Neutral and cationic rare-earth metal alkyl complexes that contain bis(2-methoxyethyl)(trimethylsilyl)amine, a neutral [ONO]-type ligand

Neutral tris(trimethylsilylmethyl) complexes [Ln(CH₂SiMe₃)₃(L)] (Ln = Sc (1), Lu (2)) and cationic bis(trimethylsilylmethyl) complexes [Ln(CH₂SiMe₃)₂(L)(THF)]⁺[BPh₄]⁻, (Ln = Sc (3), Lu (4)) that contain bis(2-methoxyethyl)(trimethylsilyl)amine (L = Me₃SiN(CH₂CH₂OMe)₂) as a neutral, tridentate ligand were synthesized and characterized by NMR spectroscopy. X-ray structural analysis was performed for the scandium complex 1 and exhibited a distorted octahedral coordination geometry with a facially arranged ligand at the neutral scandium center. NMR spectroscopy corroborated the coordination of the tertiary amine function of the ligand to the metal. Complexes 3 and 4 expand the still limited range of cationic rare-earth metal alkyl complexes with known neutral, multidentate ligands.     

Heteroleptic lanthanide terphenyl/tris(pyrazolyl)borate compounds of ytterbium

The synthesis and structural characterization of the two novel unsolvated heteroleptic ytterbium compounds DanipYb(Tp^Me,Me)Cl (1) and DanipYb(Tp^Me,Me)CH₂SiMe₃ (2) by simple salt metathesis reaction is reported [Danip = 2,6-di(o-anisol)phenyl); Tp^Me,Me = hydrotris(3,5-dimethyl-pyrazolyl)borate]. In the molecular structure of 2 a flexible bonding mode of the donor-functionalized terphenylic ligand is observed.     

Hydrogen-halide versus alkyl-halide oxidative addition in dimethyl platinum(II) complexes: Crystal structure of [PtBr2(bpy)]

Dimethyl platinum(II) complexes [PtMe₂(NN)] {NN = bu₂bpy (4,4′-di-tert-butyl-2,2′-bipyridine) (1a), bpy (2,2′-bipyridine) (1b), phen (1,10-phenanthroline) (1c)} reacted with commercial 3-bromo-1-propanol in the presence of 1,3-propylene oxide to afford cis, trans- [PtBrMe₂{(CH₂)₃OH}(NN)] (NN = bu₂bpy (2a), bpy (2b), phen (2c)). On the other hand, [PtMe₂(NN)] (1a)-(1b) reacted with the trace of HBr in commercial 3-bromo-1-propanol to give [PtBr₂(NN)] (NN = bu₂bpy (3a), bpy (3b)). The reaction pathways were monitored by ¹H NMR at various temperatures. Treatment of 1a-1b with a large excess of 3-bromo-1-propanol at −80 °C gave the corresponding methyl(hydrido)platinum(IV) complexes [PtBr(H)Me₂(NN)] (NN = bu₂bpy (4a), bpy (4b)) via the oxidative addition of dimethyl platinum(II) complexes with HBr. The complexes [PtBr(H)Me₂(NN)] decomposed by reductive elimination of methane above −20 °C for bu₂bpy and from −20 to 0 °C for bpy analogue to give methane and platinum(II) complexes [PtBrMe(NN)] (5a)-(5b) and then decomposed at about 0 °C to yield [PtBr₂(NN)] and methane. When the reactions were performed at a molar ratio of Pt:RX/1:10, the corresponding complexes [PtBrMe(NN)] (5a)-(5b) were also obtained. The crystal structure of the complex 3b shows that platinum adopts square planar geometry with a twofold axis through the platinum atom. The Pt…Pt distance (5.164 Å) is considerably larger than the interplanar spacing (3.400 Å) and there is no platinum-platinum interaction.     

Secondary ligand-metal interactions in rhodium(III) and iridium(III) phosphoramidite complexes

The synthesis, characterization, and application in asymmetric catalytic cyclopropanation of Rh(III) and Ir(III) complexes containing (S_a,R_C,R_C)-O,O′-[1,1′-binaphthyl-2,2′-diyl]-N,N′-bis[1-phenyl-ethyl]phosphoramidite (1) are reported. The X-ray structures of the half-sandwich complexes [MCl₂(C₅Me₅)(1,κP)] (M = Rh, 2a; M = Ir, 2b) show that the metal-phosphoramidite bond is significantly shorter in the Ir(III) analog. Chloride abstraction from 2a (with CF₃SO₃SiMe₃ or with CF₃SO₃Me) and from 2b (with AgSbF₆) gives the cationic species [MCl(C₅Me₅)(1,2-η-1,κP)]⁺ (M = Rh, 3a; M = Ir, 3b), which display a secondary interaction between the metal and a dangling phenethyl group (NCH(CH₃)Ph) of the phosphoramidite ligand, as indicated by NMR spectroscopic studies. Complexes 3a and 3b slowly decompose in solution. In the case of 3b, the binuclear species [Ir₂Cl₃(C₅Me₅)₂]⁺ is slowly formed, as indicated by an X-ray study. Preliminary catalytic tests showed that 3a cyclopropanates styrene with moderate yield (35%) and diastereoselectivity (70:30 trans:cis ratio) and with 32% ee (for the trans isomer).     

Synthesis and reactivity of osmium (VI) nitrido complexes containing pyridine-carboxylato ligands

A series of osmium(VI) nitrido complexes containing pyridine-carboxylato ligands Os^VI(N)(L)₂X (L = pyridine-2carboxylate (1), 2-quinaldinate (2) and X = Cl (a), Br (1b and 2c) or CH₃O (2b)) and [Os^VI(N)(L)X₃]⁻ (L = pyridine-2,6-dicarboxylate (3) and X = Cl (a) or Br (b)) have been synthesised. Complexes 1 and 2 are electrophilic and react readily with various nucleophiles such as phosphine, sulfide and azide. Reaction of Os^VI(N)(L)₂X (1 and 2) with triphenylphosphine produces the osmium(IV) phosphiniminato complexes Os^VI(NPPh₃)(L)₂X (4 and 5). The kinetics of nitrogen atom transfer from the complexes Os^VI(N)(L)₂Br (2c) (L = 2-quinaldinate) with triphenylphosphine have been studied in CH₃CN at 25.0 °C by stopped-flow spectrophotometric method. The following rate law is obtained: −d[Os(VI)]/dt = k₂[Os(VI)][PPh₃]. Os^VI(N)(L)₂Cl (L = 2-quinaldinate) (2a) reacts also with [PPN](N₃) to give an osmium(III) dichloro complex, trans-[PPN][Os^III(L)₂Cl₂] (6). Reaction of Os^VI(N)(L)₂Cl (L = 2-quinaldinate) (2a) with lithium sulfide produces an osmium(II) thionitrosyl complex Os^II(NS)(L)₂Cl (7). These complexes have been structurally characterised by X-ray crystallography.     

Scandium and yttrium complexes of a heteroscorpionate [N,N,O]-donor-set ligand: Synthesis, characterization and catalytic activity in ethylene polymerization

New scandium and yttrium complexes ScL₂(bpzmp)(THF) {L = Cl (1); L = CH₂Si(CH₃)₃ (3)}, YL₂(bpzmp) {L = Cl (2); L = OTf (5)} and Y(CH₂SiMe₃)₂(bpzmp)(THF) (4) bearing the heteroscorpionate bpzmp ligand {bpzmp = (3,5-^tBu₂-2-phenoxo)bis(3,5-Me₂-pyrazol-1-yl)methane} have been synthesized and characterized by means of NMR and Mass spectroscopy. The tridentate monoanionic ligand resulted κ³-coordinated to the metal via the oxygen and both the sp² nitrogen atoms of the heterocycles, producing complexes in C_S symmetry.The behavior of 1-4 in ethylene polymerization was investigated after proper activation with different activating agents. Complex 4, in combination with the Brönsted or Lewis acids [PhNMe₂H][B(C₆F₅)₄] or [Ph₃C][B(C₆F₅)₄], produced linear high molecular weight polyethylene in good yield.     

Synthesis, characterization and applications in ethylene polymerization of asymmetric ansa-titanocene complexes. Molecular structure of [Ti{Me2Si(η-C5Me4)(η-C5H3iPr)}Cl2]

The ansa-titanocene complexes, [Ti{Me₂Si(η⁵-C₅Me₄)(η⁵-C₅H₃R)}Cl₂] (R = Me (5), iPr (6), tBu (7), SiMe₃ (8)), were obtained from the reaction of Li₂{Me₂Si(C₅Me₄)(C₅H₃R)} (R = Me (1), iPr (2), tBu (3), SiMe₃ (4)) with [TiCl₄(THF)₂], respectively. Compounds 5-8 have been tested as catalysts in the polymerization of ethylene and compared with the ansa-titanocene complexes [Ti{Me₂Si(η⁵-C₅H₄)₂}Cl₂] and [Ti{Me₂Si(η⁵-C₅Me₄)(η⁵-C₅H₄)}Cl₂]. The resulting polyethylene showed molecular weights of about 200 000 g mol⁻¹ and polydispersity values of approximately 3. In addition, the molecular structure of 6 has been determined by single crystal X-ray diffraction studies.     

Stepwise syntheses, structure and spectroscopic studies of ruthenium complexes of 2,6-bis(benzimidazol-2-yl)pyridine with o-iminoquinone ancillary ligand

The ruthenium complexes [Ru^II(bbp)(L)(Cl)] (1), [Ru^II(bbp)(L)(H₂O)] (2) and [Ru^II(bbp)(L)(DMSO)] (3) {bbp = 2,6-bis(benzimidazol-2-yl)pyridine, L = o-iminoquinone} have been synthesized in a stepwise manner starting from [Ru^III(bbp)Cl₃]. The single crystal X-ray structures, except for the complex 2, have been determined. All the complexes were characterized by UV-Vis, FT-IR, ¹H NMR, Mass spectroscopic techniques and cyclic voltammetry. The Ru^III/Ru^II couple for complexes 1, 2, and 3 appears at 0.63, 0.49, 0.55 V, respectively versus SCE. It is observed that complex 2, on refluxing in acetonitrile, results into [Ru^II(bbp)(L)(CH₃CN)], 4 which has been prepared earlier in a different method. The structural, spectral and electrochemical properties of complexes 1, 2 and 3 were compared to those of earlier reported complex 4, [Ru^II(bbp)(L)(CH₃CN)].     

Efficient synthetic route to anhydrous mononuclear tris(8-quinolinolato)lanthanoid complexes for organic light-emitting devices

A new lanthanoid 8-quinilinolates type structure was found for lanthanum complex La₃(q^Me)₉(H)(NO₃) (1) formed in the reaction of La(NO₃)₃ · 6H₂O with 2-methyl-8-hydroxyquinoline (Hq^Me) and aqueous ammonia in methanol. The molecule of 1 contains three La atoms connected by six bridging quinolinolate ligands, two terminated η²-coordinated q^Me ligands, one terminated η¹-coordinated q^Me ligand and one terminated NO₃ group. The geometry and ¹H NMR spectrum of the complex suggest that it is bearing −1 charge balanced by proton, which was localized objectively. The arrangement of the compound in crystalline state and in pyridine solution is discussed. Syntheses of water- and acid residual-free mononuclear lanthanoid quinolinolates La(q^Me)₃(py)₂ (2) and Lnq₃(py)₂, (Ln = Y (3), La (4), Sm (5), Eu (6), Tb (7), Er (8), Tm (9); q = 8-quinolinolate, py = pyridine) by the reaction of appropriate amido complexes Ln[N(SMe₃)₂]₃ with 3 equiv. of 2-methyl-8-hydroxyquinoline or 8-hydroxyquinoline in pyridine solution is also described. The complex Laq₃(Ph₃PO)₂ (10) was prepared by treatment of 4 with triphenylphosphine oxide in pyridine solution. Lanthanum 2 complex revealed photoluminescence intensity ca. 3 × 10³ times higher than that of the compound 1 prepared by the traditional way in water-alcohol medium. These data give a ground to consider the Lnq₃(py)₂ complexes as promising material for design of light-emitting devices.     

Syntheses, crystal structures, and characterization of heteronuclear complexes based on a versatile ligand with both acetylacetonate and bis(2-pyridyl) units

A new type of multidentate ligand with both acetylacetonate and bis(2-pyridyl) units on the 1,3-dithiole moiety, 3-[2-(dipyridin-2-yl-methylene)-5-methylsulfanyl-[1,3]dithiol-4-ylsulfanyl]-pentane-2, 4-dione (L), has been prepared. Through reactions of the ligand with Re(CO)₅X (X = Cl, Br), new rhenium(I) tricarbonyl complexes ClRe(CO)₃(L) (2) and BrRe(CO)₃(L) (3), have been obtained. With the use of 2 or 3 as the precursors, the further reactions with (Tp^Ph2)Co(OAc)(Hpz^Ph2) (Tp^Ph2 = hydrotris(3,5-diphenylpyrazol-1-yl)borate); Hpz^Ph2 = 3,5-diphenyl-pyrazole) or M(OAc)₂(M = Mn, Zn), afford four new heteronuclear complexes: ClRe(CO)₃(L)Co(Tp^Ph2) (4), BrRe(CO)₃(L)Co(Tp^Ph2) (5), [ClRe(CO)₃(L)]₂Mn(CH₃OH)₂ (6) and [ClRe(CO)₃(L)]₂Zn(CH₃OH)₂ (7), respectively. Crystal structures of complexes 2 and 4-7 have been determined by X-ray diffraction. Their absorption spectra, photoluminescence and magnetic properties have been studied.     

6-Halogenopyridin-2-olato complexes with the diruthenium(2+) core: Equilibria between head-to-head and head-to-tail structures

The dinuclear bis(6-X-pyridin-2-olato) ruthenium complexes [Ru₂(μ-XpyO)₂(CO)₄(PPh₃)₂] (X = Cl (4B) and Br (5B)), [Ru₂(μ-XpyO)₂(CO)₄(CH₃CN)₂] (X = Cl (6B), Br (7B) and F (8B)) and [Ru₂(μ-ClpyO)₂(CO)₄(PhCN)₂] (9B) were prepared from the corresponding tetranuclear coordination dimers [Ru₂(μ-XpyO)₂(CO)₄]₂ (1: X = Cl; 2: X = Br) and [Ru₂(μ-FpyO)₂(CO)₆]₂ (3) by treatment with an excess of triphenylphosphane, acetonitrile and benzonitrile, respectively. In the solid state, complexes 4B-9B all have a head-to-tail arrangement of the two pyridonate ligands, as evidenced by X-ray crystal structure analyses of 4B, 6B and 9B, in contrast to the head-to-head arrangement in the precursors 1-3. A temperature- and solvent-dependent equilibrium between the yellow head-to-tail complexes and the red head-to-head complexes 4A-7A and 9A, bearing an axial ligand only at the O,O-substituted ruthenium atom, exists in solution and was studied by NMR spectroscopy. Full ¹H and ¹³C NMR assignments were made in each case. Treatment of 1 and 2 with the N-heterocyclic carbene (NHC) 1-butyl-3-methylimidazolin-2-ylidene provided the complexes [Ru₂(μ-XpyO)₂(CO)₄(NHC)], X = Cl (11A) or Br (12A). An XRD analysis revealed the head-to-head arrangement of the pyridonate ligands and axial coordination of the carbene ligand at the O,O-substituted ruthenium atom. The conversion of 11A and 12A into the corresponding head-to-tail complexes was not possible.     

Calix[4]arene supported group 5 imido complexes

The reaction of imidoyl chlorides [V(NR)Cl₃] (R = Ph 1, Tol 2, tBu 3) and calix[4]arene methyl ether H₃Mecalix unexpectedly leads to the formation of the structurally characterized vanadium (IV) complex [VCl(Mecalix)] (4). Calix[4]arene methyl ether stabilized imido complexes of the type [V(NR)(Mecalix)] (R = Ph 7, Tol 8, tBu 9) were afforded from the reaction of [V(NR)Cl₃] (R = Ph 1, Tol 2, tBu 3) and the tris(lithium) or tris(sodium) salt of the calix[4]arene ether. The lithium salt [{Li₃(Mecalix)}₂] (5) is a dimer in the solid state, in which two monomeric trianions are bridged by lithium cations. Imido complexes [M(NR)(Mecalix)] (M = Nb: R = tBu, 12, R = Tol 13, R = Mes 14, R = Dipp 15; M = Ta: R = tBu 16, R = Tol 17) (Tol = 4-C₆H₄Me, Mes = 2,6-C₆H₃Me₂; Dipp = 2,6-C₆H₃iPr₂) have been prepared from structurally characterized [NbCl₂(Mecalix)] (10) and previously known [TaCl₂(Mecalix)] (11) via reaction with two equivalents of the appropriately metallated (Li, K) primary amine. The molecular structures of 13 and 15 confirm the mononuclear nature of these complexes.     

Synthesis, characterization and l-lactide polymerization behavior of bis(amidinate) rare earth metal amide complexes

A family of neutral and solvent-free bis(amidinate) rare earth metal amide complexes with a general formula [RC(N-2,6-Me₂C₆H₃)₂]₂LnN(SiMe₃)₂ (R = phenyl (Ph), Ln = Y (1), Nd (2); R = cyclohexyl (Cy), Ln = Y (3), Nd (4)) were synthesized in high yields by one-pot salt metathesis reaction of anhydrous LnCl₃, amidinate lithium salt [RC(N-2,6-Me₂C₆H₃)₂]Li, and NaN(SiMe₃)₂ in THF at room temperature. Single crystal structural determination of complexes 1, 2 and 4 revealed that the central metal adopts distorted pyramidal geometry. In the presence of 1 equivalent of ⁱPr-OH, all these complexes were active for l-lactide polymerization in toluene at 70 °C to give high molecular weight (M_n > 10⁴) polymers.     

One-pot syntheses of alkenyl-phosphonio complexes of ruthenium(II), rhodium(III) and iridium(III) bearing p-cymene or pentamethylcyclopentadienyl groups

Reaction of [(p-cymene)RuCl₂(PPh₃)] (1) or [Cp^∗MCl₂(PPh₃)] (Cp^∗ = C₅Me₅) (3a: M = Rh; 4a: M = Ir) with 1-alkynes and PPh₃ were carried out in the presence of KPF₆, generating the corresponding alkenyl-phosphonio complexes, [(p-cymene)RuCl(PPh₃){CHCR(PPh₃)}](PF₆) (2a: R = Ph; 2b: R = p-tolyl) or [Cp^∗MCl(PPh₃){CHCPh(PPh₃)}](PF₆) (5: M = Rh; 6: M = Ir). Similar reactions of complexes [Cp^∗RhCl₂(L¹)] (3a: L¹ = PPh₃; 3c: L¹ = P(OMe)₃) with L² (L² = PPh₃, PMePh₂, P(OMe)₃) gave [Cp^∗RhCl(L¹)(L²)](PF₆) (7bb: L¹ = L² = PMePh₂; 7ca: L¹ = P(OMe)₃, L² = PPh₃; 7cc: L¹ = L² = P(OMe)₃). Alkenyl-phosphonio complex 5 was treated with P(OMe)₃ or 2,6-xylyl isocyanide, affording [Cp^∗RhCl(L){CHCPh(PPh₃)}](PF₆) (8a: L = P(OMe)₃; 8b: L = 2,6-xylNC). X-ray structural analyses of 2a, 6 and 8a revealed that the phosphonium moiety bonded to the C_β atom of the alkenyl group are E configuration.     

Synthesis and structure of the lithium, zirconium and hafnium N-silyl-N′-benzyl-benzamidinates

The interaction of LiN(SiMe₃)CH₂Ph with one equivalent of benzenitrile gave the N-silyl-N′-benzyl-benzamidinato-lithium compound [{Me₃SiNC(Ph)N(CH₂Ph)}Li(Et₂O)]₂ (1). The derivative zirconium and hafnium compounds were produced by the treatment of 1 with ZrCl₄ or HfCl₄ in tetrahydrofuran or diethyl ether at ambient temperature, respectively, with the general formula [Me₃SiNC(Ph)N(CH₂Ph)]₃MCl (M = Zr (2), Hf (3)). Compounds 1, 2 and 3 were also characterized by X-ray single crystal diffraction and NMR analysis.     

Studies of mononuclear and dinuclear complexes of dibromodimethylplatinum(IV): Preparation, characterization and crystal structures

A number of complexes of the types [PtBr₂Me₂(N^?N)] (N^?N = 4,4′-di-Me-2,2′-bpy (1); 4,4′-di-t-Bu-2,2′-bpy (2); 2,2′-bpz (3); bpym (4)) and [PtBr₂Me₂(L)₂] (L = H-pz (5); 4-Me-H-pz (6); H-idz (7); H-im (8); H-bim (9); quaz (10)) are reported. Characterization by NMR (¹H, ¹³C and ¹⁹⁵Pt), IR and EI-MS is given. In addition, crystal structures of several of these complexes are described. Furthermore, interactions within these structures including intramolecular hydrogen bonding and π-π stacking interactions are reported. The reactivity of selected mononuclear complexes was investigated and yielded two dinuclear complexes [PPh₄][(PtBrMe₂)₂(μ-Br)(μ-pz)₂] (11) and [(PtBr₂Me₂)₂(μ-bpym)] (12), respectively. The latter complex is accompanied by a solid-state structure. Finally, the thermal stability of all complexes is reported.     

Synthesis of trialkyl[60]fullerene C60(CH2SiMe3)3H and its potassium and rhodium(I) complexes

The reaction of [60]fullerene with Me₃SiCH₂MgCl in 1,2-Cl₂C₆H₄/THF (1/1) under dry air afforded a bis-alkyl adduct, C₆₀(CH₂SiMe₃)₂ (1), in 54% yield. Treatment of 1 with Me₃SiCH₂MgCl in THF under argon then afforded a trialkyl[60]fullerene, C₆₀(CH₂SiMe₃)₃H (2), in 37% yield. Further treatment of 2 with KO^tBu gave a potassium salt, [K(thf)_n][C₆₀(CH₂SiMe₃)₃] (3), which was then converted to a C_s-symmetric Rh(I) complex, Rh[η⁵-C₆₀(CH₂SiMe₃)₃](1,5-cyclooctadiene) (4), in 91% yield.     

Synthesis, structural and spectroscopic characterization of mono- and binuclear copper(I) complexes with substituted diimine and phosphine ligands

The reaction of [Cu(CH₃CN)₄]BF₄, 6-(4-methoxyl)phenyl-2,2′-bipyridine (designated as MeO-CNN), and/or tricyclohexylphosphine (PCy₃) and diimine ligands derived from 4,4′-bipyridine gave four mono- and binuclear copper(I) complexes, [Cu(MeO-CNN)₂]BF₄ (1), [Cu₂(MeO-CNN)₂(PCy₃)₂(4,4′-bipy)](BF₄)₂ · 1.5CH₂Cl₂ (2) (bipy = bipyridine), [Cu₂(MeO-CNN)₂(PCy₃)₂(bpete)](BF₄)₂ · 4CH₂Cl₂ (3) (bpete = trans-1,2-bis(4-pyridyl)ethene) and [Cu₂(MeO-CNN)₂(PCy₃)₂(4,4′-azpy)] (BF₄)₂ · 1.5CH₂Cl₂ (4) (azpy = azobispyridine). Crystallographic studies of complexes 1-4 show that each copper(I) center adopts a pseudo-tetrahedral coordination geometry. Complexes 2-4 consists of -Cu(MeO-CNN)(PCy₃) units which are linked through 4,4′-bipy, bpete and 4,4′-azpy, respectively. The UV-Vis spectra of these four complexes all exhibit intense high-energy absorptions at λ_max < 340 nm and broad visible bands in a range of 430-550 nm, ascribed to intraligand (IL π → π^∗) transitions and metal-to-ligand charge-transfer (MLCT) transitions, respectively. The density functional theory calculation was used to interpret the absorption spectrum of 1, which further supports the assignment of MLCT character. The binuclear complexes 2 and 3 both display red solid-state emissions centred at 620 and 660 nm from metal-to-ligand charge-transfer excited state, respectively. Interestingly, the electron paramagnetic resonance (EPR) spectral measurements confirm copper(I) complexes oxidized to corresponding copper(II)-halide product upon excitation at 355 nm in dichloromethane solution.     

Oxidative addition of mercury(II) halides and carboxylates to platinum(II): formation of Pt-Hg covalent and donor-acceptor bonds

The complex [PtMe₂(bu₂bpy)], 1, bu₂bpy = 4,4′-di-t-butyl-2,2′-bipyridine reacts with mercury(II) halides HgX₂ (X = Cl, Br, O₂CCF₃, O₂CMe) to give the corresponding complexes [PtMe₂X(HgX)(bu₂bpy)], 2, by trans oxidative addition followed, when X = O₂CCF₃, O₂CMe only, by easy isomerization to the cis isomers 3. The complexes 2 or 3 react with complex 1 to give the corresponding adducts [PtMe₂X(bu₂bpy)(μ-HgX)PtMe₂X(bu₂bpy)], 4, which are shown to contain both covalent and donor-acceptor Pt-Hg bonds in the solid state, and which exhibit very easy fluxionality in solution.     

Selective inclusion of DMF molecules within non-covalent cavity

[Me₄P]₄[Cu₄(mnt)₄]·2CH₃CN (1), [Me₄P]₄[Cu₄(mnt)₄]·2CH₃NO₂ (2), [Me₄P]₄[Cu₄(mnt)₄]·2DMF (3) and [Me₄P]₄[Cu₄(mnt)₄]·2C₃H₃N (4) (mnt = maleonitriledithiolate, [S₂C₂(CN)₂]²⁻) clusters are readily synthesized in several solvents like acetonitrile, nitromethane, N,N-dimethylformamide and acrylonitrile to provide respective solvent as guest within the non-covalent cavity of the cluster ion. The guest species is accommodated within non-covalent cavity that is generated by two adjacent {Cu₄(mnt)₄} cores bridging with tetramethylphosphonium cation through hydrogen bonding. These hydrogen bonds are not strong and when mixed solvents were used selective DMF binding takes place to yield only complex 3 over other complexes.