Metal-metal Bonding in Tetracyanometallates (M=PtII, PdII, NiII) of monovalent Thallium. Chrystallographic and Spectroscopic Characterization of the new Compounds Tl2Ni(CN)4 and Tl2Pd(CN)4

Maliarik, M. and Nagle, J. K. and Ilyukin, A. and Mink, János and Kovács, Margit and Horváth, Attila (2007) Metal-metal Bonding in Tetracyanometallates (M=PtII, PdII, NiII) of monovalent Thallium. Chrystallographic and Spectroscopic Characterization of the new Compounds Tl2Ni(CN)4 and Tl2Pd(CN)4. INORGANIC CHEMISTRY, 46 (11). pp. 4642-4653. ISSN 0020-1669

Text 1192101.pdf Restricted to Registered users only Download (134kB) | Request a copy

Abstract

The new crystalline compounds Tl2Ni(CN)(4) and Tl2Pd(CN)(4) were synthesized by several procedures. The structures of the compounds were determined by single-crystal X-ray diffraction. The compounds are isostructural with the previously reported platinum analogue, Tl2Pt(CN)(4). A new synthetic route to the latter compound is also suggested. In contrast to the usual infinite columnar stacking of [M(CN)(4)](2-) ions with short intrachain M-M separations, characteristic of salts of tetracyanometalates of Ni-II, Pd-II, and Pt-II, the structure of the thallium compounds is noncolumnar with the two Tl-I ions occupying axial vertices of a distorted pseudo-octahedron of the transition metal, [MTl2C4]. The Tl-M distances in the compounds are 3.0560(6), 3.1733(7), and 3.140(1) A for Ni-II, Pd-II, and Pt-II, respectively. The short Tl-Ni distance in Tl2Ni(CN)(4) is the first example of metal-metal bonding between these two metals. The strength of the metal-metal bonds in this series of compounds was assessed by means of vibrational spectroscopy. Rigorous calculations, performed on the molecules in D-4h point group symmetry, provide force constants for the Tl-M stretching vibration constants of 146.2, 139.6, and 156.2 N/m for the Ni-II, Pd-II, and Pt-II compounds, respectively, showing the strongest metal-metal bonding in the case of the Tl-Pt compound. Amsterdam density-functional calculations for isolated Tl2M(CN)(4) molecules give Tl-M geometry-optimized distances of 2.67, 2.80, and 2.84 A for M = Ni-II, Pd-II, and Pt-II, respectively. These distances are all substantially shorter than the experimental values, most likely because of intermolecular Tl-N interactions in the solid compounds. Time-dependent density-functional theory calculations reveal a low-energy, allowed transition in all three compounds that involves excitation from an a(1g) orbital of mixed Tl 6p(z)-M nd(z)(2) character to an a(2u) orbital of dominant Tl 6p(z) character.

Actions (login required)

Edit Item