Dinuclear Complex Cp Research Articles

η3-Silaallyl/Alkenylsilyl Molybdenum Complex: Synthesis, Structure, and Reactivity toward Primary Amines To Form Mo–N–Si Three-Membered Cyclic Complexes

The new η3-silaallyl/alkenylsilyl molybdenum complex Cp*Mo(CO)2(η3-Ph2SiCHCMe2) (3) was synthesized by the reaction of Cp*Mo(CO)2(py)Me with Ph2HSiCH═CMe2. Reactions of 3 with primary amines RNH2 (R = tBu, iPr, Et) gave Mo–N–Si three-membered cyclic complexes Cp*Mo(CO)2(κ2-N,Si-RHNSiPh2) (5a, R = tBu; 5b, R = iPr; 5c, R = Et) with elimination of isobutene. In NMR tube reactions using iPrNH2 and EtNH2, the Mo–N–Si–C four-membered cyclic complexes Cp*Mo(CO)2(κ2-N,C-RHNSiPh2CHiPr) (4b, R = iPr; 4c, R = Et) were observed as intermediates leading to 5b and 5c, respectively. Complex 4c was successfully isolated in a preparative reaction. The molecular structures of 3, 4c, and 5b were determined by X-ray crystal analyses. Interestingly, the contribution of silylene character was suggested for the SiPh2 moiety of 5b from the X-ray structure. The reaction of 5b with MeOH gave the dinuclear complex Cp*(CO)2Mo(μ-OMe)(μ-H)Mo(CO)2Cp* as a major product.

Synthesis, Structure, and Bonding Nature of Ethynediyl-Bridged Bis(silylene) Dinuclear Complexes of Tungsten and Molybdenum

Reactions of Ph2HSiC≡CSiHPh2 with 2 equiv of the labile complexes Cp*(CO)2M(NCMe)Me (1a, M ═ W; 2, M ═ Mo; Cp* ═ η5-C5Me5) gave the novel CC-bridged dinuclear complexes Cp*(CO)2M(SiPh2)(μ-CC)(SiPh2...

Ring-Opening Reactions of Tetrahydrofuran versus Alkyne Complexation by Group 4 Metallocene Complexes Leading to General Consequences for Synthesis and Reactions of Metallocene Complexes

The reduction of certain group 4 metallocene dichlorides by magnesium or lithium in the presence or absence of Me3SiC2SiMe3 in THF or toluene was investigated, giving in the case of titanium the dinuclear Ti(III) complex [rac-(ebthi)Ti(μ-Cl)]2 (1). For zirconium the 1-oxa-2-zirconacyclohexane 2 was formed by ring-opening reaction of rac-(ebthi)Zr(η2-Me3SiC2SiMe3) with THF. As a byproduct from the synthesis of Cp*2Zr(η2-Me3SiC2SiMe3) starting from Cp*2ZrCl2 another 1-oxa-2-zirconacyclohexane (3) was obtained by ring-opening reaction of THF via the dinuclear complex Cp*2Zr(Cl)-(CH2)4O−Zr(Cl)Cp*2 (4). In the case of hafnium the analogous dinuclear complex Cp*2Hf(Cl)−(CH2)4O−Hf(Cl)Cp*2 (5) and 1-oxa-2-hafnacyclohexane (6) were the main products of the reaction, inhibiting the synthesis of Cp*2Hf(η2-Me3SiC2SiMe3) (7). The tendency for ring opening of THF initiated by metallocenes increases in the series Ti, Zr, Hf, thus leading to consequences for the synthesis of metallocene complexes.

Ring-Opening Metathesis Polymerization of Norbornene by Cp*2Os2Br4 and Related Compounds

The dinuclear complex Cp*2Os2Br4 (Cp* = pentamethylcyclopentadienyl) and related mono(pentamethylcyclopentadienyl)osmium compounds are catalysts for the ring-opening metathesis polymerization (ROMP...

Borole Derivatives. 23. Reversible Carbonylation and Lewis Base Degradation of the Heterocubane [Rh(μ3-I)(C4H4BPh)]4and of the Bis(borole) Complex RhI(C4H4BPh)2and Synthesis and Structure of the Dinuclear Complex Cp*Rh(μ-I)3Rh(C4H4BPh)1

The heterocubane [Rh(μ3-I)(C4H4BPh)]4 (2a) readily adds Lewis bases to form the mononuclear products RhI(py)2(C4H4BPh) (4), and RhI(bpy)(C4H4BPh) (7), the labile solution species RhI(NCMe)2(C4H4BPh) (8) and RhI(CO)2(C4H4BPh) (9), RhI(PPh3)2(C4H4BPh) (11), the 1,1‘-bis(diphenylphosphino)ferrocene complex RhI(dppf)(C4H4BPh) (13), and the norbornadiene complex RhI(nbd)(C4H4BPh) (14) as well as the dinuclear products [Rh(μ-I)(py)(C4H4BPh)]2 (5), [Rh(μ-I)(CO)(C4H4BPh)]2 (10), and the bis(diphenylphosphino)methane complex [Rh2(μ-I)2(μ-dppm)(C4H4BPh)2] (12). The complexes 5 and 10 exist as mixtures of cis and trans isomers; the isomeric carbonyls 10 interconvert slowly at ambient temperature, while the isomeric pyridine complexes 5 show fast interchange on the NMR time scale at 20 °C and low-temperature limiting spectra at −80 °C. The heterocubane also adds (RhI2Cp*)2 (which acts as a Lewis base and as a Lewis acid) to produce the novel unsymmetrical dinuclear complex Cp*Rh(μ-I)3Rh(C4H4BPh) (15). Complex 15 was ...

Cp★Ru- o-C 6H 4(EH) 22 (E  O, S) komplexe. Cp★Ru(μ 2-η 4- o-C 6H 4S 2)RuCp★, ein zweifach überbrückter, einfach valenzungesättigter Ru-Zweikernkomplex. Molekülstruktur von Cp★Ru(μ 2-η 4- o-C 6H 4S 2) (P(OMe 3))RuCp★

Reaction of [Cp★Ru(μ-OMe)] 2, 1 with dithiocatechol yields the singly coordinatively unsaturated dinuclear complex Cp★Ru(μ 2 -η 4- o-C 6H 4S 2)RuCp★ ( 7). Reaction of 7 with P(OMe) 3 gave (Cp★Ru) 2(μ 2:(μ 2-S 2C 6H 4) (P(OMe) 3) ( 8). The molecular structure of 8 was determined from single crystal X-ray diffaction (space group P 1 , a = 8.367(2), b = 11.723(3), c = 17.252(8) Å, α = 94.71(3), β = 93.37(3), γ = 69.46(2)°, Z = 2, R = 0.056, R w = 0.055) and reveals strong coordination of one Ru center to a double bond of the bridging dithiocatechol ligand. The reactions are contrasted to those of 1 and 2 with catechol to give exclusively π-complexation.

Verbrückte zweikernige Zirkonocenkomplexe

The ethylene complex Cp 2Zr(C 2H 4(PMe 3 ( 1) reacts with bifunctional H-acidic compounds under protonation of the ethylene ligand to give bridged dinuclear ethyl complexes: dicarbonic acids like malonic acid, succinic acid, maleic acid, fumaric acid and citraconic acid react with 1 to form Cp 2(Et)ZrOC(O)R(O)COZr(Et)Cp 2 (R = CH 2, CH 2CH 2, HCCH, HCCMe); diols like 1,2- and 1,3-dihydroxybenzene as well as ethylene glycol react with 1 to give Cp 2(Et)ZrOR′ OZr(Et)Cp 2 (R′ = C 6H 4, CH 2CH 2). Salicylic acid and 1 yield the asymmetrically bridged dinuclear complex Cp 2(Et)ZrOC(O)C 6H 4OZr(Et)Cp 2. Ethanedithiol and 1 afford Cp 2(Et)ZrSCH 2CH 2SZr(Et)Cp 2.

Übergangsmetall-substituierte phosphane, arsane und stibane: XLII. Kohlenmonoxid/isonitril-austauschan den metallo-arsanen Cp(OC) 3W-AsR 2 (R = Me, t-Bu)

The interaction of Cp(OC) 3W-AsR 2 (R = Me, t-Bu) (Ia, Ib) with MeNC and t-BuNC leads, with CO-substitution, to the formation of the novel metalloarsanes Cp(OC) 2(R′NC)W-AsR 2 ( c/t-IIIa-IIId), which are obtained as a mixture of cis and trans isomer. Treatment of Cp(OC)W-AsMe 2 with two equivalents of t-BuNC gives Cp(OC)(t-BuNC) 2W-AsMe 2 (IV) with the two isonitrile ligands coordinated cis to each other. MeI transforms the metalloarsanes ( c/t-IIIa, IIIb to the cationic complexes [Cp(OC) 2(R′NC)W-AsMe 3]I ( c/t-Va, Vb), while C 6H 5CH 2Br trans-forms IV to [Cp(OC)(t-BuNC) 2W-AsMe 2CH 2C 6H 5]Br ( c/t-VI). By reaction of c/t-IIIa with the metal carbonyls Ni(CO) 4 and Fe 2 (CO) 9, arsenido-bridged di-nuclear complexes Cp(OC) 2(MeNC)W-AsMe 2-ML n (ML n = Ni(CO) 3, Fe(CO) 4) ( c/t-VIIa, VIIb) are obtained. In all reactions involving addition to the arsino-function the cis-isomer/ trans-isomer ratio increases. The new arsenic metal compounds are characterized by spectroscopy and elemental analysis.

Enhanced reactivity of η 1-allyl ligands in trialkylphosphite substituted CpFe(Co) 2(η 1-allyl) complexes

CpFe(CO) 2(η 1-ally) Ia and CpFe(CO) 2(η 1-methally) Ib undergo photochemically initiated carbonyl substitution by bicyclic phosphite III to give IIa and IIb respectively. These latter complexes are more readily protonated than CpFe(CO) 2(η 1-allyl) complexes and the resulting cationic olefin complexes V and VI are more stable to olefin ligand displacement than similar complexes of the parent system. Both IIa and IIb exhibit high thermal stability, in contrast to Ia or Ib. CpFe(CO) 2(η 1-2-butenyl) and CpFe(CO) 2(η 1-cyclopentyl) fail to undergo photochemically initiated CO substitution in the presence of phosphite III, but give instead the dinuclear complex Cp 2Fe 2(CO) 3(L) (L = III). The complex CpFe(CO) 2(η 1-cyclopentenyl) (VIII) can, however, be prepared indirectly from IIb → VI → VII → VIII. Complex IIa is 900 times more reactive than Ia cycloaddition reaction with β,??-dicyanostyrene.