Christian Gemel

The substitution chemistry of RuCp* (temeda)Cl

SummaryHalide abstraction from RuCp*(tmeda)Cl (1,tmeda=Me2NCH2CH2NMe2) with NaBPh4 in CH2Cl2 leads to the formation of the sandwich complex RuCp*(η6-C6H5BPh3) (2). In the presence of CH3CN (1 equiv.) and CO, however, the cationic complexes [RuCp*(tmeda)(CH3CN)]+ (3) and [RuCp*(temeda)(CO)]+ (5) are obtained. In CH3CN,tmeda is also replaced giving [RuCp*(CH3CN)3]+ (4). Complex1 reacts readily with terminal acetylenes HC≡CR, the products depending on the nature ofR (Ph, SiMe3,n-Bu, COOEt). Thus, withR=Ph the ruthenacyclopentatriene complex RuCp*(σ,σ′-C4Ph2H2)Cl (6), withR=SiMe3 the cyclobutadiene complex Ru(Cp*)(σ4-C4H2(1,2-SiMe3)2)Cl (7), and withR=n-Bu and COOEt the binuclear complexes (Cp*)RuCl2(η2:η4-μ2-C4H2(1,3-R)2)Ru(Cp*) (8,9) are obtained. Furthermore, with diethyl maleate in the presence of 1 equiv. of LiCl,1 transforms into the new anionic complex Li[Ru(Cp*) (η2-C2H2(COOEt)2)Cl2] (10). X-ray structures of2,3,4,7, and10 are included.ZusammenfassungChloridabspaltung von RuCp*(tmeda)Cl (1,tmeda=Me2NCH2CH2NMe2) mittels NaBPh4 in CH2Cl2 führt zur Bildung des Halbsandwich-Komplexes RuCp*(η6-C6H5BPh3) (2), während in Gegenwart von CH3CN oder CO die beiden kationischen Verbindungen [RuCp*(tmeda)(CH3CN)]+ (3) und [RuCp*(tmeda)(CO)]+ (5) entstehen. In CH3CN als Lösungsmittel wird sogartmeda unter Bildung von [RuCp*(CH3CN)3]+ (4) verdrängt. Komplex1 reagiert sehr leicht mit terminalen Alkinen HC≡CR, wobei die Produkte stark von der Natur des SubstituentenR (Ph, SiMe3,n-Bu, COOEt) abhängen. Im Fall vonR=Ph entsteht der Ruthenacyclopentatrien-Komplex RuCp*(σσ′-C4Ph2H2)Cl (6), mitR=SiMe3 der Cyclobutadien-Komplex Ru(Cp*)(η4-C4H2(1,2-SiMe3)2)Cl (7), und im Fall vonR=n-Bu und COOEt bilden sich die binuklearen Komplexe (Cp*)RuCl2(η2:η4-μ2-C4H2(1,3-R)2)Ru(Cp*) (8,9). Überdies reagiert1 mit Maleinsäurediethylester in Gegenwart von LiCl zum neuen anionischen Komplex Li[Ru(Cp*) (η2-C2H2(COOEt)2)Cl2] (10). Von2,3,4,7 und10 wurden die Kristallstrukturen bestimmt.

P−P Bond Activation of P4 Tetrahedron by Group 13 Carbenoid and its Bis Molybdenum Pentacarbonyl Adduct

Activation of white phosphorus with Ga(DDP) (DDP = 2-diiso-propylphenylamino-4-diiso-propylphenylimino-2-pentene) afforded [(DDP)Ga(P(4))] (1) by insertion of the Ga(I) center at one of the six P-P bonded edges of the P(4) tetrahedron. Further reaction of 1 with three equivalents of Mo(CO)(6) results in the formation of [(DDP)Ga(eta(2:1:1)-P(4)){Mo(CO)(5)}(2)] x 2 toluene (2). Compounds 1 and 2 are characterized by (1)H, (13)C, and (31)P NMR spectroscopy, elemental analysis, and single crystal X-ray structural analysis. The solid-state structure of molecule 1 reveals the first example of a structurally characterized GaP(4) core stabilized by a beta-diketiminate ligand. Compound 2 represents a rare type of coordination mode of a gallium supported P(4) butterfly structure.

Ruthenium Catalyzed Homocoupling of Terminal Alkynes

Summary. Several complexes of the type RuTp(L)(L′)Cl (L, L′=P, N, O donors) were tested with respect to their ability of promoting catalytic C–C-coupling reactions of terminal acetylenes. When L=tertiary phosphine, predominantly dimerization occurs, RuTp(PPh3)2H being the most efficient pre-catalyst. In the absence of a phosphine ligand, polymerization takes place with RuTp(COD)Cl as the most effective pre-catalyst. Both product distribution and conversion depend strongly on the substituent of the alkyne and to a lesser extent on the co-ligands of the ruthenium complex. The catalytically active species is the 16e− alkynyl complex RuTp(L)(–C*C–R) which in case of L=PCy3 and R=Bun could be trapped as RuTp(PCy3)(–C*CBun)(CO).Zusammenfassung. Die Fähigkeit einiger Komplexe des Typs RuTp(L)(L′)Cl, C–C-Kupplungsreaktion terminaler Alkine zu katalysieren, wurde getestet. Ist L ein Phosphin und L′ ein labiler Ligand, so dimerisieren die Alkine, während sie in Abwesenheit von Phosphinen polymerisieren. RuTp(PPh3)2H ist der beste Katalysator für die Dimerisierung, RuTp(COD)Cl für die Polymerisation. Produktverteilung und Ausbeute sind in erster Linie vom Substituenten am Alkin abhängig, aber auch von den Liganden am Ruthenium. Die katalytisch aktive Spezies ist der 16e−-Alkinyl-Komplex RuTp(L)(–C*C–R), der im Falle von L=PCy3 und R=Bun als RuTp(PCy3)(–C*C–Bun)(CO) abgefangen werden konnte.

Synthesis and reactivity of neutral vinylidene and σ-alkynyl complexes containing the hemilabile ligand Ph2PCH2CH2OMe

Abstract RuTp(COD)Cl reacts readily with Ph2PCH2CH2OMe to give the neutral complex RuTp(κ2(P,O)-Ph2PCH2CH2OMe)Cl (2) which transforms with terminal alkynes HCCR (R=Ph, n-Bu, C6H9) and carbon monoxide, respectively, into the neutral vinylidene complexes RuTp(κ1(P)-Ph2PCH2CH2OMe)(Cl)(CCHR) (3a–c) and RuTp(κ1(P)-Ph2PCH2CH2OMe)(Cl)(CO) (4). The κ1(P) bonding mode of the phosphinoether testifies to its hemilabile nature. Complex 3a reacts with lithium diisopropylamide to give the neutral α-acetylide complex RuTp(κ2(P,O)-Ph2PCH2CH2OMe)(CCPh) (5) which couples with stoichiometric amounts of HCCPh to give RuTp(κ1(P)-Ph2PCH2CH2OMe)(C(Ph)CHCCPh) (6), featuring a σ,η2-bound enynyl ligand. Treatment of 3a with AgCF3SO3 affords the cationic vinylidene complex [RuTp(κ2(P,O)-Ph2PCH2CH2OMe)(CCHPh)]CF3SO3 (7). Complex 5 is found to catalyze the dimerization of HCCR (RPh, SiMe3, n-Bu, t-Bu, C6H9) to give enynes. The structures of 3a, 4, 5 and 7 have been determined by X-ray crystallography.

Cationic 16-electron half-sandwich ruthenium complexes containing asymmetric diamines: understanding the stability and reactivity of coordinatively unsaturated two-legged piano stool complexes

The cationic 16e complexes [RuCp*(η 2 (N,N)-Me 2 NCH 2 CH 2 N(CH 2 CHMe 2 ) 2 )] + ( 1 ) and [RuCp*(η 2 (N,N)-Me 2 NCH 2 CH 2 H 2 ] + ( 2 ) as well as the 18e complex [RuCp*(η 6 -C 6 H 5 -N(Me)NCH 2 CH 2 NMe 2 )] + ( 3 ) have been synthesized as the BAr′ 4 (Ar′=3,5-C 6 H 3 (CF 3 ) 2 ) salts in one-pot reactions starting from [RuCp*(Cl)] 4 . For 1 , the X-ray crystal structure has also been determined showing the absence of any agostic interactions between ruthenium and the C–H bonds of the diamine ligand, and only minor deviations from the planar geometry despite the bulky diamine ligand. Based on EH model calculations, the extraordinary kinetic inertness of the planar 16e [Cp*Ru(NN)] + structure is traced to a high HOMO–LUMO gap deriving from through-bond coupling through the intervening σ skeleton of the chelating diamine (NN) ligand (in contrast to the P analogs) and further to the high π donor strength of Cp* (relative to parent Cp). Possible ligand rearrangements to increase the chemical reactivity are analyzed.

Clusters [Ma(GaCp*)b(CNR)c] (M = Ni, Pd, Pt): synthesis, structure, and Ga/Zn exchange reactions.

Reactions of homoleptic isonitrile ligated complexes or clusters of d(10)-metals with the potent carbenoid donor ligand GaCp* are presented (Cp* = pentamethylcyclopentadienyl). Treatment of [Ni4(CNt-Bu)7], [{M(CNR)2}3] (M = Pd, Pt) and [Pd(CNR)2Me2] (R = t-Bu, Ph) with suitable amounts of GaCp* lead to the formation of the heteroleptic, tri- and tetranuclear clusters [Ni4(CNt-Bu)7(GaCp*)3] (1), [{M(CNt-Bu)}3(GaCp*)4] (M = Pd: 2a, Pt: 2b), and [{Pd(CNR)}4(GaCp*)4] (R = t-Bu: 3a, Ph: 3b). The reactions involve isonitrile substitution reactions, GaCp* addition reactions, and cluster formation reactions. The new compounds were investigated for their ability to undergo Ga/Zn exchange reactions when treated with ZnMe2. The novel tetranuclear Zn-rich clusters [Ni4GaZn7(Cp*)2Me7(CNt-Bu)6] (4) and [{Pd(CNR)}4(ZnCp*)4(ZnMe)4] (R = t-Bu: 5a, Ph: 5b) were obtained and isolated. The electronic situation and geometrical arrangement of atoms of all compounds will be presented and discussed. All new compounds are characterized by solution (1)H, (13)C NMR and IR spectroscopy, elemental analysis (EA), liquid injection field desorption ionization mass spectrometry (LIFDI-MS) as well as single crystal X-ray crystallography.

Dizinc Cation [Zn2]2+ Trapped In A Homoleptic Metalloid Coordination Environment Stabilized by Dispersion Forces: [Zn2(GaCp*)6][BAr4F]2

The synthesis and characterization of the cationic mixed metal Ga/Zn cluster [Zn2(GaCp*)6](2+) (1) is presented. The reaction of [Zn2Cp*2] with [Ga2Cp*][BAr4(F)] leads to the formation of the novel complex being the first example of a [Zn2](2+) core exclusively ligated by metalloid group-13 organyl-ligands. Compound 1 exhibits two different coordination modes: In the solid state, two of the six GaCp* ligands occupy bridging positions, whereas VT (1)H NMR indicates the coexistence of a second isomer in solution featuring six terminal GaCp* ligands. Quantum chemical calculations have been carried out to assign the gallium and zinc positions; the bonding situation in 1 is characterized and the importance of dispersion forces is discussed.

Synthesis and Characterization of Ruthenium Tris (pyrazolyl)borate Complexes Containing NN-, NS-, NNN-, and OO-Donor Co-Ligands

Summary. The synthesis and characterization of RuTp complexes containing the chelating ligands N,N′-bis(phenylmethylene)-1,2-ethylenediamine (NN), 2-pyridinethiol (NS), N,N-bis-(2-(dimethylamino)ethyl)-N′,N′-dimethyl-1,2-ethanediamine) (N-crab), acetylacetonate (acac), and tetramethylethylenediamine (tmeda) is described. While with NN, N-crab, acac, and tmeda mononuclear complexes are formed, a dimeric species is obtained with NS. X-ray structures of some complexes are given. The complexes featuring NN, acac, and tmeda react readily with terminal acetylenes to give vinylidene complexes.Zusammenfassung. Die Synthese und Charakterisierung von RuTp-Komplexen mit den Koliganden N,N′-Bis(phenylmethylen)-1,2-ethylendiamin (NN), 2-Pyridinthiol (NS), N,N-Bis-(2-(dimethylamino)ethyl)-N′,N′-dimethyl-1,2-ethandiamin) (N-crab), Acetylacetonat (acac) und Tetramethylethylendiamin (tmeda) werden beschrieben. Während sich mit NN, N-crab, acac und tmeda einkernige Komplexe bilden, gibt die Umsetzung mit NS einen dimeren Komplex. Röntgenstrukturanalysen repräsentativer Verbindungen wurden durchgeführt. Die Verbindungen mit NN, acac und tmeda bilden mit terminalen Alkinen Vinylidenkomplexe.

The Organozinc Rich Compounds [Cp*M(ZnR)5] (M = Fe, Ru; R = Cp*, Me, Cl, Br)

Organozinc (ZnR with R = Cp*, Me, Cl, Br) ligated transition metal (M) half-sandwich compounds of general formula [Cp*M(ZnR)5] (M = Fe, Ru) are presented in this work. The new compounds were obtained by treatment of various GaCp* ligated precursors with suitable amounts of ZnMe2 to exchange Ga against Zn. This exchange follows a strict Ga:Zn ratio of 1:2. Accordingly, a Ga/Zn mixed compound [{Cp*Ru(GaCp*)(ZnCp*)(ZnCl)2}2] can be obtained if the amount of ZnMe2 is reduced so that one GaCp* remains coordinated to the transition metal. All new compounds were characterized by elemental analysis, (1)H and (13)C NMR spectroscopy as well as by single crystal X-ray diffraction techniques, if applicable. The coordination polyhedra of [Cp*M(ZnR)5] can be derived from the pseudo homoleptic parent compound [Ru(ZnCp*)4(ZnMe)6], as emphasized by continuous shape measures analysis (CShM). Computational investigations at the density functional theory (DFT) level of theory were performed, revealing no significant attractive interaction of the zinc atoms and therefore these compounds are best described as classical complexes, rather than cluster compounds. The Ru-L bond strength follow the order Cp* > ZnCl > ZnMe > ZnCp*.

Oxidation of Ni-ECp* Complexes: Stable Open-Shell NiI Cations [Ni(ECp*)n(PPh3)4–n]+ (n = 2, 4; E = Al, Ga)

Uncommon Ni(I) cationic complexes were synthesized by treating [Ni(ECp*)2(PPh3)2] (E = Al, Ga; Cp* = pentamethylcyclopentadienyl) with 1 equiv of [FeCp2][BAr4(F)]. All compounds have been prepared readily in high yield. The paramagnetic compounds were characterized by single-crystal X-ray crystallography, mass spectrometry, elemental analysis, magnetic susceptibility, and electron paramagnetic resonance spectroscopy.