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Chapter One: Introduction

General

Transition metal chalcogeno composites have attracted considerable attending due to their structural diverseness [ 1-6 ], chemical responsiveness, relevancy to catalysis [ 7-12 ], and biological applications as theoretical accounts for metalloenzymes [ 13-16 ]. ( 6.D )

Organoiron and sulphides and selenides [ CpFe ( CO ) 2 ] 2 ( µ-Ex ) ( E= S, Se ; x= 1-5 ) are a particular portion passage metal chalcogeno composite. The readying of this composite and there reaction will explicate below.

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Organoiron chalcogenonied composites

Iron sulphide bridged dimers

The coordination chemical science of S and polysulfides is of peculiar involvement because of the diverse adhering manners of coordination and its ligation in metal composites is of involvement in several contexts. In biochemistry, inorganic sulphide and perchance polysulfide appear as critical ligands in metalloenzymes such as ferredoxin, nitrogenase, and the xanthine oxidases, chiefly in association with Fe or molybdenum1.

In the context of industrial engineering, inorganic S is among the more common and troublesome accelerator toxicants ; 2 and as greater attempt is directed toward the use of oil pitchs and sludges, catalytic desulfurization and remotion of metal ions perchance complexed with sulphide or polysulfide will go an progressively important problem.3 Additionally, in the wide country of metal-cluster chemical science S ligands have proven really versatile in the building of transition-metal bunch composites, including heteronuclear bunchs of possible catalytic utility.4-6

Iron sulphide bridged dimers CpFe ( CO ) 2 ] 2 ( µ-Sx ) ( x= 1-5 ) was prepared by interpolation of elemental S into the iron-iron bond of the dimer [ CpFe ( CO ) 2 ] 2 as shown in equation 1.1, this reaction is an illustration of redox reaction. ( 16.A )

The organoiron tri- and tetra-sulfides, ( µ-S3 ) [ CpFe ( CO ) 2 ] 2 and ( µ-S4 ) [ CpFe ( CO ) 2 ] 2 have been structurally characterized and their constructions are shown in Figure 1.1 ( Anas ).

In another manus, organoiron sulphide can be prepared by permutation reactions affecting organoiron or S nucleophiles, symbol for the reaction of Na [ CpFe ( CO ) 2 ] with SCl2, S2Cl2 and SOCl2, and the reaction of CpFe ( CO ) 2Br with Li2S, Li2S2, Li2S4 and H2S in the nowadays of base. ( 16.A )

These composites are reasonably stable as solids, but in solution they are sensitive to oxygen and light ( 19.A ). Analogous category of substituted cyclopentadienyl organoiron sulphides ( µ-S3 ) [ CpFe ( CO ) 2 ] 2 ( Cp’= tBuC5H4, 1,3-tBuC5H3 ) has been prepared in a similar manner [ 23 ]. ( Anas )

Iron selenides bridged dimers

organoiron selenides [ ( C5H5 ) Fe ( CO ) 2 ] 2 ( µ-Se ), [ ( tBuC5H4 ) Fe ( CO ) 2 ] 2 ( µ-Se ) and [ ( I,3-tBuC5H3 ) Fe ( CO ) 2 ] 2 ( µ-Se ) severally, were formed from the reactions of the Fe dimers [ ( C5H5 ) Fe ( CO ) 2 ] 2 ( µ-Se ), [ ( tBuC5H4 ) Fe ( CO ) 2 ] 2 ( µ-Se ), [ ( 1,3-tBuC5H3 ) Fe ( CO ) 2 ] 2 ( µ-Se ) with elemental Se. The reaction of the organoiron dimers with elemental Se can be represented in Scheme 1.1 ( 14.A ).

These composites are reasonably stable as solid, but decompose in solution in the presence of visible radiation with deposition of elemental Se. The presence of tert-butyl groups on the cyclopentadienyl ring of the Fe dimers leads to a singular fluctuation in responsiveness and construction relation to the unsubstituted parallels, it is observed that the formation of the selenides enhanced by addition permutation on the ring, due to increase the thermic stableness of the dimmers. And the steric effects of the tert-butyl substituents seem to impact strongly the type of the selenide formed in these reactions. ( 14.A )

In add-on to, The organoiron selenide [ ( C5H5 ) Fe ( CO ) 2 ] ( µ-Se ) has been prepared by the reaction of Na+ [ ( C5H5 ) Fe ( CO ) 2 ] – with Se2C12. ( 20.A )

Chemical reaction of Fe chalcogenide dimers

The chalcogenide bridges in the Fe dimers composites are electron rich and are susceptible to assail by electrophiles ( 7.A ), due to the presence of lone braces of negatrons on the S or Se atom ( 13.A ). The reaction of these chalcogenides with electrophiles produce three categories of Fe composites, these merchandises will discourse in the following pages. ( 5.A )

Chalcogenosulfonate Fe composites

The reaction with sulfonyl chlorides with Fe cyclopentadienyl dimers will gave the expected chalcogenosulfonate composites CpFe ( CO ) 2ESO2R ( E = S, Se ). ( 5.A )

Thiosulfonato Fe composites ( 1.A )

Thiosulfonato composites are of import composites in petrochemistry, due to show an oxopolysulfur ligand. This ligand play a major function in the accelerator usage to change over the merchandise of hydrodesulfurization ( HDS ) ( sulfur remotion from crude oil ) H2S to elemental S.

It was found that the intervention of the Fe polysulfanes ( µ-Sx ) [ CpFe ( CO ) 2 ] 2 ( x= 3, 4 ) with sulfonyl chlorides RSO2Cl ( R= CF3, CCl3, C6F5 ) gave the corresponding Fe thiosulfonato composites CpFe ( CO ) 2SS ( O ) 2R in good outputs, and CpFe ( CO ) 2Cl as a byproduct as shown in equation 1.2.

The mechanism of this reaction is likely similar to that proposed for the readying of CpFe ( CO ) 2SCOR ( see subdivision 1.3.3 ).

These thiosulfonato composites are air stable as solids and air sensitive in solution. They are soluble in common organic dissolvers but indissoluble in hexanes. Sulfonyl chlorides with no electron-withdrawing groups ( R= CH3, C6H5, C6H4CH3 ) or even with moderate negatron retreating groups ( 2,5- ( NO2 ) 2C6H3, 4-NO2C6H4 ) did non respond with the Fe sulphide dimers.

This composites were characterized by IR, NMR spectrometry and elemental analysis and The molecular construction of CpFe ( CO ) 2SSO2CCl3 was determined and shown in figure1.1.

selenosulfonato Fe composites ( 10.A )

Organometallic Se composites have many industrial importance, such as solid province precursors [ 6-9 ], and solar energy engineering.

In a similar manner selenosulfonato composites prepared by the reaction of Fe selenide with Sulfonyl chlorides, so the reaction of Fe selenide ( µ-Se ) [ CpFe ( CO ) 2 ] 2 with sulfonyl chlorides RSO2Cl ( R=C6H5, 4-C6H4Cl, 4-C6H4Br, 4-C6H4tBu, 4-C6H4Me, CH3 ) gave the novel Fe selenosulfonato composites CpFe ( CO ) 2SeSO2R in good outputs, ( equation 1.3 ).

Selenosulfonato composites show higher responsiveness toward sulfonyl chlorides than parallels thiosulfonato composites this may impute to the presence of the electronrich Se atom.

The selenosulfonato composites were characterized and the molecular construction of CpFe ( CO ) 2SeSO2C6H5 was determined by X-ray diffraction analysis as shown in Figure 1.4.

Chalcogenocarbonate Fe composites

Recently, it has been found that Fe sulphide dimers reacted with chloroformates and its thio-derivatives to give three categories of chalcogenocarbonate composites.

Mono-chalcogenocarbonate Fe composites

A series of cyclopentadienyldicarbonyliron monothiocarbonate composites, CpFe ( CO ) 2SCO2R, were prepared by the reaction of ( µ-Sx ) [ CpFe ( CO ) 2 ] 2 with the corresponding chloroformates ROCOCl [ R= Et, iso-Bu, Ph, 4-C6H4NO2, Me ] as shown in equation. 1.4. The chloro-derivative CpFe ( CO ) 2Cl, was besides obtained as a side merchandise of this equation.

The thiocarbonate composites are air stable as solids and are air sensitive in solutions. They are soluble in most common polar organic dissolvers but indissoluble in hydrocarbons. The constructions of these composites were established by elemental analysis, IR and 1H NMR spectrometry. And the molecular construction of CpFe ( CO ) 2SCO2Et shown in Figure 1.5 ( 9.A ).

Besides it was found that the monothiocarbonate ligands are non good bidentate ligands. All efforts to fix the bidentate composites CpFe ( CO ) SCO2R, in which the thiocarbonate ligands is bonded to the Fe through both S and O atoms, were unsuccessful.

The analoguse selnocarbonates CpFe ( CO ) 2SeCO2R [ R= Me, Et, iso-Bu, Ph, 2-C6H4Cl, 4 C6H4ClMe, 4-C6H4NO2 ] were obtained in good outputs when little surplus chloroformates was reacted with ( µ-Se ) [ CpFe ( CO ) 2 ] 2 ( equation 1.5 ) ( 7.D ).

A perspective position of CpFe ( CO ) 2SeCO2Et is displayed in Figure 1.6

Chalcogenothiocarbonate Fe composites

Dithiocarbonate metal composite and its dithioacid ligands have obtained uninterrupted attractive force due to their interesting structural and chemical belongingss every bit good as their broad scope of application in biological systems. The dithioacide ligands X-CS2- ( Ten = OR, SR, NR2 ), have a rich coordination and organometallic chemical science.

In a similer manner the reaction of ( µ-Sx ) [ CpFe ( CO ) 2 ] 2 with assorted aryl chlorothionoformates returns swimmingly to give the corresponding dithiocarbonate composites CpFe ( CO ) 2SC ( S ) OAr ( Ar = Ph, 4-C6H4Cl, 4-C6H4F, C6F5, 4-C6H4CH3 ) as shown in equation 1.6 ( 6.A ).

The construction of CpFe ( CO ) 2SC ( S ) O-4-C6H4Cl was determined by single-crystal X-ray analysis and is shown in Figure 1.7.

The chelate signifier of these composites CpFe ( CO ) ( ? 2S, S-S2COAr ) obtained in high output by irradiated with UV-light for short clip, ( equation 1.7 )

In the other manus the reaction of the Fe selenide with chlorothionoformates ( ROC ( S ) Cl ) give stable selenothiocarbonates composites of general expression CpFe ( CO ) 2SeC ( S ) OR, where R = Ph, 4-C6H4Cl, 4-C6H4F, C6F5, 4-C6H4CH3 ). Besides found that these composites can be converted to the chelated composites CpFe ( CO ) ( ? 2Se, S-SeC ( S ) OR ) upon photolysis, ( Scheme ) 1.2 ( 8.A )

The construction of CpFe ( CO ) 2SeC ( S ) O-4-C6H4Cl was determined crystallographically and is shown in Figure 1.8

Chalcogenodithiocarbonate Fe composites

The Fe trithiocarbonato complex CpFe ( CO ) 2 ( ? S-SCS2Ph ) and its selenodithiocarbonato parallel CpFe ( CO ) 2 ( ? Se-SeCS2Ph ) were generated in good outputs by the reactions of ( µ-Ex ) [ CpFe ( CO ) 2 ] 2 ( E = S ; x = 2, 3. Tocopherol = Se ; x = 1 ) with chlorodithionoformates PhSC ( S ) Cl as shown in equation 1.8 ( 3.A ).

The orange complex CpFe ( CO ) 2 ( ? S-SCS2Ph ) and the brown complex CpFe ( CO ) 2 ( ? Se-SeCS2Ph ) are air stable as solids and in solution. They are soluble in common polar organic dissolvers but indissoluble in hydrocarbons. The individualities of CpFe ( CO ) 2 ( ? S-SCS2Ph ), and CpFe ( CO ) 2 ( ? Se- SeCS2Ph ) have been confirmed by crystal construction finding and shown in Figure 1.9 and 1.10 severally.

Photolyzing a solutions of composites CpFe ( CO ) ( ? E, S-ECS2Ph ) ( E= S, Se ) in the absence of added ligand produces the chelate composites CpFe ( CO ) ( ? 2E, S-ECS2Ph ) ( E= S, Se ) as shown in equation 1.9. The trithiocarbonate ligand of CpFe ( CO ) 2 ( ? 2S-SCS2Ph ) is bonded to the Fe metal through the two S atoms. In a similar manner, the dithioselenocarbonate ligand of CpFe ( CO ) 2 ( ? 2Se-SeCS2Ph ) is bonded to the metal through the Se and S atoms.

The molecular construction of CpFe ( CO ) 2 ( ? 2Se-SeCS2Ph ) represented in Figure 1.11

In add-on to, the trithiocarbonato composites CpFe ( CO ) 2 ( ? S-SCS2R ) have been made by permutation of the iodide ligand of CpFe ( CO ) 2I by the trithiocarbonate anions RSCS-2 ( R= Me, Et, Ph ) [ 15 ]. The chelated signifiers, CpFe ( CO ) ( ? 2S, S-S2CSR ) were obtained by photolysis of the dicarbonyl parallels [ 15 ].

Chalcogenocarboxylate Fe composites

The reaction of chalcogenides complxes ( µ-Ex ) [ CpFe ( CO ) 2 ] 2 ( E= S, Se ; x= 1-5 ) with acid chlorides is reported to give the chalcogenocarboxylate composites of the general expression CpFe ( CO ) 2ECOR ( E = S, Se ) [ 4-6 ]. ( 5.A )

Thiocarboxylate Fe complexe

The reactions of organoiron sulphides, ( µ-Sx ) [ FeCp ( CO ) 2 ] 2 ( x= 3, 4 ) with acid chlorides, RCOCl, produce the new organoiron thiocarboxylates, FeCp ( CO ) 2SCOR, where R = 2-CH3C6H4, 2-CH3COOC6H4, 3,5- ( O2N ) 2C6H3, 2-O2NC6H4 and 2-FC6H4 in moderate outputs, in add-on to FeCp ( CO ) 2Cl in low output, ( equation 1.10 ) ( 12.A ).

It was observed that the Fe thiocarboxylate compounds incorporating R groups with electron-withdrawing substituents like NO2 or F show the greatest thermic stableness, this enhanced thermic stableness can be attributed to comparatively stronger iron-sulfur bonds in the nitro and fluoro compounds.

It is believed that the reaction of organoiron sulphides with acerb chloride follow the proposed mechanism shown below.

The molecular construction of FeCp ( CO ) 2SCO ( 2-O2NC6H4 ) is shown in Figure 1.12. It can be seen that the thiocarboxylate ligand is S-bonded to the Fe atom in the FeCp ( CO ) 2 unit, with a cis constellation of Fe-S bond relation to C=O bond. The construction besides shows a tram constellation of Fe-Cp bond relation to C-S bond. The NO2 group lies in a plane about perpendicular to the plane of the benzine ring and in the same way as the thiocarboxylate C=O group.

However, organoiron sulfanes, ( µ-Sx ) [ FeCp ( CO ) 2 ] 2 ( X = 3,4 ) react with LiBEt3H at -97 & A ; deg ; C gives the anionic species [ Cp ( CO ) 2FeSx ] – ( ten = 1, 2 or 3 ), and the latter composites [ Cp ( CO ) 2FeSx ] – reacts with acerb chlorides RCOCl to give monothiocarboxylate composites FeCp ( CO ) 2SCOR ( R= CH3, C6H5, 3-MeOC6H4, C ( CH3 ) 3, 4-O2NC6H4, 1-C10H7 ). ( 19.A )

In the anther manus, substituted cyclopentadienyl Fe sulphides complexes [ ( tBuC5H4 ) Fe ( CO ) 2 ] 2 ( µ-Sx ) and [ ( I,3-tBuC5H3 ) Fe ( CO ) 2 ] 2 ( µ-Sx ) reacted swimmingly with acerb chlorides ( RCOCl ) ( R= alkyl, aryl ) to give the corresponding substituted cyclopentadienyl thiocarboxylate Fe composites tBuC5H4Fe ( CO ) 2SCOR and I,3-tBuC5H3Fe ( CO ) 2SCOR, ( equation 1.11 ) [ 23 ] ( Anas ).

Selenocarboxylate Fe complexe

The organoselenide and its substituted cyclopentadienyl organo selenide [ ( C5H5 ) Fe ( CO ) 2 ] 2 ( µ-Se ), [ ( tBuC5H4 ) Fe ( CO ) 2 ] 2 ( µ-Se ) and [ ( I,3-tBuC5H3 ) Fe ( CO ) 2 ] 2 ( µ-Se ) react with acerb chloride to give the Se-bonded selenocarboxylate derived functions, ( equation 1.12 ) The organoironselenides in this reaction bear a close resemblance to their sulfide parallels.

It is believed that the reaction of organoiron selenides with acerb chloride follow the proposed mechanism shown below.

This mechanism represents the lone possible path that explains the formation of monoselenocarboxylate derived functions from both mono- and diselenides.

Multinuclear and Multifunctional Fe composites

In add-on, the reaction of polysulfides or polyselenides composites with diacid chloride ( ClCORCOCl ) gave either the mono-iron or di-iron chalcogenocarboxylate composites, depending on the molar ratio of the reactants. [ 11 ] ( 13.A )

A controlled reaction of polysulfides or polyselenides with terephthaloyl chloride ( ClCO ( C6H4 ) COCl ) give the mono-iron thioterephthalates composites Cp`Fe ( CO ) 2SCO-4-C6H4COCl ( Cp`= C5H5, tBuC5H4 ; E= S, Se ), The presence of a free acid chloride group in these composites makes them valuable precursors for many reactions. An of import reaction of these composites would be the reaction with organometal sul­fides and selenides. Such a reaction offers a facile method for the synthesis of a big assortment of gay ­and hetero bimetallistic bithio-, biseleno- and thioseleno- terephthalate composites [ Cp`Fe ( CO ) 2ECO ] 2 ( 4-C6H4 ) ( Cp`= C5H5, tBuC5H4 ) ( E= S, Se ) ( Scheme 1.3 ). ( 13.A )

In anther manus, the presence of a free acid chloride group in the mono-iron thioterephthalates composites make them susceptible to assail by electrophiles or the alleged the transmutation reaction organic and inorganic. Nucleophiles such as aminoalkanes, phenols, carboxylic acids and thiols reacted with the latter Fe composites to give the bi-functional merchandises CpFe ( CO ) 2ECO-4-C6H4COX ( X = R2N, OAr, RCOO, SR ) ( E= S, Se ) All theses composites were obtained in a good outputs with the exclusion of phenols, it seems that the responsiveness of phenol enhanced with its nucleophilicty of the phenols, ( Scheme ) 1.5 ( 5.A ) ( Anas ). Furthermore, biological surveies on some of theses bifunctional composites showed that these systems possess promising biological activity, for illustration, the Se containing merchandises had fungicidal and antibacterial effects. However, both the S and Se containing compounds showed mutagenic and fungicidal activity [ 15 ]. ( 5.A )

In the same manner, Treatment of the Fe sulphides ( µ-Sx ) [ CpFe ( CO ) 2 ] 2 with ( chlorosulfonyl ) benzoyl chloride ( 3-ClCOC6H4SO2Cl ) gave the fresh organoiron thiocarboxylate complex CpFe ( CO ) 2SCO-3-C6H4SO2Cl as a stable solid which contains a free sulfonyl chloride group. This complex reacts with nucleophiles ( YH ) to give stable composites CpFe ( CO ) 2SCO-3-C6H4SO2Y ( Y= R2N, ArO, RS ) ( Scheme 1.6 ). The biiron complex CpFe ( CO ) 2SCO-3-C6H4SO2SFe ( CO ) 2Cp, which may ensue from the reaction of the sulfonyl group with the Fe sulphides, could non be obtained from this reaction even when surplus of the Fe sulphide was added. This consequence is in understanding with our earlier determination that merely strongly electrophilic sulfonyl chlorides react with the Fe sulfides [ 6 ] ( 4.A ).

The individualities of CpFe ( CO ) 2SCO-3-C6H4SO2N ( CH3 ) CH2Ph have been confirmed by crystal construction finding and shown in Figure 1.13.

Recently, the synthesis of the acid [ CpFe ( CO ) 2ECO-4-C6H4CO2H ] and the amide [ CpFe ( CO ) 2ECO-4-C6H4CONH2 ] ( E = S, Se ) derivatives from the reaction of terephthaloyl chloride with NaOH and NaNH2, severally was reported. [ 26 ] The terephthalic acid derived functions, [ CpFe ( CO ) 2ECO-4-C6H4CO2H ] were reacted with the terephthaloyl chloride parallels in the presence of pyridine to give the new anhydride bridged diiron dichalcogen composites, ( Figure 1.14 ) [ 26 ] ( Anas ).

Tocopherol = ( S, S ) ; ( S, Se ) ; ( Se, Se )

Furthermore, the amide [ CpFe ( CO ) 2ECO-4-C6H4CONH2 ] reacted with the terephthaloyl chloride parallels in the presence of few beads of pyridine to give the new stable imide bridged diiron dichalcogen composites, ( Figure 1.15 ) [ 26 ].

Tocopherol = ( S, S ) ; ( S, Se ) ; ( Se, Se )

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