Gregory O. Nelson

Preparation and reactivity of the new cyclopentadienyl-bridged complex (Me2SiCH2CH2SiMe2)(C5H4Fe(CO)2)2

Abstract A new metal-metal bonded binuclear iron system [Me 2 SiCH 2 CH 2 SiMe 2 ][η 5 -C 5 H 4 Fe(CO) 2 ] 2 ( 2 ) has been prepared by treating two equivalents of NaCp with one equivalent of ClSi(Me) 2 CH 2 CH 2 SiClMe 2 obtaining the intermediate (C 5 H 5 )Si(Me) 2 CH 2 CH 2 Si(Me) 2 (C 5 H 5 ) which then is directly allowed to react with Fe(CO) 5 given 2 in 30% yield. From this cyclopentadienyldisilyl linked system three new binuclear irom complexes are formed. Treatment of 2 with Na/Hg in THF produced the dianion [Me 2 SiCH 2 CH 2 SiMe 2 ][η 5 -C 5 H 4 Fe(CO) 2 − ] 2 which is quenched with CH 3 I giving [Me 2 SiCH 2 CH 2 SiMe 2 ][η 5 -C 4 H 4 Fe(CO) 2 CH 3 ] 2 ( 4 ) in 76% yield. Complex 2 is oxidized with 1.2 equivalent of I 2 to give [Me 2 SiCH 2 CH 2 SiMe 2 ][η 5 -C 5 H 4 Fe(CO) 2 I] 2 ( 5 ) in 85% yield. Photolysis of 5 (1 equiv.) and PPh 3 (3 equiv.) results in the formation of the bis-substituted compound [Me 2 SiCH 2 CH 2 SiMe 2 ][η 5 -C 5 H 4 Fe(CO)(PPh 3 )I] 2 ( 6 ). These four new binuclear iron complexes are characterized by 1 H, 13 C, and 31 P NMR and IR spectroscopy.

Evidence for enhanced reactivity in the photofragmentation of the bridged dinuclear system Me2Si[η5-C5H4Fe(CO)2(η1-CH2C6H5)]2

Abstract Experimental evidence that the dinuclear complex Me 2 Si[η 5 -C 5 H 4 Fe(CO) 2 -(η 1 -CH 2 C 6 H 5 )] 2 shows enhanced reactivity over its mononuclear analogy η 5 -C 5 H 5 Fe(CO) 2 (η 1 -CH 2 C 6 H 5 in photogragmentation to produce bibenzyl and FeFe bonded product is presented. Information from a series of competition and crossover experiments indicate that two factors are involved in the enhancement: (1) the ability to photochemically produce a 16-electron unsaturated benzyl unit in close proximity to a saturated partner, and (2) the inability of the FeFe bonded species 4 to quench free benzyl radicals in solution. Chemical reaction of Me 2 Si[η 5 -C 5 H 4 Fe(CO) 2 (η 1 -CH 2 C 6 H 5 )] 2 with Me 3 NO produces bibenzyl and establishes that loss of CO is the initial step in the fragmentation reaction. In addition, trapping experiments with 9,10-dihydroanthracene show that bibenzyl is formed from free benzyl radical; BBased on these results an overall mechanism is proposed.

(η5-C5R5)2Fe2(CO)2(μ-CO)(μ-CH2) (R = H, CH3): A convenient one-pot synthesis using chloromethyl pivalate

Abstract The compounds (η 5 -C 5 R 5 ) 2 Fe 2 (CO) 2 (μ-CO)(μ-CH 2 ) (R = H, CH 3 ) have been prepared through the reaction of chloromethyl pivalate with the appropriate metal anions, η 5 -C 5 H 5 Fe(CO) 2 K and η 5 -C 5 Me 5 Fe(CO) 2 K.

Doubly linked dinuclear transition metal complexes. Synthesis of Me2Si[C5H4FeCO]2L (L = dppe, dppm)

Abstract Photolysis of Me 2 Si[C 5 H 4 Fe(CO) 2 ] 2 [1] in the presence of bis-phosphine ligands (dppe and dppm) gives good yields of doubly linked diiron complexes. In the reaction with dppe, a mechanically linked tetranuclear species can also be isolated.

Unusual route to and rearrangement of four-membered ring complexes C5H5Fe (CO) [ (C6H5)2PN(R)CH (C6H5) ]

Abstract The amine substituted phosphines (C 6 H 5 ) 2 PN(H)CH 2 CH 3 and (C 6 H 5 ) 2 PN(H)CH 2 C 6 H 5 react with C 5 H 5 Fe(CO) 2 CH(C 6 H 5 ) (OCH 3 ) photolytically to give moderate yields of the four-membered chelate ring complexes C 5 H 5 Fe (CO) [(C 6 H 5 ) 2 PN (CH 2 CH 3 ) C H (C 6 H 5 )] and C 5 H 5 Fe (CO) [(C 6 H 5 ) 2 PN (CH 2 C 6 H 5 )C H(C 6 H 5 )], respectively. Photolysis of C 5 H 5 Fe(CO) 2 CH(C 6 H 5 ) (OCH 3 ) in the presence of (S)-(−)-diphenyl(1-phenylethylamino)phosphine leads to the isolation of C 5 H 5 Fe(CO)[(C 6 H 5 )2PNC(CH 3 ) (C 6 H 5 )]CH 2 C 6 H 5 which is proposed to arise from a formally 1,3-hydrogen shift rearrangement of an intermediate four-membered chelate ring complex.