Studies of κ- and κ-tripyridylamine complexes of ruthenium and π-stacking by pyridyls.

The reaction of tris(pyridin-2-yl)amine with [CyRuCl] (Cy = p-isopropyltoluene or cymene) in refluxing diglyme led to the formation of cis-[RuCl{κ-(2-py)N}]·CHCl (1a) after recrystallization from chloroform/pentane, or cis-dichloridobis[tris(pyridin-2-yl)amine-κN,N']ruthenium(II) dichloromethane disolvate, [RuCl(CHN)]·2CHCl or cis-[RuCl{κ-(2-py)N}]·2CHCl (1b). Treatment of 1a with one equivalent of silver(I) hexafluoridoantimonate in dichloromethane gave [RuCl{κ-(2-py)N}{κ-(2-py)N}][SbF]·CHCl (2a). Crystallization of 2a from chloroform provided chlorido[tris(pyridin-2-yl)amine-κN,N'][tris(pyridin-2-yl)amine-κN,N',N'']ruthenium(II) hexafluoridoantimonate chloroform monosolvate, [RuCl(CHN)][SbF]·CHCl or [RuCl{κ-(2-py)N}{κ-(2-py)N}][SbF]·CHCl (2b).

Hemilability and structural considerations in complexes of platinum(II) comprising bis(diphenylphosphanyl)methane monoxide, monosulfide, and monoselenide.

The structure of a platinum(II) complex containing (R)-(dimethylamino)ethylnapthyl and bis(diphenylphosphanyl)methane monosulfide ligands, namely, {(R)-1-[1-(dimethylamino)ethyl]napthyl-κN,C}[(diphenylphosphanylmethyl)diphenylphosphine sulfide-κP,S]platinum(II) hexafluoridoantimonate dichloromethane monosolvate, [Pt(CHN)(CHPS)][SbF]·CHCl, was determined. The structural features are compared with analogous platinum bis(diphenylphosphanyl)methane monoxide [dppm(O)] and bis(diphenylphosphanyl)methane monoselenide [dppm(Se)] complexes in relation to their potential hemilability and stereochemical nonrigidity.

Double geminal C-H activation and reversible alpha-elimination in 2-aminopyridine iridium(III) complexes: the role of hydrides and solvent in flattening the free energy surface.

[H2Ir(OCMe2)2L2]BF4 (1) (L = PPh3), a preferred catalyst for tritiation of pharmaceuticals, reacts with model substrate 2-(dimethylamino)pyridine (py-NMe2; py = 2-pyridyl) to give chelate carbene [H2Ir(py-N(Me)CH=)L2]BF4 (2a) via cyclometalation, H2 loss, and reversible alpha-elimination. Agostic intermediate [H2Ir(py-N(Me)CH2-H)L2]BF4) (4a), seen by NMR, is predicted (DFT(B3PW91) computations) to give C-H oxidative addition to form the alkyl intermediate [(H)(eta2-H2)Ir(py-N(Me)CH2-)L2]BF4. Loss of H2 leads to the fully characterized alkyl [HIr(OCMe2)(py-N(Me)CH2-)L2]BF4 (3a(Me2CO)), which loses acetone to give alkylidene hydride 2a by rapid reversible alpha-elimination.

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.