Iodo Complexes Research Articles

Organotransition-Metal Metallacarboranes. 59.1 Synthesis and Linkage of Boron-Functionalized Ferracarborane Clusters

Negishi cross-coupling has been applied to B−I and B−Br bonds in small closo-ferracarboranes as a means of effecting controlled substitution at boron, with subsequent linkage to form polymetallacarborane systems. Reaction of (η6-C6H6)Fe(2,3-Et2C2B4H3-5-I) (2) with vinyl−, butyl−, (trimethylsilyl)ethynyl−, and phenyl−organozinc reagents (RZnCl) in the presence of catalytic amounts of palladium(0) catalyst produced the corresponding B-functionalized derivatives (3−5 and 8, respectively) in moderate to good yields. Similarly, (η6-C6H6)Fe(Et2C2B4H3-7-C⋮CSiMe3) (12) was prepared from the B(7)−Br (11a) or B(7)−I derivative (11b). A second alkynyl fragment was introduced at B(5) on 12 to yield the B(5,7)-diethynyl-substituted compound 16. Treatment of (η6-C6H6)Fe(2,3-Et2C2B4H3-5-Ph) (8) with Cr(CO)6 in refluxing n-butyl ether gave the heterodimetallic complex (η6-C6H6)Fe[Et2C2B4H3-5-{(η6-C6H5)Cr(CO)3}] (9). A series of diferracarboranes bridged by thiophene (18), dihydrophenanthrene (19), or mono-, di-, or triphenylene (22−24) linking groups was generated via reaction of 2 with bis(chlorozinc) reagents and palladium(0) catalyst, as were B(5)−ferrocenyl derivatives (20, 21). Reaction of the known complex (η6-C8H10)Fe(Et2C2B4H4) with 8 at 180 °C formed (η6-C6H6)Fe(Et2C2B4H3-5-Ph)Fe(Et2C2B4H4) (25) via displacement of cyclooctatriene. Electrophilic B-iodination on the unsubstituted C2B4 cage of 25 afforded a dark red air-stable crystalline B(5)−iodo complex (26). Pd-catalyzed cross-coupling of 26 with PhZnCl, followed by cyclooctatriene displacement from (η6-C8H10)Fe(Et2C2B4H4), produced the triferracarborane-linked oligomer (η6-C6H6)Fe(Et2C2B4H3-5-Ph)Fe(Et2C2B4H3-5‘-Ph)Fe(Et2C2B4H4) (28) in an overall yield from 8 of 40% in this four-step sequence. Deprotection of 5 and 12 with fluoride gave the B(5)− and B(7)−C⋮CH derivatives 6 and 13, respectively. Homocoupling of these terminal alkynes with Pd/Cu catalyst afforded the linked isomers [(η6-C6H6)Fe(Et2C2B4H3-n-C⋮C)]2 (29, n = 5; 31, n = 7). Alternatively, 6 and 13 were treated with 1,3,5-C6H3I3 under similar conditions to form the benzene-centered triferracarborane complexes [(η6-C6H6)Fe(Et2C2B4H3-n-C⋮C)]3C6H3 (30, n = 5; 32, n = 7). X-ray diffraction analyses confirmed the structures of 9, 18, 24, and 26.

The first family of trigonal prismatic M(bidentate) 2(monodentate) 2 complexes: synthesis and characterization of halobis(2-amidothiophenolato)triphenylphosphinerhenium(V)

The 1:2 reaction of [Re VOCl 3(PPh 3) 2] with 2-aminothiophenol (H 2atp) in toluene has afforded red-brown [Re V(atp) 2(Cl)(PPh 3)]. The corresponding bromo and iodo complexes have been similarly obtained from [Re VO(OEt)Br 2(PPh 3) 2] and [Re VO(OEt)I 2(PPh 3) 2], respectively. The X-ray structure of the solvate [Re(atp) 2(Cl)(PPh 3)]·2CH 2Cl 2 has revealed trigonal prismatic geometry for the ReS 2N 2ClP coordination sphere in which the two triangular faces are defined by the S, S,P and N, N, Cl triads. The twist angle between them is 8.0°. The [Re(atp) 2(X)(PPh 3)](X=Cl, Br, I) complexes are diamagnetic (Re V, spin-paired d 2) and in acetonitrile solution these display a quasireversible Re VI–Re V response near 0.7 V. Reaction with H 2atp in air converts [Re V(atp) 2(X)(PPh 3)] to the tris chelate [Re VI(atp) 3].

Synthesis, Characterization, and Reactivity of Cationic Palladium(II) and Platinum(II) Iodo Complexes Containing a Linear or a Tripodal Aminophosphine. The X-Ray Crystal Structures of [Pd{HN(CH2CH2PPh2)2}I]I and [Pd3{N(CH2CH2PPh2}3)2I4]I2Dedicated to Professor Joachim Strähle on the Occasion of his 65th Birthday

The complexes [M(PNHP)I]I (PNHP = bis[2-(diphenylphosphino)ethyl]amine; M = Pd (1), Pt (2)) and [M(NP3)I]I (NP3 = tris[2-(diphenylphosphino)ethyl]amine; M = Pd (3), Pt (4)) were prepared by interaction of the appropriate aminophosphine in CH2Cl2 with aqueous solutions containing [MCl4]2— salts and NaI in a ratio 1:4. Complexes 2 and 3 form the polynuclear compounds [Pt2(PNHP)3]I4 (2a) and [Pd3(NP3)2I4]I2 (3a) in the presence of coordinating solvents such as the mixture CD3OD/D2O/DMSO-d6 and CH2Cl2/CH3OH, respectively. Complex 1 consists of distorted square-planar cations [Pd(PNHP)I]+ and iodide anions able to establish short N-H···I interactions of 2.850Å. The aminophosphine adopts a boat conformation and is coordinated to palladium in a tridentate chelating fashion. The crystal structure for cations of 3a reveals the presence of two types of distorted square-planar PdII atoms, PdNP2I and trans-PdP2I2, NP3 acting as tridentate chelating and bridging ligand, respectively. On the basis of 31P {1H} NMR data it has been shown that each distorted square-planar Pt(II) centre of 2a contains one PNHP acting as tridentate chelating ligand with the other aminophosphine bridging the two metals via the P atoms. Complexes 3 and 4 were shown by 31P {1H} NMR to have the metal atom bound to the three P atoms of NP3 and one iodo ligand. Additions of AcCysSH and GSH to 4 result, by a ring-opening process, in the formation of [Pt(NP2PO)(SR)] (RS = Acys (4a), GS (4b)) in which the ligand contains a dangling arm phosphine oxide group and the platinum atom achieves the four-coordination involving the N atom of the aminophosphine. Compounds [Pt2(PNHP)3]Cl4 (2a′, 2a″), [PtAu(PNHP)2I]I2 (2b), and [Pt(PNHP)(ONO2)](NO3) (2c) were detected in some extent in solution by reaction of complex 2 with Au(tdg)Cl (tdg = thiodiglycol), AuI and excess AgNO3, respectively. While 1 does not react with AuI, complex 3 affords the heterobimetallic complexes PdCu(NP3)I3 (5), PdAg2(NP3)I4 (6) and PdAu(NP3)I3 (7) by interaction with the appropriate iodide M′I (M′ = Cu, Ag, Au) via a chelate ring-opening. Synthese, Charakterisierung und Reaktivität der Palladium(II)- und Platin(II)-Iod-Komplexe mit einem linearen bzw. einem tripodalen Aminophosphan-Liganden. Die Kristallstrukturen von [Pd{HN(CH2CH2PPh2)2}I]I und [Pd3{N(CH2CH2PPh2}3)2I4]I2 Die Komplexe [M(PNHP)I]I (PNHP = Bis[2-(diphenylphosphino)ethyl]amin; M = Pd (1), Pt (2)) und [M(NP3)I]I (NP3 = Tris[2-(diphenylphosphino)ethyl]amin; M = Pd (3), Pt (4)) wurden präpariert durch Umsetzung des betreffenden Aminophosphans in CH2Cl2 mit wäßrigen Lösungen der [MCl4]2—-Salze und NaI im Verhältnis 1:4. Die Komplexe 2 und 3 bilden die mehrkernige Verbindungen [Pt2(PNHP)3]I4 (2a) und [Pd3(NP3)2I4]I2 (3a) in Gegenwart von Lösungsmittelgemischen wie CD3OD/D2O/DMSO-d6 bzw. CH2Cl2/CH3OH. Komplex 1 enthält die verzerrt quadratisch-planaren Kationen [Pd(PNHP)I]+ und Iod-Anionen mit kurzen N—H···I-Kontakten von 2, 850Å. Aminophosphan hat Boot-Konformation und ist dreizähnig, chelatartig an Palladium koordiniert. Die Kristallstruktur der Kationen von 3a zeigt die Anwesenheit von zwei Arten von verzerrt quadratisch-planaren PdII-Atomen in PdNP2I und trans-PdP2I2; NP3 ist ein dreizähniger Chelat- bzw. —Brückenligand. Auf Basis der 31P{1H}-NMR-Daten wird gezeigt, dass jedes der verzerrt quadratisch-planar koordinierten PtII-Atome von 2a ein PNHP als dreizähnigen Chelatliganden enthält und mit dem anderen Aminophosphan werden die zwei Metallatome verbrückt. In den Komplexen 3 und 4 ist nach den 31P{1H}-NMR-Daten das Metallatom an die drei P-Atome des NP3 und an einen Iod-Liganden gebunden. Zusatz der Thiole AcCysSH und GSH zu 4 führt zu einer Ringöffnung und Bildung von [Pt(NP2PO)(SR)] (RS = Acys (4a), GS (4b)) in denen der Ligand eine angehängte Phosphanoxid-Gruppe enthält und das Platinatom vierfache Koordination erreicht unter Einbeziehung des N-Atoms des Aminophosphans. Die Verbindungen [Pt2(PNHP)3]Cl4 (2a′, 2a″), [PtAu(PNHP)2I]I2 (2b) und [Pt(PNHP)(ONO2)](NO3) (2c) wurden in Lösung bei der Reaktion von 2 mit Au(tdg)Cl (tdg = Thiodiglykol), AuI bzw. einem Überschuß an AgNO3 beobachtet. Während 1 nicht mit AuI reagirt, ergibt 3 die heterobimetallischen Komplexe PdCu(NP3)I3 (5), PdAg2(NP3)I4 (6) und PdAu(NP3)I3 (7) beim Umsatz mit den Iodiden von Cu, Ag bzw. Au durch die Ringöffnungsreaktion.

New Catalyst Systems for the Catalytic Conversion of Methane into Methanol

Palladium complexes with N-heterocyclic carbenes, such as in the biscarbene chelate ligands shown (R=tBu, Me; X=Br, I), have proved to be stable in strongly acidic media and were tested in the catalytic conversion of methane into methanol. The prominent influence of the halogenide ligand is shown since, in contrast to the bromo complex, the iodo complex does not catalyze the reaction. The steric bulk of the substituents R also influences the catalytic activity.

Synthesis and characterization of cobalt and nickel chelates of 5-dimethylaminomethyl-2-thiouracil and their evaluation as antimicrobial and anticancer agents

A new antimetabolite of adenine, viz. 5-dimethylaminomethyl-2-thiouracil, was synthesized using the Mannich reaction. Owing to the biological importance of metalloelements in many biological processes, especially metabolic processes, cobalt(II) and nickel(II) complexes were also synthesized and examined for their antimicrobial and anticancer activities. These new compounds were characterized structurally by various techniques ranging from micro-elemental analyses to spectral analyses. Cobalt(II) complexes were found to be four coordinate, among which the bromo, iodo, and nitrato complexes were polymeric. The nickel(II) isothiocyanato complex exhibited four-coordinate geometry and the remaining nickel(II) complexes were six coordinate. Thermodynamic and kinetic parameters evaluated based on TG/DSC suggested that the initial stage of thermal decomposition follows a diffusion-controlled mechanism and the final stage a chemically controlled mechanism. Antibacterial, antifungal, and antitumor studies undertaken for the above compounds indicated structure–activity relationships. These metalloderivatives were more active than the parent compound. The order of activity was influenced by the chelate geometry and thermal stability. Activity increased with a decrease in coordination number and increase in thermal lability.

Synthesis, molecular structure, and reactivity of allenylideneosmium complexes of the half-sandwich-type

The reaction of the areneosmium(II) compunds [Os(η6-arene)(L)X2] 2a–2e, 3, 4 with propargylic alcohols HCCCR2(OH) (where R = phenyl or p-tolyl) in the presence of AgPF6 leads to the formation of the cationic osmium allenylidenes [Os(η6-arene)(CCCR2)(L)X]PF65a–5h in good to excellent yields. Salt metathesis of 5a (L = PMe3) and 5b (L = PCy3) with NaB(ArF)4 gives [Os(η6-mes)(CCCPh2)(PR3)Cl]B(ArF)46a, 6b while treatment of 5b with KBr, NaI and CF3CO2Ag affords the corresponding bromo, iodo and trifluoracetato complexes [Os(η6-mes)(CCCPh2)(PCy3)X]PF67a–7c. Compound 5a reacts with MeOH and EtOH to give the Fischer-type osmium carbenes [Os(η6-mes){C(OR)CHCPh2}(PMe3)Cl]PF68a and 8b, of which 8a has been converted by treatment with NaH to the neutral allenyl complex [Os(η6-mes){C(OMe)CCPh2}(PMe3)Cl] 9. The reaction of 5a and 5b with tertiary phosphines PR′3 yields a mixture of [Os(η6-mes){C(PR′3)CCPh2}(PR3)Cl]PF610a–10c and [Os(η6-mes)(PR3)(PR′3)Cl]PF611a–11c, which could not be separated by analytical tools. The cationic bis(phosphine) compounds 11a–11c were prepared independently from 2a–2c and PMe3 in the presence of NH4PF6. The molecular structures of 5a and 8b were determined crystallographically.

1:1 and 1:2 Complexes of Mercury(II) Halides with 1,3-Thiazolidine-2-thione. Spectral, Thermal, and Crystal Structure Studies

The series of compounds of the general formulae HgX2(tzdtH) and HgX2(tzdtH)2 (X = Cl, Br, I; tzdtH = 1,3-thiazolidine-2-thione) have been prepared, as well as Hg(tzdt)2. IR, 1H, and 13C NMR spectral data of the complexes indicate thione donation, which is confirmed by the crystal structure analyses of [HgBr2(tzdtH)]2, [HgI2(tzdtH)]2, and HgI2(tzdtH)2. The structures of [HgBr2(tzdtH)]2 and [HgI2(tzdtH)]2 consist of centrosymmetric doubly bridged dimers, but they are not isostructural. The asymmetry in the HgX2Hg bridge is more pronounced in the bromo than in the iodo derivative [S–Hg–X(terminal) is 138.19(9)° for X = Br and 123.49(10)° for X = I], which is accompanied by the stronger Hg–S covalent bond in the bromo than in the iodo complex [2.435(4) vs. 2.510(3) A]. The Hg–X(bridging) (X = Br, I) bond distances are shorter than the sum of van der Waals radii for mercury and X. Dimeric centrosymmetric complex units are held together only by van der Waals forces in [HgI2(tzdtH)]2, while in [HgBr2(tzdtH)]2 there is an intramolecular hydrogen bond of N–H⋅ ⋅ ⋅Br type (3.34(1) A). HgI2(tzdtH)2 exists as a mononuclear tetrahedral complex with two long Hg–S [2.672(1) A] and two short Hg–I bond distances [2.688(1) A] related by a twofold axis. The molecules of HgI2(tzdtH)2 are linked into infinite chains along the c axis by intermolecular N–H⋅ ⋅ ⋅S [3.38(1) A] hydrogen bonds.

Synthesis, properties and spectroscopic studies of rhenium(v) complexes stabilized by tridentate Schiff bases derived from S-methyl dithiocarbazate

Neutral oxorhenium(V) complexes with tridentate SNO Schiff bases have been prepared by substitution reactions on the square pyramidal ionic complex [NBu4][ReVOCl4] and on the six-coordinate rhenium precursor [ReVOCl3(PPh3)2]. The chlororhenium intermediate species [ReVOCl(Ph–SNO–CH3)] 1 allows the formation of the homologous iodo complex [ReVOI(Ph–SNO–CH3)] 2 by a halogen exchange reaction with lithium iodide. The similar complexes [ReVOCl(Ph–SNO–H)] 3 and [ReVOCl(Naph–SNO–H)] 4 have been synthesised using S-methyl-β-N-(2-hydroxyphenylmethylidene)dithiocarbazate (Ph–SNO–H) and S-methyl-β-N-(2-hydroxynaphthylmethylidene)dithiocarbazate (Naph–SNO–H). The ionic complex [NBu4][ReOCl4] reacts with 4 equivalents of PPh3 and Ph–SNO–H or Naph–SNO–H to give rise to the complexes [ReVOCl(Ph–SNO–H)(PPh3)] 5 and [ReVOCl(Naph–SNO–H)(PPh3)] 7 which are smoothly converted in ethanolic solution into [ReVOCl(Ph–SNO–H)(OPPh3)] 6 and [ReVOCl(Naph–SNO–H)(OPPh3)] 8, respectively. Each compound was characterised by elemental analysis, IR, NMR spectra and FAB mass spectrometry. The crystallographic structures of [ReOI(Ph–SNO–CH3)] 2, [ReOCl(Ph–SNO–H)(PPh3)] 5 and [ReOCl(Ph–SNO–H)(OPPh3)] 6 were determined by single crystal X-ray diffraction methods.

Synthesis and Reactivity of Heterodinuclear Fe−Ni Complexes with a Bridging Alkoxysilyl Ligand. Crystal Structure of [(OC)3Fe{μ-Si(OMe)2(OMe)}(μ-dppm)NiMe

The new heterobimetallic complex (1) was obtained in 95% yield by reaction of [NiCl2(PPh3)2] in THF with K[Fe{Si(OMe)3}(CO)3(dppm-P)] at −78 °C. The analogous bromo and iodo complexes were also obtained; the latter is, however, less stable and could not be isolated pure. They display the first examples of a bridging alkoxysilyl ligand between Fe and Ni, and the μ2-η2-SiO bridge is also present in the methyl complex (4) and its phenyl analogue 5. The presence of the four-membered rings was confirmed by a crystal structure determination of 4. Treatment of 1 with excess (allyl)MgCl led to the expected bimetallic allyl complex (6). The rapid η3-allyl → η1-allyl → η3-allyl rearrangement is potentially assisted through stabilization of the coordinatively unsaturated Ni center by a SiO→Ni interaction. The bimetallic benzyl derivative 7 was also isolated. Purging a THF or benzene solution of 4 at room temperature with CO yielded after a few seconds the acyl complex (8), which readily decarbonylates. Its reaction with norbornadiene leads to the insertion product, which is thought to exist as an isomeric mixture with terminal or chelating acyl group (11 ⇌ 11‘). When complex 4 was reacted with tBuNC, rapid insertion occurred and further coordination of a terminal tBuNC ligand to Ni led to the iminoacyl complex (12). Complex 1 proved to be a more efficient catalyst (TON = 4100) for the dehydrogenative coupling of Ph3SnH than its mononuclear counterpart [NiCl2(PPh3)2] (TON = 1050). The maximum turnover frequency (TOF) was ca. 9800 h-1.

Making a 16-electron bromo (or iodo) complex of ruthenium(II) and a C—F bond in one pot

The 16e– bromo or iodo complexes [RuX(dppp)2]+ (dppp = 1,3-bis(diphenylphosphino)propane, X = Br (1c), I (1d)) and [RuX(dppe)2]+ (dppe = 1,2-bis(diphenylphosphino)ethane, X = Br (2c), I (2d)) have been prepared exploiting the reaction of the fluoro complexes [RuF(dppp)2]+ (1a) and [Tl(µ-F)2Ru(dppe)2]+ (3) with activated alkyl bromides or iodides. The X-ray structures of 1c, 1d, 2c, and 2d suggest that the distortion of the Y-shaped trigonal-bipyramidal structure of [MX(P∩P)2]+ is possibly related to the formation of intramolecular hydrogen bonds between the halide ligand and the ortho-hydrogen atoms of the neighbouring phenyl rings. The five-coordinate species 1c, 1d, 2c, and 2d react with H2 to form the dihydrogen complexes [RuX(η2-H2)(P∩P)2]+. The reaction of the dppp derivatives 1c and 1d with H2 (P = 1 atm, 1 atm = 101.322 kPa) is an equilibrium. Quantitative formation of [RuBr(η2-H2)(dppp)2] (4c) is obtained under H2 pressure (100 bar, 1 bar = 100 kPa), whereas the iodo analogue is not stable under analogous conditions. The less crowded dppe derivatives 2c and 2d react quantitatively with H2 under ambient pressure. The iodo and bromo derivatives [RuX(η2-H2)(P∩P)2]+ contain elongated dihydrogen ligands, as indicated by their transverse relaxation times T1 (min). The present data suggest that Cl, Br, and I have similar donor properties in these dihydrogen complexes, and that the different chemical behaviour in the Cl, Br, I series is mainly a result of steric effects.Key words: 16e– complexes, ruthenium, fluoro complexes, bromo complexes, iodo complexes, dihydrogen complexes.

Intramolecular Pd-catalyzed carbocyclization, Heck reactions, and aryl-radical cyclizations with planar chiral arene tricarbonyl chromium complexes.

(o-butenylhalobenzene)Cr(CO)(3) complexes were synthesized by diastereoselectve allylmetal additions to o-halo benzaldehyde complexes. The addition of allylZnBr proved particularly convenient and clean. The complexes undergo intramolecular Pd-catalyzed cyclizations (Heck reactions) without decomplexation and/or alkene isomerization. In complexes with a benzylic stereogenic center, the diastereoselectivity of the alkene carbopalladation is governed by the planar chirality of the complex rather than by the benzylic stereogenic center in the side chain. This reaction outcome can be rationalized by the geometry of the arene plane vs that of the Pd coordination plane in the transition step of the alkene carbopalladation step. An alternative cyclization procedure involves the generation of a Cr(CO)(3)-coordinated arene radical from the bromo and iodo complexes. Intramolecular aryl-radical cyclization affords indan complexes. The transition metal arene pi-bond remains intact during this process.

Subtlety in the reactivity of a diketo phosphorus ylide towards mercuric halides: the unprecedented O-coordination of alpha-acetyl-alpha-benzoylmethylenetriphenylphosphorane to Hg(II).

The reactions of the title ylide with HgX2 (X = Cl, Br or I) lead to the regiospecific binding of the acetyl oxygen to soft Hg(II), producing a chloro complex with (2 + 2) coordination and isostructural dimeric bromo and iodo complexes containing halogen bridges with tetrahedral configurations around the metal centres.

Making a 16-electron bromo (or iodo) complex of ruthenium(II) and a C—F bond in one pot

Making a 16-electron bromo (or iodo) complex of ruthenium(II) and a C—F bond in one pot

Formation of Copper(II) Thiocyanato and Cadmium(II) Iodo Complexes in Micelles of Nonionic Surfactants with Varying Poly(ethylene oxide) Chain Lengths

Formation of copper(II) thiocyanato and cadminum(II) iodo complexes in micelles of poly(ethylene oxide) (PEO)-type nonionic surfactants with varying PEO chain lengths of 9.5 (Triton X-100), 30 (Triton X-305), and 40 (Triton X-405) has been studied by titration spectrophotometry and calorimetry at 298 K. In a given surfactant solution, all data obtained were analyzed by assuming formation of ternary complexes MXnYm(2−n)+ (M = CuII,CdII; X = SCN−, I−; Y = surfactant), and the complexes thus form in aqueous phase (m = 0) or in micelles (m = 1). In the CuII–SCN− system, spectrophotometric data obtained by varying concentrations of the surfactant can be explained well in terms of formation of Cu(NCS)2Y in micelles and Cu(NCS)+ and Cu(NCS)2 in an aqueous phase, and it turned out that formation constant of Cu(NCS)2Y increases with increasing PEO chain length. In the CdII–I− system, the formation of CdI3Y− and CdI4Y2− is concluded in micelles, and that of CdI+, CdI3−, and CdI42− in an aqueous phase. Interestingly, formation enthalpies of CdI3Y− and CdI4Y2− become significantly less negative with increasing PEO chain length. This suggests that transfer of the complexes from aqueous solution to a hydrophobic octylphenyl (OP) moiety in micelles is significantly more exothermic than that to a hydrophilic PEO one. Thermodynamic parameters of transfer of CdI3− and CdI42− from aqueous solution to the OP and PEO moieties of micelles have been evaluated.

Complexes of heterocyclic thiones and Group 12 metals: Part 3. Preparation and characterisation of 1:2 complexes of mercury(II) halides with 1-methylimidazoline-2(3 H)-thione: the crystal structures of [(HgX 2)(1-methylimidazoline-2(3 H)-thione) 2] (X=Cl, Br, I) at 160 K

The stoichiometric addition (1:2 metal–ligand) of aqueous alcoholic solutions of the metal salts to similar solutions of 1-methyl-imidazoline-2(3 H)-thione (1-meimz2SH) generated crystalline complexes of general formula, [HgX 2(1-meimz2SH) 2] (X=Cl, Br, I), in good yield. The chemical formulae of the complexes have been characterised by elemental chemical analysis. Infrared and 13C NMR spectra indicated the presence of the thione form of the heterocyclic ligands in the complexes, as well as their thione–sulfur ligating character. X-ray crystal structure analyses have been performed on the three complexes. The metal in the chloro complex occupies a crystallographic two-fold axis which bisects the SHgS angle. The bromo and iodo complexes occupy general positions, but one of the ligands is disordered in the bromo complex. All of the complexes are mononuclear with the four-coordinate metals possessing distorted tetrahedral geometry. The extent of the distortion is indicated by the angles at the metal which range from 93.71(7) to 127.73(7)°. Metal–sulfur distances range from 2.4514(14) to 2.571(3) Å. Metal–halogen distances range from 2.5984(13) Å (chloro) through 2.641(3) and 2.647(3) Å (bromo) to 2.7866(11) and 2.8047(9) Å (iodo). Hydrogen bonds, involving the thioamide hydrogen (NH) and halogen atoms are exclusively intramolecular in the chloro complex, but both intramolecular and intermolecular in the bromo and iodo complexes.

Transition Metal Silyl Complexes. 62.1 Platinum Dimethyl Complexes with Hemilabile P,N-Chelating Ligands: Synthesis, Structure, and Reactions with Iodotrimethylsilane and 1,2-Bis(dimethylsilyl)benzene

Reaction of (η4-2,5-norbornadiene)dimethylplatinum(II) with (2-diphenylphosphinoethyl)dimethylamine, (3-diphenylphosphinopropyl)dimethylamine, 2-diphenylphosphino-N,N-dimethylaniline, or (o-diphenylphosphinobenzyl)dimethylamine resulted in the formation of the corresponding dimethyl platinum complexes containing the P,N-chelating ligands, while reaction with (diphenylphosphinomethyl)dimethylamine gave only the bis(phosphine) complex. Reaction of the P,N-chelated dimethyl complexes with iodotrimethylsilane stereoselectively gave the corresponding methyl iodo complexes in which only the methyl group trans to the phosphorus atom was exchanged. Reaction with 1,2-bis(dimethylsilyl)benzene yielded cyclic bis(silyl) complexes. Analogous experiments with (dppe)PtMe2 revealed that the P,N-chelated complexes exhibit a considerably higher reactivity than the bis(phosphine) complex. The most interesting feature in the solid-state structures of [(κ2-P,N)-Ph2PC2H4NMe2]PtMe2, trans-[(κ2-P,N)-Ph2PC6H4-2-CH2NMe2]Pt(I)Me, ...

Mercury(II) compounds with 1,3-imidazole-2-thione and its 1-methyl analogue. Preparative and NMR spectroscopic studies. The crystal structures of di-μ-iodo-bis[iodo(1,3-imidazolium-2-thiolato- S)mercury(II)], bis[bromo(1,3-imidazolium-2-thiolato- S)]mercury(II) and bis[μ-(1- N-methyl-1,3-imidazole-2-thiolato- S)]mercury(II)

A series of mercury(II) compounds of the empirical formulae HgX 2L, and HgX 2L 2 (X=Cl −, Br −, I −, SCN −; L=imtH 2, meimtH; imtH 2=1,3-imidazole-2-thione, meimtH=1-methyl-1,3-imidazole-2-thione) has been obtained by the reaction of mercury(II) salts and 1,3-imidazole-2-thione and 1-methyl-1,3-imidazole-2-thione, respectively. Mercury(II) acetate yields HgL 2 complexes where L=imtH −, meimt −. The isolated compounds have been characterised by elemental chemical analysis, IR and 1H and 13C NMR spectroscopy. Complexation effects on chemical shifts in 1H and 13C spectra were shown to be a reliable probe for distinguishing HgX 2L and HgX 2L 2 complexes. In the former molecules the thione carbon (C-2) is shielded up to 3.0 ppm and the thioamide protons (NH) are deshielded up to 0.5 ppm, as compared to the corresponding atoms in the latter molecules. In all complexes the 13C complexation shift at C-2 decreases with decreasing electronegativity of the halogen atom (X), indicating the corresponding increase in π-character of the C-2–S bond. The crystal structures of HgI 2(imtH 2), HgBr 2(imtH 2) 2 and Hg(meimt) 2 have been determined by X-ray diffractometry and revealed S-bound imtH 2 in the iodo and bromo complex, while in Hg(meimt) 2 the ligand acts as bridging with stronger S and weaker N bonds.

Solvent-Extraction Separation of Manganese(II) with Calixarene Substituted with an Acetyl Group at the Lower Rim

A trace level concentration of Mn(II) was quantitatively extracted at pH 6.0 with 1×10−4 M of hexaacetatocalix(6)arene in hexane. Manganese(II) from the organic phase was stripped with 2 M sulfuric acid and determined as its iodo complex spectrophotometrically at 545 nm. The various parameters influencing extraction, such as pH, reagent concentration, nature of diluents, stripping agents, and effects of diverse ions, were studied to determine the optimum conditions for the separation of Mn(II). Manganese(II) was separated from Fe(III), Th(IV), Cr(III) as well as alkali and alkaline earth elements which are generally associated with it in a complex mixture. The method was extended for an analysis of Mn in real samples, such as minerals, alloys and pharmaceutical samples. The method is reproducible with a relative standard deviation of ±1.2%.

Halogenation of Alkenes in Five-Coordinate Platinum(II) Complexes – A Route to Stable (β-Haloalkyl)platinum(IV) Species

Five-coordinate complexes [PtX2(olefin)(2,9-Me2-phen)] (1; 2,9-Me2-phen = 2,9-dimethyl-1,10-phenanthroline; olefin = ethene denoted by a, propene by b, 1-butene by c; × = Cl denoted by x, Br by y) undergo photoactivated reactions with Cl2 and Br2 to give the (β-haloalkyl)platinum(IV) complexes [Pt(CH2CHRX)(2,9-Me2-phen)X3] (2). Bromination of the chloro species 1ax leads to the formation of the PtIV species 2axy containing the bromide, the bromoalkyl, and the phenanthroline ligands in the equatorial plane and two chloride ions in axial positions. The iodo complexes 1(a–c)z are not oxidized by iodine even under UV irradiation but react readily with Cl2 or Br2 to give 2(a–c)x and 2(a–c)y. The structure of 2ay, the first structurally characterized (β-haloalkyl)platinum complex, has been determined by X-ray diffraction methods. The stereochemistry of the (β-haloalkyl)platinum(IV) complexes is in accord with a simultaneous addition of two halogen atoms to the coordinated olefin and to the metal center.

Demetalation of Tricarbonyl(cyclopentadienone)iron Complexes Initiated by a Ligand Exchange Reaction with NaOH-X-Ray Analysis of a Complex with Nearly Square-Planar Coordinated Sodium.

A sequential exchange of one carbonyl ligand by a hydrido ligand with NaOH, and then by an iodo ligand with iodopentane and finally treatment with acid transforms tricarbonyl(η4-cyclopentadienone)iron complexes into dicarbonyl(η5-hydroxycyclopentadienyl)iodoiron complexes. These iodo complexes demetalate with high selectivity to the corresponding free ligands on contact with air in daylight. Under basic reaction conditions at the stage of the iodo complex an anionic dicarbonyl(η4-cyclopentadienone)iodoiron complex is generated, which is dimeric in the solid state and has an almost square-planar arrangement of the ligands at the sodium counterion.