A series of ruthenium(II) acetonitrile, pyridine (py), carbonyl, SO 2 , and nitrosyl complexes [Ru(bdmpza)(O 2 CR)(L)(PPh 3 )] (L ) NCMe, py, CO, SO 2 ) and [Ru(bdmpza)(O 2 CR)(L)(PPh 3 )]BF 4 (L ) NO) containing the bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) ligand, a N,N,O heteroscorpionate ligand, have been prepared. Starting from ruthenium chlorido, carboxylato, or 2-oxocarboxylato complexes, a variety of acetonitrile complexes [Ru(bdmpza)Cl(NCMe)(PPh 3 )] (4) and [Ru(bdmpza)(O 2 CR)(NCMe)(PPh 3 )] (R ) Me (5a), R ) Ph (5b)), as well as the pyridine complexes [Ru(bdmpza)Cl(PPh 3 )(py)] ( 6) and [Ru(bdmpza 9a, 9b). In the same way, the corresponding sulfur dioxide complexes [Ru(bdmpza)(O 2 CMe)(PPh 3 )(SO 2 )] (10a) and [Ru(bdmpza)(O 2 CPh)(PPh 3 )(SO 2 )] (10b) were formed in a reaction of the carboxylato complexes with gaseous SO 2 . None of the 2-oxocarboxylato complexes [Ru(bdmpza)(O 2 C(CO)R)(PPh 3 ) 2 ] (R ) Me (3a), Et (3b), Ph (3c)) showed any reactivity toward CO or SO 2 , whereas the nitrosyl complex cations [Ru(bdmpza)(O 2 -CMe)(NO)(PPh 3 )] + (11) and [Ru(bdmpza)(O 2 C(CO)Ph)(NO)(PPh 3 )] + (12) were formed in a reaction of the acetato 2a or the benzoylformato complex 3c with an excess of nitric oxide. Similar cationic carboxylato nitrosyl complexes 14c)) are also accessible via a reaction with NO[BF 4 ]. X-ray crystal structures of the chlorido acetonitrile complex [Ru(bdmpza)Cl(NCMe)(PPh 3 )] (4), the pyridine complexes [Ru(bdmpza)(O 2 CMe)(PPh 3 )(py)] (7a) and [Ru(bdmpza)(O 2 CC(O)Et)(PPh 3 )(py)] (8b), the carbonyl complex [Ru(bdmpza)(O 2 CPh)(CO)(PPh 3 )] (9b), the sulfur dioxide complex [Ru(bdmpza)(O 2 -CPh)(PPh 3 )(SO 2 )] (10b), as well as the nitrosyl complex [Ru(bdmpza)(O 2 C(CO)Me)(NO)(PPh 3 )]BF 4 (14a), are reported. The molecular structure of the sulfur dioxide complex [Ru(bdmpza)(O 2 CPh)(PPh 3 )(SO 2 )] (10b) revealed a rather unusual intramolecular SO 2 -O 2 CPh Lewis acid-base adduct.

The syntheses of the two dicarbonyl complexes [Ru(bdmpza)Cl(CO)2] (3) and [Ru(2,2-bdmpzp)Cl(CO)2] (4), bearing a bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) or a 2,2-bis(3,5-dimethylpyrazol-1-yl)propionato (2,2-bdmpzp) scorpionate ligand, are described. Both complexes are obtained by reacting the polymer [RuCl2(CO)2] n with either K[bdmpza] or K[2,2-bdmpzp]. Reaction of the acid Hbdmpza with [Ru3(CO)12] results in the formation of two structural isomers of a hydrido complex, [Ru(bdmpza)H(CO)2] (5a,b). Under aerobic conditions conversion of [Ru(bdmpza)H(CO)2] (5a,b) to form the Ru(I) dimer [Ru(bdmpza)(CO)(μ-CO)]2 (6) seems to be hindered in comparison to the case for the η5-C5H5 (Cp) analogues. Dimer 6 is obtained via a reaction of Hbdmpza with catena-[Ru(OAc)(CO)2] n instead. The molecular structures of 3, 4, and 6 have been obtained by single-crystal X-ray structure determinations. The precatalytic properties of the two dicarbonyl complexes 3 and 4 toward the catalytic oxidation of cyclohexene with different oxidizing agents are discussed as well.

The new compound 4-ferrocenyl-3,5-dimethylpyrazole (4; fcdmpzH) has been synthesized from 4-iodo-3,5-dimethyl-1-tritylpyrazole (2) via a Negishi type cross-coupling reaction and subsequent deprotection of the intermediate 4-ferrocenyl-3,5-dimethyl-1-tritylpyrazole (3; fcdmpzTrt). Reaction of the pyrazole 4 with dichloromethane, base, and phase transfer catalyst results in the chelating N,N ligand bis(4-ferrocenyl-3,5-dimethylpyrazol-1-yl)methane (5; bfcdmpzm). Bis(4-ferrocenyl-3,5dimethylpyrazol-1-yl)ketone (6; bfcdmpzk) is obtained by reacting 4 with NEt 3 and triphosgene. The N,N,O heteroscorpionate ligand bis(4ferrocenyl-3,5-dimethylpyrazol-1-yl)acetic acid (7; H[bfcdmpza]) can be accessed by reacting pyrazole 4 with dibromoacetic acid, KOtBu, and phase transfer catalyst and subsequent acidic workup. The heteroscorpionate ligand H[bfcdmpza] ( 7) is suitable to bind metal ions in a κ 3 coordination mode, as could be proven by the formation of a the bis-ligand complex [Fe(bfcdmpza) 2 ] (8). The molecular structures of 3, 5, 6, and 8 have been obtained by single-crystal X-ray structure determination. The electrochemical properties of the four ferrocenyl-substituted compounds 3−6 have been studied by cyclic voltammetric measurements and discussed as well.

The heteroscorpionate ligand bis(3,5-di-tert-butylpyrazol-1-yl)dithioacetate (bdtbpzdta) has been synthesized by reacting bis(3,5-di-tert-butylpyrazol-1-yl)methane with n-BuLi and CS2. The ligand was isolated as [bis(3,5-di-tert-butylpyrazol-1-yl)dithioacetato](tetrahydrofuran)lithium(I) tetrahydrofuran monosolvate, [Li(C24H39N4S2)(C4H8O)]·C4H8O or [Li(bdtbpzdta)(THF)]·THF, in which the lithium cation is bound by the κ(3)N,N',S-coordinated heteroscorpionate ligand. A similar coordination mode is observed for a zinc chloride complex bearing the bdtbpzdta ligand, namely [bis(3,5-di-tert-butylpyrazol-1-yl)dithioacetato]chloridozinc(II), [Zn(C24H39N4S2)Cl] or [Zn(bdtbpzdta)Cl], which exhibits κ(3)N,N',S-coordination and resembles the active site of zinc-containing peptide deformylases (PDFs).