Novel reactivity aspects of cis-bis(1-alkenyl)platinum(II) compounds of the type Pt(CH2(CH2)nCHCH2)2L2 (where L2 = dppp, dppe, dppm and n = 1, 2)

We describe the synthesis, structure and reactivity of novel bis(1-alkenyl)platinum(II) complexes, Pt[CH₂(CH₂)_nCHCH₂]₂L₂ (where L₂ = dppp, dppe, dppm and n = 1, 2). The stability of the title complexes with the different ligands is discussed. The steric, chelating and electronic properties of the ligands have a significant impact on the structure as well as on the reactivity of the complexes. Novel reactions with elemental sulfur and carbon dioxide are described and discussed.     

Synthesis and coordination of the bifunctionalized ylides Ph2P(CH2)n(Ph)2PCHCOOMe (n = 1, 2) and ketenylidene Ph2P(CH2)2(Ph)2PCCO to Pd and Pt complexes

In this paper it is reported the synthesis of the phosphonium salts [Ph₂P(CH₂)_n(Ph)₂PCH₂COOMe]Br (n = 1 (1), 2 (2)) and [Ph₂P(CH₂COOMe)(CH₂)_n(Ph)₂PCH₂COOMe]Br₂ (n = 3 (3)) derived from the reactions of the diphosphines dppm, dppe and dppp with methyl bromoacetate. By reaction of the monophosphonium salt of dppm and dppe with the strong base Na[N(SiMe₃)₂] the corresponding carbonyl stabilized ylides Ph₂P(CH₂)_n(Ph)₂PCHCOOMe (n = 1 (4), 2 (5)) were obtained. The Ph₂P(CH₂)₂(Ph)₂PCHCOOMe (5) ylide was reacted with Pd(II) and Pt(II) substrates. From these reactions were isolated exclusively complexes in which the ylide was chelated to the metal through the free phosphine group and the ylidic carbon atom. A further reaction of the Ph₂P(CH₂)₂(Ph)₂PCHCOOMe (5) ylide with 1.5 equiv. of Na[N(SiMe₃)₂] gives the bifunctionalized ketenylidene Ph₂P(CH₂)₂(Ph)₂PCCO (6) system. This cumulenic ylide reacts with Pt(II) complexes to form a chelated derivative in which IR and NMR spectra suggest the breaking of the CC bond of the -CCO group.     

Synthesis and characterization of some oxovanadium(V) complexes with internally functionalized oximes: Crystal and molecular structures of heptacoordinated [VO{ONC(CH3)(C4H3O-2)}3] and [VO{ONC(CH3)(C4H3S-2)}3] · 0.5C6H6

New oxovanadium(V) complexes with internally functionalized oximes of the type VO{OPrⁱ}_3−n{ONC(CH₃)(Ar)}_n] (where Ar = C₄H₃O-2, C₄H₃S-2 and C₅H₄N-2 and n = 1-3) have been prepared in quantitative yields by the reaction of VO(OPrⁱ)₃ with the corresponding oximes in various stoichiometric ratios in refluxing anhydrous benzene. The products have been characterized by elemental analyses and spectroscopic (FT IR, ¹H, ¹³C{¹H} and ⁵¹V NMR) studies. FAB mass spectral analysis of [VO{OPrⁱ}{ONC(CH₃)C₄H₃S}₂] indicates the monomeric nature of the complex. ⁵¹V NMR values for these complexes suggest the formation of tetra-coordinate species in solution. However, the single crystal X-ray diffraction studies of [VO{ONC(CH₃)(C₄H₃O-2)}₃] and [VO{ONC(CH₃)(C₄H₃S-2)}₃] · 0.5C₆H₆ exhibit the presence of vanadium(V) atoms in a unique hepta-coordination state with distorted pentagonal bipyramidal geometry in the solid state. The oxo- atom occupies the axial position while the oximato ligands are bonded in a dihapto (η²-N,O) manner with the formation of three membered rings.     

Synthesis, characterization and emission properties of yttrium(III) and europium(III) complexes of a tripodal heptadentate Schiff-base ligand N[CH2CH2NCH(2-OH-3-MeC6H3)]3

The preparation and characterization of yttrium(III) and europium(III) complexes of tripodal heptadentate Schiff-base ligand N[CH₂CH₂NCH(2-OH-3-MeC₆H₃)]₃ (H₃L¹) have been studied. These complexes were prepared by the reaction of tris(2-aminoethyl)amine with 3-methylsalicylaldehyde in presence of M(CF₃SO₃)₃ (M = Y, Eu) in methanol. The molecular structures of [YL¹] (1) and [EuL¹] (2) were determined by X-ray crystallography. The crystal structure analysis revealed that the Schiff-base behaves as a tri-deprotonated heptadentate ligand encapsulating the metal ion within the N₄O₃ cavity. Under the excitation of UV light, the solid state of these complexes exhibited blue and red emission, respectively. The optical properties of 1 and 2 in solution and in the solid state were examined.     

Functionalised dithiocarbamate complexes: Synthesis and molecular structures of bis(2-methoxyethyl)dithiocarbamate complexes [M{S2CN(CH2CH2OMe)2}2] (M = Ni, Cu, Zn) and [Cu{S2CN(CH2CH2OMe)2}2][ClO4]

The bis(2-methoxyethyl)dithiocarbamate complexes [M{S₂CN(CH₂CH₂OMe)₂}₂] (M = Ni, Cu, Zn, Pd) are readily prepared and the three lighter complexes have been crystallographically characterised. Disproportionation of [Cu{S₂CN(CH₂CH₂OMe)₂}₂] upon addition of Cu(ClO₄)₂ · 6H₂O affords the copper(III) complex [Cu{S₂CN(CH₂CH₂OMe)₂}₂][ClO₄] which has also been crystallographically characterised. Unlike other copper(III) dithiocarbamate salts, there are no intermolecular cation-cation or cation-anion interactions.     

Preparation and crystal structure of two novel cadmium (II)-trimesates, Cd(HTMA)(NC5H5)2 · 0.5CH3OH · 0.5DMF and Cd(HTMA) · 2H2O

Two novel complexes, Cd(HTMA)(NC₅H₅)₂ · 0.5CH₃OH · 0.5DMF (1) and Cd(HTMA) · 2H₂O (2), of cadmium (II)-trimesates are obtained from slow vapor diffusion and urea hydrolysis, respectively. The Cd(II) centers in the two complexes are bridged by three separate HTMA³⁻ ligands using a same coordination fashion, which contains one monodentate and two chelating bidentate carboxyl groups to form the herringbone-like motif. The herringbone-like motif is further interlinked to construct the two-dimensional Cd(II)-HTMA layer, which is stacked by mutual π-stacking of pyridines for 1 and by hydrogen bond of waters for 2. Thermal stabilities of the two complexes were investigated and the results indicated that Cd(II)-TMA layers in the two complexes are stable still upon 190 °C.     

Coordination chemistry of acrylamide 3: Synthesis, crystal structure and IR spectroscopic properties of dichloro-tetrakis(O-acrylamide)copper(II), [Cu(O-OC(NH2)CHCH2)4Cl2]

The molecular structure of copper(II) chloride complex with acrylamide (AAmCH₂CHCONH₂), [Cu(AAm)₄Cl₂], was determined using X-ray diffraction analysis. The complex crystallizes in the cubic space group I-43d with a = 17. 8310(2) Å, β = 90°, and V = 5669.27(11) ų for Z = 12. The acrylamide molecules bind to the metal center via the carbonyl oxygen atom (Cu-O 1.996 Å). The coordination geometry of the metal center in the complex involves a tetragonally distorted octahedral structure with four O-donor atoms of acrylamide bonded in the equatorial positions and two chlorides in the apical positions. Comparison of crystal structure data of acrylamide and metal acrylamide complexes of those formed with divalent transition metal chlorides has been summarized.     

Cd(II) complexes with N8 and N4O4 donor macrocyclic ligands

The coordination capability of the octaaza 24-membered (L¹) and the tetraoxotetraaza 28-membered (L²) macrocycle ligands - with different sizes, nature and number of the donor atoms - has been investigated with nitrate and perchlorate Cd(II) salts. The complexes were prepared in 1:1 and 2:1 Cd:L molar ratio. The characterization by elemental analysis, IR, LSI mass spectrometry, conductivity measurements and ¹H NMR spectroscopy, together with the crystal structure of the complexes [CdL¹](NO₃)₂ · 0.5H₂O, [CdL¹](ClO₄)₂ and [CdL²(CH₃CN)₂](ClO₄)₂ · CH₃CN · H₂O confirms the formation of mononuclear complexes in all cases. The [CdL¹](NO₃)₂ · 0.5H₂O and [CdL¹](ClO₄)₂ present a mononuclear endomacrocyclic structure with the metal ion coordinated by the eight donor nitrogen atoms from the macrocyclic backbone in a square antiprism geometry. The complex [CdL²(CH₃CN)₂](ClO₄)₂ · CH₃CN · H₂O is also mononuclear, but the cadmium ion is in an octahedral environment coordinated by four amine nitrogen atoms from the macrocyclic framework and two nitrogen atoms from two acetonitrile molecules. The ether oxygen atoms from the ligand are not coordinated.     

The synthesis and characterization of a cationic technetium nitrosyl complex: The X-ray crystal structure of [TcCl(NO)(DPPE)2](PF6) · CH2Cl2

The reaction of the ammonium pertechnetate with a stochiometric excess of hydroxylamine hydrochloride in methanol yields a nitrosyl containing intermediate which can subsequently be reacted with reducing ligands to form nitrosyl complexes in various oxidation states. The reaction with a sixfold excess of diphenyl-phosphinoethane (DPPE) yields the Tc(I) cation [TcCl(NO)(DPPE)₂]⁺ which can be precipitated cleanly with tetraphenylborate. The infrared spectrum displays an absorption at 1728 cm⁻¹ which corresponds to the nitrosyl group. The ESI(+) mass spectrum displays the parent ion [TcCl(NO)(DPPE)₂]⁺ as the only signal at 960 m/z.The X-ray crystal structure of the hexafluorophosphate salt shows a mutually trans arrangement of the nitrosyl and chloride ligands with the two bidentate phosphine ligands coordinated in the equatorial plane. The nitrosyl and chloride ligands display the usual site disorder which makes discussion of bond lengths tenuous. However, the Tc-N-O bond angle of 179.0(2)° reflects the sp hybridization of the nitrosyl nitrogen atom. The Tc-P bonds are somewhat elongated at 2.3810(6), 2.3947(6), 2.4096(5) and 2.4321(6) Å, due to the steric congestion around the metal ion. The Tc-Cl bond is unexceptional at 2.3262(7) Å. The coordination geometry of this complex is best described as a distorted octahedron.     

Synthesis, structure, and reactivity of fluorous phosphorus/carbon/phosphorus pincer complexes derived from P(CH2)5P backbones

Reactions of the diphosphine H₂P(CH₂)₅PH₂ and fluorous alkenes H₂CCHR_fn (excess; R_fn = (CF₂)_n−1CF₃; n = a, 6; b, 8; c, 10) at 60 °C in the presence of AIBN give the precursors (R_fnCH₂CH₂)₂P(CH₂)₅P(CH₂CH₂R_fn)₂ (2a-c; 68-74%). These react with Pd(O₂CCF₃)₂ in CF₃C₆F₅ at 80 °C to give the title complexes (5a-c, 51-18%). Addition of LiCl to 5b gives (6b, 97%); subsequent reaction with MeLi affords the corresponding methyl complex (97%). A solvate of 6b is crystallographically characterized. The structure exhibits CH₂CH₂R_f8 groups with nearly anti C-C-C-C conformations, extending in parallel above and below the palladium square plane to create fluorous lattice domains. Reactions of 2b and other metal complexes are described; in the cases of (PhCN)₂PdCl₂ or (COD)₂PtCl₂ (CF₃C₆H₅, room temperature), bimetallic species in which two MCl₂ moieties are bridged by two diphosphines appear to form. The CF₃C₆F₁₁/toluene partition coefficients of 2a-c and 5a-c establish high fluorophilicities; despite the lower fluorine weight%, those of 5a-c are slightly greater ((97.4-99.7):(2.6-0.3) versus (95.3-99.3):(4.7-0.7)).     

Synthesis and characterization of complexes of the type [Pt(amine)4]I2 and trans-[Pt(CH3NH2)2(H3CNC(CH3)2)2]I2 by crystallography and multinuclear magnetic resonance spectroscopy

Complexes of the type [Pt(amine)₄]I₂ were synthesized and characterized mainly by multinuclear (¹⁹⁵Pt, ¹H and ¹³C) magnetic resonance spectroscopy. The compounds were prepared with different primary amines, but not with bulky amines, due to steric hindrance. In ¹⁹⁵Pt NMR, the signals were observed between −2715 and −2769 ppm in D₂O. The coupling constant ³J(¹⁹⁵Pt-¹H) for the MeNH₂ complex is 42 Hz. In ¹³C NMR, the average values of the coupling constants ²J(¹⁹⁵Pt-¹³C) and ³J(¹⁹⁵Pt-¹³C) are 18 and 30 Hz, respectively. The crystal structure of [Pt(EtNH₂)₄]I₂ was determined by X-ray diffraction methods. The Pt atom is located on an inversion center. The structure is stabilized by H-bonding between the amines and the iodide ions. The compound with n-BuNH₂ was found by crystallographic methods to be [Pt(n-BuNH₂)₄]₂I₃(n-BuNHCOO). The crystal contains two independent [Pt(CH₃NH₂)₄]²⁺ cations, three iodide ions and a carbamate ion formed from the reaction of butylamine with CO₂ from the air. When the compound [Pt(CH₃NH₂)₄]I₂ was dissolved in acetone, crystals identified as trans-[Pt(CH₃NH₂)₂(H₃CNC(CH₃)₂)₂]I₂ were isolated and characterized by crystallographic methods. Two trans bonded MeNH₂ ligands had reacted with acetone to produce the two N-bonded Schiff base Pt(II) compound.     

Complexes formed from 2,4,6-trimercaptotriazine (H3TMT): synthesis and structural characterization of [M(PhP(CH2CH2P(Ph)2)2(HTMT)], M=Ni(II), Pd(II), Pt(II)

Na₃TMT · 9H₂O (H₃TMT=2,4,6-trimercaptotriazine) reacts with M(PPP)Cl₂, PPP=PhP(CH₂CH₂PPh₂)₂, M=Ni, Pd, Pt, to give the compounds [M(PPP)(HTMT)]. The nickel and palladium complexes have been characterized by single-crystal X-ray diffraction analysis. PPP is tridentate in both complexes. The nickel complex has an irregular trigonal bipyramidal configuration in which the triazine is bidentate, coordinating through one sulfur and one nitrogen donor atom. The palladium complex has an approximately square planar geometry in which the triazine forms a strong Pd-S bond in the plane and also a very weak Pd-N interaction above the plane. The ³¹P NMR spectrum of the platinum complex is similar to that of the palladium complex, which is consistent with the Pt complex also having an approximately square-planar structure. Variable temperature NMR spectra show that two conformational isomers of the nickel complex are present in solution at low temperatures, though exchange is fast at room temperature. DFT calculations have confirmed the possible existence of two five-coordinate isomers of comparable stability.     

Heterobimetallic Fe-Pd and Fe-Pt NCN pincer complexes (NCN = [C6H2(CH2NMe2)2-2,6])

The meta-diaminoaryl ferrocenes Fc-NCN-H (3) and Fc-CC-NCN-H (5) (Fc = (η⁵-C₅H₅)(η⁵-C₅H₄)Fe, NCN-H = C₆H₃(CH₂NMe₂)₂-3,5) can be used as precursors in the preparation of heterobimetallic transition metal complexes of structural type Fc-NCN-MX (NCN = [C₆H₂(CH₂NMe₂)₂-2,6]⁻; MX = PdCl (7), PtCl (8), PtI (9)) and Fc-CC-NCN-MX (MX = PdCl (11), PdI (12), PtCl (13)), respectively. They are accessible by applying different synthesis procedures, including oxidative addition and metallation-transmetallation processes.Cyclovoltammetric studies show that the ferrocene moieties in 3, 5, 7-9 and 11-13 can reversibly be oxidised. The potential of the Fe(II)/Fe(III) redox couple decreases with increasing electron density at the NCN pincer unit. The use of 8 as a possible (electro)chemical sensor in the detection of SO₂ is discussed as well.The solid-state structures of 8 and 13 are reported. The crystals of 8 contain two molecules of 8 in the asymmetric unit. The plane of the C₆H₂ moiety is with 27.2(3)° and 38.2(3)° tilted towards the C₅H₄ entity, while in 13 an angle of 45.9(3)° can be found. The d⁸-electron configured platinum atoms possess a somewhat distorted square-planar surrounding, setup by two Me₂NCH₂ortho-substituents, the NCN C_ipso carbon atom and the chloride ligand.     

[Co{Ph2P(O)CH2P(O)Ph2}3][CoCl4] · 8CHCl3: Crystal structure and formation from [Co2(Ph2PCH2PPh2)(CO)6] in chloroform

When a solution of [Co₂(Ph₂PCH₂PPh₂)(CO)₆] in chloroform or deuterochloroform is allowed to stand in air at room temperature, it deposits dark green crystals of [Co{Ph₂P(O)CH₂P(O)Ph₂}₃][CoCl₄] · 8CHCl₃. The same product is formed more quickly and in much higher yield (80% based on Co) if the reaction is carried out in the presence of 2 equiv. of [Ph₂PCH₂PPh₂]; the Co^II appears to catalyse the air-oxidation of [Ph₂PCH₂PPh₂]. The salt was characterised by X-ray crystallography and shown to contain octahedral Co^II cations and Co^II tetrahedral anions having normal bond lengths and angles.     

Synthesis, characterization and bioactivity of a novel 18-metallacrown-6: [Mn(pcshz)(CH3OH)]6 · 4CH3OH · 4H2O

The reaction of N-propionyl-5-chlorosalicylhydrazide (H₃pcshz) with Mn(OAc)₂ · 4H₂O in methanol solution gives a novel 18-metallacrown-6 [Mn(pcshz)(CH₃OH)]₆ · 4CH₃OH · 4H₂O (1). The structure of 1 has been determined by X-ray diffraction and it crystallizes in the monoclinic system and space group P2(1)/n. The ring of the metallacrown is consisted of six interlink [Mn-N-N] repeated units through hydrazide N-N group bridging the ring manganese ions. And the ligand enforces the metal ions to form the stereochemistry as a propeller configuration with alternation Λ/Δ form. The largest diameters of the disc-shaped hexanuclear ring are about 8.82 Å at entrance, 9.83 Å at the central of the cavity, respectively. The solution integrity and stability of the metallacrown was studied by electrospray ionization (ESI)-MS and UV-Vis spectroscopy. The results show it is soluble and stable in methanol. Antibacterial screening data indicate the forming of the complex weakens dramatically the antibacterial activity of the ligand H₃pcshz except for Eschericha coli.     

Electrochemical oxidation of Mo(CO)4(LL) and Mo(CO)3(LL)(CH3CN): Generation, infrared characterization, and reactivity of [Mo(CO)4(LL)] and [Mo(CO)3(LL)(CH3CN)] (LL = 2,2′-bipyridine, 1,10-phenanthroline and related ligands)

Mo(CO)₄(LL) complexes, where LL = polypyridyl ligands such as 2,2′-bipyridine and 1,10-phenanthroline, undergo quasi-reversible, one-electron oxidations in methylene chloride yielding the corresponding radical cations, [Mo(CO)₄(LL)]⁺. These electrogenerated species undergo rapid ligand substitution in the presence of acetonitrile, yielding [Mo(CO)₃(LL)(CH₃CN)]⁺; rate constants for these substitutions were measured using chronocoulometry and were found to be influenced by the steric and electronic properties of the polypyridyl ligands. [Mo(CO)₃(LL)(CH₃CN)]⁺ radical cations, which could also be generated by reversible oxidation of Mo(CO)₃(LL)(CH₃CN) in acetonitrile, can be irreversibly oxidized yielding [Mo(CO)₃(LL)(CH₃CN)₂]²⁺ after coordination by an additional acetonitrile. Infrared spectroelectrochemical experiments indicate the radical cations undergo ligand-induced net disproportionations that follow first-order kinetics in acetonitrile, ultimately yielding the corresponding Mo(CO)₄(LL) and [Mo(CO)₂(LL)(CH₃CN)₃]²⁺ species. Rate constants for the net disproportionation of [Mo(CO)₃(LL)(CH₃CN)]⁺ and the carbonyl substitution reaction of [Mo(CO)₃(LL)(CH₃CN)₂]²⁺ were measured. Thin-layer bulk oxidation studies also provided infrared characterization data of [Mo(CO)₄(ncp)]⁺ (ncp = neocuproine), [Mo(CO)₃(LL)(CH₃CN)]⁺, [Mo(CO)₃(LL)(CH₃CN)₂]²⁺ and [Mo(CO)₂(LL)(CH₃CN)₃]²⁺ complexes.     

Syntheses, characterizations and crystal structures of two lead(II) diphosphonates: Pb2[NH(CH2PO3)2] · 2H2O and Pb3[HO2C(CH2)3NH(CH2PO3)2]2 · 2H2O

Hydrothermal reactions of lead(II) acetate and HO₂C(CH₂)₃N(CH₂PO₃H₂)₂ at 170 and 140 °C, respectively, resulted in two different lead diphosphonates, namely, Pb₂[NH(CH₂PO₃)₂] · 2H₂O (1), in which the butyric acid moiety of the HO₂C(CH₂)₃N(CH₂PO₃H₂)₂ has been cleaved and a novel layered compound, Pb₃[HO₂C(CH₂)₃NH(CH₂PO₃)₂]₂ · 2H₂O (2). Their crystal structures have been determined by single crystal X-ray diffraction. In compound 1, the interconnection of the lead(II) ions by bridging amino-diphosphonate ligands leads to the formation of a 3D network. Compound 2 features an unusual triple-layer structure with the non-coordinated butyric acid moieties as pendant groups between the layers.     

Ru2(CO)4(OOCR)2L2 sawhorse-type complexes containing axial 5-(4-pyridyl)-10,15,20-triphenylporphyrin ligands

The thermal reaction of Ru₃(CO)₁₂ with various carboxylic acids (benzoic, 4-hydroxyphenylacetic, ferrocenic, stearic, oleic, 4-(octadecyloxy)benzoic) in refluxing tetrahydrofuran, followed by addition of 5-(4-pyridyl)-10,15,20-triphenylporphyrin (L), gives the dinuclear complexes Ru₂(CO)₄(OOCR)₂L₂ (1: R = -C₆H₅, 2: R = -CH₂-p-C₆H₄OH, 3: R = -C₅H₄FeC₅H₅, 4: R = -(CH₂)₁₆CH₃, 5: R = -(CH₂)₇CHCH(CH₂)₇CH₃, 6: R = -p-C₆H₄O(CH₂)₁₇CH₃). Complexes 1-6 were characterised by IR, NMR, and ESI-MS as well as by elemental analysis. The UV-Vis spectra show the Soret band centred at 417 nm and the Q bands at 515, 550, 590 and 645 nm, respectively.     

Sn-S and Ru-Ru bonds cleavage reactions between [Ph3SnS(CH2)3SSnPh3] and Ru3(CO)12: X-ray crystal structures of [Ph3SnS(CH2)3SSnPh3] and trans-[Ru(CO)4(SnPh3)2]

The organotin complex [Ph₃SnS(CH₂)₃SSnPh₃] (1) was synthesized by PdCl₂ catalyzed reaction between Ph₃SnCl and disodium-1,3-propanedithiolate which in turn was prepared from 1,2-propanedithiol and sodium in refluxing THF. Reaction of 1 with Ru₃(CO)₁₂ in refluxing THF affords the mononuclear complex trans-[Ru(CO)₄(SnPh₃)₂] (2) and the dinuclear complex [Ru₂(CO)₆(μ-κ²-SCH₂CH₂CH₂S)] (3) in 20 and 11% yields, respectively, formed by cleavage of Sn-S bond of the ligand and Ru-Ru bonds of the cluster. Treatment of pymSSnPPh₃ (pymS = pyrimidine-2-thiolate) with Ru₃(CO)₁₂ at 55-60 °C also gives 2 in 38% yield. Both 1 and 2 have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction analysis.