Zirconium complexes with -ligands

Zirconium complexes with ligand system 35 have been prepared by Fryzuk, and their chemistry has been investigated.Anion 35 was treated with ZrCl4(THT)2 (THT = tetrahydrothiophene) in toluene to obtain zirconium complex 176 in 93% yield (Scheme... 

A related zirconium complex with a [N2 ]-type of ligation is tetrakis(l,3-diphenyltriazenido)zirconium(lv) 74,85 which is obtained from the amine elimination approach. Thus, treatment of Zr(NMe2)4 with 4equiv. of 1,3-diphenyltriazene in hexanes at ambient temperature affords 74 in 79% yield as a deep red crystalline solid (Equation (6)). This Zr complex is eight coordinate with four 2-l,3-diphenyltriazenido ligands. Complex 74 crystallizes with a distorted dodecahedral geometry about Zr consistent with this solid-state structure, the solution molecular weight measurements indicate a monomeric structure in benzene. 

Experimental data are available only at three different ionic strengths (2, 2.33 and 4 M perchloric acid solutions). As for zirconium complexes with other ligands, the limited number of available experimental data makes the extrapolation to infinite dilution relatively uncertain. 

Quite recently, Fryzuk and co-workers observed the N-H bond formation when a dinuclear zirconium complex with a side-on bridging dinitrogen ligand was treated with molecular dihydrogen. However, no ammonia was formed (a) M. D. Fryzuk, J. B. Love, S. J. Rettig, V. G. Young, Science 275 (1997) 1445. (b) H. Basch, D. G. Musaev, K. Morokuma, M. D. Fryzuk, J. B. Love, W. W. Seidel, A. Albinati, T. F. Koetzle, W. T. Klooster, S. A. Mason, J. Eckert, J. Am. Chem. Soc. 121 (1999) 523. 

The complexation of zirconium alkoxides with ligands carrying an azobis group from which radical polymerization could be initiated... 

Chen, Y.-X. Rausch, M. D. Chien, J. C. W. Silylene-bridged fluorenyl-containing ligands and zirconium complexes with C and Cj symmetry General synthesis and olefin polymerization catalysis. J. Organomet. Chem. 1995, 497, 1-9. 

Anderson, G. K. Lin, M. Preparation of phenylplatinum-zirconium complexes with Ph2PC5H4 or PhP(C5H4)2 bridging ligands and their reactions with carbon monoxide. Organometallics 1988, 7, 2285-2288. 

Jeon, Y.M., Park, S.J., Heo, J., and Kim, K. (1998) Zirconium complexes with the new ancillary diamido ligand 2,2 -ethylenebis(iV,A -(triisopropylsilyl)anilinido) Syntheses, structures, and living a-olefinpolymerization activities. 

The crystal structure of a mono(cyclopentadienyl)zirconium complex containing a novel Me2Si-linked bis(amidinate) ligand was reported (Scheme 203). In this compound the central Zr atom is octahedrally coordinated with the bis(amidi-nate) acting as a tridentate ligand. ... 

While essentially all the metal carbonyl complexes for group 4B contain terminal CO ligands, only recently have some bonafide doubly bridging carbonyl complexes been reported. However, these complexes are hetero-nuclear, since the carbonyl ligand bridges a zirconium atom with the metal center of a late transition metal. 

Vinylboronates are generally less reactive than vinylzirconocenes towards various electrophiles and hence selective reactions of the latter should be possible. It was found that selective cleavage of the carbon—zirconium bond in 45 by N-halosuccinimides provides (a-haloalkenyl)boronic esters 53 in excellent chemical yields and with complete re-gioselectivity (Scheme 7.17) [54], An X-ray crystal structure determination of 45 confirmed the configuration of the four-coordinate Zr complex, with two cyclopentadienyl rings, Cl, and C(sp2) as the four ligands (Fig. 7.5) [54,126]. 

The bis(trimethylphosphino)zirconium complex 92 undergoes unusual reactions with alkynes.114 With diynes, metallocyclic products 93 are formed, whereas acetylene affords 94 whose nonplanar boratanaphthalene ligand is... 

The interesting feature of 20 is that the Si-H interaction occurs for the set of electron-donating ancillary ligands Cp2/PMe3. Thus, the only factor that can, in principle, account for the different behavior of titanium and its heavier analogs in these reactions is the contracted nature of the titanium d-orbitals and hence the less effective backdonation from metal as discussed in Section II.B. The nonclassical nature of the zirconium complex 19 compared with neutral 18 can be then attributed to the presence of a positive charge. 

Complexes with Oxyanion Ligands. The zirconium-peroxo-oxalato-complex [Zr(02)(C204 )(H20)2],3—4H2O, has been assigned the trans-diaquo octahedral structure (28) from spectroscopic and thermal studies. ... 

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