Several clusters complexes of composition [Pt4(μ2-CO)5L4] have been synthesized and characterized, using 31P and 195Pt NMR. L = PEt3, PMe2Ph, PMePh2, PEt2But. The molecular structure of a new monoclinic modification of the PMe2Ph derivative has been determined: space group P21/n with a = 19.698(4), b = 10.9440(20), and c = 21.360(6) Å, β = 112.432(18)°, Z = 4. Using 4751 reflections measured at 290 ± 1 K on a four-circle diffractometer the structure has been refined to R = 0.0846. The molecule has no imposed symmetry, but the central Pt4(CO)5P4 core has the approximate C2v architecture established for the previously known orthorhombic modification. The Pt4 unit is thus a highly distorted, edge-opened (3.3347 Å) tetrahedron, with five edge-bridging carbonyl and four terminal phosphine ligands. In contrast to the crystallographic results 31P and 195Pt NMR spectra reveal equivalent 31P and 195Pt spins, which can be interpreted in terms of a tetrahedral arrangement of platinum atoms. It is suggested that this equivalence arises from time-averaging of all possible isomeric edge-opened tetrahedra.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry