Me₂Si(η⁵-C₅H₄)₂-Bridged Dinuclear Ruthenium Complexes:  X-ray Crystal Structures of [Ru₂{μ-(η⁵-C₅H₄)₂SiMe₂}(Cl)₂(CO)₄] and [Ru₂{μ-(η⁵-C₅H₄)₂SiMe₂}(μ-Br)(CO)₄][BF₄]

Abstract

The treatment of the binuclear tetracarbonyl complex [Ru2{μ-(η5-C5H4)2SiMe2}(μ-CO)2(CO)2] (1) with HBF4 in dichloromethane leads to the electrophilic addition of one proton to yield the bridging hydride complex [Ru2{μ-(η5-C5H4)2SiMe2}(μ-H)(CO)4][BF4] (2). Complex 1 also reacts with Li[BHEt3] to afford the bridging methylene complex [Ru2{μ-(η5-C5H4)2SiMe2}(μ-CH2)(μ-CO)(CO)2] (3). Binuclear complexes [Ru2{μ-(η5-C5H4)2SiMe2}(X)2(CO)4] (X = Cl (4a), Br (4b), and I (4c)) have been synthesized in good yields from the reaction of complex 1 with N-chlorosuccinimide (X = Cl) and X2 (X = Br, I) in CH2Cl2. The structure of complex 4a which has been determined by X-ray crystallography shows a three-legged piano-stool geometry around each ruthenium atom linked by the bridging Me2Si(η5-C5H4)2 group. The cyclopentadienyl rings which are coordinated in a η5 fashion are rotated in opposite directions around the Si−C(bridgehead) bond, leading to the trans arrrangement of the metal fragments and giving rise to a long ruthenium−ruthenium distance (6.120(6) Å). Complex 4c has been used as a precursor in a series of halide and carbonyl substitution reactions. The reaction of 4c with the cuprate derivative Li[CuMe2] in THF leads to the exchange of both iodide anions to give the dimethyl complex [Ru2(μ-(η5-C5H4)2SiMe2}(CH3)2(CO)4] (5). The treatment of complex 4c with AgBF4 in refluxing acetonitrile leads to halide abstraction to afford the cationic complex [Ru2{μ-(η5-C5H4)2SiMe2}(CO)4(NCMe)2][BF4]2 (9). The analogous reaction of complexes 4a−c with AgBF4 in CH2Cl2 or acetone at room temperature gives the cationic double-bridged derivatives [Ru2{μ-(η5-C5H4)2SiMe2)}(μ-X)(CO)4][BF4] (10a − c). The X-ray crystal structure of 10b shows the two ruthenium moieties bridged by a halogen atom, forcing a cisoid arrangement in the molecule. Irradiation of a solution of 4c and PCy3 in THF leads to carbonyl substitutions to yield the monocarbonyl complex [Ru2{μ-(η5-C5H4)2SiMe2}(I)2(CO)2(PCy3)2] (6c). Analogous isocyanide carbonyl substituted complexes [Ru2{μ-(η5-C5H4)2SiMe2}(I)2(CNR) x (CO)4 - x ] (R = CH2Ph, x = 1 (7a), x = 2 (7b), x = 3 (7c), x = 4 (7d); R = Cy, x = 1 (8a), x = 2 (8b), x = 3 (8c), x = 4 (8d)) have been obtained by UV irradiation of 4c and the corresponding isocyanide in THF, depending on the ligand:complex ratio.

Intramolecular C–H Bond Activation in Bridged Dicyclopentadienyl Dimethyl Dinuclear Complexes

“…The most remarkable feature of the molecular structure is that the two Ru(CO) 2 Me fragments are coordinated in an exo disposition with respect to the Cp rings of the bridging ligand and are located in a mutually cis orientation. This structural feature is quite different from that of the dichloro complex [(η 5 -C 5 H 3 ) 2 (SiMe 2 )]Ru 2 (CO) 4 Cl 2 reported by Gimeno’s group, in which two metal fragments adopt a trans arrangement. Complex 5b , as reported by Gimeno, was synthesized by a different method: namely, by the reaction of the corresponding diiodo compound with Li[CuMe 2 ] …”

“…In contrast to the method (Scheme ) used to prepare the methylene-bridged 3a – c , the nonbridged and singly bridged dicyclopentadienyl ruthenium analogues are synthesized by the reactions of the corresponding dinuclear tetracarbonyl complexes with LiBHEt 3 in aromatic solvents − or in a rare case from the thermolysis of diruthenium carbonyl complexes (η 5 -C 5 H 4 R) 2 Ru 2 (μ-CO) 2 (CO) 2 with di- or trihydrosilanes H n SiR′ 4– n ( n = 2, 3) for 1 week . This paper reports for the first time that compounds 3a – c with bridging carbonyl and methylene ligands can be synthesized directly by the photolysis of the corresponding dimethyl dinuclear complexes in aromatic solvents.…”

Synthesis, structures and reactions of doubly bridged biscyclopentadienyl diruthenium complexes (CR2)(EMe2)[(η5-C5H3)Ru(CO)2]2 (R = Me, H; E = Si, Ge)

“…It is well-known that the dimeric Cp' 2 M 2 (CO) 4 (M ¼ Fe, Ru, Os) complexes readily undergo oxidative additions of halogens to give metal (II) halide carbonyl complexes Cp'M(CO) 2 X [21e24], and a series of singly bridged (CH 2 [4], SiMe 2 [25], SiMe 2 SiMe 2 [26,27]) biscyclopentadienyl dimeric carbonyl complexes can also be oxidized by halogens to give the corresponding metal halide derivatives. Similarly, the reaction of complex 2 with I 2 (ratio 1:1) was carried out, and it gave the expected RueRu-cleaved di-iodo complex (CMe 2 )(SiMe 2 )[(h 5 -C 5 H 3 )Ru(CO) 2 I] 2 (11), at the same time, it also produced trace of compound 12, but the amount of 12 was not enough for full characterization (Scheme 3).…”

Synthesis and structures of binuclear half-sandwich cobalt (III) ortho-carboranedithiolato complexes with silyl-bridged bis(cyclopentadienyl) ligands

“…Due to the repulsion of the bulky iodine atoms, two cyclopentadienyl rings face each other with their non-coordinated sides and the dihedral angle is about 105°. With the rotation property of the Cp rings around the two silyl-cyclopentadienyl bonds, the whole molecular appears exo-cis conformation, and both of the metal centers are located far away from each other in a distance of 6.9081(26) Å [12].…”

“…Different from complex 3, two metal fragments coordinated in an endo fashion with respect to the rings and in a mutually cis orientation, which induces the bridging interaction and the M-M bonding of the metal centers [12]. The Co-Co length (2.3467(19) Å ), is a little shorter than that of the analogue with the etherbridged Cp ligand [8], due to the restriction of the silyl group between the Cp rings.…”