Iridium(III)-vinylidene chemistry: Conversion of an iridacyclopentadiene-chlorido complex and terminal alkynes to iridacyclopentadiene-vinyl complexes

The reactions of [κ²(C¹,C⁴)-CRCRCRCR](PPh₃)₂Ir(Cl) (9, R = CO₂Me) with propargyl alcohol derivatives (2-propyn-1-ol, 2-methyl-3-butyn-2-ol, 1-ethynylcyclopentanol, and 1-ethynylcyclooctanol), in the presence of water leads to the formation of iridium(III)-vinyl complexes bearing the general structure [κ²(C¹,C⁴)-CRCRCRCR](PPh₃)₂Ir(CO)(κ¹-vinyl) where vinyl = -CHCH₂, -(E)-CHCHMe, -CHC(CH₂)₄, or -CHC(CH₂)₇. In these, the CO ligand was derived from the terminal carbon of the starting alkyne and the oxygen atom from water. Under anhydrous conditions, 9 undergoes reaction with 2-propyn-1-ol to give trimethyl 1,3-dihydro-3-oxo-4,5,6-isobenzofurantricarboxylate, the result of a cycloaromatization/transesterification involving the buta-1,3-dien-1,4-diyl ligand in 9 and 2-propyn-1-ol.     

Modification of aminoallenylidene complexes of chromium via exchange of the C3-bound amino group

The aminoallenylidene(pentacarbonyl)chromium complexes [(CO)₅CrCCC(NR¹R²)Ph] (1a-c) react with dimethylamine by addition of the amine to the C1C2 bond of the allenylidene ligand to give alkenyl(amino)carbene complexes [(CO)₅CrC(NMe₂)CHC(NR¹R²)Ph] (2a-c) (R¹ = Me: R² = Me (a), Ph (b); R¹ = Et: R² = Ph (c)). In contrast, addition of a large excess (usually 20 equivalents) of ammonia or primary amines, H₂NR, to solutions of [(CO)₅CrCCC(NMe₂)Ph] (1a) affords the aminoallenylidene complexes [(CO)₅CrCCC(NHR)Ph] (1d-w) in which the dimethylamino group is replaced by NH₂ or NHR, respectively. In addition to simple amines such as methylamine, butylamine, and aniline, amines carrying a functional group (allylamine, propargylamine) and amino acid esters as well as amino terpenes and amino sugars can be used to displace the NMe₂ substituent. Usually the Z isomer (with respect to the partial C3-N double bond) is formed exclusively. Products derived from addition of H₂NR to the C1C2 bond of 1a are not observed. The amino group in 1d-w is rapidly deprotonated by excess of amine to form iminium alkynyl chromates [1d-w]⁻, thus protecting 1d-w from addition of free amine to either C3 or across the C1C2 bond. The iminium alkynyl chromates are readily reprotonated by acids or by chromatography on wet SiO₂ to reform 1d-w.     

Alkoxy-substituted group 6 allenylidene complexes - Synthesis and properties

Bis(alkoxy)allenylidene complexes, [(CO)₅MCCC(OR′)OR], as well as mono(alkoxy)allenylidene complexes, [(CO)₅MCCC(OR′)Ph], of chromium and tungsten are accessible from propynones [HCCC(O)Ph] or propynoic acid esters [HCCC(O)OR; R = Et, (−)-menthyl, endo-bornyl] by the following reaction sequence: (a) deprotonation of the alkynes, (b) reaction with [(CO)₅M-THF] (M = Cr, W), and (c) alkylation of the resulting alkynyl metallate, [(CO)₅MCCC(O)R], with Meerwein salts. Vinylidene complexes, [(CO)₅MCC(R′)C(O)OR], are formed as a by-product by C_β-alkylation of the alkynyl metallate. Dimethylamine displaces one alkoxy substituent of the bis(alkoxy)allenylidene complexes to give dimethylamino(alkoxy)allenylidene complexes, [(CO)₅MCCC(OR)NMe₂]. The analogous reaction of dimethylamine with a mono(alkoxy)-substituted allenylidene complex affords the aminoallenylidene complex [(CO)₅CrCCC(NMe₂)Ph]. When the amine is used in large excess, the α,β-unsaturated aminocarbene complex [(CO)₅CrC(NMe₂)C(H)C(NMe₂)Ph] is additionally formed by addition of the amine across the C_αC_β-bond of the allenylidene ligand. The reaction of [(CO)₅MCCC(OEt)₂] with dimethyl ethylenediamine offers access to bis(amino)allenylidene complexes, in which C_γ is part of a five-membered heterocycle. Photolysis of bis(alkoxy)allenylidene complexes in the presence of triphenylphosphine yields tetracarbonyl- and tricarbonyl{bis(phosphine)}allenylidene complexes. Diethylaminopropyne inserts into the C_βC_γ bond of [(CO)₅MCCC(OEt)OMethyl] to give alkenylallenylidene complexes. Subsequent acid-catalyzed intramolecular cyclization affords a pyranylidene complex.     

Platinum allenylidene complexes and formation of platinum and palladium acetonitrile alkynyl complexes

The platinum(0) complex [Pt(PPh₃)₄] reacts with brominated propargylic amides and esters in benzene by oxidative addition to give trans-[Br(PPh₃)₂Pt-CC-C(O)R] complexes whereas no reaction occurs when halogenated solvents (CH₂Cl₂, CHCl₃) are used. The cis-ligands PPh₃ can be replaced by P(ⁱPr)₃ and the bromide by trifluoroacetate. O-Alkylation of those trans-[X(PR′₃)₂Pt-CC-C(O)R] complexes (X = Br, CF₃COO; R′ = Ph, ⁱPr) derived from propargylic amides with MeOTf or [Me₃O]BF₄ in CH₂Cl₂ gives the first cationic monoallenylidene complexes of platinum, trans-[X(PR′₃)₂PtCCC(OMe)NR₂]⁺Y⁻ (Y = OTf, BF₄). In contrast, trans-[Br(PPh₃)₂Pt-CC-C(O)OMenthyl] derived from a propargylic ester does not react with MeOTf in CH₂Cl₂. However, in acetonitrile instead of O-methylation the substitution of acetonitrile for the bromide ligand to yield the cationic acetonitrile alkynyl platinum complex trans-[MeCN(PPh₃)₂Pt-CC-C(O)OMenthyl]⁺OTf⁻ is observed. The related palladium complexes trans-[X(PR′₃)₂Pd-CC-C(O)OR] (X = Br, CF₃COO; R′ = Ph, ⁱPr, R = menthyl, Et) react with MeOTf or [Et₃O]BF₄ analogously affording trans-[MeCN(PR′₃)₂Pd-CC-C(O)OR]⁺Y⁻ (Y = OTf, BF₄).     

Ruthenium hydride and vinyl complexes supported by nitrogen-oxygen mixed-donor ligands

The Schiff base, 2-chlorophenylsalicylaldimine (HL₁), is formed readily from salicylaldehyde and 2-chloroaniline. After deprotonation, this ligand is found to react as a bidentate mixed-donor chelate with the complexes [RuRCl(CO)(BTD)(PPh₃)₂] (R = H, CHCHC₆H₅, CHCHC₆H₄Me-4, CHCH^tBu, CCCPhCHPh; BTD = 2,1,3-benzothiadiazole) to form the compounds [RuR(L₁)(CO)(PPh₃)₂] through displacement of the chloride and BTD ligands. An analogous reaction occurs with the osmium complex [OsHCl(CO)(BTD)(PPh₃)₂] to provide [OsH(L₁)(CO)(PPh₃)₂]. The compound [Ru(CHCHC₆H₄Me-4)(L₂)(CO)(PPh₃)₂] is formed through reaction of salicylaldehyde (HL₂) with [Ru(CHCHC₆H₄Me-4)Cl(CO)(BTD)(PPh₃)₂] in the presence of base. Two further ligands were investigated to extend the study to encompass 5- and 4-membered chelates; 8-hydroxyquinoline (HL₃) and 2-hydroxy-4-methylquinoline (HL₄) react with [Ru(CHCHPh)Cl(CO)(BTD)(PPh₃)₂] and [Ru(CHCHC₆H₄Me-4)Cl(CO)(BTD)(PPh₃)₂] in the presence of base to yield the complexes [Ru(CHCHPh)(L₃)(CO)(PPh₃)₂] and [Ru(CHCHC₆H₄Me-4)(L₄)(CO)(PPh₃)₂], respectively. The crystal structure of [Ru(CHCHC₆H₄Me-4)(L₁)(CO)(PPh₃)₂] is reported.     

Ferrocenyl-substituted allenylidene complexes of chromium, molybdenum and tungsten: Synthesis, structure and reactivity

Bis(ferrocenyl)-substituted allenylidene complexes, [(CO)₅MCCCFc₂] (1a-c, Fc = (C₅H₄)Fe(C₅H₅), M = Cr (a), Mo (b), W (c)) were obtained by sequential reaction of Fc₂CO with Me₃Si-CCH, KF/MeOH, n-BuLi, and [(CO)₅M(THF)]. For the synthesis of related mono(ferrocenyl)allenylidene chromium complexes, [(CO)₅CrCCC(Fc)R] (R = Ph, NMe₂), three different routes were developed: (a) reaction of the deprotonated propargylic alcohol HCCC(Fc)(Ph)OH with [(CO)₅Cr(THF)] followed by desoxygenation with Cl₂CO, (b) Lewis acid induced alcohol elimination from alkenyl(alkoxy)carbene complexes, [(CO)₅CrC(OR)CHC(NMe₂)Fc], and (c) replacement of OMe in [(CO)₅CrCCC(OMe)NMe₂] by Fc. Complex 1a was also formed when the mono(ferrocenyl)allenylidene complex [(CO)₅CrCCC(Fc)NMe₂] was treated first with Li[Fc] and the resulting adduct then with SiO₂. The replacement route (c) was also applied to the synthesis of an allenylidene complex (7a) with a CC spacer in between the ferrocenyl unit and C_γ of the allenylidene ligand, [(CO)₅CrCCC(NMe₂)-CCFc]. The related complex containing a CHCH spacer (9a) was prepared by condensation of [(CO)₅CrCCC(Me)NMe₂] with formylferrocene in the presence of NEt₃. The bis(ferrocenyl)-substituted allenylidene complexes 1a-c added HNMe₂ across the C_α-C_β bond to give alkenyl(dimethylamino)carbene complexes and reacted with diethylaminopropyne by regioselective insertion of the CC bond into the C_β-C_γ bond to afford alkenyl(diethylamino)allenylidene complexes, [(CO)₅MCCC(NEt₂)CMeCFc₂]. The structures of 5a, 7a, and 9a were established by X-ray diffraction studies.     

Synthesis and solid-state structures of (triphos)iridacyclopentadiene complexes as models for vinylidene intermediates in the [2 + 2 + 1] cyclotrimerization of alkynes

The iridium 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos) complexes [{κ²(C¹,C⁴)-CRCRCRCR}{CH₃C(CH₂PPh₂)₃}Ir(NCMe)]BF₄ (2-NCMe, R = CO₂Me) and [{κ²(C¹,C⁴)-CRCRCRCR}{CH₃C(CH₂PPh₂)₃}Ir(CO)]BF₄ (2-CO, R = CO₂Me) serve as models for proposed iridium-vinylidene intermediates of relevance to the [2 + 2 + 1] cyclotrimerization of alkynes. The solid-state structures of 2-NCMe, 2-CO, and [κ²(C¹,C⁴)-CRCRCRCR]{CH₃C(CH₂PPh₂)₃}Ir(Cl) (2-Cl), were determined by X-ray crystallography.     

Synthesis and characterization of triphenylphosphine stabilized silver α,β-unsaturated carboxylate: Crystal structure of [Ag(O2CCHC(CH3)2)(PPh3)2]

A series of triphenylphosphine coordinated silver α,β-unsaturated carboxylates of type [Ag(O₂CR)(PPh₃)_n: n = 1, R = CH₃CHCH (2a), (CH₃)₂CCH (2b), CH₃CH₂CHCH (2c), CH₃CH₂CH₂CHCH (2d), PhCHCH (2e), CH₂CH (2f); n = 2, CH₃CHCH (3a), (CH₃)₂CCH (3b), CH₃CH₂CHCH (3c), CH₃CH₂CH₂CHCH (3d)] were prepared by reaction of relative silver carboxylates (1a-1f) with triphenylphosphine in chloroform. These complexes were obtained in high yields and characterized by elemental analysis, ¹H NMR, ¹³C NMR, ³¹P NMR and IR spectroscopy. Thermal stability of the complexes has been determined by TG analysis. The molecular structure of [Ag((O₂CCHC(CH₃)₂))(PPh₃)₂] (3b) shows that the senecioato ligand is chelated with silver atom and generate, a distorted tetrahedron.     

Peroxynitrite detoxification by ferryl Mycobacterium leprae truncated hemoglobin O

During infection, Mycobacterium leprae is faced with the host macrophagic environment limiting the growth of the bacilli. However, (pseudo-)enzymatic detoxification systems, including truncated hemoglobin O (Ml-trHbO), could allow this mycobacterium to persist in vivo. Here, kinetics of peroxynitrite (ONOOH/ONOO⁻) detoxification by ferryl Ml-trHbO (Ml-trHbOFe(IV)O), obtained by treatment with H₂O₂, is reported. Values of the second-order rate constant for peroxynitrite detoxification by Ml-trHbOFe(IV)O (i.e., of Ml-trHbOFe(III) formation; k_on), at pH 7.2 and 22.0 °C, are 1.5 × 10⁴ M⁻¹ s⁻¹, and 2.2 × 10⁴ M⁻¹ s⁻¹, in the absence of and presence of physiological levels of CO₂ (∼1.2 × 10⁻³ M), respectively. Values of k_on increase on decreasing pH with a pK_a value of 6.7, this suggests that ONOOH reacts preferentially with Ml-trHbOFe(IV)O. In turn, peroxynitrite acts as an antioxidant of Ml-trHbOFe(IV)O, which could be responsible for the oxidative damage of the mycobacterium. As a whole, Ml-trHbO can undertake within the same cycle H₂O₂ and peroxynitrite detoxification.     

A new cumulene diiron complex related to the active site of Fe-only hydrogenases and its phosphine substituted derivatives: synthesis, electrochemistry and structural characterization

A new cumulene diiron complex related to the Fe-only hydrogenase active site [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₆] (1) was obtained by treatment of (μ-LiS)₂Fe₂(CO)₆ with excess 1,4-dichloro-2-butyne. By controllable CO displacement of 1 with PPh₃ and bis(diphenylphosphino)methane (dppm), mono- and di-substituted complexes, namely [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₅L] (2: L = PPh₃; 3: L = dppm) and [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₄L₂] (4: L = PPh₃; 5: L = dppm) could be prepared in moderate yields. Treatment of 1 with bis(diphenylphosphino)ethane (dppe) afforded a double butterfly complex [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₅]₂(μ-dppe) (7). With dppm in refluxing toluene, a dppm-bridged complex [(μ-SCH₂C(S)CCH₂)Fe₂(CO)₄(μ-dppm)] (6) was obtained. These model complexes were characterized by IR, ¹H, ³¹P NMR spectra and the molecular structures of 1, 2 and 5-7 were determined by single crystal X-ray analyses. The electrochemistry of 1-3 was studied and the electrocatalytic property of 1 was investigated for proton reduction in the presence of HOAc.     

Diphosphinoazine rhodium(III) and iridium(III) octahedral complexes

Rhodium(III) and iridium(III) octahedral complexes of general formula [MCl₃{R₂PCH₂C(Bu^t)NNC(Bu^t)CH₂PR₂}] (M = Rh, Ir; R = Ph, c-C₆H₁₁, Prⁱ, Bu^t; not all the combinations) were prepared either from the corresponding diphosphinoazines and RhCl₃ · 3H₂O or by the oxidation of previously reported bridging complexes [{MCl(1,2-η:5,6-η-CHCHCH₂CH₂CHCHCH₂CH₂)}₂{μ-R₂PCH₂C(Bu^t)NNC(Bu^t)CH₂PR₂}] with chlorine-containing solvents. Depending on the steric properties of the ligands, complexes with facial or meridional configuration were obtained. Crystal and molecular structures of three facial and two meridional complexes were determined by X-ray diffraction. Hemilability of ligand in the complex fac-[RhCl₃{(C₆H₁₁)₂PCH₂C(Bu^t)NNC(Bu^t)CH₂P(C₆H₁₁)₂}] consisting in reversible decoordination of the phosphine donor group in the six-membered ring was observed as the first step of isomerization between fac and mer isomers.     

H2O2 and (.)NO scavenging by Mycobacterium leprae truncated hemoglobin O

Kinetics of ferric Mycobacterium leprae truncated hemoglobin O (trHbOFe(III)) oxidation by H₂O₂ and of trHbOFe(IV)O reduction by NO and NO₂⁻ are reported. The value of the second-order rate constant for H₂O₂-mediated oxidation of trHbOFe(III) is 2.4 × 10³ M⁻¹ s⁻¹. The value of the second-order rate constant for NO-mediated reduction of trHbOFe(IV)O is 7.8 × 10⁶ M⁻¹ s⁻¹. The value of the first-order rate constant for trHbOFe(III)ONO decay to the resting form trHbOFe(III) is 2.1 × 10¹ s⁻¹. The value of the second-order rate constant for NO₂⁻-mediated reduction of trHbOFe(IV)O is 3.1 × 10³ M⁻¹ s⁻¹. As a whole, trHbOFe(IV)O, generated upon reaction with H₂O₂, catalyzes NO reduction to NO₂⁻. In turn, NO and NO₂⁻ act as antioxidants of trHbOFe(IV)O, which could be responsible for the oxidative damage of the mycobacterium. Therefore, Mycobacterium leprae trHbO could be involved in both H₂O₂ and NO scavenging, protecting from nitrosative and oxidative stress, and sustaining mycobacterial respiration.     

Oxidovanadium(IV) complexes containing ligands derived from dithiocarbazates - Models for the interaction of VO with thiofunctional ligands

The tetragonal-pyramidal VO²⁺ complexes [VO{(RSC-S)N-NX}₂] (1-6) were synthesised by the reactions of VO(OCHMe₂)₃ with the dithiocarbazate ligands RSC(S)-NH-NX, where X = cyclo-pentyl, cyclo-hexyl or 4-Me₂N-C₆H₄-CH, and R = CH₃ or CH₂C₆H₅. The compounds were characterised by elemental analysis, IR- and mass spectrometries, and in cases of compounds 1, 3, 4 and 5, by X-ray diffraction. The chiral compound 4 (X = cyclo-hexyl, R = CH₂C₆H₅) crystallises in the C configuration. In compound 5, the VO moiety is disordered (83.3:16.7%) with respect to the plane spanned by the four equatorial ligand functions.     

Ketimine synthesis in the coordination sphere of thallium (I)

[AuTl(C₆F₅)₂(en)] (en = ethylenediamine) reacts with cyclic ketones as cyclopentanone (Cy⁵O), cyclohexanone (Cy⁶O) or cycloheptanone (Cy⁷O) in 1:1 or 1:2 molar ratio leading to products of stoichiometry [AuTl(C₆F₅)₂{Cy^xN(CH₂)₂NH₂}] (x = 5 1, 6 2 or 7 3), or [AuTl(C₆F₅)₂{Cy^xN(CH₂)₂NCy^x}] (x = 5 4, 6 5 or 7 6). Addition of ethylenediamine to the ketimine complexes in chloroform regenerates [AuTl(C₆F₅)₂(en)], the starting material, and the free ketimines, as their NMR and mass spectra evidenced. The ketimine complexes display luminescence in solid state at room temperature and at 77 K at higher wavelengths than the diamine starting product (505 nm). The excited states responsible for this behaviour are assigned to orbitals due to the gold-thallium interactions.     

Reaction of Mo(CO)4(NCCH3)2 and 7-aza-2-Tosylnorbornadiene

Reaction of Mo(CO)₄(NCCH₃)₂ and 7-aza-2-tosylnorbornadiene (7-azaNBD) yielded five air-stable Mo complexes. One is Mo(CO)₄(η⁴-7-azaNBD), in which the molybdenum atom is chelated by the two π-bonds of 7-azaNBD. The other four are isomers of Mo(CO)₂(η²-7-azaNBD)₂, in which the molybdenum atoms are chelated by the nitrogen atom and one of the two double bonds of 7-azaNBD. In one pair of the isomers, the metal binds to C(2)C(3) of both 7-azaNBD ligands; whereas in the other pair of isomers the metal binds to C(2)C(3) of one 7-azaNBD ligand and C(5)C(6) of another ligand. All structures were fully characterized by NMR spectra. A single crystal of compound 4 was analyzed by X-ray diffraction analysis, which was found to be monoclinic with a = 8.4199, b = 23.984, c = 16.395 Å, and β = 99.99°.     

Synthesis and reactivity of gold(III) complexes containing cycloaurated iminophosphorane ligands

Transmetallation reactions of ortho-mercurated iminophosphoranes (2-ClHgC₆H₄)Ph₂PNR with [AuCl₄]⁻ gives new cycloaurated iminophosphorane complexes of gold(III) (2-Cl₂AuC₆H₄)Ph₂PNR [R = (R,S)- or (S)-CHMePh, p-C₆H₄F, ^tBu], characterised by NMR and IR spectroscopies, ESI mass spectrometry and an X-ray structure determination on the chiral derivative R = (S)-CHMePh. The chloride ligands of these complexes can be readily replaced by the chelating ligands thiosalicylate and catecholate; the resulting derivatives show markedly higher anti-tumour activity versus P388 murine leukaemia cells compared to the parent chloride complexes. Reaction of (2-Cl₂AuC₆H₄)Ph₂PNPh with PPh₃ results in displacement of a chloride ligand giving the cationic complex [(2-Cl(PPh₃)AuC₆H₄)Ph₂PNPh]⁺, indicating that the PN donor is strongly bonded to the gold centre.     

Gas-phase molecular structures of substituted 1,3-bisketenes: A challenge for theory and experiment

Molecular structures of dimethylbis(trimethylsilylketyl)silane (Me₂Si[C(SiMe₃)CO]₂), dimethylbis(trimethylgermylketyl)silane (Me₂Si[C(GeMe₃)CO]₂), and dimethylbis(trimethylstannylketyl)germane (Me₂Ge[C(SnMe₃)CO]₂) have been studied in the gas phase by electron diffraction accompanied by high level ab initio and DFT calculations. Extensive theoretical conformational analyses of the molecules in the vapour predicted a possibility of existence of two types of conformers with small energy differences. The first type had gauche-gauche arrangements of the ketenyl groups in the central C(CO)XC(CO) fragments directed away from each other. The second type had nearly syn-gauche arrangements of the ketenyl groups. In addition, the energy differences were found to depend on the level of computations used. The experimental analysis, in turn, was unable to distinguish between different conformers due to the large number of similar overlapping distances. The experimental data were fitted by an averaged single-conformer model, which nevertheless allowed reliable determination of bonds and bonded angles in the molecules. Main experimental (r_h1) structural parameters for Me₂Si[C(SiMe₃)CO]₂, Me₂Si[C(GeMe₃)CO]₂, and Me₂Ge[C(SnMe₃)CO]₂, i.e. Me₂X[C(YMe₃)CO]₂ (X,Y = Si, Ge, Sn), are (X-C)_mean 187.7(1) pm, 194.6(2) pm, 216.1(3) pm; (Y-C)_mean, 187.7(1) pm, 188.8(8) pm, 194.6(4) pm; (CC)_mean, 135.3(5) pm, 131.6(5) pm, 131.5(13) pm; (CO)_mean, 117.0(7) pm, 117.4(7) pm, 119.0(11) pm; (C-H)_mean, 110.6(7) pm, 110.0(4) pm, 109.1(13) pm; (X(Y)-CC)_mean, 114.4(2)°, 115.6(1)°, 115.6(2)°; (C-X(Y)-C_Me)_mean, 108.3(3)°, 108.4(3)°, 108.9(13)°; C(2)-C(1)-Y(4)-C(10), −19(6)°, 5(4)°, −9(10)°; C(7)-C(6)-Y(9)-C(38),−22(7)°, −32(3)°, −9(10)°; C(2)-C(1)-X(5)-C(6), 128(4)°, 142(1)°, 108(9)°; C(7)-C(6)-X(5)-C(1), 92(6)°, 115(2)°, 108(9)°, respectively.     

Ferrocene- and ruthenocene-containing chalcones: A spectroscopic and electrochemical study

Chalcones of the type Mc-CO-CHCH-Ph, Ph-CO-CHCH-Mc and Mc-CO-CHCH-Mc with Mc = Fc = ferrocenyl or Rc = ruthenocenyl, and Ph = phenyl were synthesized. Synthesis was achieved by base catalyzed Claisen-Schmidt condensation of the appropriated acetyl and aldehyde in ethanol. Cyclic voltammetry in CH₃CN in the presence of 0.1 mol dm⁻³ [N(Bu)₄][PF₆] revealed chemical and electrochemical reversible behaviour for the Fc/Fc⁺ couple and irreversible electrochemistry for the two electron Rc/Rc²⁺ couple. The potential ranges for the Fc/Fc⁺ couple varied in the range 138 ? E°′ ? 302 mV while E_pa for Rc/Rc²⁺ couple was between 358 and 510 mV vs. FcH/FcH⁺, the internal standard. Chalcones with the carbonyl group adjacent to the metallocene, are more difficult to oxidize.