CHEMICAL MODIFICATION OF THE METAL-CARBENE APPENDAGE IN NEW, TRIMETALLIC ADDUCTS OF FE-2(CO)(6)(MU-EE') (E = S, SE AND E' = SE, TE) AND ALKYNYL FISCHER CARBENE COMPLEXES (CO)(5)M=C(OET)(C-CPH) (M = CR, W)

From the room temperature reaction of the transition metal alkynyl Fis cher carbene complexes (CO)(5)M=C(OEt)(C=Ph) (M = Cr, W) with the homo chalcogenide compounds Fe-2(CO)(6)(mu-E-2) (E = S, Se, Te), the follow ing new trimetallic adducts were obtained: [(CO)(6)Fe2E2{mu-PhC=CC(OEt )}M(CO)(5)] (1-5; 1, 30%, E = S, M = Cr; 2, 85%, E = Se, M = Cr; 3, 85 %, E = Se, M = W; 4, 28%, E = Te, M = Cr; 5, 25%, E = Te, M = W). Alko xy groups are readily replaced by amino groups in adducts 2, 3, and 5 at room temperature as syn-and anti-isomers, [(CO)(6)Fe2E2{mu-PhC=CCN( H)R}M(CO)(5)] (syn-8a-f and anti-8a-f; where R = CH3, CH2Ph, CH2CH=CH2 ), in 70-90% yield. When a methanolic solution of [(CO)(6)Fe2EE'{mu-Ph C=CC(OEt)}M(CO)(5)] (E not equal E', E = S, Se; E' = Se, Te; M = Cr, W ) was stirred at room temperature for 1-2 days, the ester and ortho es ter derivatives (CO)(6)Fe-2{mu-EC(PH)=C(CO)(OR)E'} (12-15) and (CO)(6) Fe-2{mu-EC(Ph)=CC(OR)(OMe)(2)E'} (16-19) (R = CH3, C2H5) were formed, All compounds were characterized by IR and H-1, C-13, Se-77, and Te-12 5 NMR spectroscopies. Crystallographic analysis of the compound Fe-2(C O)(6){mu-SC-(Ph)=CC(OCH3)(2)(OC2H5)Te} (17) established its structure as a Fe2STe tetrahedral butterfly core containing the ortho ester unit , C(Ph)=C-C(OCH3)(2)(OC2H5)} as a bridge between the two wing-tip chal cogens.