Dinuclear zirconium complexes with Me₂Si(C₅H₄)₂as bridging ligand. Molecular structure of [{Zr(η⁵-C₅H₃-Bu^t₂)Me}₂(µ-O){µ-Me₂Si(C₅H₄)₂}]

Abstract

The reaction of Li,[Me,Si(C,H,),] with 2 equivalents of [ZrLCI,] (L = C,Me, or C,H,But2) in toluene under reflux gave the known [{Zr(C,Me,)CI,},{p-Me,Si(C,H,),}] 1 and the new chloro derivative [{Zr(C,H,-But,)CI,},{p-Me,Si(C,H,),}] 2 in good yields. Addition of 4 equivalents of LiMe (or MgMeCI) to a pentane solution of 1 or 2 afforded the tetramethyl derivatives [{Zr(C,Me,) Me,},{p-Me,Si(C,H,),}]3 and [{Zr(C,H,But,) Me,},{p-Me,Si(C,H,),}] 4. Compound 3 is extremely moisture sensitive leading to the p-0x0 dinuclear complex [{Zr(C,Me,)Me},(p-O){p-Me,Si(C,H,),}] 5, as demonstrated by 'H N M R spectroscopy. Compound 4 reacted with water, in pentane or toluene, to give the p-0x0 dimethyl complex [{Zr(C,H,Bu',) Me},(p-O){p-Me,Si(C,H,),}] ' . I J. CHEM. SOC. DALTON 2 MC13 + Li2[Me2Si(C5H,)d -1 L = C5Me5 2 L = C5H3But2 Me, Me ' . f Me, Me ' . 1 5 L = C5Me5 3 L = C5M% 6 L = C5H3B~t2 4 L = C5H3But2 Scheme 1 (i) LiMe or MgMeC1; (ii) water

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]

“…These derivatives are especially attractive for studying the potential interactions between two reactive sites, since the presence of the bridge places the two metal atoms in close proximity. Most of the [X(C 5 H 4 ) 2 ] (X = CH 2 , SiMe 2 ) bridged metal complexes belong to groups 4, 6, and 9 (Rh and Ir), but to the best of our knowledge only a few examples are known for group 8 metals …”

“…Due to the free rotation around the two silicon−cyclopentadienyl bonds, a number of different conformations may be adopted by a dimetallic fragment of the type [M 2 {μ-(η 5 -C 5 H 4 ) 2 SiMe 2 }]. To date, three structural types (Chart ) have been observed and crystallographically characterized for transition metals: (a) type A , in which the metal fragments are coordinated in an exo disposition with respect to the rings of the bridging group and are located in a mutually cis orientation giving rise to a formally exo-cis dimetallic arrangement; 1c,2a (b) type B , in which the metal fragments are coordinated in an endo fashion with respect to the rings and in a mutually cis orientation (endo-cis dimetallic arrangement); 1b-f,2c-f,4a-d and (c) type C , which results from the rotation in type A or B of one of the (η 5 -C 5 H 4 )M fragments around the corresponding Si−C bond leading to a formally trans dimetallic arrangement 1a. In complexes of type B the metals atoms may also be linked either by an additional bridging ligand or by a metal−metal bond,2d which prevents the two metallic fragments from being located far away from each other, as in types A and C .…”

Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(η5-cyclopentadienyl) ligand

“…Many dinuclear compounds containing bridging h 5 -h 1 cyclopentadienyl rings and h 5 -h 5 -fulvalene systems, resulting from ring C H activation in dicyclopentadienyl derivatives, have been reported [1,11]. However di-h 5 -cyclopentadienyl ligands singly bridged by various alkyl [2 -5] and silyl [6][7][8][9][10][11][12][13][14] groups are among the most frequently used systems to bridge dinuclear metal compounds. We have recently reported the use of the 1,1%-2,2%-(dimethylsilanediyl)dicyclopentadienyl ligand to synthesize ansadicyclopentadienyl and bridged homodinuclear monoand di-cyclopentadienyl complexes of the Group 4 and 6 metals [15][16][17][18][19][20].…”

tert-Butylsilylcyclopentadienyl Group 4 metal complexes

“…Pure products were obtained as red (11), orange (12) and yellow (13) solids and a waxy oil (14) respectively and their formulation is consistent with the analytical and spectroscopic NMR data (see Section 4). An analogous reaction of the zirconocene dichloride (5) All of the alkyl compounds (9 Á/15) were thermally stable when heated to 80 8C, although the dibenzyl complexes (11Á/13) produced small amounts of dibenzyl after prolonged heating (4 h).…”