THE PREPARATION AND REACTIVITY OF FUNCTIONALLY-SUBSTITUTED CYCLOPENTADIENYL TRANSITION METAL COMPOUNDS

• Main Author: HART, WILLIAM PIUS
• Language: ENG
• Published: ScholarWorks@UMass Amherst 1981
• Subjects: Chemistry
• Online Access: https://scholarworks.umass.edu/dissertations/AAI8118005

Reaction of sodium cyclopentadienide with ethyl formate, ethyl acetate, dimethyl carbonate, or diethyl carbonate afford sodium salts, formyl- (53), acetyl- (55), carbomethyoxy- (61), and carbethoxycyclopentadienide (125), respectively. Sodium- (52) and lithium nitrocyclopentadienide (126) have been prepared from ethyl nitrate and sodium or lithium cyclopentadienide. The synthesis of lithium isopropenylcyclopentadienide (95) from 6,6-dimethylfulvene (94) and lithium diisopropylamide has also been achieved. 1,1'-Diacetylcobaltocene (128) and 1,1'-dicarbomethoxy- cobaltocene (129) have been prepared from CoCl(,2) and 55 or 61, respectively. 1,1'-Diacetylnickelocene (131) and 1,1'-dicarbomethoxynickelocene (132) can be obtained from NiBr(,2)(.)2DME and 55 or 61 respectively. The synthesis of functionalized metallocenes include the formation of monocarbomethoxytitanocene dichloride (133) from 61 and (h('5)-cyclopentadienyl)trichlorotitanium. Reduction of 133 with Al(Hg)/CO afforded monocarbomethoxytitanocene dicarbonyl (134). With {Rh(CO)(,2)Cl}(,2), (h('5)-formylcyclopentadienyl)- (59), (h('5)-acetylcyclopentadienyl)- (135), (h('5)-carbomethoxycyclopentadienyl)- (60) and (h('5)-carbethoxycyclopentadienyl)dicarbonylrhodium (136) were prepared, respectively. Treatment of {Rh(CO)(,2)Cl}(,2) with 126 afforded (h('5)-nitrocyclopentadienyl)dicarbonylrhodium (137) as shown by x-ray analysis. With Co(,2)(CO)(,8) + I(,2), (h('5)-formylcyclopentadienyl)- (140), (h('5)- acetylcyclopentadienyl)- (141), (h('5)-carbomethoxycyclopen- tadienyl)- (63) and (h('5)-carbethoxycyclopentadienyl)dicarbonyl- cobalt (142) were prepared. Also, 141 can be prepared via Friedel- Crafts acetylation of (h('5)-cyclopentadienyl)dicarbonylcobalt (35). (h('5)-Benzoylcyclopentadienyl)dicarbonylcobalt (37) has been prepared via Friedel-Crafts benzoylation of 35. (h('5)-Vinylcyclopentadienyl)dicarbonylcobalt (118) and (h('5)-isopropenylcyclopentadienyl)dicarbonylcobalt (105) can be obtained via a Wittig reaction of 140 and 141, respectively with CH(,2)=PPh(,3). Compound 105 has also been prepared from lithium isopropenylcyclopentadienide (95) and Co(,2)(CO)(,8) + I(,2). NaBH(,4) reduction of 140 and 141 gave (h('5)-hydroxymethyl- and (h('5)-hydroxyethylcyclopentadienyl)dicarbonylcobalt, (143) and (146). The addition of CH(,3)MgI to 140 and 141 gave alcohols 146 and 150 respectively. Reaction of 143 and 146 with acryloyl chloride gave acrylate derivatives 153 and 155. Free radical polymerization reactions of 105, 118 and 153 are discussed. The addition of PhMgBr to 140 and 141 gave alcohols 151 and 152. (h('5)-Carbomethoxycyclopentadienyl)dicarbonylcobalt (63) underwent saponification to afford the carboxylic acid (156). Further, 156 was converted to its acid chloride (157) with oxalyl chloride. A reaction of 157 with ferrocene (1) gave the ferrocenoyl derivative (159), whereas, a reaction of 157 with aniline afforded the N-phenylcarbamoyl derivative (158). Evidence of metal-stabilized carbocations is presented.