Structural and Dynamic Properties of OsH2X2L2 (X = Cl, Br, I; L = PiPr3) Complexes: Interconversion between Remarkable Non-Octahedral Isomers

New d4dihydrides of Ru(iv) and Os(iv) with π-donor ligands: M(H)2(chelate)(PiPr3)2with chelate = ortho-XYC6H4with X, Y = O, NR; R = H or CH3

“…Even considering only the heavier atoms, which are more accurately determined than the hydrides, the RuP 2 and the RuO 2 planes are neither orthogonal nor coplanar. This structure thus bears a remarkable similarity to that of M(H) 2 Cl 2 (P i Pr 3 ) 2 (M ¼ Ru 19 and Os 1 ), and it was reasoned there 2,12,13 that the observed structure was a compromise between the nonoctahedral structure dictated electronically for a d 4 six-coordinate species and the steric dictates of P i Pr 3 in conflict with chloride. Those arguments thus also pertain here, even if they force the two bulky phosphines into a small +P-Ru-P (114.41) and even though the catecholate ligand has a small bite angle (+O-Ru-O ¼ 80.51).…”

“…Six-coordinate species of ruthenium and osmium in oxidation state þ4 represent an interesting development, especially when they are unsaturated. Synthetic access to M(H) 2 Cl 2 L 2 (L ¼ P i Pr 3 ) in recent years 1,2 was followed by an exploration of their reactivity towards alkynes (yielding carbenes and carbynes), as well as binding H 2 and catalytic alkene and alkyne hydrogenation. [3][4][5][6][7][8][9][10][11] The molecules M(H) 2 Cl 2 L 2 are exceptional in not being octahedral, but also in having the two bulky phosphines cisoid (+P-M-P B1121).…”

“…[3][4][5][6][7][8][9][10][11] The molecules M(H) 2 Cl 2 L 2 are exceptional in not being octahedral, but also in having the two bulky phosphines cisoid (+P-M-P B1121). The actual structure has been deduced 2,12,13 to be a compromise between the conflicting dictates of the d 4 electronic configuration and the minimization of steric pressures and this feature of the d 4 configuration has recently been generalized. 14,15 In part because these are crowded molecules, reactivity can sometimes require heating (atypical for 16-electron species).…”

A Career in Catalysis: Odile Eisenstein

“…The expected geometry for this electron count and coordination number is a bicapped tetrahedron, which had been in fact the result of previous calculations with an OsCl 2 H 2 (PH 3 ) 2 model. 17 Introduction of the real tris(isopropyl)phosphine in the calculation leads to results in much better agreement with experiment, with a key dihedral angle changing by more than 30°. The reasons for the distortion are steric interactions between the chloride ligands and the bulky substituents in the phosphine ligands.…”

Geminal dehydrogenation of ether and amine C(sp3)H2 groups by electron-rich Ru(ii) and OsElectronic supplementary information (ESI) available: crystallographic data, fractional coordinates and isotropic thermal parameters, anisotropic thermal parameters, and bond distances and angles. See http://www.rsc.org/suppdata/nj/b2/b200168n/

“…If [RuHClL 2 ] 2 is synthesized in THF at room temperature (by dehydrohalogenation of RuH 2 Cl 2 L 2 ), 15-20% of the carbene, RuHClL 2 (=COC 3 H 6 ), is observed since the initially formed RuHClL 2 monomer can be solvated by THF and form carbene in competition with its dimerization. The molecule is characterized by a well-defined AMX pattern by 31 P{ 1 H}NMR in C 6 D 12 consisting of three doublets of doublets centered at d À7.2, 61.3, and 91.7. The metallated phosphine (P a ) is assigned to the highest field resonance and displays large couplings to the other two phosphines of 177 (P a -P b ) and 111 (P a -P c ) Hz.…”