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The first fully inorganic Pt(IV) carbonato-complex trans -[Pt(CO 3 ) 2 (OH) 2 ] 2- with a {PtO 6 } coordination sphere was isolated as the (Me 4 N) 2 [Pt(CO 3 ) 2 (OH) 2 ] ( 1 ) salt. The compound 1 was characterized using single-crystal and powder X-ray diffraction, Raman spectroscopy, infrared spectroscopy (FTIR), electrospray ionization mass spectrometry (ESI-MS), nuclear magnetic resonance spectroscopy (NMR), and thermogravimetric analysis (TG). Density functional theory (DFT) calculations were also performed to analyze the spectral features of the complex. 1 crystallizes in the triclinic system (P-1) with a Z of 1. The trans -[Pt(CO 3 ) 2 (OH) 2 ] 2- anion has axial hydroxo ligands and κ 2 -CO 3 ligands, which form an equatorial plane. This anionic complex exhibits notable stability in aqueous solutions, while the axial hydroxo ligand can be readily modified, as exemplified by the acylation of the trans -[Pt(CO 3 ) 2 (OH) 2 ] 2- into trans -[Pt(CO 3 ) 2 (OAc) 2 ] 2- anion. Furthermore, it has been shown that rigid and glittering platinum coatings can be electrochemically deposited from an aqueous solution of 1 without the addition of surfactants.

A series of tetraalkylammonium salts with anionic platinum nitrato complexes (Me 4 N) 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] (1), (Et 4 N) 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] (2), ( n-Pr 4 N) 2 [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] (3b), ( n-Pr 4 N) 2 [Pt(NO 3 ) 6 ] (3a), and ( n-Bu 4 N) 2 [Pt(NO 3 ) 6 ] (4) were isolated from nitric acid solutions of [Pt(H 2 O) 2 (OH) 4 ] in high yield. The structures of salts 2, 3a, 3b, and 4, prepared for the first time, were characterized by X-ray diffraction. The sorption of [Pt(NO 3 ) 6 ] 2- and [Pt 2 (μ-OH) 2 (NO 3 ) 8 ] 2- complexes onto the ceria surface from acetone solutions of salts 4 and 1 was examined. The dimeric anion was shown to quickly and irreversibly chemisorb onto the CeO 2 carrier, selectively transforming into Pt(II) centers after thermal treatment, becoming active in the low-temperature CO oxidation reaction ( T 50% = 110 °C at a space velocity of 240 000 h -1 ). By contrast, the homoleptic complex [Pt(NO 3 ) 6 ] 2- did not interact with the ceria, which may be attributed to the substitutional inertness of the [Pt(NO 3 ) 6 ] 2- anion. We believe that the strategy based on the sorption of polynuclear platinum nitrato complexes is an effective route to prepare ionic platinum species uniformly distributed on an oxide carrier for various catalytic applications.