Bulk Synthesis of Octa- and Nonamethylfluorene (Flu‘ ‘H and Flu*H) and the Characterization of the Organometallic Derivatives Flu*SnMe₃, [(FeCp)₂Flu*H][PF₆]₂, and [(FeCp)₂Flu‘ ‘H][PF₆]₂

Abstract

The large-scale synthesis of two highly methylated fluorene ligands is reported, and the synthesis and characterization of three organometallic derivatives are reported. Starting with 1,2,3,4-tetramethylbenzene, 1,2,3,4,5,6,7,8-octa- and 1,2,3,4,5,6,7,8,9-nonamethylfluorene (Flu‘ ‘H and Flu*H) have been synthesized in overall yields of above 50%. Both fluorenes may be deprotonated at the 9 position to yield useful organometallic synthons; the Sn derivative, Flu*SnMe3, is synthesized using this reagent, and its molecular structure has been elucidated. The Fe bimetallics [(FeCp)2Flu*H][PF6]2 and [(FeCp)2Flu‘ ‘H][PF6]2 have been isolated, and their electrochemical properties ascertained. Electrochemical measurements on these complexes show the methylated fluorene ligand acts as a strong electron donor and acts to increase the electronic communication between the metal centers, in comparison with the nonmethylated analogues. The solid-state structure of [(FeCp)2Flu‘ ‘H][PF6]2 has been determined and, unlike the Sn complex, does not show a significantly twisted fluorenyl core.

Synthesis and Characterization of Group 4 Permethylpentalene Dichloride Complexes

“…This differs from cis -(SnMe 3 ) 2 Pn*, which possesses an angle of 7.9° between the best planes of the two C 5 rings as a result of steric repulsion between the two large SnMe 3 groups. The C(1)–Sn(1) bond length [2.220(4) Å] is comparable with other C–Sn transfer reagents: cis- (SnMe 3 ) 2 Pn* [2.215(2) Å], trans- (SnMe 3 ) 2 Pn [2.209(7) Å], SnMe 3 (η 1 -Flu*) [2.221(3) Å], and SnMe 3 (η 1 -Ind*) [2.232(6) Å] …”

The synthesis of [(η6-Flu∗H)Mn(CO)3]PF6, and its deprotonation to yield a novel coordination mode of fluorene

“…In all Flu * complexes that have been crystallographically characterised, including the free ligand, the two methyl groups in the ''bay'' area of the molecule are significantly bent out of plane of the rest of the arene fragment, shown in Fig. 5 [16,18].…”

“…Subsequent full-matrix leastsquares refinement was carried out using the CRYSTALS program suite [13][14][15]. Flu * H was synthesised via the literature method [16].…”

Organometallic chemistry of bi- and poly-metallic complexes

“…reported to have much greater communication between the metal centres than the analogous nonmethylated species. 43 A convenient synthetic route to a range of novel bridging carbene complexes has been devised using the terminal carbonyl species [Fe 2 (CO) 5 (Z 3 ,Z 5 -C 9 H 8 )]. This versatile methodology has so far led to the isolation of complexes containing arylcarbene, arylthiocarbene and aryl(pentacarbonylcyanometal) carbene units.…”