Alkynyl-zirconium complexes

The tendency to form ate complexes observed for yttrium is also seen in the preparation of a novel zirconium alkynyl complex. Reaction of Zr(Por)Cl2 (Por = OEP or TPP) with either two or three equivalents of LiC=CR (R = Ph or SiMe ) gives the trisalkynyl complexes Zr(Por)(C=CR)3Li(TFIF). An X-ray crystal structure of Zr(OEP)(C=CPh)2Li(THF) shows that all three alkynyl ligands are on... 

Bis(alkyl) complexes, with mercury, preparation, 2, 428 Bis(alkylidene)s, in Ru and Os half-sandwiches, 6, 583 Bis(alkylimido) complexes, with chromium(VI), 5, 346 Bis(rj2-alkyne)platinum(0) complexes, preparation, 8, 640 Bis(alkynyl) complexes in [5+2+l + l]-cycloadditions, 10, 643 with manganese, 5, 819 with mercury, preparation, 2, 426 mononuclear Ru and Os compounds, 6, 409 with platinum, 12, 125 with platinum(II), 8, 539 with titanium(IV), 4, 643 with zirconium, 4, 722... 

Bis(cyclopentadienyl)zirconium(III) complexes alkynyl-bridged complexes, 4, 749 dinitrogen complexes, 4, 747 electrochemical reduction, 4, 745 phosphido-bridged complexes, 4, 750 Bis(cyclopentadienyl)zirconium(IV) complexes electrochemical reduction, 4, 745 with M-C r/)-bonds, 4, 895 with M-C r/i2-bonds, 4, 887 with M-C r/i3-bonds, 4, 884 with M-H bonds, 4, 878 with M-N bonds, 4, 910 with M-0 bonds, 4, 917 with M-P bonds, 4, 927 with M-S bonds, 4, 930 with M-Si bonds, 4, 925 non-functionalized metallocene halides, 4, 870 ring-functionalized metallocene halides, 4, 874 Bis(cyclopentadienyl)zirconium(III) halides, in organic synthesis, 4, 754... 

Compound 33 is paramagnetic the ESR data are given in Table 3, and are similar to other reports of zirconocenate(m) complexes.2 The UV/Vis spectrum has bands suggestive of a d—d (800-580 nm) and zirconium-alkynyl (440, 383 nm) transitions. The IR spectrum has intense //(C eC) bands (1940 and 1933 cm-1), which are shifted to low frequency relative to those in the zirconium(iv) precursor due to potassium coordination. 

Metallacyclic complexes containing two molecules of diyne per MCp2 group have also been isolated, that with titanium containing 2,4-alkynyl substituents (225) while with zirconium, the unusual seven-membered metallacumulene structure 226 is adopted, which has only one alkynyl substituent. The bi- and tricyclic 2/2 complexes 227 and 228 have so far been obtained only from reactions of TiCp2 with PhC=CC=CPh.30 ... 

Addition of organometallic reagents to imines is not limited to allylmetal derivatives. Hoveyda and Snapper have demonstrated that dialkylzinc reagents can add to imines in a one-pot procedure. Using a zirconium complex as metal catalyst and a chiral peptide, diverse enantioenriched aryl, aliphatic and alkynyl amines 142 have been obtained with high levels of enantioselectivity (Scheme 8.60) [136],... 

AUcynylchalcogenato ruthenium complexes react with zirconocene to give rise to heterobimetallic early-late dissymmetrically bridged complexes of family (76) (equation 39). In those specific complexes, the two metal centers are linked by /u.-chalcogenido and /x-a, jr-alkynyl moieties. The acetylenic bridge is unsymmetrical because the terminal carbon of alkynyl is ct-bonded to ruthenium, while zirconium interacts with both alkynyl carbons in a side-on fashion. 

The reaction of (OEP)ZrCl2 with 3equiv. of LiC=CPh produces the alkynyl (OEP)Zr(lv) porphyrin complex (OEP)Zr(7]1-C=CPh)3Li(THF) 242194 (Equation (18)). The molecular structure shows that three alkynyl ligands are coordinated to the Zr center in a piano-stool fashion and that the lithium cation is bound to the pocket formed by three alkynyl ligands. Treatment of complex 242 with anhydrous HC1 produces a C-C bond-coupled product H2C=C(Ph)=CPh and HC=CPh quantitatively. This example shows different reactivity of the zirconium porphyrin from that of analogous metallocene complexes. 

Zirconocene complexes 705 that contain an acetylide ligand bridging between a main group metal (aluminum) and a transition metal (zirconium) are obtained by treatment of dimethyl zirconocene with (alkynyl)dimethylaluminum, (Equation (43)).529 In this reaction, an ( 72-alkyne)zirconocene complex is presumably formed in situ, and it is then trapped by the excess (alkynyl)dimethylaluminum to yield the final product. The molecular structures of the complexes 705 (R = SiMe3, Cy) contain a dimetallabicyclic framework, and one of the bridgehead positions is a planar tetracoordinate carbon center. In these complexes, the -C=CR bridge between zirconium and aluminum can be described as being mainly of /x-(cr-acetylide) character. 

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