ja980055p_si_001.cif (103.27 kB)
A New One-Dimensional Platinum System Consisting of Carboxylate-Bridged cis-Diammineplatinum Dimers1
dataset
posted on 1998-10-27, 00:00 authored by Ken Sakai, Masao Takeshita, Yuko Tanaka, Takuma Ue, Masayuki Yanagisawa, Masaya Kosaka, Taro Tsubomura, Masamichi Ato, Takeo NakanoWith 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 [Pt2(NH3)4(μ-CH3CO2)2]X2·nH2O (X2, n = (ClO4)2, 2,
1; (NO3)2, 1, 2; (BF4)2, 4, 3; (PF6)2, 2, 4; (SiF6), 4, 5) have been prepared. The crystal structure of 5 has
revealed that an infinite dimer chain [Pt2(NH3)4(μ-CH3CO2)2]n2n+ can be given as a result of hydrogen bond
formation between the ammines and the oxygen atoms of acetates, demonstrating our prediction that the N2O2
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, [Pt2(NH3)4(μ-CH3CO2)(μ-OH)](SiF6)
(6), has also been isolated as a byproduct of 5, and a similar 1D framework, [Pt2(NH3)4(μ-CH3CO2)(μ-OH)]n2n+,
has been characterized by X-ray diffraction. In addition, some glycolate-bridged analogues of similar frameworks
have been synthesized and characterized: [Pt2(NH3)4(μ-CH2(OH)CO2)2](SiF6)·4H2O (7), [Pt2(NH3)4(μ-CH2(OH)CO2)2](ClO4)2·H2O (8), and [Pt2(NH3)4(μ-CH2(OH)CO2)(μ-OH)](NO3)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, [Pt2(NH3)4(μ-C6H5CO2)2]2(SiF6) (BF4)2·[cis-Pt(NH3)2(C6H5CO2)2]·3H2O (10). Nevertheless, our final efforts in this work
have revealed that a p-hydroxybenzoate system, [Pt(2.25+)2(NH3)4(μ-p-C6H4(OH)CO2)2]2X5·nH2O (X5, n =
(SO4)2.25(p-C6H4(OH)CO2)0.5, 5, 12a; (PF6)2(SO4)(p-C6H4(OH)CO2), 6, 12b; (PF6)2(NO3)2(p-C6H4(OH)CO2),
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).
