137966-80-4Relevant academic research and scientific papers
A novel class of nitrosyl A-frames. Crystal and molecular structure of [Pt2Cl2(μ-NO)(μ-dppm)2]BPh 4·CH2Cl2
Neve, Francesco,Ghedini, Mauro,Tiripicchio, Antonio,Ugozzoli, Franco
, p. 795 - 801 (2008/10/08)
The reaction of Pt2Cl2(μ-dppm)2 (dppm = bis(diphenylphosphino)methane) with an excess of NO+A- in dichloromethane-methanol leads to the stable cationic species [Pt2Cl2(μ-NO)(μ-dppm)2]+, isolated as the BF4- (1a) or PF6- (1b) salt. The corresponding BPh4- salt (1c) is obtained by treatment of 1a with NaBPh4. Pt2X2(μ-dppm)2 species (X = Br, I) are also reactive toward NO+BF4-, giving rise to the orange [Pt2Br2(μ-NO)(μ-dppm)2]BF4 (2) or the dark red [Pt2I2(μ-NO)(μ-dppm)2]BF4 (3). The reactivity of the platinum(I) precursors with the nitrosonium ion is compared with that of Pd2Cl2(μ-dppm)2, which gives either a much less stable μ-NO species or a non-nitrosyl Pd(II) complex. NMR characterization of complexes 1-3 at room temperature shows the presence in solution of nonfluxional, symmetrical A-frame structures. The crystal structure of the dichloromethane solvate [Pt2Cl2(μ-NO)(μ-dppm)2]BPh4 (1c) has been determined by X-ray diffraction. It crystallizes in the monoclinic space group P21/a with Z = 4 in a unit cell of dimensions a = 26.295 (6) A?, b = 16.338 (4) A?, c = 16.414 (7) A?, β = 106.99 (2)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares on the basis of 4582 observed reflections to R and Rw values of 0.0501 and 0.0621, respectively. The cationic complex has an A-frame structure with terminal chloride and bridging dppm ligands and a bridgehead NO group, the nonbonding Pt-Pt separation being 3.246 (3) A?. The NO bridge is almost symmetric, with Pt(1)-N and Pt(2)-N bond distances of 1.947 (14) and 1.919 (16) A? and Pt(1)-N-O and Pt(2)-N-O angles of 120.4 (11) and 125.4 (12)°. This result contrasts with that previously found in the tetrafluoroborate salt of the same cation, but it is in agreement with theoretical studies predicting that the oscillation of the NO bridge from the symmetric to the asymmetric position requires a very low energy cost.
