Palladium complexes ammines

Dispersed Metals. Bifimctional zeoHte catalysts, principally zeoHte Y, are used in commercial processes such as hydrocracking. These are acidic zeoHtes containing dispersed metals such as platinum or palladium. The metals are introduced by cation exchange of the ammine complexes, foUowed by a reductive decomposition (21) ... 

A wide variety of complexes are formed by both metals in the +2 oxidation state indeed, it is the most important one for palladium. The complexes can be cationic, neutral or anionic. Both Pd2+ and Pt2+ are soft acids so that many stable complexes are formed with S or P as donor atoms but few with O-donors, though there are important ammines. There are pronounced similarities between corresponding palladium and platinum complexes the latter are more studied (and less labile). 

The preparation of catalyst Ir-8 was analogous to that of Pd-15, but for the use of the Ir ammine complex instead of palladium. 

Brief mentions of kinetics and mechanisms of reactions of nitrogen bases with a selection of palladium(II) complexes with ammine, amines, pyridine-2-carboxylate, pyridoxine, and related ligands are included in a review of analogous platinum(II) reactions (194). 

Complexes of the explosively imstable nitramine ligands 7/-nitromethylamine (HL), iV,iV -dinitrodiaminoethane (ff2L ), and 5-nitraminotetrazole (H2L") with ammine derivatives of divalent copper, nickel or palladium explode on heating or under a hammer blow. Compoimds prepared were ... 

Ammonia unites readily with iridium salts, giving rise to complex ammino-derivatives. The first compounds described appear to be ammines analogous to those of palladium and platinum, to which they were compared by Berzelius 8 and Skoblikoff.4 A further series were described by Claus 5 wliich he represented like those of ammino-rhodium salts, as they bore a marked resemblance to these. After Jorgensen had established the constitution of the ammines of rhodium, cobalt, and chromium salts, Palmaer gave similar constitution to the iridium compounds. 

Coordination Compounds. Palladium forms numerous complexes with ammonia and with simple amines. Examples are [Pd(NH3)4]2+ [15974-14-8], [PdCl(dien)]+ [17549-31-4], cis-[PdCL (NH3)2] [15684-18-1], and trans-[PdC (NH3)2] [13782-33-7]. Monoammine complexes such as [PdCl3 (NH3)] [15691-32-4] are stable but less common. Examples of aromatic amine complexes include trans- [PdCf (pyr)2] [14052-12-1], [PdCl2(bipy)] [14871-92-2], and nucleosides such as [PdCl(dien)(guanosine)]+ [73601-42-0] (193). Complexes of Pd(IV) such as [PdCl2(NH3)4]2+ [70491-81-5] and [PdCl4(bipy)] [57209-01-5] may be prepared by chlorine oxidation of the corresponding Pd(2+). The aromatic amine Pd(IV) complexes are more stable than ammine and aliphatic amine species, which are reduced to Pd(II) in water or thermally (194). 

Palladium(II) complex compounds, with biguanide and its deriva-tives, structure of, 6 66 nonelectrolytes, ammines, trans-[Pd(NH,) (NO ) ], 4 179 with 1,4-butadiene, PdC ChHe, 6 218... 

Here, there is no evidence that masking interferes in any way with these reactions. When the complexes of palladium (II) were examined for a similar reactivity, no complexes containing coordinated chloramines could be isolated (43, 44)- The reaction of ammines of platinum (IV) with bromine can be used to introduce bromoamine in the coordination sphere, but the products are somewhat less stable than those obtained with chlorine. The general nature of the processes is similar. One example of a bromination reaction established by Kukushkin is ... 

The palladium catalyst supported on aluminosilicate is prepared by exchanging the surface protons of aluminosilicate with palladium-ammine complex cations, followed by washing with water, thermal decomposition, and reduction with hydrogen. This reduction easily transforms the exchanged palladiumammine complex cations into metallic palladium particles which are fine spheres and homogeneously dispersed through a cloud of the fine particles of aluminosilicate. 

Palladium (Pd, at. mass 106.42) is a platinum-group metal, and occurs in the II and IV oxidation states. Palladium(II) compounds are the more stable. Unlike the other platinum metals, palladium is soluble in cone. HNO3. Brown-red Pd(OH)2 precipitates at pH 4, but dissolves in excess of an alkali-metal hydroxide. Palladium(ll) gives stable nitrite, ammine, cyanide, chloride, bromide, and iodide complexes. Palladium(ll)- and (IV) are reduced to the metal by SO2, Fe(II), and ethanol. 

Ion-exchange separation methods are based on the retention of the palladium chloride complex on strongly basic anion-exchangers, and of the cationic ammine complex on cation-exchangers [16]. A cellulose anion-exchanger has been used to separate Pd from Pt and Ir [17], and from Ir [16]. 

Palladium(II) normally coordinates to the N3 atoms of the cytosine base forming a square planar geometry. " An unexpected isomerization from trans- to cA-coordination of ammine ligands about Pd" occurs when tr<2 x-[Pd (NH3)2(H20)2] is added to the mononuclear trans-Pd"(NH3)2(1-methyl cytosine)2(N03)2. The resulting bridged dinuclear Pd" complex has two cis-[Pd (NH3)2] units bridged by cytosines through their to both N3 and deprotonated N4... 

The catalytic activity of co-ordination compounds in oxidations continues to be examined and, together with the Faraday Society Discussion, other aspects of this area of investigation have been the subject of recent reviews. Redox reactions involving bipyridyl and u-phenanthroline complexes of transition metals have been discussed and catalytic oxidations of complexes of manganese, cobalt, copper, and palladium have also been surveyed. Reviews are also available of ruthenium ammine chemistry, and redox reactions involving molybdenum complexes, together with an account of catalase and peroxidase reactivity of copper(ii) complexes. ... 

The most straightforward case of electrostatic adsorption occurs with the most stable metal complexes such as platinum or palladium tetraammines, [(NH3)4Pt]+ and [(NH3)4Pd]+ or PTA and PdTAs, respectively. Over the wide pH and concentration ranges that can be employed during syntheses from the lab to the industrial scale, the relatively strongly bound ammine ligands of these coordination complexes remain intact. This has been most directly confirmed in the case of Pt by extended X-ray absorption fine structure (EXAFS) analysis of PTA solutions and adsorbed species [23], and for PdTAs less directly by XPS [24]. 

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