Synthesis and structural characterization of the first transition metal cluster containing a PPh2AuPPh3 ligand,Ir4(CO)8(μ-CO)3(PPh2AuPPh3), and its conversion into Ir4(CO)9(μ-CO)(μ-PPh2)(μ-AuPPh3)

Deprotonation of Ir₄(CO)₁₁PPh₂H (1) in the presence of [AuPPh₃][PF₆] yields the novel species Ir₄(CO)₁₁(PPh₂AuPPh₃) (2), which possesses a tetrahedral framework bearing a terminally bound PPh₂AuPPh₃ ligand. When heated in toluene, 2 is converted into the phosphido species Ir₄(CO)₁₀(μ-PPh₂)(μ-AuPPh₃).     

Synthesis and characterisation of [Ag2Pt4(μ-S)4(PPh3)8](BF4)2 · 0.25CHCl3

[Pt₂(μ₂-S)₂(PPh₃)₄] functions effectively as a bridging bidentate ligand towards Ag⁺ to form [Ag₂Pt₄(μ₃-S)₄(PPh₃)₈]²⁺. A single crystal X-ray crystallographic anaylsis of the BF₄⁻ salt has demonstrated that both Ag⁺ ions are linearly coordinated to the sulphur atoms, but the small bite angle of the [Pt₂(μ-S)₂(PPh₃)₄] ligand leads to an Ag…Ag contact distance of only 2.815(4) Å.     

Synthesis and molecular and crystal structure of the octanuclear palladium cluster Pd8(μ3-CO)2(μ2-CO)6(PMe3)7

Treatment of bis(dibenzylideneacetone)palladium with trimethylphosphine under a carbon monoxide atmosphere gives the title complex in good yield. X-ray crystallography has shown the structure of the complex to consist of an octahedron of palladium atoms which is bicapped by two further palladium atoms in an asymmetric fashion. Seven of the eight palladium centres carry terminal trimethylphosphine ligands. Two face-bridging and six edge-bridging CO molecules complete the ligand shell.     

Properties of a New 58-Electron Butterfly [Pt4(μ2-dpam)3(μ2-CO)3(η1-dpam)]2+ Cluster

A new organometallic cluster [Pt₄(₂-dpam)₃(₂-CO)₃(¹-dpam)] X₂ (X=CF₃CO ₂ ^- ; 4a) was prepared from a reaction between Pt(dpam)(CF₃CO₂)₂ and CO in a methanol (water mixture). The PF ₆ ^- salt 4b is obtained from an anion exchange with NH₄PF₆ in methanol. Dark red crystals suitable for X-ray crystallography (X=PF ₆ ^- ) revealed the commonly encountered butterfly structure for a 58-electron Pt cluster (angle between the two Pt₃ planes =95.36(8)°, nonbonding Pt...Pt distance =3.094(1) Å). The structure consists of two edge sharing Pt₃ triangles, a small one 'Pt₃(₂-dpam) ₃ ²⁺ and a larger one Pt₃(₂-CO)₃(L)₃ where L=As group. The Extended Huckel Molecular Orbital calculations (EHMO) have been rationalized from interactions of two L and PtL ₂ ²⁺ fragments onto the planar triangular Pt₃(₂-CO)₃L₃ cluster (L = AsH₃). The compound is luminescent at 77 K with a structureless band located at 690 nm (_e=3.2 ±0.2s). Finally, the ¹H NMR spectra are interpreted, particularly with respect to fluxionality and presence of two isomers. X-ray data for 4b: orthorhombic, C c2a, a=26.320(9), b=27.613(6), c=28.891(4) Å, V=20998(9) ų, Z=4, D(calc.)=1.925 Mg/m³.     

Platinum-silver clusters: synthesis and crystal structure of [Pt3Ag(μ-CO)3(PPh3)5]ClO4 · 2H2O

Reaction of [NBu₄]₂[Pt₁₂(CO)₂₄] with [Ag(PPh₃)₄]ClO₄ and PPh₃ leads to two isolable platinum-silver clusters; the title complex was characterised by single crystal X-ray diffraction. the Pt₃Ag core is tetrahedral; one Pt atom is seven-coordinated, the other two are six-coordinate.     

Theoretical Analysis of the Mackay Icosahedral Cluster Pd55(PiPr3)12(μ3-CO)20: An Open-Shell 20-Electron Superatom

The electronic structure of the spherical Mackay icosahedral nanosized cluster Pd₅₅(PiPr₃)₁₂(μ₃-CO)₂₀ is analyzed by using DFT calculations. Results reveal that it can be considered as a regular superatom with a “magic” electron count of 20, characterized by a 1S² 1P⁶ 1D¹⁰ 2S² jellium configuration. Its open shell nature is associated with partial occupation of non-jellium, 4d-type, levels located on the interior of the Pd₅₅ kernel. This shows that the superatom model can be used to rationalize the bonding and stability of spherical ligated group 10 clusters, despite their apparent 0-electron count.     

An Improved Synthesis for Novel Hexaruthenium Cluster Compound Bearing Two Quadruply-Bridging CO Ligands: Synthesis, Characterization, and X-Ray Structural Analysis of Ru6(CO)12(μ3-H)(μ-CO) (μ4-η2-CO)2[η5-C5H4(SiMe3)]

The hexaruthenium cluster compound Ru₆(₃-H)(CO)₁₅[C₅H₄(SiMe₃)] (2), possessing two ₄-²-CO ligands and with the Ru[C₅H₄(SiMe₃)] fragment located at the apex of the central tetrahedral framework, was prepared in low yield by refluxing a toluene solution of C₅H₅(SiMe₃) with excess Ru₃(CO)₁₂. This unique complex was characterized by spectroscopic methods and by X-ray structural analysis. The possible mechanism leading to its formation is discussed.     

Synthesis and structural characterization of [Au2Pd14(μ3-CO)7(μ2-CO)2(PMe3)11](PF6)2—An icosahedrally-based high nuclearity mixed metal cluster

[Au₂Pd₁₄(₃-CO)₇(₂-CO)₂(PMe₃)₁₁](PF₆)₂ has been synthesized from [Pd₈(CO)₈(PMe₃)₇] and AuCl(PCy₃) in the presence of TIPF₆. It has been characterised on the basis of mass spectrometry, infrared and NMR spectroscopy, and a single crystal X-ray diffraction study. The structure is based on a palladium-centered Au₂Pd₁₁ icosahedron which shares an edge with a Pd₅ trigonal bipyramid.This paper is dedicated to Larry Dahl on his 65th Birthday—his enthusiasm and achievements in cluster chemistry have inspired us all for more than 30 years.     

Alkylation of [Pt2(μ-S)2(PPh3)4] with boronic acid derivatives

The reactivity of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄] with the boron-functionalized alkylating agents BrCH₂(C₆H₄)B(OR)₂ (R = H or C(CH₃)₂) was investigated by electrospray ionization mass spectrometry (ESI-MS) in real time using pressurized sample infusion (PSI). The macroscopic reaction of [Pt₂(μ-S)₂(PPh₃)₄] with one mole equivalent of alkylating agents BrCH₂(C₆H₄)B{OC(CH₃)₂}₂ and BrCH₂(C₆H₄)B(OH)₂ gave the dinuclear monocationic μ-sulfide thiolate complexes [Pt₂(μ-S){μ-SCH₂(C₆H₄)B{OC(CH₃)₂}₂}(PPh₃)₄]⁺ and [Pt₂(μ-S){μ-S⁺CH₂(C₆H₄)B(OH)(O^?)}(PPh₃)₄]. The products were isolated as the [PF₆]^? salt and zwitterion, respectively, and fully characterized by ESI-MS, IR, ¹H and ³¹P NMR spectroscopy, and single-crystal X-ray structure determinations.     

A study of zinc complexes of the metalloligand [Pt2(μ-S)2(PPh3)4] of the type [Pt2(μ-S)2(PPh3)4ZnL]+ (L = bidentate chelating ligand)

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with zinc acetate and an ancillary chelating ligand L (HL = 8-hydroxyquinoline, 8-tosylaminoquinoline or maltol) with added trimethylamine in methanol give new cationic platinum–zinc sulfide aggregates [Pt₂(μ-S)₂(PPh₃)₄ZnL]⁺, isolated as their BF₄^? salts. The complexes were characterized by NMR spectroscopy, ESI mass spectrometry, microelemental analysis, and an X-ray structure determination of the tosylamidoquinoline derivative [Pt₂(μ-S)₂(PPh₃)₄Zn(TAQ)]BF₄, which showed a distorted tetrahedral coordination geometry at zinc. Additional examples, containing picolinate, dithiocarbamate, or dithiophosphinate ligands were also synthesized and partly characterized in order to demonstrate a wider range of available derivatives.     

Further investigations on the methylation chemistry of [Pt2(µ-S)2(PPh3)4]

The methylation product of the reaction between [Pt₂(µ-S)₂(PPh₃)₄] and MeI in diethyl ether has been reinvestigated using positive-ion electrospray mass spectrometry and found to be contaminated with the dimethylated iodide-containing complex [Pt₂(µ-SMe)₂(PPh₃)₃I]⁺, which is believed to be formed early in the reaction. New, facile routes to the monomethylated complex [Pt₂(µ-S)(µ-SMe)(PPh₃)₄]⁺ have been developed using mild methylating agents. Heating [Pt₂(µ-S)₂(PPh₃)₄] in neat dimethyl methylphosphonate results in rapid and selective conversion to [Pt₂(µ-S)(µ-SMe)(PPh₃)₄]⁺; methylation with Me₃S⁺OH^? in refluxing methanol also affords pure [Pt₂(µ-S)(µ-SMe)(PPh₃)₄]⁺, isolated as its hexafluorophosphate salt. The X-ray structure of the previously reported complex [Pt₂(µ-SMe)₂(PPh₃)₂I₂] has also been undertaken.     

Synthesis and Structure of a Molybdenum–Cobalt Bimetallic Carbide Cluster [N(PPh3)2][Mo3Co3(μ6-C)(μ-CO)3(CO)15] Bearing Only Carbonyl Ligands

The reaction of a trinuclear cobalt cluster [ClCCo₃(CO)₉] with [Mo(CO)₃(CH₃CN)₃] gave a molybdenum–cobalt bimetallic cluster complex [Mo₃Co₃( ₆-C)(-CO)₃(CO)₁₅]^–. The cluster anion has a carbide-centered Mo₃Co₃ octahedral metal core, where the three molybdenum and three cobalt atoms are placed in facial positions. The six metal atoms are coordinated by only carbonyl ligands. The cluster is suitable for a model of heterogeneous desulfurization catalysts.     

A zwitterionic monoalkylated derivative of [Pt2(μ-S)2(PPh3)4] from 1,3-propanesultone

Reaction of dinuclear platinum(II) sulfido complex [Pt₂(μ-S)₂(PPh₃)₄] with 1,3-propanesultone gives the novel zwitterionic monoalkylated thiolate complex [Pt₂(μ-S){μ-S(CH₂)₃SO₃}·(PPh₃)₄], which was characterized by NMR spectroscopy, electrospray ionisation mass spectrometry, and a single crystal X-ray structure determination. Crystals are monoclinic, space group P2(1)/c with unit cell dimensions a = 16.8957(3) Å, b = 15.5031(3) Å, c = 28.0121(5) Å, β = 99.780(1)°, for Z = 4.     

Komplexchemie perhalogenierter Cyclopentadiene und Alkine: III. Reaktion von Pt(PPh3)2(C2H4) mit Monofluoracetylen und Dichloracetylen. Kristallstruktur von Pt(PPh3)2(Cl)(CCCl)

Pt(PPh₃)₂(C₂H₄) reacts with monofluoroacetylene to give the π-complex Pt(PPh₃)₂(FCCH), and with dichloroacetylene under oxidative addition to yield Pt(PPh₃)₂(Cl)(ClCCl), the structure of which was determined by X-ray crystallography.     

Synthesis and structure of three isomeric cluster complexes (μ-H)Os3μ-O2CC5H4Mn(CO)3(PPh3)2(CO)8

The reaction of (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃(CO)₁₀ with PPh₃ in the presence of Me₃NO gave mono- and disubstituted heterometallic complexes (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃(PPh₃)(CO)₉ and (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃ (PPh₃)₂(CO)₈. Crystal structure determination was performed for three isomeric cluster complexes (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃(PPh₃)₂(CO)₈, which are both geometrical and conformational isomers differing in color. The geometrical isomerism is due to the attachment of the PPh₃ group at different vertices of the Os₃ triangle relative to the O₂CC₅H₄Mn(CO)₃ bridging ligand. The conform ational isomerism implies that the molecules have the same arrangement of ligands and differ only in the values of bond angles between the planar fragments of the clusters.     

Theoretical study of the interaction between Pt(0) and MPH3 + fragments in complexes of the [Pt3 (��-CO)3(PH3)3]�CMPH3 + (M?=?Cu+, Au+, Ag+) type

Ab initio calculations suggest that a series of complexes of the [Pt₃(??-CO)₃(PH₃)₃]?CMPH₃ ⁺ type (M?=?Cu, Au, Ag) are stable. We have studied these complexes at the HF, MP2, B3LYP, and PBE levels of theory. The magnitude of the interaction energies and Pt₃?CM distances indicate a substantial covalent character of the bond, the latter being confirmed by orbital diagrams. The chemical bond is sensitive to electron correlation effects. In addition, the Fukui index of nucleophilic attack and electrophilicity index on the metal were used to explore possible sites where chemical reactivity may play a role.     

Reactivity of the metalloligand [Pt2(µ-S)2(PPh3)4] toward tellurium(II) thiourea complexes: synthesis and structural characterization of the ditellurium(I) derivative [{Pt2(µ-S)2(PPh3)4}2Te2]2+

Abstract

Reaction of the platinum(II) sulfide metalloligand [Pt₂(µ-S)₂(PPh₃)₄] with the tellurium(II) source TeCl₂(tu)₂ (tu?=?thiourea) is dependent on reaction conditions employed. In the presence of added acid, the dominant species observed in the electrospray ionization (ESI) mass spectrum is the tetraplatinum species [{Pt₂(µ-S)₂(PPh₃)₄}₂Te₂]²⁺. This contains the Te₂²⁺ moiety and is related to the previously reported tellurium(I) dithiophosphinate analog [(Ph₂PS₂)₂Te₂]. However, in the absence of acid, considerable degradation of the {Pt₂S₂} metalloligand occurs as evidenced by the formation of the mononuclear complex [Pt{SC(NH₂)NH}(PPh₃)₂]⁺ containing a deprotonated thiourea ligand, together with other thiourea-containing ions, identified by ESI MS. Likewise, attempted use of a fully substituted thiourea, viz. Me₂NC(S)NMe₂ (tmtu) in TeCl₂(tmtu)₂, also resulted in degradation of the {Pt₂S₂} core and detection of the known complex [(Ph₃P)₂PtCl{SC(NMe₂)₂}]⁺. The [{Pt₂(µ-S)₂(PPh₃)₄}₂Te₂]²⁺ cation was isolated with several anions, and unequivocal confirmation of the structure of the complex was obtained by an X-ray structure determination on the BF₄^- salt, which shows the presence of the Te₂²⁺ unit, with the Te–Te bond bridged by two {Pt₂S₂} metalloligands. Density functional theory was used to further probe the Te₂²⁺ bonding interactions in [{Pt₂(μ-S)₂(PPh₃)₄}₂Te₂]²⁺ and the previously reported [(Ph₂PS₂)₂Te₂].