-C₅Me₅, Cp′ = η⁵-C₅H₂-1,2,4-<i>t</i>Bu₃) and [Cp′Fe­(μ-C₁₀H₈)­RuCp*] (<b>4</b>) were synthesized via a one-pot procedure from FeCl₂(thf)_1.5, Cp′K, KC₁₀H₈, and [Cp*FeCl­(tmeda)] (tmeda = <i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetramethylethylenediamine) or [Cp*RuCl]₄, respectively. The symmetrically substituted iron ruthenium complex [Cp*Fe­(μ-C₁₀H₈)­RuCp*] (<b>5</b>) bearing two Cp* ligands was prepared as a reference compound. Compounds <b>3</b>–<b>5</b> are diamagnetic and display similar molecular structures, where the metal atoms are coordinated to opposite sides of the bridging naphthalene molecule. Cyclic voltammetry and UV/vis spectroelectrochemistry studies revealed that neutral <b>3</b>–<b>5</b> can be oxidized to monocations <b>3</b>⁺–<b>5</b>⁺ and dications <b>3</b>²⁺–<b>5</b>²⁺. The chemical oxidation of <b>3</b> and <b>4</b> with [Cp₂Fe]­PF₆ afforded the paramagnetic hexafluorophosphate salts [Cp′Fe­(μ-C₁₀H₈)­FeCp*]­PF₆ ([<b>3</b>]­PF₆) and [Cp′Fe­(μ-C₁₀H₈)­RuCp*]­PF₆ ([<b>4</b>]­PF₆), which were characterized by various spectroscopic techniques, including EPR and ⁵⁷Fe Mössbauer spectroscopy. The molecular structure of [<b>4</b>]­PF₆ was determined by X-ray crystallography. DFT calculations support the structural and spectroscopic data and determine the compositions of frontier molecular orbitals in the investigated complexes. The effects of substituting Cp* with Cp′ and Fe with Ru on the electronic structures and the structural and spectroscopic properties are analyzed