Platinblau [blue platinum amide complex]

Abstract

Platinblau, the anomalously blue platinum amide complex previously thought to have the composition Ptn(CH3CONH)2 • H20, has been shown by crystallographic, analytical, infrared, and nmr studies to be PtIV(CHs-CONH)2(OH)2, the corresponding blue dichloride also having been prepared. A related divalent platinum complex, Ptn[(CH3)3CCONH2]2Cl2 (I), contains trimethylacetamide in its iminol form, RC(OH)=NH, with coordination of the square-planar Pt by the =NH group. In a second compound of the formula PtIV[(CH3)3CCONH]2-Cl2 (II), one of the amide ligands is present as an amide anion, -C(=0)NH~, and the other as an iminol anion, -C(OH)=N~. Yellow II is readily converted into its blue tautomer (III), which is the trimethylacetamide analog of the original Platinblau, and contains both amide groups as amide anions. The crystallographic study was performed on a crystal of I doped with 20% of II and 10% of III.The complexes of platinum having first-row atoms as ligands exhibit a certain uniformity of color, being only infrequently red, and quite often yellow or even colorless. Such would seem to be the case almost without exception, for both the divalent and tetravalent oxidation states. In view of this, it is highly anomalous that the simple complex generally agreed to have the composition Ptn(CH3CONH)2 H20 has a deep blue color. Called Platinblau by the early German workers,1 this anomalous material was first prepared in 1909 by shaking Ag2S04 with the yellow complex PtnCl2(CH8CN)2. The blue reaction product has a monomeric molecular weight in water and was concluded to be a divalent platinum complex, since on treatment with concentrated HC1, 90% of the platinum was recovered as PtnCl42-. Actually, other blueviolet platinum complexes are known,2 but they are in all cases polymeric materials having strong metalmetal interactions.As can be seen from Figure 1, Platinblau has been assigned a variety of structures, all of which have the common feature that the platinum is divalent. The structure most generally accepted involves squareplanar platinum and chelating acetamido groups (A),3•4 whereas other postulated structures involve six-coordinate dimers (B),5 polymeric chains with bridging acetamido groups (C),6 and one novel suggestion involving diazocyclobutadiene as a ligand (D).7 Structures B and C are contradicted, of course, by the molecular weight first reported by Hofmann and Bugge.1 It was our original intention to study the electronic structure and electronic spectrum of this material after first having satisfied ourselves as to its molecular structure. This first step has now been completed, and we report the results of this study here. Inasmuch as unambiguous conclusions came rather slowly, we have (1) K. A. Hofmann and G.

One‐Dimensional Inorganic Complexes

“…Recent work on the trimethylacetamide analogue of platinum blue suggested a PtIv-(NHCOCH3)2(0H)2 formulation, 34, for platinum blue (68). However, the results of x-ray photoelectron spectra do not support this formulation because only divalent platinum is observed (77).…”

The vibrational spectra, crystal and molecular structure of bis(acetonitrile)dichloroplatinum(II)

“…It was postulated that "p1atinblau"-was an acetamide complex of platinum, the acetamide being obtained by insertion of water into coordinated acetonitrile (7). Brown et al (8) determined that the reaction product of Pt(CH3CN),Cl2 and molten trimethylacetamide had a trans stereochemistry. They implied that this product was a typical "platinblau" complex.…”

Synthesis and Characterization of Palladium(II) Complexes with 2-(2'-hydroxylphenyl)benzoxazole, 2-(2'-hydroxyl phenyl)benzothiazole or the Mixed Ligands

“…The spectra also showed a strong bond at 338, 342 and 335 cm -1 assigned to ν(Pd-Cl) in a trans arrangement around palladium 35,36 . The ν(OH) and (Pd-Cl) bands disappeared in the spectra of complexes (2), (4) and (6) and a new medium intensity band at around 420-433 cm -1 appeared.…”