Arene ruthenium complexes of the thermally resistant ligand tri-2-pyridylamine

Summary The degradation-resistant ligand tri-2-pyridylamine (tripyam) (1) forms a variety of stable ruthenium complexes. Reaction of (1) with RuCl₂(PPh₃)₃ yields the complex RuCl₂(PPh₃)(tripyam) (2) and, upon prolonged heating in pyridine, forms RuCl₂(py)(tripyam) (3). Complexes (2) and (3) display unusual thermal stability, resisting degradation at temperatures of 270 °C. Reaction of (2) with two equivalents of AgSbF₆ in water yields the solvento complex [Ru(PPh₃)(tripyam)(OH₂)₂] (SbF₆)₂ (2a). Reaction of (1) with RuCl₃·H₂O also yields the trichloro complex RuCl₃(tripyam) (4). The organometallic precursor [RuCl₂(p-cymene)]₂ reacts with (1) and either two or four equivalents of AgSbF₆ to yield [RuCl(p-cymene)( ²-tripyam)]SbF₆ (5) and [Ru(p-cymene) ( ³-tripyam)](SbF₆)₂ (6), respectively. Each of these complexes has been characterized by spectroscopic techniques and, in the case of (5), by single-crystal X-ray diffraction.     

Abnormal ligand binding and reversible ring hydrogenation in the reaction of imidazolium salts with IrH(5)(PPh(3))(2)

We show that imidazolium salts do not always give normal or even aromatic carbenes on metalation, and the chemistry of these ligands can be much more complicated than previously thought. N,N'-disubstituted imidazolium salts of type [(2-py)(CH(2))(n)(C(3)H(3)N(2))R]BF(4) react with IrH(5)(PPh(3))(2) to give N,C-chelated products (n = 0, 1; 2-py = 2-pyridyl; C(3)H(3)N(2) = imidazolium; R = mesityl, n-butyl, i-propyl, methyl). Depending on the circumstances, three types of kinetic products can be formed: in one, the imidazole metalation site is the normal C2 as expected; in another, the metalation occurs at the abnormal C4 site; and in the third, C4 metalation is accompanied by hydrogenation of the imidazolium ring. The bonding mode is confirmed by structural studies, and spectroscopic criteria can also distinguish the cases. Initial hydrogen transfer can take place from the metal to the carbene to give the imidazolium ring hydrogenation product, as shown by isotope labeling; this hydrogen transfer proves reversible on reflux when the abnormal aromatic carbene is obtained as final product. Care may therefore be needed in the future in verifying the structure(s) formed in cases where a catalyst is generated in situ from imidazolium salt and metal precursor.     

Abnormal binding in a carbene complex formed from an imidazolium salt and a metal hydride complex

2-Pyridylmethylimidazolium salts and IrH5(PPh3)2 give an [(N-C)IrH2(PPh3)2]+ species with the imidazole ring bound in the 'wrong way': at C-5, not at the expected C-2.     

The isolation of intermediates in hydrogen halide additions to some iridium complexes

The complexes [Ir(cod)L_n]PF₆(I, L = PPh₃, PMePh₂; n = 2. L = PMe₂Ph; n = 3) react with HX to give [IrHX(cod)L₂]PF₆ (II, L = PMePh₂ or PMe₂Ph) or [IrHX₂(cod)(PPh₃)] (III). The intermediates [IrX(cod)L₂] have, in two cases (L = PMePh₂, X = I, Br), been directly isolated from the reaction mixtures at 0°C, and are also formed from I with KX (L = PPh₃, X = Cl; L = PMePh₂, X = Cl, Br, I); these intermediates protonate to give II (L = PMePh₂), or an equimolar mixture of III and I (L = PPh₃, X = Cl). Surprisingly, I₂ reacts with I in MeOH to give III (L = PPh₃). The stereochemistries of II and III were determined by < ¹H NMR and especially by new methods using ¹³C NMR spectroscopy. The complexes I exhibit a Lewis acid reactivity pattern.     

η- and η-benzene coordination in [Ag(C6D6)3BF4]

The title complex with one η² and two η¹ deuterobenzene and one monodentate BF₄ ligands was isolated as a by-product in the reaction between [(dppe)RhCl]₂ and EtCl in C₆D₆, in the presence of AgBF₄ and its X-ray crystal structure determined.     

High-spin chloro mononuclear MnIII complexes: a multifrequency high-field EPR study.

The isolation, structural characterization, and electronic properties of two six-coordinated chloromanganese (III) complexes, [Mn(terpy)(Cl)3] (1) and [Mn(Phterpy)(Cl)3] (2), are reported (terpy = 2,2':6'2"-terpyridine, Phterpy = 4'-phenyl-2,2':6',2"-terpyridine). These complexes complement a series of mononuclear azide and fluoride Mn(lll) complexes synthesized with neutral N-tridentate ligands, [Mn(L)(X)3] (X = F- or N3 and L = terpy or bpea [N,N-bis(2-pyridylmethyl)-ethylamine)], previously described. Similar to these previous complexes, 1 and 2 exhibit a Jahn-Teller distortion of the octahedron, characteristic of a high-spin Mn(III) complex (S = 2). The analysis of the crystallographic data shows that, in both cases, the manganese ion lies in the center of a distorted octahedron characterized by an elongation along the tetragonal axis. Their electronic properties were investigated by multifrequency EPR (190-475 GHz) performed in the solid state at different temperatures (5-15 K). This study confirms our previous results and further shows that: i) the sign of D is correlated with the nature of the tetragonal distortion; ii) the magnitude of D is not sensitive to the nature of the anions in our series of rhombic complexes, contrary to the porphyrinic systems; iii) the [E/D] values (0.124 for 1 and 0.085 for 2) are smaller compared to those found for the [Mn(L)(X)3] complexes (in the range of 0.146 to 0.234); and iv) the E term increases when the ligand-field strength of the equatorial ligands decreases.     

Reactions of ReH3(CO)(PMe2Ph)3 with Metallic Lewis Acids. Synthesis and Structural Characterization of Hydrido-Bridged Heterometallic Rhenium-Gold, Rhenium-Silver, and Rhenium-Copper Complexes

This contribution presents a study of the reactions of ReH₃(CO)(PMe₂Ph)₃ (1) with a variety of metallic Lewis acids of the coinage metals to form hydrido-bridged heterometallic rhenium-gold, rhenium-silver, and rhenium-copper complexes. The reaction of 1 with AuCl(PPh₃) proceeds with elimination of hydrogen to give the hydrido-bridged heterobinuclear rhenium-gold complex (PMe₂Ph)₃(CO)ClRe(-H)Au(PPh₃) (2). In contrast, the reactions of 1 with AgPF₆, [Cu(CH₃CN)₄]PF₆ or CuCl proceed without elimination of hydrogen to give the hydrido-bridged heterotrinuclear rhenium-silver and rhenium-copper complexes [(PMe₂Ph)₃(CO)HRe(-H)₂M(-H)₂ReH(CO)(PMe₂Ph)₃]PF₆ (M=Ag (3), Cu (4)) and the hydrido-bridged heterotetranuclear rhenium-copper complex (PMe₂Ph)₃(CO)HRe(-H)₂Cu(-Cl)₂Cu(-H)₂ReH(CO)(PMe₂Ph)₃ (5), respectively. The molecular structures of compounds 2 and 3 have been determined by single-crystal X-ray diffraction studies. Crystallographic data for 2: monoclinic, space group P2₁2₁2₁, a=12.804(2) Å, b=13.512(2) Å, c=24.312(3) Å, V=4206(1) ų, Z=4, and R=0.042. Crystallographic data for 3: monoclinic, space group C2/c, a=24.212(6) Å, b=13.098(3) Å, c=20.177(5) Å, b=116.40(2)°, V=5732(2) ų, Z=4, and R=0.044. The X-ray crystal structure of 2 exhibits a short contact (2.798(12) Å) between the gold atom and the CO ligand that is primarily bound to the adjacent rhenium atom, suggesting an incipient semibridging relationship.