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Metallocenyl ketones (η5-C5H4COC6H5)Cr(NO)2(X) (X = Cl, 3b; X = I, 5b), (η5-C5H5)Fe[(η5-C5H4)CO(η5-C5H5)]Cr(NO)2(X)(X = Cl, 3c; X = I, 5c), and (η5-C5H5)Fe[(η5-C5H4)CO(η5-C5H5)]W(CO)3(CH3) 6c are synthesized. The structures of 3b and 5b are determined by X-ray diffraction studies. The exocyclic carbon of 5b bends toward the Cr atom with a θ value of 3.46°. The correlation between the magnitudes of nonplanarity of Cp-exocyclic carbon to π-acceptor carbonyl substituents and the twist angle of NO to Cp-exocyclic carbon are discussed. Based on the 2D HETCOR, C(2,5) resonating at a lower field than C(3,4) on the Cp(Cr) ring whereas C(3,4) resonating at a lower field than C(2,5) on the Cp(Fe) and the Cp(W) ring are revealed. The hypothesis to elucidate these data assignments has been proposed. The electron density distribution in the cyclopentadienyl ring has been discussed on the basis of 13C NMR data and compared with calculations using the density functional B3LYP exchange–correlation method for those with X-ray diffraction studies.

Complexes (NO)2(X)Cr(η5-C5H4NHCOOCH2C6H5) (X = Cl 2; I, 3; CH3, 4) were synthesized. A reaction between (CO)3(CH3)W(η5-C5H4COY) 8 (Y = OH) and PCl5 yielded 9 (Y = Cl). 9 was converted to 10 (Y = N3) with NaN3. 10 underwent Curtius rearrangement in the presence of CH3OH to give (CO)3(CH3)W(η5-C5H4NHCOOCH3) 7. Reaction of 9 with aniline led to carboxamide 11 (Y = NHC6H5). We observed that C(3,4) resonates at a lower field than C(2,5) in all Cp(M) (M = W, Fe) metallocene derivatives bearing either an electron-donating substituent or an electron-withdrawing substituent via resonance. The hypothesis to elucidate these data assignments was proposed. The electron density distribution in the cyclopentadienyl ring was discussed on the basis of 13C NMR data and those of 5–7, 10, 11, 13, 16, and 17 were compared with calculations using the density functional B3LYP exchange-correlation method based on their X-ray structural data.

Complete demethylation of Cp 2 Ti(CH 3 ) 2 in dichloromethane with 2 M equivalent of [η 5 -(C 5 H 4 COOH)]Cr(CO) 2 NO ( 5 ), [η 5 -(C 5 H 4 COOH)]Cr(NO) 2 X] (X = Cl 6 , X = I 7 ), and [η 5 -(C 5 H 4 COOH)]W(CO) 3 CH 3 ( 8 ); gives Cp 2 Ti{[OC(O)C 5 H 4 ]Cr(CO) 2 NO} 2 ( 13 ), Cp 2 Ti{[OC(O)C 5 H 4 ]Cr(NO) 2 Cl} 2 ( 14 ), Cp 2 Ti{[OC(O)C 5 H 4 ]Cr(NO) 2 I} 2 ( 15 ),and Cp 2 Ti{[OC(O)C 5 H 4 ]W(CO) 3 CH 3 } 2 ( 16) , respectively. The chemical shifts of C(2)–C(5) carbon atoms of compounds 13–15 have been assigned using two-dimensional HetCOR NMR spectroscopy. The assigned chemical shifts were compared with the NMR data of their analogues of ferrocene, and the opposite correlation on the assignments was observed for cynichrodenoyl moieties.

Friedel–Crafts acylation of ruthenocene with (η5-chloroformylcyclopentadienyl)dicarbonylnitrosylchromium 15 has afforded cynichrodenyl ruthenocenyl ketone 6 in 39% yield. Reduction of 6 and acetylcynichrodene 11 with lithium aluminum hydride/aluminum chloride leads to cynichrodenylruthenocenylmethane 8 and ethylcynichrodene 2 in 45% and 63% yield, respectively. Structures of compound 6 and 8 have been solved by X-ray diffraction studies. Both cisoid and transoid conformations at the organic carbonyl carbon were observed in 6. The twist angle is 177.2°, 105.8°, 72.3°, and 24.4° for NO ligand of Cp(CO)2(NO) moiety in 5, transoid 6, cisoid 6, and 8, respectively. Compared the HetCOR NMR data of 6–8 with those of their ferrocene analogues, the opposite correlation was observed on the chemical shift assignments of C(2)–C(5) of Cp(Cr) in compound 5 and 6, while the correlation in compound 7 and 8 is the same. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data and those of 5, 8, and 9 are compared with the calculations via density functional B3LYP correlation-exchange method.

With copper(I) iodide as catalyst, σ-alkynyls, compounds (η5-C5H5)Cr(NO)2(C C–C6H5) (5), [(η5-C5H4)-COOCH3]Cr(NO)2(C C–C6H5) (10), and [(η5-C5H4)-COOCH3]W(CO)3(C C–C6H5) (13), were prepared from their corresponding metal chloride 1, 6 and 12. Structures of compound 3, 5 and 12 have been solved by X-ray diffraction studies. In the case of 5, there is an internal mirror plane passing through the phenylethynyl ligand and bisecting the Cp ring. The phenyl group is oriented perpendicularly to the Cp with an eclipsed conformation. The twist angle is 0° and 118.4° for –C C–Ph and two NO ligands, respectively. The orientation is rationalized in terms of orbital overlap between ψ3 of Cp, dπ of Cr atom, and π∗ of alkynyl ligand, and complemented by molecular orbital calculation. The opposite correlation was observed on the chemical shift assignments of C(2)–C(5) on Cp ring in compounds 6 and 12, using HetCOR NMR spectroscopy. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data and compared with the calculations via density functional B3LYP correlation-exchange method.

Mono-demethylation of Cp 2 Ti(CH 3 ) 2 in dichloromethane with 1 M equivalent of [η 5 -(C 5 H 4 COOH)]Cr(CO) 2 NO ( 5 ), [η 5 -(C 5 H 4 COOH)]Cr(NO) 2 X] (X = Cl 6 , X = I 7 ) and [η 5 -(C 5 H 4 COOH)]W(CO) 3 CH 3 ( 8 ) gives Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]Cr(CO) 2 NO} ( 9 ), Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]Cr(NO) 2 Cl} ( 10 ), Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]Cr(NO) 2 I} ( 11 ) and Cp 2 Ti(CH 3 ){[OC(O)C 5 H 4 ]W(CO) 3 CH 3 } ( 12 ), respectively. The structure of 10 has been solved by X-ray diffraction studies. One of the nitrosyl groups is located at the site away from the exocyclic carbonyl carbon of the Cp(Cr) ring with twist angle of 178.1°. All the data reveals that Cp 2 Ti(CH 3 )– is a strong electron-donating group. The opposite correlation was observed on the chemical shift assignments of C(2)–C(5) in compounds 5 – 12 , using HetCOR NMR spectroscopy, as compared with the NMR data of their ferrocene analogues. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13 C NMR data and those of 10 are compared with the calculations via density functional B3LYP correlation- exchange method.

Bromination/nitrosylation of [η5-(carbomethoxy)cyclopentadienyl]dicarbonylnitrosylchromium (8) (hereafter called carbomethoxycynichrodene) with hydrogen bromide/isoamyl nitrite gives bromo [η5-(carboxymethoxy)cyclopentadienyl]dinitrosylchromium (10) in 84%. Compounds 15 in 74% and 16 in 90% were obtained from the corresponding cynichrodene derivatives via the same method. Compounds [η5-(carbomethoxy)cyclopentadienyl](isothiocyanato)dinitrosylchromium (13) and [η5-(carbomethoxy)cyclopentadienyl](isoselenocyanato)dinitrosylchromium (14) were prepared from [η5-(carbomethoxy)cyclopentadienyl]chlorodinitrosylchromium (9) with excess potassium thiocyanate and selenocyanate, respectively, after detaching the chloride by the action of silver nitrate. One of the nitrosyl groups in each compound is located at the site away from the exocyclic carbonyl carbon of the Cp(Cr) ring with twist angles of 168.5° and 172.3°, respectively. The chemical shifts of C(2)–C(5) carbon atoms of a series of substituted-cyclopentadienyldinitrosylchromium derivatives, [η5-(C5H4-sub)]Cr(NO)2X, have been assigned using two-dimensional HetCOR NMR spectroscopy. The assigned chemical shifts were compared with the NMR data of their analogues of ferrocene, and the opposite correlation on the assignments was observed. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data and those of 10 and 13 are compared with the calculations via density functional B3LYP correlation-exchange method.

Novel red phosphorescent emitter bis(4-phenylquinazolinato-N,C 2′ ) iridium(acetylacetonate) [(pqz) 2 Ir(acac)], bis(1-(1′-naphthyl)-5-methylisoquinolinato-N,C 2′ )iridium(acetylacetonate) [(1-mniq) 2 Ir(acac)] and bis(1-(2′-naphthyl)-5-methylisoquinolinato-N,C 2′ )iridium(acetylacetonate) [(2-mniq) 2 Ir(acac)] have been synthesized and fully characterized. The electronegative effect of (pqz) 2 Ir(acac) ligand shows almost the same influence as the extended π-conjugation effect of (2-mniq) 2 Ir(acac). Density functional theory (DFT) was applied to calculate the Kohn–Sham orbitals of HOMOs and LUMOs in the iridium complexes to illustrate the N(1) electronegative atom effect. Finally, lowest triplet state (T 1 ) energies calculated by time-dependent DFT (TDDFT) were compared with the experimental electroluminescent data. The calculated data for the iridium complexes agreed fairly well with experimental data. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ 3 /LiF/Al were fabricated. The device using (pqz) 2 Ir(acac) as a dopant showed deep-red emission with 1931 CIE (Commission International de L’Eclairage) chromaticity coordinates x = 0.70, y = 0.30.

Compounds 1,2-bis[( η 5 -cyclopentadienyl)dicarbonylnitrosylchromium]ethene ( 7 ) (hereafter called 1,2-dicynichrodenylethene) and 1,2-diferrocenylethene ( 10 ) were prepared from formylcynichrodene ( 3 ) and formylferrocene ( 9 ), respectively, via the McMurry’s low-valent titanium coupling method. Compounds ( η 5 -vinylcyclopentadienyl)dicarbonylnitrosylchromium ( 6 ) and vinylferrocene ( 11 ) were obtained by the dehydration of the corresponding alcohols. The structure of 7 was solved by an X-ray diffraction study: space group, P 2 1 / c ; monoclinic; a =6.379(5), b =11.295(3) and c =11.9352(24); Z =2. It turns out that compound 7 adopts a transoid conformation at the ethenylene bridge and the two cyclopentadienyl rings are coplanar. The nitrosyl group in each cynichrodenyl moiety of 7 is located at the side towards the corresponding ethenylene carbon atom with a twist angle of 46.5°. The chemical shifts of H(2)–H(5) protons and C(2)–C(5) carbon atoms of a series of vinyl derivatives of compounds bearing cyclopentadienyl rings have been assigned using two-dimensional HetCOR-NMR spectroscopy. For the derivatives of cynichrodene ( 1 ) and ferrocene, it was found that the shielding of C(2,5) and C(3,4) carbon atoms is parallel to the shielding of the ortho - and para -carbon atoms of benzene derivatives. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13 C-NMR data. Surprisingly, the vinyl group donates electron density to the adjacent cynichrodene moieties rather than withdraws from them.

(η 5 -Isocyanatocyclopentadienyl)dicarbonylnitrosylchromium( 5 ) (hereafter called isocyanatocynichrodene) was prepared from cynichrodenoic acid ( 2 ) via the Curtius rearrangement. Hydrolysis of 5 with 20% aqueous potassium hydroxide solution gave dicynichrodenylurea ( 8 ) with a 40% and aminocynichrodene ( 6 ) with a 30% yield. The structure of 8 was solved by an X-ray diffraction study: space group, I 4 1 / a ; tetragonal; a = 20.383(4) and c = 18.001(4); Z = 16. Compound 8 adopts a transoid conformation at the organic imido bridge. The dihedral angle between the two planes of imido-substituted cyclopentadienyl rings is 38.9°. The nitrosyl group in each cynichrodenyl moiety is located at the site towards the corresponding imido nitrogen atom with twist angles of 8.3° and 9.7° respectively. The chemical shifts of H(2)−H(5) protons and C(2)−C(5) carbon atoms of a series of cynichrodene derivatives have been assigned using two-dimensional HetCOR NMR spectroscopy. The assigned chemical shifts of selected monosubstituted cynichrodene derivatives were compared with the NMR data of their analogues of ferrocene and benzene derivatives. For derivatives with electron-donating substituents, an analogy was observed between the shielding of C(2,5) and C(3,4) carbon atoms of cynichrodene derivatives and ferrocene derivatives and ortho- and para- carbon atoms of benzene derivatives. For derivatives bearing electron-withdrawing substituents, the opposite correlation on the assignments was observed between cynichrodene derivatives and the derivatives of ferrocene and benzene. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of 13 C NMR data and that of 8 is compared with the ab-initio calculations.

Friedel-Crafts cynichrodenoylation of [η 5 -(ferrocenylmethyl)cyclopentadienyl)]dicarbonylnitrosylchromium (hereafter called cynichrodenylferrocenylmethane ( 3 )) has afforded (1′-cynichrodenoylferrocenyl)cynichrodenylmethane ( 5 ), (3-cynichrodenoylferrocenyl)cynichrodenylmethane ( 6 ) and (2-cynichrodenoylferrocenyl)cynichrodenylmethane ( 7 ) in 32% total yield. The reactivities and orientations of the three Cp rings on 3 towards the Friedel-Crafts reaction are discussed. X-ray diffraction studies of 5 and 7 are reported; crystallographic date for 5 are as follows, space group P 2 1 / c , a 16.739(4), b 12.171(4), c 13.112(3) A, β = 106.84(2)°, Z = 4; crystallographic data for 7 are as follows, space group P 2 1 / n , a 8.226(3), b 24.78(1), c 12.742(6) A, β = 106.22(4)°, and Z = 4. The cynichrodenylmethyl and cynichrodenoyl moieties of 5 are in the 1,3′-configuration. Compound 7 adopts a transoid conformation at the organic carbonyl carbon and the dihedral angle between the two planes of methylene substituted cyclopentadienyl rings is 89.0°.

The reaction between cynichrodenoic acid, (η 5 -C 5 H 4 COOH)Cr(CO) 2 NO ( 6 ) and phosphorus pentachloride produces cynichrodenoyl chloride ( II ) in high yield. Subsequent reaction of 11 with sodium azide affords cynichrodenoyl azide ( 12 ), which undergoes Curtius rearrangement to form cynichrodenyl isocyanate ( 13 ). Subsequent hydrolysis of isocyanate 13 in aqueous KOH solution yields aminocyanichrodene ( 14 ). Azide 12 also undergoes Curtius rearrangement in the presence of benzyl alcohol to produce benzyl N -cynichrodenylcarbamate ( 15 ). Reactions of acid chloride 11 with ammonia, dimethylamine or aniline lead to the corresponding carboxamides ( 16–18 ). Amide 16 is readily dehydrated to produce cynichrodenecarbonitrile ( 19 ). Reactions of acid chloride 11 with either benzyl alcohol or hydroxymethylferrocene generate the corresponding esters ( 20–21 ), whereas treatment of a tetrahydrofuran solution of 11 with pyridine affords cynichrodenecarboxylic anhydride ( 22 in low yield. Reactions of acetylcynichrodene ( 2 ) with organolithium reagents, leading to both carbonyl addition and condensation products, have been investigated. Treatment of 2 with lithium diisopropylamide in diethyl ether solution produces the self-condensation product 1,3-dicynichrodenyl-but-2-en-1-one ( 24 ). Acetyl derivative 2 and benzaldehyde also undergo Claisen-Schmidt condensation in the presence of lithium diisopropylamide to afford cinnamoylcynichrodene ( 27 ).

Chlorination/nitrosylation of [μ 5 -(carbomethoxyl)cyclopentadienyl]dicarbonylnitroslychromium 5 with hydrogen chloride/isoamyl nitrite gives chloro[μ 5 -(carbomethoxy)cyclopentadienyl]dinitrosylchromium 6 in 78% yield. Compound 6 was converted to [μ 5 -(carbomethoxy)cyclopentadienyl iododinitrosylchromium 7 with potassium iodide in 85% yield. Compound 7 in turn was methylated with Grignard reagent to give 8 in 45% yield. The structures of 6 and 7 have been solved by X-ray diffraction studies. Both 6 and 7 crystallize in the monoclinic space group P 2 1 / n . Lattice constants of 6 are a 6.932(2), b 18.239(5), c 8.117(2) A, β 93.48(2)° and Z = 4. Lattice constants of 7 are a 7.229(2), b 8.177(3), c 19.201(7) A, β 993.8(3)° and Z = 4. The organic carbonyl plane (C(1), C(11), O(3), O(4)) deviates from the coplanarity of the corresponding ring plane Cp(Cr) by 1.4 and 0.3° in compounds 6 and 7 , respectively. In 6 the chlorine atom is located at the site twoard the exocyclic carbon of the Cp(Cr) ring with a twist angle of 72.2°, while in 7 , the iodine atom has a twist angle of 68.9°.

Chlorination/nitrosylation of [η5-(ferrocenoyl)cyclopentadienyl]dicarbonylnitrosylchromium (3) with hydrogen chloride/isoamyl nitrite gives chloro[η5-(ferrocenoyl)cyclopentadienyl]dinitrosylchromium 6 which is also obtained by an unexpected Friedel—Crafts acylation of 3 with [η5-(chloroformyl)cyclopentadienyl]dicarbonylnitrosylchromium (5).

Friedel-Crafts reaction of [ h 5 -(ferrocenylmethyl)cyclopentadienyl]dicarbonylnitrosylchromium ( 3 ) (hereafter called cynichrodenylferrocenylmethane) with various acyl chlorides (R = CH 3 , C 6 H 5 , (C 5 H 4 )Cr(CO) 2 (NO), (C 5 H 4 )Fe(C 5 -H 5 )) has afforded new metallocenyl ketones (1′-acylferrocenyl)cynichrodenylmethane ( 5a–5d ) in 21–63% yield. The structure of [1′-(cynichrodenoyl)ferrocenyl]-cynichrodenylmethane ( 5c ) has been solved by an X-ray diffraction study: space group P 2 1 / n , a 16.739(4), b 12.171(4), c 13.112(3) A, β 106.84(2)°, Z = 4. Compound 5c adopts a transoid conformation at the organic carbonyl carbon and cisoid conformation at methylene carbon in which the cynichrodenyl moiety resides at the methylene site of ferrocenyl fragment. The cynichrodenylmethyl and cynichrodenoyl moieties are in the 1,3′-configuration.

Friedel-Crafts acetylation of [h5-(ferrocenylmethyl)cyclopentadienyl]dicarbonyl-nitrosylchromium (hereafter called cynichrodenylferrocenylmethane) (3) has afforded (1′-acetylferrocenyl)cynichrodenylmethane (5), (3-acetylferrocenyl)cynichrodenylmethane (6) and (2-acetylferrocenyl)cynichrodenylmethane (7) in 87% total yield. The relative reactivity and orientation of the three Cp rings on 3 toward the Friedel-Crafts reaction are discussed. The structure of 6 has been solved by an X-ray diffraction study: space group P21/c, a 22.445(4), b 7.129(2), c 11.467(4) A, β 93.06(2)°, and Z = 4. The nitrosyl group is located at the site toward the exocyclic methylene carbon with a twist angle of 1.8°, and the two cyclopentadienyl rings of ferrocenyl moiety exhibit an average twist angle of 17°.

Reduction of [η 5 -(ferrocenoyl)cyclopentadienyl]dicarbonylnitrosylchromium (hereafter called cynichrodenylferrocenylketone) ( 1 ) with sodium borohydride gives cynichrodenylferrocenyl carbinol ( 5 ), whereas reduction with lithium aluminum hydride/ alluminum chloride leads to cynichrodenylferrocenylmethane ( 6 ). Protonation of 5 with fluoroboric acid produces α-cynichrodenyl-α-ferrocenylmethylium tetrafluoroborate ( 4 ), a new dimetallocenyl-stabilized carbonium ion. The diastereotopism of 1 H and 13 C nuclei was observed in both of 4 and 5 . The chemical shifts of H(2–5) protons and C(2–5) carbons in 1 H and 13 C NMR spectra respectively have been assigned using two dimensional NMR spectroscopy.

FriedelCrafts ferrocenoylation of (η 5 -cyclopentadienyl)dicarbonylnitrosylchromium ( 10 ) (hereafter called cynichrodene) has afforded a new metallocenyl ketone ferrocenoylcyclopentadienyldicarbonylnitrosylchromium ( 7 ) in 72% yield. The structure of 7 has been solved by an X-ray diffraction study: space group P 2 1 / n , a 13.530(3), b 6.387(2), c 18.933(4) A, β 101.09(2)° and Z = 4. 7 adopts a transoid conformation at the organic carbonyl carbon. The nitrosyl group of the cynichrodenyl moiety is located at the site away from the exocyclic organic carbonyl carbon with a twist angel 177.2°.

FriedelCrafts acetylation of [η5-(ferrocenylmethyl)cyclopentadienyl]dicarbonylnitrosylchromium (hereafter called cynichrodenylferrocenylmethane) (3) has afforded (1′-acetylferrocenyl)-cynichrodenylmethane (5) in 63% yield. Reduction of 5 with sodium borohydride gives 1-[1′-(cynichrodenylmethyl)ferrocenyl]ethanol (6). Dehydration of 6 produces [η5-(1′-vinylferrocenyl)methyl]cyclopentadienyl]dicarbonylnitrosylchromium (7), a promising organometallic monomer, in 80% yield. The structure of 7 has been solved by an X-ray diffraction study: space group Pbca, a 10.966(2), b 12.595(1), c 26137(3) A, and Z = 8. The vinyl group and the exocyclic carbon are in the 1,3′-configuration with an average rotation of 7° of the corresponding Cp(Fe) rings from the eclipsed configuration.