A New One-Dimensional Platinum System Consisting of Carboxylate-Bridged cis-Diammineplatinum Dimers1

This is the authors' abstract. We don't add key points for this paper.

With the aim of developing new 1D platinum chain solids having infinite Pt−Pt bonds, several carboxylate-bridged cis -diammineplatinum dimers have been prepared and structurally characterized. For a dimer doubly bridged with acetates, five different salts [Pt 2 (NH 3 ) 4 (μ-CH 3 CO 2 ) 2 ]X 2 · n H 2 O (X 2, n = (ClO 4 ) 2, 2, 1; (NO 3 ) 2, 1, 2; (BF 4 ) 2, 4, 3; (PF 6 ) 2, 2, 4; (SiF 6 ), 4, 5 ) have been prepared. The crystal structure of 5 has revealed that an infinite dimer chain [Pt 2 (NH 3 ) 4 (μ-CH 3 CO 2 ) 2 ] n 2 n + can be given as a result of hydrogen bond formation between the ammines and the oxygen atoms of acetates, demonstrating our prediction that the N 2 O 2 coordination sphere may serve as a hydrogen-bonding moiety to assist formation of an infinite dimer chain. An asymmetric dimer bridged by both acetate and hydroxide ligands, [Pt 2 (NH 3 ) 4 (μ-CH 3 CO 2 )(μ-OH)](SiF 6 ) ( 6 ), has also been isolated as a byproduct of 5, and a similar 1D framework, [Pt 2 (NH 3 ) 4 (μ-CH 3 CO 2 )(μ-OH)] n 2 n +, has been characterized by X-ray diffraction. In addition, some glycolate-bridged analogues of similar frameworks have been synthesized and characterized: [Pt 2 (NH 3 ) 4 (μ-CH 2 (OH)CO 2 ) 2 ](SiF 6 )·4H 2 O ( 7 ), [Pt 2 (NH 3 ) 4 (μ-CH 2 (OH)CO 2 ) 2 ](ClO 4 ) 2 ·H 2 O ( 8 ), and [Pt 2 (NH 3 ) 4 (μ-CH 2 (OH)CO 2 )(μ-OH)](NO 3 ) 2 ( 9 ). To obtain partially oxidized systems, benzoate derivatives have been selected as bridging ligands. Although a benzoate system gave dark blue solids ascribable to mixed-valence Pt(2.25+) compounds, a crystallographically analyzed complex has turned out to be a double complex involving both a Pt(II) monomer and a dinuclear Pt(II) complex, [Pt 2 (NH 3 ) 4 (μ-C 6 H 5 CO 2 ) 2 ] 2 (SiF 6 ) (BF 4 ) 2 ·[ cis -Pt(NH 3 ) 2 (C 6 H 5 CO 2 ) 2 ]·3H 2 O ( 10 ). Nevertheless, our final efforts in this work have revealed that a p -hydroxybenzoate system, [Pt(2.25+) 2 (NH 3 ) 4 (μ- p -C 6 H 4 (OH)CO 2 ) 2 ] 2 X 5 · n H 2 O (X 5, n = (SO 4 ) 2.25 ( p -C 6 H 4 (OH)CO 2 ) 0.5, 5, 12a; (PF 6 ) 2 (SO 4 )( p -C 6 H 4 (OH)CO 2 ), 6, 12b; (PF 6 ) 2 (NO 3 ) 2 ( p -C 6 H 4 (OH)CO 2 ), 7, 12c ), may be suited to achieve a 1D platinum blue system. The compounds display a blue chromophore at 630 nm ascribable to the Pt(2.25+) 4 species. Moreover, the compounds have been judged to be diamagnetic, and therefore the S = 1 / 2 spins derived from the Pt(2.25+) 4 units must be diamagnetically coupled in the solid state, suggesting that the repeating unit should be expressed as [Pt(2.25+) 8 ] n ( n is undetermined).