in accordance with the present invention , provided are methods for the preparation of fluorenyl - type ligand structures by a protocol which employs readily available reactants and provides a fluorenyl ligand in high yields , in contrast to the use of a copper agent as described previously . the process of the present invention can be carried out under moderate temperature conditions and is not attended by laborious and time consuming purification procedures . as noted previously , in a typical numbering scheme applied to fluorenyl groups , the central carbon atom ( the bridgehead carbon atom ) extending between the phenylene groups , is numbered 9 and the carbon atoms of the phenylene groups are numbered 1 - 8 . in the diphenylmethylene group from which the fluorenyl group may be derived , the carbon atoms in one phenyl group are numbered 1 - 6 and the counterpart carbon atoms of the other phenyl group are numbered 1 ′- 6 ′. these numbering schemes are shown in the following reaction illustrating the reaction of a halogenated diphenylmethylene with a coupling agent to produce a corresponding fluorenyl ligand . this reaction indicates the basic reaction employed in the present invention in which the 2 , 2 - dihalogen diphenylmethylene is reacted with a zinc , cadmium or magnesium coupling agent over a nickel or palladium - based catalyst . in reaction ( 28 ), x is a halogen , preferably chlorine , bromine or iodine , and more preferably , iodine . in reaction ( 28 ), the carbon atom in the methylene bridge of the diphenylmethylene corresponds to the bridgehead carbon atom 9 of the fluorenyl group . the carbon atoms 3 , 4 , 5 and 6 correspond respectively to carbon atoms 4 , 3 , 2 and 1 of the fluorenyl group and the carbon atoms 3 ′, 4 ′, 5 ′ and 6 ′ correspond respectively to carbon atoms 8 , 7 , 6 and 5 of the fluorenyl group . in the case where the fluorenyl group is only monosubstituted , it will be recognized that 2 - substitution is equivalent to 7 - substitution , 3 - substitution is equivalent to 6 - substitution and so on . the foregoing reaction is carried out in the presence of nickel ( ii ) catalysts , preferably phosphine nickel ( ii ) complexes , specifically , ni [( pph 3 ) 2 ] cl 2 , [ ph 2 pc 2 h 4 pph 2 ] nicl 2 and [ ph 2 pc 3 h 6 pph 2 ] nicl 2 or palladium ( 0 ) catalyst , preferably pd ( pph 3 ) 4 preferably , at least 0 . 5 mol . %, and more preferably 0 . 5 - 2 . 0 mol . %, of catalyst is employed . according to a preferred embodiment of the invention , the process is carried out in the presence of a polar solvent , such as tetrahydrofuran ( thf ) or n , n - dimethylformamide . the reaction is preferably carried out at a temperature within the range of 20 - 80 ° c ., for a period of 1 - 48 hours , and more preferably for 2 - 3 hours . examples of reaction routes which may be employed in carrying out the invention are as follows , with | indicating a methyl group and the reaction involves the use of a brominating reagent and a grignard reagent or an arylboronic acid as described previously . the term “ grignard reagent ” as used herein , is meant to denote a conventional grignard reagent characterized by the formula : and also the zinc equivalent in which the magnesium atom is replaced with a zinc atom to provide the reagent : another reaction route can be used to make tetra - substituted fluorenes . this procedure includes reacting a 3 , 6 - substituted fluorene having the same or different substituent groups with at least 2 equivalents and preferably 2 . 0 - 2 . 2 equivalents of a brominating agent , preferably n - bromosuccinimide in propylene oxide at 60 - 80 ° c . for 2 - 6 hours to produce a 2 , 7 - dibromo - 3 , 6 - disubstituted fluorene as follows : the 2 , 7 - dibromo - 3 , 6 - disubstituted fluorene is reacted with a grignard compound rmgx or rznx in the presence of a nickel or palladium - based catalyst to produce a 2 , 3 , 6 , 7 - susbstituted fluorene : alternatively , the 2 , 7 - dibromo - 3 , 6 - disubstituted fluorene is reacted with an arylboronic acid as depicted by formula ( 13 ) in which the aryl group may be phenyl , substituted phenyl , naphthyl or substituted naphthyl , in the presence of a palladium - based catalyst to produce 2 , 3 , 6 , 7 - susbstituted fluorene as exemplified by the following reaction : the first procedure comprises reacting the 2 , 7 - dibromo - 3 , 6 - disubstituted fluorene with at least 2 equivalents and preferably 2 - 7 equivalents of the grignard reagent , magnesium or zinc - organic compound . this reaction is carried out in the presence of a nickel or palladium catalyst , preferably ni [( pph 3 ) 2 ] cl 2 , [ ph 2 pc 2 h 4 pph 2 ] nicl 2 , [ ph 2 pc 3 h 6 pph 2 ] nicl 2 or pd ( pph 3 ) 4 , with at least 0 . 5 mol . %, and preferably 0 . 5 - 2 . 0 mol . % of catalyst . the reaction procedure is preferably carried out in the presence of a polar solvent such as diethyl ether or thf . the reaction is preferably carried out at a temperature within the range of 20 - 60 ° c . for a time period of 1 hour to 5 days , and more preferably , for 2 - 24 hours . the alternative procedure involves the reaction 2 , 7 - dibromo - 3 , 6 - disubstituted fluorene with at least 2 equivalents and preferably 2 - 3 equivalents of the arylboronic acid . this reaction is carried out in the presence of a palladium catalyst , preferably pd ( pph 3 ) 4 , with at least 0 . 5 mol . %, and preferably 0 . 5 - 5 . 0 mol . % of palladium catalyst , and in the presence of at least 3 equivalents of na 2 co 3 or k 2 co 3 , preferably 3 - 7 equivalents of na 2 co 3 or k 2 co 3 . preferably , the alternative reaction procedure is carried out in the presence of toluene , alcohol and water at ratios of 10 :( 1 - 2 ):( 1 - 0 . 1 ), respectively . the reaction is preferably carried out at a temperature ranging from 20 - 150 ° c . for a period of 1 - 24 hours , and more preferably , 2 - 3 hours . the resulting fluorene product can be purified by any suitable procedure such as by crystallization or by column chromatography . another reaction route which can be used to make tri -, tetra - and penta - substituted fluorenes includes reacting a 3 , 6 - substituted fluorene having same or different groups with an chloromethylation agent to produce a 2 ( 7 )- monochloromethylene - 3 , 6 - disubstituted fluorene , 2 , 7 - di - chloromethylene - 3 , 6 - disubstituted fluorene , and 2 , 4 , 7 - tri - chloromethylene - 3 , 6 - disubstituted fluorene in accordance with the following reactions : the chloromethylene fluorene derivatives are reacted with a reduction agent to produce the corresponding tri -, tetra - and penta - substituted fluorenes as follows : the reaction of 3 , 6 - disubstituted fluorene producing the monochloromethylene derivative is carried out with at least 1 equivalent and preferably 1 - 2 equivalents of chloromethyl methyl ether to produce the 2 ( 7 )- monochloromethylene - 3 , 6 - disubstituted fluorene . this reaction is carried out in the presence of at least 1 mol . % and preferably 5 - 30 mol . % of mcl 4 ( m = ti , zr , hf ) or mcl 2 ( m = zn , cd ), preferably ticl 4 or zncl 2 . the reaction is carried out at a temperature within the rang of 0 - 40 ° c ., preferably o - 10 ° c . for a period of 1 - 72 hours , and more preferably for 1 - 5 hours . the 2 , 7 - dichloromethylene - 3 , 6 - disubstituted fluorene is produced under similar condition using at least 2 equivalents and preferably 2 - 7 equivalents of chloromethyl methyl ether , 10 - 30 mol . % of mcl 4 ( m = ti , zr , hf ) or mcl 2 ( m = zn , cd ), preferably ticl 4 or zncl 2 , at a temperature within the range of 0 - 40 ° c ., preferably 20 ° c ., for a period of 3 - 72 hours , and more preferably for about 24 hours . the 2 , 4 , 7 - trichloromethylene - 3 , 6 - disubstituted fluorene is produced under conditions involving at least 3 equivalents and preferably 5 - 7 equivalents of chloromethyl methyl ether , 10 - 30 mol . % of mcl 4 ( m = ti , zr , hf ) or mcl 2 ( m = zn , cd ), preferably ticl 4 or zncl 2 , at a temperature within the range of 0 - 40 ° c ., preferably 20 ° c ., for a period of 3 - 72 hours , and more preferably for about 24 hours . the reactions are carried out in an organic solvent , preferable carbon disulfide or without solvent . the products are purified by crystallization from hot heptanes . an alternate procedure involves reacting the chloromethylene derivatives with at least 0 . 5 equivalent and preferably 0 . 5 - 1 . 0 equivalent per each chloromethylene unit of lialh 4 in thf for 1 - 5 hours at 20 - 60 ° c . to produce the corresponding methyl - fluorenes . another process which can be used to make 2 , 4 , 7 - substituted fluorenes involves the following procedure . a 2 , 7 - substituted fluorene having the same or different substituent groups ( alkyl or cyclic , c 1 - c 20 ) is reacted with a bromination agent to produce a 4 - bromo - 2 , 7 - disubstituted fluorene in accordance with the following reaction : the 4 - bromo - 2 , 7 - disubstituted fluorene is reacted with a grignard reagent rmgx or rznx r = alk , ( c 1 - c 20 ), cyclic ( c 6 - c 20 )) in the presence of a nickel or palladium - based catalyst to produce a 2 , 4 , 7 - susbstituted fluorene in accordance with the following reaction : alternatively , the 4 - bromo - 2 , 7 - disubstituted fluorene is reacted in the presence of a palladium - based catalyst with an arylboronic acid in which the aryl group may be phenyl , substituted phenyl , naphthyl or substituted naphthyl , to produce 2 , 4 , 7 - susbstituted fluorene as exemplified by the following reaction : the initial reaction involving the 2 , 7 - disubstituted fluorene is carried out with at least 1 . 0 equivalent and preferably 1 . 0 - 1 . 2 equivalents of bromine to produce the 4 - bromo - 2 , 7 - disubstituted fluorene . this reaction is carried out in the presence of iron powder in ccl 4 for 1 - 5 hours at 60 - 80 ° c . the next reaction involves reacting 4 - bromo - 2 , 7 - disubstituted fluorene with at least 1 equivalent and preferably 2 - 7 equivalents of the grignard reagent magnesium or zinc - organic compounds , this reaction is carried out in the presence of a nickel or palladium - based catalyst , preferably ni [( pph 3 ) 2 ] cl 2 , [ ph 2 pc 2 h 4 pph 2 ] nicl 2 , [ ph 2 pc 3 h 6 pph 2 ] nicl 2 or pd ( pph 3 ) 4 , with at least 0 . 5 mol . %, and preferably 0 . 5 - 2 . 0 mol . % of catalyst . in a preferred embodiment of the invention , the reaction is carried out in the presence of polar solvent , preferably in diethyl ether or thf . this reaction is preferably carried out at a temperature within the range of 20 - 60 ° c . for a period of 1 hour to 5 days , and more preferably for 2 - 24 hours . the alternative reaction involves reacting the 4 - bromo - 2 , 7 - disubstituted fluorene with at least 1 equivalent and preferably 1 . 5 equivalents of the arylboronic acid . this reaction is carried out in the presence of a palladium - based catalyst , preferably pd ( pph 3 ) 4 , and with at least 0 . 5 mol . %, and preferably 0 . 5 - 5 . 0 mol . % of palladium catalyst , and in the presence of at least 3 equivalents of na 2 co 3 or k 2 co 3 . preferably , the reaction involves 3 - 7 equivalents of na 2 co 3 or k 2 co 3 . in a preferred embodiment of the invention , this reaction is carried out in the presence of toluene , alcohol and water , preferably in ratios of 10 :( 1 - 2 ):( 1 - 0 . 1 ), respectively . the initial reaction is preferably carried out at a temperature within the range of 20 - 150 ° c . for a period of 1 - 24 hours , and more preferably for a period of 2 - 3 hours . the resulting fluorene product is purified by crystallization or by column chromatography . another procedure for producing a 4 - substituted fluorene involves the following reaction sequence . fluorene is reacted with a tert - butylation agent to produce a 2 , 7 - di - t - butyl - fluorene as follows : the 2 , 7 - di t - butyl - fluorene is reacted with a bromination agent to produce a 4 - bromo - 2 , 7 - di - t - butyl - fluorene in accordance with the following reaction : the 4 - bromo - 2 , 7 - di - t - butyl - fluorene is then reacted with benzene and alcl 3 to produce 4 - bromo - fluorene as follows : the 4 - bromo - fluorene is reacted with a grignard reagent rmgx or rznx ( k = alk , ( c 1 - c 20 ), cyclic ( c 6 - c 20 ) as defined above in the presence of a nickel or palladium - based catalyst , or with an arylboronic acid in which the aryl group may be phenyl , substituted phenyl , naphthyl or substituted naphthyl , to produce 4 - r - fluorene as exemplified by the following reaction : the reaction of fluorene with the tert - butylating agent involves the reaction of at least 1 . 0 equivalent of and preferably 1 . 0 - 1 . 2 equivalents of 2 , 6 - di - t - butyl - p - cresol to provide a protection of the 2 - and 7 - positions of the fluorene . this reaction can be carried out in the presence of alcl 3 in nitromethane . the reaction of 2 , 7 - di - t - butyl - fluorene with bromine is carried out under the conditions as described previously . the next reaction is a deprotection reaction carried out with benzene in the presence of alcl 3 . the benzene functions as a solvent and a reactant . the reaction temperature ranges from 20 - 80 ° c ., preferably 50 ° c . the reaction is carried out over a period of 0 . 5 - 5 hours , and preferably for 1 - 2 hours . the final reaction involves reacting 4 - bromo - fluorene with the grignard alkylation reagent or the arylboronic acid under the conditions described above to produce the 4 - substituted fluorene . for a further description of the invention , reference is made to the following illustrative examples . to a solution of diphenylmethane ( 20 . 0 g , 0 . 119 mol ) and 2 , 6 - di - t - butyl - 4 - methylphenol ( 54 . 4 g , 0 . 238 mol ) in nitromethane ( 300 ml ) was added alcl 3 ( 31 . 7 g , 0 . 238 mol ) in nitromethane ( 100 ml ) at 0 ° c . the reaction mixture was stirred for 120 min at 0 ° c . and then poured into ice water and extracted with ether ( 50 ml × 2 ). the organic phase was washed with 10 % naoh ( 40 ml × 5 ) and dried over mgso 4 . the solvents ( nitromethane and ether ) were evaporated using a rotary evaporator . the solid was washed with etoh and dried . the yield was 17 . 1 g . 1 h nmr ( cdcl 3 ): δ 7 . 31 ( d , j = 7 . 8 hz , 4h , h arom ), 7 . 14 ( d , j = 7 . 8 hz , 4h , h arom ), 4 . 06 ( s , impurity ), 3 . 93 ( s , 2h , ch 2 ), 1 . 32 ( s , 18h , t - bu ). to a solution of 4 , 4 ′- di - t - butyldiphenylmethane ( 9 . 17 g , 32 . 7 mmol ), periodic acid dihydrate ( 4 . 47 g , 19 . 6 mmol ) and iodine ( 8 . 30 g , 32 . 7 mmol ) in glacial acetic acid ( 100 ml ) was added h 2 so 4 ( 2 ml , 95 %) and water ( 7 ml ). the mixture was stirred at 85 - 90 ° c . for 20 hours and then poured into ice water and extracted with ether . the ether layer was washed with a nahso 3 solution , na 2 co 3 , followed by water and brine . the organic phase was dried over mgso 4 . the solvent was distilled off to obtain a yellow oil . the oil was chromatographed through al 2 o 3 to provide 15 . 3 g of product . twelve replications of reaction ( 51 ) were carried out under the reaction conditions and with the fluorene yields as set forth in table i . n , n - dimethylformamide was used as a solvent . * activated zinc ( zinc powder was treated with 10 % hcl , washed with water , etoh and dried ) the same procedures as in example 1 , replications 1 - 10 were repeated except that the reaction was carried out with 2 , 2 ′- diiodo - 4 , 4 ′- di - t - butyl - 5 , 5 ′- dimethyl - diphenylmethane in accordance with the following reaction : the results in terms of yield of the fluorenyl compound were roughly equivalent to those of example 1 . the same procedures as in example 1 , replications 1 - 10 were repeated except that the reaction was carried out with 2 , 2 ′- diiodo - 4 - t - butyl - diphenylmethane in accordance with the following reaction : the results in terms of yield of the fluorenyl compound were roughly equivalent to those of example 1 . to a solution of 3 , 6 - di - t - butylfluorene ( 2 . 10 g , 7 . 55 mmol ) in propylene carbonate ( 60 ml ) was added nbs ( 2 . 70 g ). the reaction mixture was stirred for 6 hours at 70 - 75 ° c . the mixture was then poured into water , and the precipitated solid was filtered , washed with water and dried to yield 2 . 71 g at a purity of 82 %. 1 h nmr ( cdcl 3 ): δ 7 . 80 and 7 . 72 ( each s , 2h , 1 , 8 - and 4 , 5 - h ( flu ), 3 . 74 ( s , 2h , h9 ), 1 . 59 ( s , 18h , t - bu ). to a solution of zncl 2 ( 545 mg , 4 . 00 mmol ) in thf ( 20 ml ) was added memgbr ( 1 . 3 ml , 3m in et 2 o , 4 . 90 mmol ). a mixture of 2 , 7 - dibromo - 3 , 6 - di - t - butyl - fluorene ( 0 . 65 g , 1 . 50 mmol ) and 1 , 2 - bis ( diphenyl phosphine ) ethane nickel dichloride ( 0 . 110 g , 0 . 20 mmol ) in thf ( 10 ml ) was added to the prepared meznbr solution . the mixture was stirred at 25 ° c . for 6 hours . the reaction mixture was quenched with water , extracted with ether , dried over mgso 4 , and evaporated under vacuum to produce a residue which was purified by column chromatography ( silica gel , hexane / ch 2 cl 2 = 5 / 1 ) to give 2 , 7 - dimethyl - 3 , 6 - di - t - butyl - fluorene at a yield of 10 %. the bromination of 3 , 6 - di - t - butyl - fluorene was carried out following the procedure of example 4a in accordance with reaction ( 54 ). to a mixture of 2 , 7 - dibromo - 3 , 6 - di - t - butylfluorcne ( 0 . 96 g , 2 . 20 mmol ) and pd ( pph 3 ) 4 ( 260 mg , 0 . 22 mmol ) in toluene ( 50 ml ) was added a solution of phenylboronic acid ( 0 . 81 g , 6 . 63 mmol ) in etoh ( 10 ml ) and a solution of na 2 co 3 ( 1 . 5 g ) in water ( 10 ml ). the reaction mixture was stirred for 6 hours under reflux . the reaction mixture was quenched with water , extracted with ether , dried over mgso 4 , and evaporated under vacuum to produce a residue which was purified by column chromatography ( silica gel , hexane / ch 2 cl 2 = 5 / 1 ) to yield 2 , 7 - diphenyl - 3 , 6 - di - t - butyl - fluorene ( 0 . 85 g , 90 %). 1 h nmr ( cdcl 3 ): δ 7 . 96 and 7 . 15 ( each s , 2h , 1 , 8 - and 4 , 5 - h ( flu ), 7 . 33 ( m , 10h , ph ), 3 . 77 ( s , 2h , h9 ), 1 . 27 ( s , 18h , t - bu ). to a solution of 3 , 6 - di - t - buthyl fluorene ( 2 . 00 g , 7 . 19 mmol ) and chloromethyl methyl ether ( 2 . 5 ml ) in cs 2 ( 15 ml ) was added at 0 ° c . a solution of ticl 4 ( 0 . 4 ml ) in cs 2 ( 5 ml ). the reaction mixture was stirred for 3 hours at room temperature . the mixture was poured into ice water and extracted with ether . the ether extract was dried over sodium sulfate and evaporated under vacuum to leave a residue , which was purified by column chromatography ( hexane / ch 2 cl 2 = 10 / 1 ) and crystallization from hot heptanes . 2 - chloromethyl - 3 , 6 - di - t - butylfluorene ( yield 0 . 75 g ) 1 h nmr ( cdcl 3 ): δ 7 . 80 and 7 . 78 ( each d , 1h , 4 , 5 - h ), 7 . 47 ( d , 1h , j = 8 . 1 hz , h8 ), 7 . 34 ( dd , 1h , j = 8 . 1 hz , j = 1 . 5 hz , h7 ), 7 . 31 ( d , 1h , 1h , j = 1 . 5 hz , h1 ), 4 . 72 ( s , 2h , ch 2 cl ), 3 . 87 ( s , 2h , h9 ), 1 . 41 ( s , 18h , t - bu ). 2 , 7 - dichloromethyl - 3 , 6 - di - t - butylfluorene ( yield 0 . 63 g ) 1 h nmr ( cdcl 3 ): δ 7 . 87 ( br s , 2h , 4 , 5 - h ), 7 . 34 ( br s , 2h , 1 , 8 - h ), 4 . 75 ( s , 4h , ch 2 cl ), 3 . 95 ( s , 2h , h9 ), 1 . 42 ( s , 188h , t - bu ). to a solution of 2 - chloromethyl - 3 , 6 - di - t - butylfluorene ( 0 . 74 g , 2 . 26 mmol ) in thf ( 15 ml ) was added a small portion of lialh 4 ( 129 mg , 3 . 39 mmol ) under stirring and the mixture was refluxed for 5 hours . the reaction was quenched with water and naoh and extracted with ether . the ether solution was evaporated under vacuum to give a white solid yield of 0 . 68 g . 1 h nmr ( cdc3 ): δ 7 . 80 and 7 . 66 ( each d , 1h , 4 , 5 - h ), 7 . 45 ( d , 1h , j = 8 . 1 hz , h8 ), 7 . 31 ( dd , 1h , j = 8 . 1 hz , j = 1 . 5 hz , h7 ), 7 . 14 ( br s , 1h , 1h , h1 ), 3 . 69 ( s , 2h , h9 ), 2 . 40 ( s , 3h , me ), 1 . 41 ( s , 18h , t - bu ). to a solution of 2 , 7 - dichloromethyl - 3 , 6 - di - t - butylfluorene ( 0 . 75 g , 2 . 0 mmol ) in thf ( 15 ml ) was added a small portion of lialh 4 ( 220 mg , 5 . 8 mmol ) under stirring and the mixture was refluxed for 4 hours . the reaction was quenched with water and naoh and extracted with ether . the ether solution was evaporated under vacuum to give a white solid of 2 , 7 - di - methyl - 3 , 6 - di - tert - butyl - fluorene with a yield of 85 %. the same procedure as in example 6 was repeated except the chloroalkylation reaction was run for 24 hours to provide a yield of 10 %. having described specific embodiments of the present invention , it will be understood that modifications thereof may be suggested to those skilled in the art , and it is intended to cover all such modifications as fall within the scope of the appended claims .