Nucleophilic substitution reactions of acetylides on substituted tricarbonyl(eta(6)-fluoroarene)chromium and reactions of tricarbonyl[eta(6)-(2-trimethylsilylethynyl) toluene]chromium and tricarbonyl[eta(6)-(p-ethynylphenylethynyl)benzene]chromium with dicobalt octacarbonyl

Nucleophilic substitution reactions of various acetylides on substituted tr icarbonyl(eta(6)-fluoroarene)chromiums were pursued. The reaction presumabl y underwent a more complicated mechanism rather than the direct substitutio n on the fluorine-bearing carbon. The organometallic compounds (eta(6)-(C6H 3RRR3)-R-1-R-2)Cr(CO)(3) (R-1: C=C-C6H4CH3, R-2: o-Me, R-3: H (5a), R-1: C= C-C6H4CH3, R-2: o-OMe, R-3: H (6a), R-1: C=C-C6H4CH3, R-2: m-OMe, R-3: H (6 b), R-1: C=CPh, R-2: o-Me, R-3: o-OMe (8b), R-1: C=CPh, R-2: m-Me, R-3: m-O Me (8c), R-1: C=CSiMe3, R-2: o-Me, R-3: H (9a), R-1: C=C-C6H4C=CH, R-2: H, R-3: H (12), R-1: C=C-C6H4C=CH, R-2: o-Me, R-3: H (13)) as well as the orga nometallic dimmer [{(eta(6)-o-Me-C6H4)Cr(CO)(3)(di-ethynyl)] (di-ethynyl: C =C-C6H4C=C (14)) have been synthesized from nucleophilic substitution react ions of tricarbonyl(eta(6)-fluoroarene)(chromium) compounds with suitable a cetylides. The products have been characterized by spectroscopic means. In addition, (8b) and (8c) were characterized by X-ray diffraction studies. Fu rther reactions of (9a) and (12) with appropriate amount of Co-2(CO)(8) yie lded mu-alkyne bridged bimetallic complexes, Co-2(CO)(6){mu-Me3SiC=C-(o-tol ueneCr(CO)(3)} (10) and (Co-2(CO)(6))(2){mu-HC=C-C6H4-C=C-(benzene)Cr(CO)(3 ))}(15), respectively. Both (10) and (15) were characterized by spectroscop ic means as well as single crystal X-ray crystallography. The core of these molecules is quasi-tetrahedron containing a Co2C2 unit. A two-dicobalt-fra gments coordinated di-enyls complex, (Co-2(CO)(6))(2){mu-HC=C-C6H4-C=C-H} ( 17), was synthesized from the reaction of 1,3-diethynylbenzene with Co-2(CO )(8). Crystallographic studies of (17) show that it exhibits a distorted Co 2C2 quasi-tetrahedral geometry. (C) 1999 Elsevier Science Ltd. All rights r eserved.