Pincer-like amido complexes of platinum, palladium, and nickel

The ligands bis(8-quinolinyl)amine (BQAH, 1), (2-pyridin-2-yl-ethyl)-(8-quinolinyl)amine (2-pyridin-2-yl-ethyl-QAH, 2), o-dimethylaminophenyl(8-quinolinyl)amine (o-(NMe2)Ph-QAH, 3), and 3,5-dimethylphenyl(8-quinolinyl)amine (3,5-Me2Ph-QAH, 4) have been prepared in high yield from aryl halide and amine precursors by palladium-catalyzed coupling reactions. Deprotonation of 1 with nBuLi in toluene affords the lithium amide complex [Li][BQA] (5), whose dimeric solid-state crystal structure is presented. Lithium amide 5 was transmetalated by TlOTf to afford the thallium(I) amido complex [Tl][BQA] (6). An X-ray structural study of 6 shows it to be a 1:1 complex of the BQA ligand and Tl. Entry into the group 10 chemistry of the parent ligand 1 was effected by both protolytic and metathetical strategies. Thus, the divalent chloride complexes (BQA)PtCl (7), (BQA)PdCl (8), and (BQA)NiCl (9) were prepared and fully characterized. An X-ray structural study for each of these three complexes shows them to be well-defined, square-planar complexes in which the auxiliary BQA ligand binds in a planar, eta(3)-fashion. For comparison, the reactivity of ligands 2-4 with (COD)PtCl2 was studied. While reaction with ligand 2 afforded an ill-defined product mixture, ligands 3 and 4 reacted with (COD)PtCl2 to generate the unusual alkyl complexes (o-(NMe2)Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (10) and (3,5-Me2Ph-QA)Pt(1,2-eta(2)-6-sigma-cycloocta-1,4-dienyl) (11), both of which have been structurally characterized.     

2-(N-Alkylcarboxamide)-6-iminopyridyl palladium and nickel complexes: coordination chemistry and catalysis

The 2-(N-alkylcarboxamide)-6-iminopyridine ligands (L1-L7) can bind as either mono-anionic tridentate N^N^N ligands on reaction with PdCl(2)(CH(3)CN)(2), to form complexes LPdCl (C1-C7), or as neutral tridentate N^N^O ligands with NiCl(2)·6H(2)O, to produce complexes LNiCl(2) (C8-C14). All metal complexes were characterized by IR spectroscopy and elemental analysis, and in the case of the palladium complexes, by (1)H and (13)C NMR spectroscopy. The crystal structures of C3, C4, C6, C10, and C12 were determined by X-ray crystallography, and revealed a distorted square geometry around the palladium centre, whereas for nickel, a distorted square-pyramidal geometry was adopted. The representative palladium complex (C3) was further reacted with AgBF(4) in acetonitrile affording the salt [L3Pd(CH(3)CN)][BF(4)] (C15) and the structure of this was confirmed by single-crystal X-ray diffraction. By contrast, carrying out the reaction in dichloromethane rather than acetonitrile, in the presence of malononitrile (CNCH(2)CN), resulted in the formation of the bimetallic palladium complex [L3Pd(CNCH(2)CN)PdL3]·2[BF(4)] (C16). Upon activation with diethylaluminium chloride, all the nickel complexes showed high activity for ethylene dimerization. Furthermore, the palladium complexes exhibited good activities in the vinyl-polymerization of norbornene upon activation with MAO.     

Halo-carbonyl complexes of palladium,platinum and gold

In this review we summarize some recent literature data concerning synthetic procedures, properties, structure, reactivity and applications of halo-carbonyl complexes of palladium, platinum and gold, taking into consideration that the organometallic chemistry of these metals, with a particular attention to the halo-carbonyls, has been reviewed 20 years ago [F. Calderazzo, J. Organomet. Chem. 400 (1990) 303]. A brief overview of the early studies is provided.     

Structural variations in nickel, palladium, and platinum complexes containing pyrimidyl N-heterocyclic carbene ligand

Nickel(II), palladium(II), and platinum(II) complexes of 2-(3-mesitylimidazolylidenyl)pyrimidine (L), [Ni₂(μ-Cl)₂(L)₄][Ag₂Cl₄] (3), [Ni₂(μ-I)₂(L)₄][NiI(L)₂(CH₃CN)]₂[Ag₄I₈] (4), [PdCl₂(L)] (5), [PdI₂(L)] (6), and [PtCl(L)₂][AgCl₂] (7) have been obtained from the carbene transfer reactions of [Ag(L)Cl] (2). These complexes have been fully characterized by spectroscopic methods and single-crystal X-ray structure analyses. The mono(carbene)palladium and bis(carbene)platinum complexes display normal square–planar structures. Nickel complexes 3 and 4 are rare examples of paramagnetic nickel(II) complexes of N-heterocyclic carbenes having octahedral geometry.     

Matrix isolation infrared spectroscopic and theoretical study of nickel, palladium, and platinum nitrous oxide complexes

Binary nickel, palladium, and platinum nitrous oxide complexes Ni(NNO)x, Pd(NNO)x (x = 1, 2), and PtNNO have been produced by the reactions of laser-evaporated metal atoms with nitrous oxide in solid argon. The complexes were identified on the basis of isotopically substituted infrared absorptions as well as theoretical frequency calculations. These complexes were characterized to have structures with the terminal N atom of N(2)O bound to the metal atoms. The MNNO complexes are photosensitive and rearrange to OMNN or MO + N(2) upon ultraviolet-visible irradiation.     

电感耦合等离子体原子发射光谱（ICP-AES）法测定高镍铜液体样品中金、钯、铂

为实现中控液体物料中金、钯、铂元素的精准定量分析,为工艺生产定向富集和高效提取提供数据支持,本文建立了ICP—AES法测定中控冶炼系统中高镍铜液体样品中金、铂和钯3种元素含量的测定方法。确定了试液用碲共沉淀,贵金属进入滤渣,经火试金分离富集得到贵金属合粒,合粒经王水溶解后,于王水介质中在电感耦合等离子光谱仪上同时测定金钯铂的量。该方法金、铂、钯的测定范围为 0.014mg/L～5mg/L,回收率为92.2%～104.4%, RSD为3.21%～10.58%,方法满足高镍、铜液体样品中金、钯、铂元素的测定。     

Low-valence palladium complexes: Stoichiometric reactions and catalysis

New data on the structure and reactivity of palladium clusters are surveyed. The mechanisms of stoichiometric and catalytic reactions of the palladium cluster complexes with alkenes, alcohols, aldehydes, formic acid, CO, and phenol are discussed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 807–815, March, 1998.     

Nitrate complexes of divalent palladium and platinum

Conclusions Some nitrate complexes of Pd(II) and Pt(II) were synthesized. The absorption bands of the nitrate groups in the IR spectra of the obtained complexes were studied in the 900–1700 cm^–1 region. A study was also made of the NMR spectra of the nitrate complexes of Pt(II) in D₂O.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1677–1679, July, 1977.     

Synthesis and properties of polymeric partially oxidized complexes of nickel,palladium, and platinum with tetradentate schiff bases

The results of the synthesis and investigation of the physicochemical properties of the partially oxidized complexes of nickel, palladium, and platinum with bis(acetylacetone)ethylenediamine, bis(salicylaldehyde)ethylenediimine, and bis(salicylaldehyde)-o-phenylenediimine have been presented. The mechanism and kinetic laws governing the formation of these compounds have been studied. The characteristics of the conductivity of the new redox polymers obtained have been determined, and its mechanism has been investigated.A. I. Gertsen State Teachers Institute of the RSFSR, Leningrad. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 330–338, May–June, 1991. Original article submitted February 22, 1991.     

Triphenylphosphine carboxylate complexes of platinum and palladium

Conclusions Some carboxylate complexes of platinum and palladium of type (Ph₃P)₂M(OOCR)₂ were obtained by the reaction of organic acids with the complexes (Ph₃P)₄Pt and (Ph₃P)₄Pd.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 946–947, April, 1973.     

Transition metal allyls : III. The (η3-allyl)2M complexes of nickel,palladium and platinum: structural considerations

The structures of a series of (η³-allyl)₂M complexes of nickel, palladium and platinum have been investigated with the help of ¹³C NMR, ¹H NMR and Raman spectroscopy. The crystal structure of (η³-cyclooctatrienyl)₂Ni has been determined by X-ray methods; the two nickel-bonded η³-allyl groups are mutually trans.     

Heterobimetallic complexes of cis-1,2-bis(diphenylphosphine)ethene containing tin and nickel,palladium or platinum

Summary New heterobimetallic complexes of nickel, palladium or platinum and the ligand cis-1,2-bis(diphenylphosphine)-ethene, dppen, and tin were prepared. The transition metal is bonded either directly or via chlorine bridges to the tin atom. The compounds were obtained from precursor complexes of the general formula [M(dppen)Cl₂] (M = Ni, Pd or Pt) by reaction with Ph₃SnH or SnCl₂.     

Paramagnetic complexes of platinum and palladium with acetamide

Summary Direct reaction of K₂MCl₄ (M=Pt or Pd) with acetamide leads reproducibly to complexes which can be formulated as [Pt(C₂H₄ON)₂Cl]_n and Pd₄(C₂H₄ON)₇(OH)₂. Analytical and spectroscopic (i.r., n.m.r. and e.p.r.) data support the existence of polynuclear structures involving bridging ligands and partially oxidized metal centres.     

Transition metal allyls : IV. The (η3-allyl)2M complexes of nickel,palladium and platinum: reaction with tertiary phosphines

A series of 1 : 1 adducts have been prepared by treating the bis-η³-allyl complexes of nickel, palladium and platinum with tertiary phosphines. Investigations of their structure in solution as well as in the crystal have shown that both 18-electron (η³-allyl)₂ML complexes as well as 16-electron (η¹-allyl)-(η³-allyl)ML complexes may be formed.     

Piezochromism in nickel salicylaldoximato complexes: tuning crystal-field splitting with high pressure

The crystal structures of bis(3-fluoro-salicylaldoximato)nickel(II) and bis(3-methoxy-salicylaldoximato)nickel(II) have been determined at room temperature between ambient pressure and approximately 6?GPa. The principal effect of pressure is to reduce intermolecular contact distances. In the fluoro system molecules are stacked, and the Ni???Ni distance decreases from 3.19?? at ambient pressure to 2.82?? at 5.4?GPa. These data are similar to those observed in bis(dimethylglyoximato)nickel(II) over a similar pressure range, though contrary to that system, and in spite of their structural similarity, the salicyloximato does not become conducting at high pressure. Ni-ligand distances also shorten, on average by 0.017 and 0.011?? for the fluoro and methoxy complexes, respectively. Bond compression is small if the bond in question is directed towards an interstitial void. A band at 620?nm, which occurs in the visible spectrum of each derivative, can be assigned to a transition to an antibonding molecular orbital based on the metal 3d(x(2)-y(2)) orbital. Time-dependent density functional theory calculations show that the energy of this orbital is sensitive to pressure, increasing in energy as the Ni-ligand distances are compressed, and consequently increasing the energy of the transition. The resulting blueshift of the UV-visible band leads to piezochromism, and crystals of both complexes, which are green at ambient pressure, become red at 5?GPa.     

Synthesis and characterization of platinum and palladium pyrrolidinedithiocarbamate complexes

Treatment of (PPh₃)₂MCl₂ (M = Pd or Pt) with ammonium pyrrolidinedithiocarbamate (NH₄S₂CNC₄H₈) in a 1:1 molar ratio gave (PPh₃)M(Cl)(κ ² S,S-S₂CNC₄H₈) [M = Pt (1), Pd (2)]. On the other hand, the interaction of these compounds in a 1:2 [M:L] molar ratio gave (PPh₃)Pt(κS-S₂CNC₄H₈)(κ ² S,S-S₂CNC₄H₈) (3), which contains both terminal and chelated dithiocarbamato ligands, or a yellow insoluble solid for M = Pd. The bis(diphenylphosphino)ethane platinum or palladium dichlorides [(dppe)MCl₂] reacted with the same ligand to give the salts [(dppe)M(κ ² S,S-S₂CNC₄H₈)]Cl (M = Pt (4), Pd (5) which have only one chelating dithiocarbamato ligand. The new compounds were characterized by ¹H-, ¹³C{¹H}- and ³¹P-n.m.r. spectroscopy, mass spectrometry, elemental analysis and X-ray single crystal structure analysis.     

Highly efficient asymmetric Lewis acid catalysis with platinum group complexes of conformationally flexible 1,3-butadiene-bridged diphosphines, NUPHOS

[structure: see text] Palladium and platinum complexes of conformationally flexible 1,3-butadiene-bridged diphosphines NUPHOS can be resolved with (S)-BINOL at elevated temperatures to afford diastereopure delta-[(NUPHOS)M[(S)-BINOL]] (M = Pd, Pt). The homochiral Lewis acid complexes delta-[(NUPHOS)M][OTf](2), generated by protonation of delta-[(NUPHOS)M[(S)-BINOL]] with trifluoromethanesulfonic acid, catalyze the Diels-Alder reaction between acryloyl-N-oxazolidinones and cyclopentadiene to give ee values up to 96%. The corresponding enantiopure dichlorides delta-[(NUPHOS)PtCl(2)] react with AgClO(4) to form highly efficient catalysts that give good endo/exo selectivities and high endo enantioselectivity.     

Extraction chromatography of palladium and platinum complexes with nitroso-R-salt

The retention of palladium and platinum complexes with nitroso-R-salt on silica gel treated with Aliquat 336 has been investigated. The complexation of platinum with nitroso-R-salt (NRS) requires heating of H₂PtCl₆ with an excess of NRS at 100°. The affinity of the complexes for an Aliquat 336 stationary phase increases in the following order: PdCl₄²⁻ ˜ Pt-NRS < PtCl₆²⁻ Pd-NRS. The complexes of palladium and platinum can be separated by column chromatography on silica treated with Aliquat 336 and eluted with 0.25M perchloric acid (Pt) and 1M perchloric acid (Pd).     

N-heterocyclic carbene tethered amido complexes of palladium and platinum

With a view to applications in bifunctional catalysis, a modular cross-coupling strategy has been used to prepare amine bis(imidazolium) salts (3a and 3b) and an amine mono(imidazolium) salt (6) as precursors to chelating amido-NHC ligands. Treating the pro-ligands 3 with 3 equivalents of the bulky base KHMDS and Pd(OAc)(2) or PtCl(2)(COD) gave the four amido bis(N-heterocyclic carbene) pincer complexes [CNC-R]M-I [M = Pd (7) or Pt (8); R = i-Pr (a) or n-Bu (b)], including the first examples of platinum complexes of a CNC ligand. The reaction of 7a with AgOTf in pyridine gave the cationic complex {[CNC-i-Pr]Pd-py}OTf (9a). Heating a mixture of amine mono(imidazolium) salt 6 with PdCl(2) or K(2)PtCl(4), K(2)CO(3) and KI in pyridine at 100 °C gave the complexes [C,NH]MI(2)py [M = Pd (10) or Pt (11)], in which the amine arm of the NHC ligand is not deprotonated and does not coordinate to the metal. For a solution of 10 in 1,4-dioxane, deprotonation of the amine occurred in a biphasic reaction with aqueous KOH at 40 °C, giving the dimeric amido complex {[C,N]Pd(μ-OH)}(2) (12). The more inert Pt analogue 11 was unreactive under the same conditions. Solid-state structures of the complexes 7a, 7b, 9a, 10, 11 and 12 have been determined by single crystal X-ray diffraction.