The structure of a dinuclear silver(I) complex: Ag2[S2C2(CN)2] [P(C6H5)3]4

The crystal structure of the dimeric Ag maleonitriledithiolate complex, Ag₂[S₂C₂(CN)₂] [P(C₆- H₅)₃]₄ (1), has been performed. Complex 1 crystallizes in the space group P2₁/c with a = 12.2898(77), b = 23.8325(91), c = 23.1790(118) Å, β = 101.315(43)° and Z = 4. Refinement using 3253 reflections with F_o²>3σ(F_o²) yielded R = 0.0662, R_w= 0.0669. The most interesting aspect of the structure is the strong bridging interaction of the chelating maleonitriledithiolate ligand with the second Ag center, where a Ag-S distance of 2.478 Å is observed. The residual bonding capability of the sulfur atoms in the chelating anion [Ag(S₂C₂(CN)₂)(PPh₃)₂]⁻ for [Ag(PPh₃)₂]⁺ is demonstrated.     

Synthesis and structural characterization of gold(III) dioximates with anions [AuCl4] and [AuCl2]

Two complexes of Au(III) with dimethylglyoxime of compositions [Au^III(HDMG)₂][Au^IIICl₄] (1) and [Au^III(HDMG)₂][Au^ICl₂] (2) were synthesized and characterized by X-ray structural analysis. It was shown that in [Au^III(HDMG)₂]⁺ cation Au(III) has a square-planar environment, and the oxygen atoms of oxime groups are joined by intramolecular H-bond. The secondary Au?Au and Au?Cl interactions in the crystal are discussed.     

3D coordination polymers of [2.2]paracyclophane and in situ silver(I) perfluoro-dicarboxylates: effects of the dicarboxylate spacers and conformations on the formation of complexes

Coordination polymers of [2.2]paracyclophane (pcp) with in situ silver(I) perfluoro-dicarboxylates characterized by single crystal X-ray analysis are described. Structures are found to strongly depend on the dicarboxylate spacer (n). With disilver(I) tetrafluorosuccinate ((CF₂)_n(COOAg)₂, n = 2), 3D network with composition of [Ag₄(pcp)(C₂F₄(CO₂)₂)₂] (1) forms in which silver salts afford infinite double chains and pcp act as linkages between chains. Changing the silver salt to disilver hexafluoroglutarate ((CF₂)_n(COOAg)₂, n = 3) produces 3D pillared-layer structure of composition of [Ag₄(pcp)(C₃F₆(CO₂)₂)₂] · THF (2) (THF = tetrahydrofuran), in which silver salts form 2D sheets and pcp act as pillars between the sheets. With silver octafluoroadipate (HO₂C(CF₂)_nCO₂Ag, n = 4), 2-fold interpenetrated diamond structure, [Ag₂(pcp)₂(HO₂CC₄F₈CO₂)₂]₂ · 2toluene (3), is obtained in which silver-anion chains and silver-pcp chains are connected with each other in the perpendicular manner. The three complexes represent unprecedented metal-organic networks of silver(I) multicarboxylates and polycyclic aromatic compounds. Additionally, the effects of the dicarboxylate conformations as well as the solvents on the resulting structures were discussed.     

Synthesis of [SnPh2(SR)2] SR = SC6F4-4-H, SC6F5: Reactivity towards group 10 transition metal complexes

The organometallic tin(IV) complexes [SnPh₂(SR^F)₂] SR^F = ⁻SC₆F₄-4-H (1), ⁻SC₆F₅ (2), were synthesized and their reactivity with [MCl₂(PPh₃)₂] M = Ni, Pd and Pt explored. Thus, transmetallation products were obtained affording polymeric [Ni(SR^F)(μ-SR^F)]_n, monomeric cis-[Pt(PPh₃)₂(SC₆F₄-4-H)₂] (3) and cis-[Pt(PPh₃)₂(SC₆F₅)₂] (4) and dimeric species [Pd(PPh₃)(SC₆F₄-4-H)(μ-SC₆F₄-4-H)]₂ (5) and [Pd(PPh₃)(SC₆F₅)(μ-SC₆F₅)]₂ (6) for Ni, Pt and Pd, respectively. The crystal structures of complexes 1, 2, 3, 4 and 6 were determined.     

Cationic copper(I) and silver(I) nitrile complexes with fluorinated weakly coordinating anions: Metal–nitrile bond strength and its influence on the catalytic performance

Copper(I) and silver(I) complexes of formulae [Cu(NCCH₃)₄]⁺[A]⁻ ([A]⁻ = [B(C₆F₅)₄]⁻ (1), {B[C₆H₃(CF₃)₂]₄}⁻ (2), [(C₆F₅)₃B–C₃H₃N₂–B(C₆F₅)₃]⁻ (3), and [Ag(NCCH₃)₄]⁺[B(C₆F₅)₄]⁻ (4) are examined with particular emphasis on the strength of their M–N bond and its influence on the catalytic performance of these complexes in cyclopropanation and aziridination. To examine the strength of the M–N interactions, vibrational spectra of the related hydrogenated and deuterated species [Cu(NCCH₃)₄]⁺, [Cu(NCCD₃)₄]⁺, [Ag(NCCH₃)₄]⁺, and [Ag(NCCD₃)₄]⁺ are also determined. It is found that the metal–nitrile bond strength is an important factor for the catalytic activity of the respective complexes.     

‘Synthetic prospecting’ using an electrospray ionisation mass spectrometry directed survey of the alkylation and arylation chemistry of [Pt2(μ-S)2(PPh3)4]

Electrospray ionisation mass spectrometry (ESI-MS) has been used as an analytical tool in a wide-ranging scoping study of the alkylation and arylation reactions of [Pt₂(μ-S)₂(PPh₃)₄]. From these experiments, the factors that influence the formation of different product species - formed by mono- or di-alkylation - are determined. If the alkylating agent is an alkyl chloride or sulfate, monoalkylation followed by dialkylation of the two sulfido groups occurs, dependent on the alkylating power of the reagent used. For example, n-butyl chloride gives solely [Pt₂(μ-S)(μ-SBu)(PPh₃)₄]⁺ while dimethyl sulfate gives [Pt₂(μ-SMe)₂(PPh₃)₄]²⁺. This species, previously unisolated is stable in the absence of good nucleophiles, but the addition of potassium iodide results in rapid conversion to [Pt₂(μ-SMe)₂(PPh₃)₃I]⁺. This iodo complex is also observed from the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with excess MeI, after the initial formation of mono- and di-methylated species. In these reactions, the iodide presumably displaces a phosphine ligand, which is then quaternised by excess alkylating agent. Changing the alkylating agent to a longer chain alkyl iodide or methyl bromide decreases the rate of alkylation of the sulfide in the initially formed [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺. Mixed-thiolate species of the type [Pt₂(μ-SMe)(μ-SR)(PPh₃)₄]²⁺ are easily generated by reaction of [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ with excess Me₂SO₄ and is also dependent on the avoidance of nucleophiles. Reactions towards α,ω-dialkylating agents are surveyed; the chain length is found to have a dramatic effect on the rate of the second intramolecular cyclisation process, illustrated by a competitive reactivity study involving a mixture of Br(CH₂)₄Br and Br(CH₂)₅Br; on completion of the reaction the former gives [Pt₂{μ-S(CH₂)₄S}(PPh₃)₄]²⁺ while the latter predominantly gives monoalkylated[Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]⁺. The reactivity of o- and p-dihaloxylenes has been explored, with the reaction with p-BrCH₂C₆H₄CH₂Br giving the bridged species [(PPh₃)₄Pt₂(μ-S)(μ-SCH₂C₆H₄CH₂S)(μ-S)Pt₂(PPh₃)₄]²⁺. Arylation reactions of [Pt₂(μ-S)₂(PPh₃)₄] with halobenzenes and 2-bromoheterocyclic compounds (pyridine, thiophene) are also described.     

Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt2(μ-S)2(PPh3)4] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes

The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with α,ω-dibromoalkanes Br(CH₂)_nBr (n = 4, 5, 6, 8, 12) gave mono-alkylated [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)_nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂(μ-S){μ-S(CH₂)_nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)₁₂}]²⁺ was accessible from the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)₁₂Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at −18 °C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂(μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to ω-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S}(PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)_n−2CHCH₂}(PPh₃)_m]⁺ (m = 2 or 3; m ≠ 4), most significant for n = 4, formed by elimination of HBr.     

Further studies on the coordination chemistry of [Pt2(μ-S)2(PPh3)4] towards indium(III) substrates

The reactivity of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄] towards a variety of indium(III) substrates has been explored. Reaction with excess In(NO₃)₃ and halide (KBr or NaI) gave the four-coordinate adducts [Pt₂(μ-S)₂(PPh₃)₄InX₂]⁺[InX₄]⁻ (X = Br, I). An X-ray structure determination on the iodo complex revealed a slightly distorted tetrahedral coordination geometry at indium. In contrast, reaction of [Pt₂(μ-S)₂(PPh₃)₄] with indium(III) chloride was more complex; the ion [Pt₂(μ-S)₂(PPh₃)₄InCl₂]⁺ was initially observed in solution (using ESI mass spectrometry), and isolated as its BPh₄⁻ salt. Analysis of [Pt₂(μ-S)₂(PPh₃)₄InCl₂]⁺[BPh₄]⁻ by ESI MS showed the parent cation when analysed in MeCN solution. However in solutions containing methanol, partial solvolysis occurred to give the di-indium species [{Pt₂(μ-S)₂(PPh₃)₄InCl(OMe)}₂]²⁺ (proposed to contain an In₂(μ-OMe)₂ unit with five-coordinate indium) and its fragment ion [Pt₂(μ-S)₂(PPh₃)₄InCl(OMe)]⁺. Reaction of [Pt₂(μ-S)₂(PPh₃)₄] with InCl₃·3H₂O, 8-hydroxyquinoline (HQ) and trimethylamine in methanol gave the adduct [Pt₂(μ-S)₂(PPh₃)₄InQ₂]⁺, isolated as its PF₆⁻ salt. The same cationic complex is formed when [Pt₂(μ-S)₂(PPh₃)₄] is reacted with InQ₃ in methanol, but in this case the product is contaminated with the mononuclear complex [(Ph₃P)₂PtQ]⁺ formed by disintegration of the trinuclear complex [Pt₂(μ-S)₂(PPh₃)₄InQ₂]⁺ with byproduct Q⁻. [(Ph₃P)₂PtQ]⁺BPh₄⁻ was independently prepared from cis-[PtCl₂(PPh₃)₂] and HQ/Me₃N, and is the first example of a platinum 8-hydroxyquinolinate complex containing phosphine ligands.     

N-Heterocyclic carbene gold(I) and silver(I) adducts of [Pt2(μ-S)2(PPh3)4]

Reaction of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄] with the N-heterocyclic carbene (NHC) complexes IPrAuCl, IMesAuCl and IMesAgCl in methanol gave the first examples of metal adducts of [Pt₂(μ-S)₂(PPh₃)₄] that contain NHC ligands, namely [Pt₂(μ-S)₂(PPh₃)₄AuL]⁺ (L = IPr, IMes) and [Pt₂(μ-S)₂(PPh₃)₄AgIMes]⁺. The complexes were isolated as hexafluorophosphate salts. Reaction of [Pt₂(μ-S)₂(PPh₃)₄] with excess IPrAuCl in refluxing methanol yielded only the mono-adduct, in contrast to the behaviour with the gold(I) phosphine complex Ph₃PAuCl, which undergoes double addition giving [Pt₂(μ-SAuPPh₃)₂(PPh₃)₄]²⁺. The X-ray structure of [Pt₂(μ-S)₂(PPh₃)₄AuIPr]PF₆ was determined and reveals that the ‘free’ sulfide is substantially sterically protected by the IPr ligand, accounting for the low reactivity towards addition of a second AgIPr⁺ moiety.     

Pyridine and phosphine reactions with [CPh3][B(C6F5)4]

Trityl borate salts [4-RPyCPh₃][B(C₆F₅)₄] (R = H 1, ^tBu 2, Et 3, NMe₂4) and [R₃PCPh₃][B(C₆F₅)₄] (R = Me 5, ⁿBu 6, Ph[1] 7, p-MeC₆H₄8) are readily prepared via equimolar reaction of the appropriate pyridine or phosphine and trityl borate [CPh₃][B(C₆F₅)₄]. The analogous reactions of PⁱPr₃ affords the product [(p-ⁱPr₃P-C₆H₄)Ph₂CH][B(C₆F₅)₄] (9) while the corresponding reactions of Cy₃P and ^tBu₃P gave the cyclohexadienyl derivatives [(p-R₃PC₆H₅)CPh₂][B(C₆F₅)₄] (R = Cy 10, ^tBu 11). X-ray structures of 5 and 9 are reported.     

The preparation and structural characterisation of thiolato anions of bismuth(III)

The preparation and structures of the bismuth thiolato anions [Bi₂(SC₆F₅)₆(μ-SC₆F₅)]⁻ and [Bi₂(SC₆F₅)₆(μ-SC₆F₅)₂]²⁻ and the halothiolato anions [Bi₂(SC₆F₅)₆(μ-Br)]⁻, [Bi₂(SC₆F₅)₆(μ-Cl)₂]²⁻ and [Bi₃(SC₆F₅)₉(μ-Br)₂]²⁻ are described. All compounds have been isolated from reactions between Bi(SC₆F₅)₃ and ammonium or phosphonium halides. The basic structural units in the dinuclear species are of two types namely [Bi₂(SR)₆(μ-X)]⁻ and [Bi₂(SR)₆(μ-X)₂]²⁻, where X=thiolate or halide. In the former case the single bridging groups occupy an axial site within the disphenoidal (equatorially vacant, trigonal bipyramidal) geometry around the bismuth centres whereas in the latter the two bridging groups occupy cis basal sites in square based pyramidal bismuth environments. The trinuclear anion [Bi₃(SC₆F₅)₉(μ-Br)₂]²⁻ has features in common with the basic [Bi₂(SC₆F₅)₆(μ-Br)]⁻ unit.     

Coordination chemistry of the metalloligand [Pt2(μ-S)2(PPh3)4] with nickel(II) complexes - an electrospray mass spectrometry directed synthetic study

The reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards a range of nickel(II) complexes has been probed using electrospray ionisation mass spectrometry coupled with synthesis and characterisation in selected systems. Reaction of [Pt₂(μ-S)₂(PPh₃)₄] with [Ni(NCS)₂(PPh₃)₂] gives [Pt₂(μ-S)₂(PPh₃)₄Ni(NCS)(PPh₃)]⁺, isolated as its BPh₄ ⁻ salt; the same product is obtained in the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with [NiBr₂(PPh₃)₂] and KNCS. An X-ray structure determination reveals the expected sulfide-bridged structure, with an N-bonded thiocyanate ligand and a square-planar coordination geometry about nickel. A range of nickel(II) complexes NiL₂, containing β-diketonate, 8-hydroxyquinolinate, or salicylaldehyde oximate ligands react similarly, giving [Pt₂(μ-S)₂(PPh₃)₄NiL]⁺ cations.     

The arylation of [Pt2(μ-S)2(PPh3)4]

Routes to the synthesis of the mixed sulfide-phenylthiolate complex [Pt₂(μ-S)(μ-SPh)(PPh₃)₄]⁺ have been explored; reaction of [Pt₂(μ-S)₂(PPh₃)₄] with excess Ph₂IBr proceeds readily to selectively produce this complex, which was structurally characterised as its PF₆⁻ salt. Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with other potent arylating reagents (1-chloro-2,4-dinitrobenzene and 1,5-difluoro-2,4-dinitrobenzene) also produce the corresponding nitroaryl-thiolate complexes [Pt₂(μ-S){μ-SC₆H₂(NO₂)₂X}(PPh₃)₄]⁺ (X = H, F). The complex [Pt₂(μ-S)(μ-SPh)(PPh₃)₄]⁺ reacts with Me₂SO₄ to produce the mixed alkyl/aryl bis-thiolate complex [Pt₂(μ-SMe)(μ-SPh)(PPh₃)₄]²⁺, but corresponding reactions with the nitroaryl-thiolate complexes are plagued by elimination of the nitroaryl group and formation of [Pt₂(μ-SMe)₂(PPh₃)₄]²⁺. [Pt₂(μ-S)(μ-SPh)(PPh₃)₄]⁺ also reacts with Ph₃PAuCl to give [Pt₂(μ-SAuPPh₃)(μ-SPh)(PPh₃)₄]²⁺.     

Interactions of tertiary phosphines with p-benzoquinones; X-ray structures of [HO(CH2)3]3PC6H2(O)(OH)(MeO) and Ph3PC6H3(O)(OH)

Phosphonium zwitterions of a known type were obtained in high yield via a 1:1 reaction of p-benzoquinone or methoxy-p-benzoquinone with the tertiary phosphines R₃P [R = (CH₂)₃OH, Ph, Et, Me] and Ph₂MeP, in acetone or benzene at room temperature. In all cases, attack of the P-atom occurs at a C-atom rather than at an O-atom. The products were characterized to various degrees by elemental analysis, ³¹P{¹H}, ¹H and ¹³C NMR spectroscopies, and mass spectrometry, and two of the zwitterions, the new [HO(CH₂)₃]₃P⁺C₆H₂(O⁻)(OH)(MeO) and the known Ph₃P⁺C₆H₃(O⁻)(OH), were structurally characterized by X-ray analysis. The PEt₃ reaction also produces small amounts of the ‘dimeric’, μ-oxo co-product Et₃P⁺C₆H₂(O⁻)(OH)-O-C₆H₃(O⁻)P⁺Et₃ that is tentatively characterized by 1D- and 2D-NMR data. 2,5-Di-tert-butyl- and 2,3,5,6-tetramethyl-p-benzoquinone do not react with [HO(CH₂)₃]₃P under the conditions noted above. Heating D₂O solutions of the water-soluble zwitterions R₃P⁺C₆H₃(O⁻)(OH) [R = (CH₂)₃OH, Et] at 90 °C for 72 h leads to complete H/D exchange of the H-atom in the position ortho to the phosphonium center.     

Self-assembly of cationic palladium complexes by redistribution of pyridine ligands

The reaction of [Pd(OAc)₂(py)₂] with [Li((OEt₂)_2.5)][B(C₆F₅)₄] was conducted with intent to generate the cationic palladium complex [Pd(OAc)(py)₃][B(C₆F₅)₄], (2, py = pyridine). A single crystal structure of this material, however, reveals a 1-D polymer structure formed by the self-assembly of alternating dicationic ([Pd(py)₄]²⁺) and neutral ([Pd(OAc)₂(py)₂]) palladium units bridged by acetato linkages to give [Pd(py)₄][Pd(OAc)₂(py)₂][B(C₆F₅)₄]₂ (3). These two palladium sites are produced by disproportionation of the pyridine ligands in [Pd(OAc)(py)₃][B(C₆F₅)₄]. Proton NMR studies confirm the existence of a solvent dependent equilibrium between [Pd(py)₄]²⁺, [Pd(OAc)₂(py)₂] and [Pd(OAc)(py)₃]⁺.     

New thiocarbamate and thioureate palladium and platinum complexes: synthesis and use as metalloligands. Unprecedented coordination of the thioureate ligand in [(C6F5)2Pd{μ2,η-SC(NMe2)NPh}Pd(C6F5)(bpzm)]

The di-μ-hydroxo complexes [NBu₄]₂[{(C₆F₅)₂M(μ-OH)}₂] (M=Pd, Pt) react with PhNCS in alcohol ROH solution to yield the N,S-chelating thiocarbamate metal complexes [NBu₄][(C₆F₅)₂M{η²-SC(OR)NPh}] (R=Me, Et or Prⁿ). [NBu₄]₂[{(C₆F₅)₂Pd(μ-OH)}₂] also reacts with PhNCS in the presence of dialkylamines R₂NH to yield the N,S-chelating thioureate (1−) palladium complexes [NBu₄][(C₆F₅)₂Pd{η²-SC(NR₂)NPh}] (R=Me or Et). [NBu₄][(C₆F₅)₂M{η²-SC(X)NPh}] (M=Pd or Pt; X=OMe or NR₂) reacts with [(C₆F₅)Pd(bpzm)(acetone)]ClO₄ to yield the dinuclear complexes [(C₆F₅)₂M{(μ₂,η²-{SC(X)NPh}Pd(C₆F₅)(bpzm)] (M=Pd or Pt, X=OMe or NR₂; bpzm=bis(3,5-dimethylpyrazol-1-yl)methane). The single-crystal structures of [NBu₄][(C₆F₅)₂Pd{η²-SC(OMe)NPh}] and [(C₆F₅)₂Pd{μ₂,η²-SC(NMe₂)NPh}Pd(C₆F₅)(bpzm)] have been established by X-ray diffraction.     

Oxoselenide triangular molybdenum clusters: Synthesis and characterization of [Mo3SeO3(acac)3(py)3]PF6

New cluster complex [Mo₃SeO₃(acac)₃(py)₃]⁺ was obtained by ligand substitution in the aqua complex [Mo₃SeO₃(H₂O)₉]⁴⁺. Crystal structure was determined for [Mo₃SeO₃(acac)₃(py)₃]PF₆·C₆H₅CH₃. The complex was characterized by ⁷⁷Se NMR, electrospray mass-spectrometry, and cyclic voltammetry. DFT calculations were used to confirm the assignment of chemical shift and to study Mo-Mo bonding in the cluster core.     

Two luminescent alkali-silver heterometallic sulfonates

Systematic survey on the reactions of silver nitrate with H₃Ssal ligand (H₃Ssal = 5-sulfo-salicylic acid) accompanying with different alkali metal ions under alkali conditions leads to two novel luminescent alkali-silver heterometallic sulfonates, [KAg(HSsal)(H₂O)₃]_n (1) with a 3-D structure constructed by [K₂O₁₀] binuclear units linking 1-D_∞¹[Ag₂(HSsal)₂] double chains, [NaAg(HSsal)(H₂O)₃]_n (2) with a 3-D structure constructed by the [Ag₂(HSsal)₂] dimers connecting 1-D_∞¹[NaO₆] chains, and also reveals the coordination strength of the alkali metal cations and Ag⁺ towards the sulfonate groups with K⁺ > Na⁺ > Ag⁺ > Li⁺ order. The two compounds show intense blue emissions in both solid state and water solution.     

Metal-metal stacking patterns between and with [Pt(tpy)X] cations

A comparative study of metallophilic interactions of [Pt(tpy)X]⁺ cations (tpy = 2,2′:6′,2″-terpyridine) in the presence of two different types of anions, (i) []⁻ anions that form double salts and (ii) simple p-block anions, is reported. Single-crystal X-ray diffraction data, solution-state ¹⁹⁵Pt NMR spectra, and variable temperature solid-state luminescence spectra are reported. Three [Pt(tpy)Cl]Y derivatives (Y = SbF₆, 1, SbF₆·CH₃CN, 4, PF₆, 2) and the [Pt(tpy)Br]PF₆ analog, 3, as well as two new double salts [Pt(tpy)CN][Au(CN)₂], 5, and [Pt(tpy)CN]₂[Au(C₆F₅)₂](PF₆), 6, have been synthesized and characterized. Structural analysis shows consistent patterns in Pt···Pt interactions that vary slightly depending on the coordinating halogen or pseudo-halogen X, counter anion Y, and lattice solvent. Metallophilic interactions are seen between [Pt(tpy)X]⁺ cations with all types of X ligands, but only with π-accepting X′ ligands from []⁻ anions are Pt?Au metallophilic interactions seen to be favored over Pt?Pt interactions. The [Au(CN)₂]⁻ anion consistently forms Pt···Au metallophilic contacts, unlike [Au(C₆F₅)₂]⁻. The ¹⁹⁵Pt NMR chemical shifts are ∼−2750 ppm for π-donor ligands and near −3120 ppm for π-acceptor ligands in [Pt(tpy)X]PF₆ compounds. Luminescence data show an unusual blue shift in [Pt(tpy)CCPh][Au(C₆F₅)₂] versus [Pt(tpy)CCPh]PF₆ ascribed to an intermolecular charge transfer.     

Vibrational and structural mapping of [Os(bpy)3] and [Os(phen)3]

Structural changes between [Os^IIL₃]²⁺ and [Os^IIIL₃]³⁺ (L: 2,2′-bipyridine; 1,10-phenanthroline) and molecular and electronic structures of the Os^III complexes [Os^III(bpy)₃]³⁺ and [Os^III(phen)₃]³⁺ are discussed in this paper. Mid-infrared spectra in the ν(bpy) and ν(phen) ring stretching region for [Os^II(bpy)₃](PF₆)₂, [Os^III(bpy)₃](PF₆)₃, [Os^II(phen)₃](PF₆)₂, and [Os^III(phen)₃](PF₆)₃ are compared, as are X-ray crystal structures. Absorption spectra in the UV region for [Os^III(bpy)₃](PF₆)₃ and [Os^III(phen)₃](PF₆)₃ are dominated by very intense absorptions (ε = 40 000-50 000 M⁻¹ cm⁻¹) due to bpy and phen intra-ligand π → π^∗ transitions. In the visible region, relatively narrow bands with vibronic progressions of ∼1500 cm⁻¹ appear, and have been assigned to bpy or phen-based, spin-orbit coupling enhanced, ¹π → ³π^∗ electronic transitions. Also present in the visible region are ligand-to-metal charge transfer bands (LMCT) arising from π(bpy) → t_2g(Os^III) or π(phen) → t_2g(Os^III) transitions. In the near infrared, two broad absorption features appear for oxidized forms [Os^III(bpy)₃](PF₆)₃ and [Os^III(phen)₃](PF₆)₃ arising from dπ-dπ interconfigurational bands characteristic of dπ⁵Os^III. They are observed at 4580 and 5090 cm⁻¹ for [Os^III(bpy)₃](PF₆)₃ and at 4400 and 4990 cm⁻¹ for [Os^III(phen)₃](PF₆)₃. The bpy and phen infrared vibrational bands shift to higher energy upon oxidation of Os(II) to Os(III). In the cation structure in [Os^III(bpy)₃](PF₆)₃, the Os^III atom resides at a distorted octahedral site, as judged by ∠N-Os-N, which varies from 78.78(22)° to 96.61(22)°. Os-N bond lengths are also in general longer for [Os^III(bpy)₃](PF₆)₃ compared to [Os^II(bpy)₃](PF₆)₂ (0.010 Å), and for [Os^III(phen)₃](PF₆)₃ compared to [Os^II(phen)₃](PF₆)₂ (0.014 Å). Structural changes in the ligands between oxidation states are discussed as originating from a combination of dπ(Os^II) → π^∗ (bpy or phen) backbonding and charge redistribution on the ligands as calculated by natural population analysis.