Structural correlations for 1H, 13C and 15N NMR coordination shifts in Au(III), Pd(II) and Pt(II) chloride complexes with lutidines and collidine

¹H, ¹³C and ¹⁵N NMR studies of gold(III), palladium(II) and platinum(II) chloride complexes with dimethylpyridines (lutidines: 2,3‐lutidine, 2,3lut; 2,4‐lutidine, 2,4lut; 3,5‐lutidine, 3,5lut; 2,6‐lutidine, 2,6lut) and 2,4,6‐trimethylpyridine (2,4,6‐collidine, 2,4,6col) having general formulae [AuLCl₃], trans‐[PdL₂Cl₂] and trans‐/cis‐[PtL₂Cl₂] were performed and the respective chemical shifts (δ^1H, δ^13C, δ^15N) reported. The deshielding of protons and carbons, as well as the shielding of nitrogens was observed. The ¹H, ¹³C and ¹⁵N NMR coordination shifts (Δ^1H_coord, Δ^13C_coord, Δ^15N_coord; Δ_coord = δ_complex ? δ_ligand) were discussed in relation to some structural features of the title complexes, such as the type of the central atom [Au(III), Pd(II), Pt(II)], geometry (trans‐ or cis‐), metal‐nitrogen bond lengths and the position of both methyl groups in the pyridine ring system. Copyright © 2010 John Wiley & Sons, Ltd.     

Heterometallic trinuclear {CdII—MII—CdII} pivalates (M = Mg,Ca, or Sr): ways of assembly and structural features

Conditions for chemical assembly of new heterometallic trinuclear pivalates [Cd₂M(piv)₆L₂] (M = Mg, Ca, or Sr; piv is pivalate) were found. Reactions with the nonchelating ligand 2,4-lutidine (lut) gave the crystals of heterometallic complexes [Cd₂M(piv)₆(lut)₂] (M = Mg (1), Ca (2), and Sr (3)). With the chelating ligand 1,10-phenanthroline (phen), only the homometallic dimer [Cd₂(piv)₄(phen)₂] (4) was obtained under these conditions. Yet heterometallic trinuclear complexes with 1,10-phenanthroline ([Cd₂Mg(piv)₆(H₂O)(phen)₂] (5), [CaCd₂(piv)₆(phen)₂] (6), and [Cd₂Sr(piv)₆(phen)₂]?2MeCN (7)) were synthesized by reactions of phen with complexes 1—3. For all the complexes obtained, the molecular and crystal structures as well as the details of their molecular architecture were determined. The thermal behavior of aqua complex 5 was studied by TG and DSC. The complex eliminated the water molecule between 130 and 180 °C with a high endothermic effect (Q = 101 kJ mol^–1) due to (1) intramolecular hydrogen bonds that stabilize its molecular architecture and (2) subsequent structural rearrangements.     

Influence of geometric and electronic features of pyridine derivatives and triethylamine on the formation of a metal carboxylate core in reactions producing cadmium(<Emphasis Type="SmallCaps">ii</Emphasis>) pivalate complexes

The reaction products of [Cd(piv)₂] (piv is–O₂CBu^t) with isoquinoline (iqn), 2,4-lutidine (lut), phenanthridine (phend), 2,3-cyclododecenopyridine (cpy), and triethylamine (Et₃N) were synthesized and their structures were determined. The steric factors were found to play a more important role in cadmium(ii) pivalate complexes compared to 3d metal carboxylates in the +2 oxidation state. The reaction of [Cd(piv)₂] with isoquinoline produces only the mononuclear complex [Cd(piv)₂(iqn)₃] (1). The reaction of [Cd(piv)₂] with pyridine derivatives bearing a bulky substituent at the α position is accompanied by the formation of symmetrical dinuclear complexes of the composition [Cd₂(piv)₄(L)₂]. In the complexes with L = lut (2) or phend (3), the cadmium(ii) atoms are linked by two chelating-bridging carboxylate groups; in the complex with L = cpy (4), by four bidentate-bridging groups. The reaction of [Cd(piv)₂] with Et₃N in a solution of MeCN gives the centrosymmetric linear trinuclear complex [Cd₃(piv)₆(Et₃N)₂] (6); in a mixture of benzene and hexane, the ionic compound (HEt₃N)[Cd₂(piv)₅(H₂O)] (7). The crystal structures of all synthesized compounds were determined by X-ray diffraction.     

3,4‐Lutidinium salts with the diiodidoaurate(I) anion: structure of [(3,4‐lut)2H]+·[AuI2]− and of two polymorphs of [(3,4‐lut)2H+]2·[AuI2]−·I−

Reactions between potassium tetraiodidoaurate(III) and pyridine (py, C₅H₅N) or 3,4‐lutidine (3,4‐dimethylpyridine, 3,4‐lut, C₇H₉N) were tested as possible sources of azaaromatic complexes of gold(III) iodide, but all identifiable products contained gold(I). The previously known structure dipyridinegold(I) diiodidoaurate(I), [Au(py)₂]⁺·[AuI₂]⁻, ( 3 ) [Adams et al. (1982). Z. Anorg. Allg. Chem. 485 , 81–91], was redetermined at 100 K. The reactions with 3,4‐lutidine gave three different types of crystal in small quantities. 3,4‐Dimethylpyridine–3,4‐dimethylpyridinium diiodidoaurate(I), [(3,4‐lut)₂H]⁺·[AuI₂]⁻, ( 1 ), consists of an [AuI₂]⁻ anion on a general position and two [(3,4‐lut)₂H]⁺ cations across twofold axes. Bis(3,4‐dimethylpyridine–3,4‐dimethylpyridinium) diiodidoaurate(I) iodide, [(3,4‐lut)₂H⁺]₂·[AuI₂]⁻·I⁻, ( 2 ), crystallizes as two polymorphs, each forming pseudosymmetric inversion twins, in the space groups P2₁ and Pc (but resembling P2₁/m and P2/c), respectively. These are essentially identical layer structures differing only in their stacking patterns and thus might be regarded as polytypes.     

Exploring Electronic and Steric Effects on the Insertion and Polymerization Reactivity of Phosphinesulfonato PdII Catalysts

Thirteen different symmetric and asymmetric phosphinesulfonato palladium complexes ([{( ^X 1 ‐Cl)‐μ‐M}_n], M=Na, Li, 1 =^X(P^O)PdMe) were prepared (see Figure 1). The solid‐state structures of the corresponding pyridine or lutidine complexes were determined for ^(MeO)2 1‐py , ^(iPrO)2 1‐lut , ^(MeO,Me2) 1‐lut , ^(MeO)3 1‐lut , ^CF3 1‐lut , and ^Ph 1‐lut . The reactivities of the catalysts ^X 1 , obtained after chloride abstraction with AgBF₄, toward methyl acrylate (MA) were quantified through determination of the rate constants for the first and the consecutive MA insertion and the analysis of β‐H and other decomposition products through NMR spectroscopy. Differences in the homo‐ and copolymerization of ethylene and MA regarding catalyst activity and stability over time, polymer molecular weight, and polar co‐monomer incorporation were investigated. DFT calculations were performed on the main insertion steps for both monomers to rationalize the effect of the ligand substitution patterns on the polymerization behaviors of the complexes. Full analysis of the data revealed that: 1) electron‐deficient catalysts polymerize with higher activity, but fast deactivation is also observed; 2) the double ortho‐substituted catalysts ^(MeO)2 1 and ^(MeO)3 1 allow very high degrees of MA incorporation at low MA concentrations in the copolymerization; and 3) steric shielding leads to a pronounced increase in polymer molecular weight in the copolymerization. The catalyst properties induced by a given P‐aryl (alkyl) moiety were combined effectively in catalysts with two different non‐chelating aryl moieties, such as ^{c HexO/(MeO)2} 1 , which led to copolymers with significantly increased molecular weights compared to the prototypical ^MeO 1 .     

Substitution reactions of trans-[PdXPh(SbPh3)2J (X=Cl or Br) with nitrogen,phosphines and arsenic donor ligands. Crystal structures of trans-[PdClPh(PPh3)2], [PdClPh(bipy)], [PdClPh(dppm)]2, and [PdBrPh(dppm)]2

Exchange reactions of trans-[PdXPh(SbPh₃)₂] (1) (X=Cl or Br) with ligands L in refluxing dichloromethane give the palladium phenyl complexes [PdXPhL₂] (X=Cl, L=PPh₃, AsPh₃, L₂=2,2′-bipyridine (bipy), 4,4′-dimethyl-2,2′-bipyridine (dmbipy), 1,10-phenanthroline (phen); X=Br, L=PPh₃, L₂=bipy). Treatment of the complexes with bis(diphenylphosphino)methane (dppm) in refluxing dichloromethane gives [PdXPh(dppm]₂. These complexes have been characterised by microanalysis, IR and ¹H NMR spectroscopic data together with single crystal X-ray determinations of the phenyl palladium complexes, trans-[PdClPh(PPh₃)₂], [PdClPh(bipy)], [PdClPh(dppm)]₂, and [PdBrPh(dppm)]₂.     

Improved syntheses of Ru(CO)2 (O3SCF3)2 (bidentate) complexes and their conversion into new [Ru(CO)2 (bidentate)2]2+ complexes

Reaction of the complexes Ru(CO)₂Cl₂L [L = 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen)] with trifluoromethanesulphonic acid under carefully controlled conditions yields Ru[cis-(CO)₂] [cis-(O₃SCF₃)₂] (bidentate complexes. From reactions of the trifluoromethanesulphonates with the appropriate bidentate ligands, the new complexes [cis-Ru(CO)₂-L(L′)]²⁺ (L as above; L′ = 4,4′-dimethyl-2,2′-bipyridyl or 4,4′-diisopropyl-2,2′-bipyridyl) as well as the known [_cis-Ru(CO)₂L₂]²⁺ and [cis-Ru(CO)₂bpy(phen)]²⁺ have been prepared.     

Stereoisomeric Pt(IV) complexes with threonine

Stereoisomeric Pt(IV) complexes with threonine (ThrH = HOCH(CH₃)CH(NH₂)COOH, ??-amino-??-hydroxybutyric acid) were obtained. In the complexes trans-[Pt(S-ThrH)₂Cl₄] and trans-[Pt(R-ThrH)(S-ThrH)Cl₄], the ThrH molecules act as monodentate ligands coordinated through the NH₂ group. In the complexes cis- and trans-[Pt(S-Thr)₂Cl₂] and trans-[Pt(R-Thr)(S-Thr)Cl₂], the deprotonated ligands are coordinated in a bidentate fashion through the NH₂ and COO^?-groups (R,S is the absolute configuration of the asymmetric carbon atom). All the complexes were identified using elemental analysis, IR spectroscopy, and ¹⁹⁵Pt, ¹³C, and ¹H NMR spectroscopy. The complexes trans-[Pt(S-ThrH)₂Cl₄] · 3H₂O and cis-[Pt(S-Thr)₂Cl₂] · 2H₂O were additionally characterized by X-ray diffraction.     

Intramolecular hydroamination of 6-aminohex-1-yne catalyzed by Lewis acidic rhenium(I) carbonyl complexes

With the aim to determine the effect of Lewis acidity of rhenium(I) carbonyl complexes on their catalytic properties, and to develop more efficient catalysts based on Re(I) carbonyl systems, a series of rhenium(I) carbonyl triflate complexes with various degrees of Lewis acidity was investigated. Pyridine-substituted bromo tricarbonyl rhenium(I) complexes of the type fac-[ReBr(CO)₃L₂] (L = py-Cl, py, py-Me and py-NMe₂) were synthesized from [ReBr(CO)₅] using trimethylamine N-oxide (TMNO) as decarbonylating agent. The complexes [ReBr(CO)₅] and fac-[ReBr(CO)₃L₂] were then reacted with silver triflate to yield the complexes [Re(CF₃SO₃)(CO)₅] and fac-[Re(CF₃SO₃)(CO)₃L₂]. The synthesis and characterization of these complexes and their application in the catalysis of the cyclization of 6-aminohex-1-yne are discussed. The crystal structure of [Re(CF₃SO₃)(CO)₃(py)₂] is also presented.     

1H and 13C NRM and infrared spectral studies on mixed ligand complexes of the type cis-[Co(en)2(Im)Cl]Cl2

A number of mixed ligand complexes of the type [Co(en)₂(Im)Cl]Cl₂ (Im = imidazole or a substituted imidazole) have been synthesized by reaction of trans-[Co(en₂Cl₂]Cl with the imidazole ligands. Electrical conductivity measurements support the ionic (1:2) formulation of the compounds, the electronic spectra is in agreement with an octahedral stereochemistry, and the IR and NMR (¹H and ¹³C) spectra strongly favour the cis configuration for the isolated complexes, [Co(en)₂(Im)Cl]Cl₂.Trans-[Co(en)₂Cl₂]Cl reacts with KNCS to form cis-[Co(en)₂(NCS)₂Cl, the crystal structure of which is briefly reported. This lends additional support in favour of the probable cis configuration of the above complexes.     

The mer-[RuCl3(dppb)(H2O)] complex: A versatile tool for synthesis of Ru compounds

The complex mer-[RuCl₃(dppb)(H₂O)] [dppb = 1,4-bis(diphenylphosphino)butane] was used as a precursor in the synthesis of the complexes tc-[RuCl₂(CO)₂(dppb)], ct-[RuCl₂(CO)₂(dppb)], cis-[RuCl₂(dppb)(Cl-bipy)], [RuCl(2Ac4mT)(dppb)] (2Ac4mT = N(4)-meta-tolyl-2-acetylpyridine thiosemicarbazone ion) and trans-[RuCl₂(dppb)(mang)] (mang = mangiferin or 1,3,6,7-tetrahydroxyxanthone-C2-β-D-glucoside) complexes. For the synthesis of Ru^II complexes, the Ru^III atom in mer-[RuCl₃(dppb)(H₂O)] may be reduced by H₂(g), forming the intermediate [Ru₂Cl₄(dppb)₂], or by a ligand (such as H2Ac4mT or mangiferin). The X-ray structures of the cis-[RuCl₂(dppb)(Cl-bipy)], tc-[RuCl₂(CO)₂(dppb)] and [RuCl(2Ac4mT)(dppb)] complexes were determined.     

Complexation of copper(II) with 2′,2′-dialkyl-para-tert-butylbenzohydrazides

The complexation of copper(II) with 2′,2′-dimethyl-, 2′,2′-dibutyl-, and 2′,2′-diisobutyl-para-tert-butylbenzohydrazide in water-ethanol media was studied. The reagents (HL) formed [Cu(HL)]²⁺ and [Cu(HL)₂]²⁺ cationic complexes in a weakly acidic medium and uncharged CuL₂ complexes in an alkaline medium. logK _st was calculated for these complexes. The effect of 2′,2′-alkyl radicals on the stability of the complexes was considered. The obtained results were compared with data on the complexation of copper(II) ions with 2′,2′-dialkylbenzohydrazides.     

EPR studies on some mixed ligand copper(II) complexes of 3,3'-diaminodipropylamine and 1,3-diaminopropane

Results are presented for mixed ligand copper(II) complexes of 3,3'-diaminodipropyl-amine and 1,3-diaminopropane studied by electron paramagnetic resonance. The spectra of the complexes in polycrystalline powder form and in frozen solutions of N,N'-dimethyl-formamide indicate that the complexes [Cu(dpt)tn]Cl₂·H₂O and [Cu(dpt)tn]Br₂ have a square based pyramidal CuN₅ chromophore and that the complexes [Cu(dpt)tn]I₂ and [Cu(dpt)tn](ClO₄)₂ possess a compressed trigonal bipyramidal CuN₅ chromophore.     

Cucurbit[8]uril-based inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with cyclam and cyclen as guest molecules: Synthesis and crystal structures

New inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with the cyclic polyamine ligands cyclam and cyclen in the macrocyclic cavitand cucurbit[8]uril (CB[8]) were obtained: {trans-[Fe(Cyclam)(CO)(OCHO)]@CB[8]}Cl · 15H₂O, {cis-[Co(Cyclen)(H₂O)Cl]@CB[8]}Cl₂ · 20H₂O, and {cis-[Ni(Cyclen)(H₂O)Cl]@CB[8]}Cl · 12H₂O. According to X-ray diffraction data, the complexes are in the cavity of each CB[8] molecule. The complexes of the above molecular formulas were isolated in the solid state as supramolecular compounds with CB[8] and structurally characterized for the first time.     

Molybdenum(V) dimeric complexes with dialkyl carbamates

Syntheses are reported for a number of novel oxo and sulphido bridged molybdenum(V) complexes with N-methyl-N-cyclohexyl carbamate and N,N-dicyclohexyl carbamate as ligands, and we have compared these complexes with the molybdenum(V) complexes with dialkyldithiocarbamates as ligands. These complexes were identified by IR and electronic spectra, magnetic susceptibility and analytical data, and were assigned the formulae [Mo₂O₃(LL)₄], [Mo₂O₄(LL)₂], [Mo₂O₂S₂(LL)₂] and [Mo₂O₃S(LL)₂]. IR and electronic spectra of these compounds are sensitive to substitution of sulphur atoms into the bridge system. It is suggested that the low magnetic moments observed are due, at least in part, to intramolecular metal-metal interactions.     

The synthesis,characterization and melting properties of thiophene-containing dithiocarboxylate complexes of nickel(II)

The reactions of a series of 5-alkyl-2-thiophenedithiocarboxylates with nickel(II) chloride afforded two types of complexes, blue nickel(II) complexes with two terminal dithiocarboxylate ligands, [Ni(S₂CTR)₂] and violet nickel(II) complexes with perthio- and dithiocarboxylate ligands, [Ni(S₂CTR)(S₃CTR)] (where T = 2,5-disubstituted thiophene, R = C_nH_2n+1, n = 4, 6, 8, 12, 16). The blue monomers are preferred for the shorter chains (C₄ and C₆) and the violet compounds form exclusively for the longer chains (C₈, C₁₂, and C₁₆) in the alkylthiophene complexes. In addition to the above series, [Ni(S₂CTCH₃)₂], was prepared in a one-pot reaction in THF and both the blue and violet products were isolated. It was possible to convert the blue complexes [Ni(S₂CTR)₂] (R = butyl, hexyl) into the corresponding violet complexes [Ni(S₂CTR)(S₃CTR)] after stirring in THF solutions for prolonged periods of time. Liquid-crystalline properties of these complexes were examined by DSC and POM. The violet complexes with C₈ and C₁₂ alkyl chains showed liquid-crystalline properties.     

Synthesis and structural chemistry of arene-ruthenium half-sandwich complexes bearing an oxazolinyl-carbene ligand

Reaction of a series of directly connected oxazoline-imidazolium salts with silver(I) oxide and subsequent transmetallation with [Ru(p-cymene)Cl₂]₂ and anion exchange with KPF₆ cleanly gave the corresponding 2-oxazolinyl-(N-mesityl)imidazolidene(chloro)ruthenium(II) half-sandwich complexes [RuCl(oxcarb)(p-cymene)]PF₆, two derivatives of which were characterized by X-ray diffraction. Abstraction of the chloro ligand furnished the dicationic aqua complexes [Ru(H₂O)(oxcarb)(p-cymene)](PF₆)₂ which possess a similar coordination geometry. The syntheses were found to be highly diastereoselective, since only one diastereoisomer could be observed in all ruthenium complexes upon reaction of the chiral enantiopure oxazoline-imidazolium salts. Their potential as transfer hydrogenation and Lewis acid catalysts has been probed.     

Synthesis and characterization of copper and nickel complexes of LIX63 oxime

Several complexes of 5,8-diethyl-7-hydroxy-6-dodecanone oxime [H₂L] with Cu(II) and Ni(II) have been synthesized and characterized by means of a number of techniques including elemental analysis, IR spectra, magnetic susceptibility measurements, electronic absorption spectra, NMR spectra, and mass spectra. The results indicate that Cu(II) and Ni(II) generally form analogous, isomorphous complexes, although no bis-[H₂L] complex with Cu(II) has been isolated. [Cu(L)]_n and [Ni(L)]_n are oligomeric complexes with pseudo-octahedral geometry. [Ni(HL)₂] is cis-square-planar (C_2ν) with bifurcated hydrogen bridges. [Ni(H₂L)₃SO₄] and [Cu(H₂L)₃SO₄] have octahedral symmetry in which the sulphate is coordinated as a unidentate ligand and the oxime is functioning as a neutral ligand.     

Silver(I) and mercury(II) complexes of meta- and para-xylyl linked bis(imidazol-2-ylidenes)

Mononuclear silver and mercury complexes bearing bis-N-heterocyclic carbene (NHC) ligands with linear coordination modes have been prepared and structurally characterised. The complexes form metallocyclic structures that display rigid solution behaviour. A larger metallocycle of the form [L₂Ag₂]²⁺ [where L = para-bis(N-methylimidazolylidene)xylylene] has been isolated from the reaction of para-xylylene-bis(N-methylimidazolium) chloride and Ag₂O. Reaction of silver- and mercury-NHC complexes with Pd(NCCH₃)₂Cl₂ affords palladium-NHC complexes via NHC-transfer reactions, the mercury case being only the second example of a NHC-transfer reaction using a mercury-NHC complex.     

Synthesis and characterization of some organotin(IV) adducts containing a related series of pyridines: Crystal structure of [SnMe2Cl2(bu2bpy)]

Organotin(IV) complexes of [SnR_(4−n)Cl_n] (n = 2, R = Me, ⁿBu; n = 1, R = Ph) react with the bidentate pyridyl ligand 4,4′-di-tert-butyl-2,2′-bipyridine (bu₂bpy) to give hexa-coordinated adducts with the general formula [SnR_(4−n)Cl_n(bu₂bpy)]. However, the reaction of these organotin(IV) complexes with the corresponding monodentate ligand 4-tert-butylpyridine (bupy) resulted in the formation of the hexa-coordinated complex [SnMe₂Cl₂(bupy)₂] and the penta-coordinated complexes [SnR_(4−n)Cl_n(bupy)] (n = 2, R = ⁿBu; n = 1, R = Ph). Moreover, the reaction of the above organotin(IV) complexes with 4,4′-trimethylenedipyridine (tmdp) yields hexa-coordinated adducts with the general formula [SnR₂Cl₂(tmdp)] (R = Me, ⁿBu) and the penta-coordinated complex [ClPh₃Sn-μ-(tmdp)SnPh₃Cl] in the solid state. The resulting complexes have been characterized by multinuclear NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and elemental analysis. NMR data shows that the triphenyltin(IV) adducts are not stable in solution and dissociate to give tetra-coordinated tin(IV) complexes. The X-ray crystal structure determination of [SnMe₂Cl₂(bu₂bpy)] reveals that the tin atom is hexa-coordinated in an octahedral geometry with a trans-[SnMe₂] configuration.