An Ru-Substituted Tris(ethynyl)methyl Cation: Synthesis, Properties, and Structure of [{Cp(dppe)Ru(C≡C)}3C]PF6·C6H6

The dark blue complex [{Cp(dppe)Ru(C≡C)}3C]PF6 1 (Cp=cyclopentadienyl, dppe=1,2-bis(diphenylphosphino)ethane) was obtained in 46% yield by treatment of Ru(C≡CH)(dppe)Cp with CuCl/TMEDA (tetramethylethanediamine), followed by KOH and [NH4]PF6 in acetone; it was accompanied by known complexes {Cp(dppe)Ru}C≡CC≡C{Ru(dppe)Cp} 2 (22%) and yellow [1,3-{Cp(dppe)Ru}2C4H3]PF6 3 (2.6%). The structure of the cationic fragment of 1 in its benzene solvate consists of a central planar C attached to three C≡CRu(dppe)Cp fragments. The cation of 3 consists of a cyclobuten-1,3-diyl group bearing two Ru(dppe)Cp groups. The 13C NMR resonance of the central C in 1 is found at δ 66.11. The cyclic voltammogram of 1 contains three irreversible oxidation waves at +0.87, +0.79, and +0.25V, together with a reversible reduction wave at −1.38V (versus FeCp2/[FeCp2]+).

An iridium complex with an unsupported Ir—Zn bond: diiodido(η5-pentamethylcyclopentadienyl)bis(trimethylphosphane)iridiumzinc(Ir—Zn) benzene hemisolvate

The title compound, [IrZnI2(C10H15)(C3H9P)2]·0.5C6H6 or [Cp*(PMe3)2Ir]-[ZnI2] (Cp* = cyclo-C5Me5) was obtained and characterized as its benzene solvate [Cp*(PMe3)2Ir]-[ZnI2]·0.5C6H6. The bimetallic complex in this structure contains the Lewis-acidic fragment ZnI2 bonded to the Lewis-basic fragment Cp*(PMe3)2Ir, with an Ir—Zn bond distance of 2.452 (1) Å. The compound was obtained by reacting [Cp*(PMe3)IrI2] with 2-Ad2Zn (2-Ad = 2-adamantyl), resulting in the reduction of the IrIII complex and formation of the IrI–ZnII adduct. The crystal studied was a twin by non-merohedry with a refined BASF parameter of 0.223 (1).

C2-isomer of [Pd(tfd)]6[tfd is S2C2(CF3)2] as its benzene solvate: a new member of the small but growing class of homoleptic palladium(II) monodithiolenes in the form of hexameric cubes

The title compound, hexakis[μ3-1,2-bis(trifluoromethyl)ethene-1,2-dithiolato]-octahedro-hexapalladium(II), [Pd(C4F6S2)]6, crystallizes as its benzene solvate, [Pd(tfd)]6·2.5C6H6, where tfd is the dithiolene S2C2(CF3)2. The molecular structure of [Pd(tfd)]6is of the hexametallic cube type seen previously in three examples of hexameric homoleptic palladium monodithiolene structures. All structures have in common: (a) the cluster closely approximates a cube containing six PdIIatoms, one at the centre of each cube face; (b) 12 S atoms occupy the mid-points of all 12 cube edges, providing for each PdIIatom an approximately square-planarS4environment; (c) each S atom is part of a dithiolene molecule, where the size of the dithiolene ligand necessitates that only sulfur atoms on adjacent cube edges can be part of the same dithiolene. This general cube-type framework has so far given rise to two isomeric types: anS6-symmetric isomer and aC2-chiral type (two isomers that are enantiomers of each other). The structure of [Pd(tfd)]6is of theC2-type. Out of the 12 CF3groups, three are rotationally disordered over two positions. Further, we answer the question of whether additional, previously undiscovered, isomers could follow from the cube rules (a) through (c) above. An exhaustive analysis shows that no additional isomers are possible and that the list of isomers (oneS6isomer, twoC2enantiomers) is complete. Each isomer type could give rise to an unlimited number of compounds if the specific dithiolene used is varied.

Crystal structure of μ-carbonyl-1:2κ2C:C-carbonyl-1κC-(1η5-cyclopentadienyl)iodido-2κI-[μ-2-(pyridin-2-yl)ethene-1,1-diyl-1κC1:2κ2N,C1]ironpalladium(Fe—Pd) benzene monosolvate

The reaction of Cp(CO)2FeI with 2-ethynylpyridine under Sonogashira conditions [5% PdCl2(PPh3)2, 10% CuI, THF–NEt3(2:1)] afforded the title binuclear μ-pyridylvinylidene FePd complex (FePd1) as a benzene solvate, [FePd(C5H5)(C7H5N)I(CO)2]·C6H6, in a very low yield rather than the expected irono-pyridylethynyl complex Cp(CO)2Fe—C[triple-bond]C-(2-C5H4N). The Fe and Pd atoms inFePd1are bridged by carbonyl and pyridylvinylidene ligands, the pyridyl N atom being bonded to the palladium atom. The use of equimolar amounts of PdCl2increases the yield ofFePd1to 12%. The reaction pathway leading toFePd1is proposed.

Crystal structure of 4′-{[4-(2,2′:6′,2′′-terpyridyl-4′-yl)phenyl]ethynyl}biphenyl-4-yl (2,2,5,5-tetramethyl-1-oxyl-3-pyrrolin-3-yl)formate benzene 2.5-solvate

The title compound, C44H35N4O3·2.5C6H6(1), consists of a terpyridine and aN-oxylpyrroline-3-formate group separated by an aromatic spacer,viz.4-(phenylethynyl)-1,1′-biphenyl. It crystallized in the triclinic space groupP-1 with two and a half benzene solvate molecules (one benzene molecule is located about an inversion center), while the dichloromethane solvate (2) of the same molecule [Ackermannet al.(2015).Chem. Commun.51, 5257–5260] crystallized in the tetragonal space groupP42/n, with considerable disorder in the molecule. In (1), the terpyridine (terpy) group assumes an all-transconformation typical for terpyridines. It is essentially planar with the two outer pyridine rings (BandC) inclined to the central pyridine ring (A) by 8.70 (15) and 14.55 (14)°, respectively. The planes of the aromatic spacer (D,EandF) are nearly coplanar with dihedral anglesD/E,D/FandE/Fbeing 3.42 (15), 5.80 (15) and 4.00 (16)°, respectively. It is twisted with respect to the terpy group with, for example, dihedral angleA/Dbeing 24.48 (14)°. The mean plane of theN-oxylpyrroline is almost normal to the biphenyl ringF, making a dihedral angle of 86.57 (16)°, and it is inclined to pyridine ringAby 72.61 (15)°. The intramolecular separation between the O atom of the nitroxyl group and the N atom of the central pyridine ring of the terpyridine group is 25.044 (3) Å. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers. The dimers stack along thecaxis forming columns. Within and between the columns, the spaces are occupied by benzene molecules. The shortest oxygen–oxygen separation between nitroxyl groups is 4.004 (4) Å. The details of the title compound are compared with those of the dichloromethane solvate (2) and with the structure of a related molecule, 4′-{4-[(2,2,5,5-tetramethyl-N-oxyl-3-pyrrolin-3-yl)ethynyl]phenyl}-2,2′:6′,2′′-terpyridine (3), which has an ethynylphenyl spacer [Meyeret al.(2015).Acta Cryst.E71, 870–874].