Stanislav Chaloupka

Synthetic, structural and inelastic neutron scattering studies of the hydridobridged cationic complexes [(PMe3)2(Y) Pt(μ-H)Pt(Y)(PMe3)2]+ (Y = Ph, C6F5, C6Cl5) and of [(PEt3)2(H)Pt(μ-H) Pt(Ph) (PEt3)2]+

Abstract The mono-hydrido-bridgeddiplatinumcomplexes [(PMe3)2(C6X5)Pt(μ-H)Pt(C6X5)(PMe3)2](CF3SO3) (X = H, F, Cl) were prepared from the corresponding mononuclear species trans- [PtH(C6X5)(PMe3)2] and trans-[Pt(C6X5)(S)(PMe3)2](CF3SO3) (S-weakly coadinating solvent). The X-ray crystal structures of [(PMe3)2(Ph)Pt(μ-H)Pt(Ph)(PMe3)2] [BPh4], prepared from the cares triflate (space group P 1 , a=13.731(5), b=16.192(2), c=23.425(8) A , α=96.46(2), β=100.54(3), y=95.05(2)°, Z=4, R=0.043, R w =0.056 for 6914 observed reflections) and of [(PMe3)2(C6F5)Pt(μ-H)Pt(C6F5)(PMe3)2](CF3SO3)-CH2Cl2 (space group P21/n, a=11.762(2), b=19.500(3), c=19.112(3), β=105.64(1), Z=4, R=0.038, RW=0.049 for 2528 observed reflections) were determined. Both cations contain the two planar (Pt(C6X5) (PMe3)2) moieties bridged by a hydride ligand, the Pt-Pt bonds being 3.0641(7) and 3.0969(9) A for X = H and 3.009(1) A for X = F. Inelastic incoherent neutron scattering studies were carried out on [(PMe3)2(C6)F5)Pt(μ-H)-Pt(C6F5)(PMe3)2](CF3SO3), (PEt3)2(H)Pt(μ-H)Pt(Ph)(PEt3)2](CF3SO3) and [(PEt3)2(Ph)Pt(μ-H)Pt(Ph)(PEt3)2](CF3SO3), and vibrational data for the PtHPt fragments obtained. The values of the νasynm/ νsym ratios and a semi-empirical correlation were used to obtain approximate values of the Pt-H-Pt bond angles in compounds of this type.

Structural studies of the hydrido-bridged iridium gold complexes ‘IrHm{CH3C(CH2PPh2)3}{Au(PR3)}n’

Abstract The X-ray crystal structure of [{(triphos)H (3− x ) Ir}(μ-H) x {Au(PR 3 )}][PF 6 ] (triphos=CH 3 C(CH 2 PPh 2 ) 3 , x =2) shows that the gold atom builds two almost equal IrHAu bridges with the he ‘IrH 3 (triphos)’ building block. The IrHAu bridging parameters are typical of three-center-two-electron interactions. The X-ray crystal structure of [{(triphos)H (3− y ) Ir}(μ-H) y {Au(PR 3 )} 2 ][PF 6 ] 2 shows that each gold atom builds two Ir(μ 2 -H)Au bridges with the three hydrides of the ‘IrH 3 (triphos)’ building block; one Ir(μ 3 -H)Au 2 bridge is also present ( y =3). The relative positions of the Ir, H, Au and P atoms show that typical three-center-two-electron interactions predominate in this compound, in which there is no direct AuAu bonding. The neutron diffraction structure of [{(triphos)Ir}(μ-H) 2 {Au(PPh 3 )} 3 ][PF 6 ] 2 confirms the earlier hypothesis that only two of the three IrAu edges are associated with a hydride with formation of Ir(μ 2 -H)Au bridges. The presence or absence of the latter ligand changes the IrAu distance only marginally, in contrast to the general trend in hydride clusters. It is shown that the formation of a ‘classical’ cluster in this set of compounds requires a quadrimetallic unit and the two additional electrons generated by loss of a proton from an IrH bond in the trication [{(triphos)Ir (μ 2 -H) 3 {Au(PR 3 )} 3 } 3+ .