The so-called "platinum carbonyl", which probably consists of [Pt 3n (CO) 6n ] 2À oligomers with an average n value of approximately 10, was reported several years ago. [1,2] To date only discrete [Pt 3n (CO) 6n ] 2À oligomers with n = 1-5 have been selectively synthesized and characterized. [2][3][4][5][6][7] 1D molecular metal wires, [8,9] and 1D and 2D superclusters [10,11] are interesting in themselves as low-dimensional molecular materials with possible applications in molecular electronics and nanolithography. [12][13][14] The recent improvement of the synthesis of "platinum carbonyl" [7] prompted a reinvestigation of the chemistry of the [Pt 3n (CO) (CO) 48 ] reveals a distribution of oligomers centered at n = 5, with peaks of lesser intensity at n = 4 and n = 6. The observed distribution is narrower than the bellshaped distribution of n = 3-10 oligomers, centered at n = 6 or 7, exhibited by "platinum carbonyl".[7] The absence of the expected molecular peak for the [Pt 24 (CO) 48 ] 2À ion and the observed distribution of oligomers with n = 4-6 is clearly due to fragmentation processes occurring during the ESI-MS analysis, because the IR spectrum of the injected solution does not show the characteristic carbonyl absorptions of oligomers with n = 4-6.[2]The nature of the [NBu 4 2À oligomer consists of a sequence of eight {Pt 3 (CO) 6 } units stacked with a clock-or anticlockwise twist of 3-268 between consecutive units. The twist probably allows the minimization of repulsive intra-and intermolecular nonbonding interactions between the carbonyl groups of consecutive units and of adjacent oligomers. This twist is also responsible for the Pt À Pt contacts between neighboring {Pt 3 (CO) 6 } units being longer than the distance between the Pt 3 planes of these units. The PtÀPt bond distances within the individual {Pt 3 (CO) 6 } units fall in the narrow range of 2.666(2)-2.679(2) . In contrast, the PtÀPt contacts between neighboring {Pt 3 (CO) 6 } units are spread over a wider range of 3.024(2)-3.307(2) . The shortest interplane distances occur between the inner {Pt 3 (CO) 6 } units. The interplane distances become longer towards the top and bottom of the stack, like in an accordion (Figure 1). The longest PtÀPt contacts between neighboring {Pt 3 (CO) 6 } units (3.292(2)-3.307(2) ) are those involving the top {Pt 3 (CO) 6 } unit, and these are deliberately not shown as bonds in Figure 1. The PtÀPt contacts and the interplane distances (3.21 ) between this unit and the {Pt 21 (CO) 42 } stacks above and below it are the same. Thus, the pseudo-1D [Pt 24 (CO) 48 ] 2À molecular ions are arranged in infinite chains composed of alternating
Using a simple ligand design, we have prepared neutral, nine-coordinate lanthanide complexes that exclude water from the inner coordination sphere, thus leading to high emission quantum yields and long excited-state lifetimes. The complexes form in high synthetic yields (49-87 %) by simply mixing the ligand and the lanthanide. Visible luminescence from Eu III (Φ = 60%, τ = 2.2 ms) and Tb III (Φ = 7%,
Carbonylation of Na2PtCl6.6H2O, as well as K2PtCl6, in water under a CO pressure of 900 mm Hg selectively and quantitatively affords [Pt3n(CO)6n]2- (n > 6) salts; conversely, their corresponding carbonylation at reduced CO pressure of 760-800 mm Hg leads to a convenient one-step synthesis of [Pt38(CO)44]2-.
A tetrametallic iridium-ytterbium complex has been synthesised that shows sensitized near-infrared emission (lambda(max) = 976 nm) upon excitation of the iridium unit in the visible region (400 nm) due to efficient energy transfer from the iridium units to the Yb(III) ion. The iridium phosphorescence is quenched nearly quantitatively while the ytterbium ion emits brightly in the NIR.
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