LITHIOALKYNYL IRON(II) OR RUTHENIUM(II) COMPLEXES AS PRECURSORS OF NOVEL ALKYNYL AND VINYLIDENE DERIVATIVES - HETEROBIMETALLIC COMPLEXES CONTAINING A BRIDGING ETHYNEDIYL SYSTEM

Deprotonation of ethynyl complexes [Fe(C=CH)(eta(5)-C5H5)(dppm)] 1a (d ppm = Ph(2)PCH(2)PPh(2)) and [Ru(C=CH)(eta(5)-C9H7)L(2)] [L(2) = 2PPh( 3) 1b, Ph(2)PCH(2)CH(2)PPh(2)(dppe) 1c or (PMe(3))(PPh(3)) 1d] with Li Bu(t) at -78 degrees C gave the lithiated complexes [Fe(C=CLi)(eta(5)- C5H5)(dppm)] 2a and [Ru(C=CLi)(eta(5)-C9H7)L(2)] 2b-2d. respectively. These species have been used in situ as precursors of novel alkynyl an d vinylidene complexes by reactions with electrophiles. Treatment of c omplexes 2a-2d with MeOSO(2)CF(3) at -78 degrees C gave vinylidene com plexes [Fe(=C=CMe(2))(eta(5)-C5H5)(dppm)][CF3SO3] 3a and [Ru(=C=CMe(2) )(eta(5)-C9H7)L(2)][CF3SO3] [L(2) = 2PPh(3) 3b. dppe 3c or (PPh(3))(PM e(3)) 3d]. Iodoalkynyl complexes [Ru(C=Cl)(eta(5)-C9H7)L(2)] (L(2) = 2 PPh(3) 4b or dppe 4c) have been obtained by reaction of [I(py)(2)][BF4 ] (py = pyridine) with 2b and 2c. respectively. Reaction of 2a-2d with SnPh(3)Cl yielded the ethynediyl bridging bimetallic complexes [(eta( 5)-C5H5)(dppm)Fe-C=C-SnPh(3)] 5a and [(eta(5)-C9H7)L(2)Ru-C=C-SnPh(3)] [L(2)=2PPh(3) 5b, dppe 5c or (PPh(3))(PMe(3)) 5d]. Similar heterobime tallic complexes [(eta(5)-C5H5)(dppm)Fe-C=C-Au(PPh(3))] 6a and [(eta(5 )-C9H7)L(2)Ru-C=C-Au(PPh(3))] 6b-6d have been obtained by treatment of ethynyl complexes 1a-1d with [AuCl(PPh(3))] and Tl(acac) (acac = acet ylacetonate) in dichloromethane. Complexes 6a and 6b can alternatively be obtained by reaction of 5a and 5b with [AuCl(PPh(3))] in the prese nce of [PdCl2(MeCN)(2)]. The crystal structure of 5a has been determin ed by X-ray diffraction methods. It shows a typical three-legged piano -stool geometry. The iron atom is bonded to the cyclopentadienyl ring, the two phosphorus atoms of a chelating dppm ligand, with a narrow bi te angle [74.90(5)degrees] and the terminal carbon of the triphenyltin acetylide group. The ethynyl bridge is bound to the iron and tin form ing an C=C-Sn angle of 162.8(4)degrees and an almost linear Fe-C=C arr angement [178.0(3)degrees].