Aminocarbyne Complexes Research Articles

Triiron Complex with N-Ferrocenyl Aminocarbyne Ligand Bridging a Diiron Core: DFT, Electrochemical, and Biological Insights.

The first N-ferrocenyl aminocarbyne complex, [Fe2Cp2(CO)2(μ-CO){μ-CN(Me)(Fc)}]CF3SO3 ([2]CF3SO3), was synthesized with an 88% yield from [Fe2Cp2(CO)4], isocyanoferrocene (CNFc), and methyl triflate. The synthesis proceeded through the intermediate formation of [Fe2Cp2(CO)3(CNFc)], 1. Multinuclear NMR experiments revealed the presence of cis and trans isomers for [2]CF3SO3 in organic solvents, in agreement with DFT outcomes. Electrochemical and spectroelectrochemical studies demonstrated one reduction process occurring prevalently at the diiron core and one oxidation involving the ferrocenyl substituent. The oxidation process is expected to favor the redox activation of [2]+ in a biological environment. Both [2]CF3SO3 and its phenyl analogue [Fe2Cp2(CO)2(μ-CO){μ-CN(Me)(Ph)}]CF3SO3 ([3]CF3SO3), prepared for comparison, exerted moderate antiproliferative activity against the human cancer cell lines A431, HCT-15, PSN-1, 2008, and U1285. However, [2]CF3SO3 exhibited a higher cytotoxicity than [3]CF3SO3, showed a substantial ability to induce intracellular ROS production, and outperformed cisplatin in a three-dimensional SCLC cell model.

Synthesis and studies of aqueous-stable diruthenium aminocarbyne complexes uncovered an N-indolyl derivative as a prospective anticancer agent

Within a set of diruthenium aminocarbyne analogues, an indolyl-decorated complex, displaying optimal physicochemical properties, exhibited potent in vitro cytotoxicity against a panel of cancer cell lines, coupled with remarkable selectivity.

Correction: Synthesis and studies of aqueous-stable diruthenium aminocarbyne complexes uncovered an N-indolyl derivative as a prospective anticancer agent

Correction for ‘Synthesis and studies of aqueous-stable diruthenium aminocarbyne complexes uncovered an N-indolyl derivative as a prospective anticancer agent’ by Matteo Fiaschi et al., Inorg. Chem. Front., 2024, 11, 2841–2862, https://doi.org/10.1039/D4QI00096J.

Adding Diversity to Diiron Aminocarbyne Complexes with Amine Ligands

The reactions of the diiron aminocarbyne complexes [Fe2Cp2(NCMe)(CO)(μ-CO){μ-CN(Me)(R)}]CF3SO3 (R = Me, 1aNCMe; R = Cy, 1bNCMe), freshly prepared from the tricarbonyl precursors 1a–b, with primary amines containing an additional function (i.e., alcohol or ether) proceeded with the replacement of the labile acetonitrile ligand and formation of [Fe2Cp2(NH2CH2CH2OR’)(CO)(μ-CO){μ-CN(Me)(R)}]CF3SO3 (R = Me, R’ = H, 2a; R = Cy, R’ = H, 2b; R = Cy, R’ = Me, 2c) in 81–95% yields. The diiron-oxazolidinone conjugate [Fe2Cp2(NH2OX)(CO)(μ-CO){μ-CN(Me)2}]CF3SO3, 3, was prepared from 1a, 3-(2-aminoethyl)-5-phenyloxazolidin-2-one (NH2OX) and Me3NO, and finally isolated in 96% yield. In contrast, the one pot reactions of 1a-b with NHEt2 in the presence of Me3NO gave the unstable [Fe2Cp2(NHEt2)(CO)(μ-CO){μ-CN(Me)(R)}]CF3SO3 (R = Me, 4a; R = Cy, 4b) as unclean products. All diiron complexes were characterized by analytical and spectroscopic techniques; moreover, the behavior of 2a–c and 3 in aqueous media was ascertained.

A comparative structural and spectroscopic study of diiron and diruthenium isocyanide and aminocarbyne complexes

The chemistry of [Fe2Cp2(CO)4] (1-Fe; Cp = η5-C5H5) has been widely investigated, and straightforward carbonyl/isocyanide substitution, followed by isocyanide alkylation, provides access to a variety of aminocarbyne complexes, displaying a rich and versatile reactivity. On the other hand, the parallel chemistry of [Ru2Cp2(CO)4] (1-Ru) has been much less developed, and relevant structural/bonding aspects scarcely elucidated. We report an IR study on 1-Ru in different solvents and in the solid state. The IR data of [M2Cp2(CO)3(CNR)] (M = Ru, R = 2,6-C6H3Me2 = Xyl, 2a-Ru; M = Ru, R = CH2Ph = Bn, 2b-Ru; M = Ru, R = Me, 2c-Ru; M = Fe, R = Xyl, 2a-Fe; M = Fe, R = Bn, 2b-Fe; M = Fe, R = Me, 2c-Fe) and [M2Cp2(CO)3{μ-CNR(Me)}]CF3SO3 (M = Ru, R = Xyl, 4a-Ru; M = Ru, R = Bn, 4b-Ru; M = Ru, R = Me, 4c-Ru; M = Fe, R = Xyl, 4a-Fe; M = Fe, R = Bn, 4b-Fe; M = Fe, R = Me, 4c-Fe) are comparatively presented, and the back-donation from the dimetallic core to π-acceptor ligands in complexes 4 is discussed. A new synthetic procedure to access 2a-Ru is reported, affording [Ru2Cp2(CO)2(CNXyl)2] (3) as by-product, as well as the single crystal X-ray structures of 2b-Ru and 4b-Ru. DFT calculations were carried out to elucidate the relative stability of isomeric forms within the series of isocyanide adducts 2-Ru and 3.

C–N Coupling of Isocyanide Ligands Promoted by Acetylide Addition to Diiron Aminocarbyne Complexes

The bis-isocyanide aminocarbyne diiron complexes [Fe2{μ-CN(Me)(R)}(μ-CO)(CNR′)2(Cp)2][SO3CF3] (R = R′ = Xyl, 1a; R = Me, R′ = Xyl, 1b; R = Xyl, R′ = tBu, 1c; Xyl = 2,6-C6H3Me2) and the analogous thiocarbyne complex [Fe2{μ-CS(Me)}(μ-CO)(CNXyl)2(Cp)2][SO3CF3], 2, were prepared in high yields from [Fe2{μ-C(E)}(μ-CO)(CO)2(Cp)2][SO3CF3] [E = N(Me)(R) or SMe, respectively], by reaction with Me3NO in the presence of the appropriate isocyanide. The addition of LiC≡CR′′ to 1a–b promoted intramolecular C–N coupling between the two isocyanide moieties, resulting in the formation of [Fe2(μ-CO){μ-CN(Me)(R)}{μ-C(NXyl)N(Xyl)C(C≡CR′′)}(Cp)2] (R = Xyl, R″ = Ph, 3a; R = Xyl, R″ = Tol, 3b; R = Me, R″ = Ph, 3c; Tol = 4-C6H5Me), in ca. 60% yields. The reaction of 1a with LiC≡CSiMe3 proceeded with coupling between two dinuclear units, to give the tetranuclear complex C2[Fe2(μ-CO)(Cp)2{μ-CN(Me)(Xyl)}{μ-C(NXyl)N(Xyl)C}]2, 4, in 65% yield. The reaction of 2 with LiC≡CTol resulted in the formation of a mixture of nonidentified products. The new complexes were purified by alumina chromatography and fully characterized by analytical techniques, IR and NMR spectroscopy. The molecular structures of 3b and 4 were ascertained by X-ray diffraction studies.

Synthesis and reactivity of bis(diphenylphosphino)amine-bridged heterobimetallic iron–platinum μ-isonitrile and μ-aminocarbyne complexes

Reaction of [(OC)3Fe(μ-CO)(μ-dppa)Pt(PPh3)] (1) (dppa = bis(diphenylphosphino)amine) with various isonitriles in a 1:1 or 1:2 ratio yields the isonitrile-bridged compounds [(OC)3Fe(μ-CN-R)(μ-dppa)Pt(PPh3)] (2) and [(OC)2(RNC)Fe(μ-CN-R)(μ-dppa)Pt(PPh3)] (3), respectively. However, addition of tert-butylisonitrile to 1 affords the carbonyl-bridged complex [(OC)2(tert-BuNC)Fe(μ-CO)(μ-dppa)Pt(PPh3)] (2g). Upon treatment of [(OC)3Fe(μ-CN-o-anisyl)(μ-dppa)Pt(PPh3)] (2b) with SO2, the μ-CNR ligand is chased from its bridging position to give the sulfur dioxide-bridged compound [(OC)2(o-anisylNC)Fe(μ-SO2)(μ-dppa)Pt(PPh3)] (4). These compounds are converted to the μ-aminocarbyne salts [(OC)2(L)Fe{μ-CN(R)R’}(μ-dppa)Pt(PPh3)]+ (5 R’ = Me, Et) by N-alkylation using [Me3O][BF4] or ethyl triflate as electrophiles. In function of the sterical crowding exerted by μ-aminocarbyne groups, two stereoisomers can be formed. Upon addition of P(OMe)3 or tert-BuNC to 5, no carbonyl substitution occurs. Instead the Pt-bound PPh3 ligand is replaced by L′ in a regioselective manner to give [(OC)2(L)Fe{μ-CN(Me)R}(μ-dppa)Pt(L′)][BF4] (5e, 5f, 5g). Deprotonation of the N–H function of the bis(diphenylphosphino)amine ligand of salts 5 by KSi(OMe)3 or KH produces the zwitterionic compounds [(OC)2(L)Fe{μ-CN(R)R’}(μ-Ph2PNPPh2)Pt(PPh3)] (6). The latter react with various organic and inorganic electrophiles to produce the N-alkylated or metallated aminocarbyne complexes [(OC)2(L)Fe{μ-CN(R)R’}{μ-Ph2PN(E)PPh2}Pt(PPh3)]+ (7: E = Me, 8: E = AuPPh3, CuAsPh3, CuPPh3, HgMe). The molecular structures of 2c, 3b, 5b, 8a and 8b have been determined by X-ray diffraction studies.

Insertion, Rearrangement, and Coupling Processes in the Reactions of the Unsaturated Hydride Complex [W2(η5-C5H5)2(H)(μ-PCy2)(CO)2] with Isocyanides

The title complex reacted with stoichiometric amounts of CNR rapidly at room temperature or below to give two types of formimidoyl derivatives: the symmetrically bridged complexes [W2Cp2(μ-C,N:C,N-HCNR)(μ-PCy2)(CO)2] (R = tBu (W–W = 2.8645(5) Å), 4-C6H4OMe), and the asymmetrically bridged [W2Cp2{μ-C:N-HCN(Xyl)}(μ-PCy2)(CO)2] (Cp = η5-C5H5; Xyl = 2,6-C6H3Me2). The latter complex underwent slow isomerization at room temperature to give the corresponding aminocarbyne derivative [W2Cp2{μ-CNH(Xyl)}(μ-PCy2)(CO)2], which in turn could be decarbonylated through irradiation with UV–vis light to yield the 30-electron aminocarbyne complex [W2Cp2{μ-CNH(Xyl)}(μ-PCy2)(μ-CO)] (W–W = 2.4928(4) Å). Density functional theory calculations revealed that the aminocarbyne complex was the most stable isomer for the three isocyanides under study, while subtle steric effects marked the relative stability of the formimidoyl isomers, which therefore are the kinetic products of these reactions. The reaction of the title complex with excess CN(4-C6H4OMe) at room temperature gave in good yield the complex [W2Cp2(μ-C,N:C,C′-HCN(4-C6H4OMe)C{N(4-C6H4OMe)})(μ-PCy2)(CO)2] (W–W = 2.9370(2) Å), having a 5-electron donor aminocarbene-iminoacyl ligand derived from the N–C coupling of formimidoyl and isocyanide ligands, whereas the analogous reaction with CNXyl gave the aminocarbyne complex [W2Cp2{μ-CNH(Xyl)}(μ-PCy2){CN(Xyl)}(CO)] (W–W = 2.677(2) Å) having a terminal bent isocyanide ligand.

Addition of Isocyanides at Diiron μ-Vinyliminium Complexes: Synthesis of Novel Ketenimine−Bis(alkylidene) Complexes

Reactions of the vinyliminium complexes [Fe2{μ-η1:η3-Cγ(R′)Cβ(H)CαN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = Xyl, R′ = Me, 1a; R = Xyl, R′ = CO2Me, 1b; R = 4-C6H4OMe, R′ = CO2Me, 1c; Xyl = 2,6-Me2C6H3) with isocyanides (CNR′′), in the presence of NaH, lead to abstraction of the Cβ−H proton and to isocyanide addition with formation of a carbon−carbon double bond. The observed products are the ketenimine−bis(alkylidene) complexes [Fe2{μ-η1:η2-Cγ(R′)Cβ(CNR′′)CαN(Me)(R)}(μ-CO)(CO)(Cp)2] (R = Xyl, R′ = Me, R′′ = Xyl, 2a; R = Xyl, R′ = CO2Me, R′′ = Xyl, 2b; R = Xyl, R′ = CO2Me, R′′ = But, 2c; R = Xyl, R′ = CO2Me, R′′ = 4-C6H4CN, 2d; R = 4-C6H4OMe, R′ = CO2Me, R′′ = But, 2e), obtained in 60−70% yields. Conversely, the vinyliminium complex [Fe2{μ-η1:η3-Cγ(CO2Me)Cβ(H)CαN(Me)2}(μ-CO)(CO)(Cp)2][SO3CF3] (1d) undergoes double isocyanide addition. Reactions of 1d with a 2-fold excess of CNXyl or CNBut, in the presence of NaH, afford [Fe(CO)(Cp)Cα(NMe2)Cβ(CNXyl)Cγ(CO2Me)C(NXy)Fe(CO)(Cp)] (3) and [Fe(CO)(Cp)C(NBut)Cα(NMe2)CβCγ(CO2Me)Fe(Cp)(CO)CNBut] (4), respectively. Finally, the vinyliminium complex [Fe2{μ-η1:η3-Cγ(H)Cβ(H)CαN(Me)2}(μ-CO)(CO)(Cp)2][SO3CF3] (1e), treated with with CNBut and NaH, yields a mixture of the diiron aminocarbyne complexes [Fe2{μ-CN(Me)2}(μ-CO)(CO)(Cp)(C5H5CH2CN)(CNBut)], (6) and [Fe2{μ-CN(Me)2}(μ-CO)(CO)(Cp)2(CNBut)] (5). The molecular structures of 2a,b, 3·1.5CH2Cl2, 4, and 6·0.5Et2O have been ascertained by X-ray diffraction studies.

Reactions of [Mo(≡CBr)(CO)2{HB(pzMe2)3}] (pz = pyrazol-1-yl) with Amines: Synthesis of Amino, Pyridinium, and Thiolato Carbyne Complexes

The reactions of the bromocarbyne complex [Mo(≡CBr)(CO)2{HB(pzMe2)3}] (pz = pyrazol-1-yl) with a range of secondary and heterocyclic amines have been investigated and found in each case to proceed via simple nucleophilic halide substitution to provide N-functionalized carbyne derivatives, some of which are not available via conventional approaches. With diethylamine or piperazine the simple dialkyaminocarbyne complexes [Mo(≡CNEt2)(CO)2{HB(pzMe2)3}] or [Mo{≡CN(C2H4)2NH}(CO)2{HB(pzMe2)3}] were obtained. With 4-N,N-dimethylaminopyridine the pyridiniumcarbyne salt [Mo(≡CNC5H4NMe2-4)(CO)2{HB(pzMe2)3}]Br was obtained; pyridine provided a complex intractable mixture and collidine failed to react. N-Methylimidazole provided the imidazolium derivative [Mo(≡CNC3H3NMe)(CO)2{HB(pzMe2)3}]Br, while N-(trimethylsilyl)imidazole gave the neutral imidazolyl derivative [Mo(≡CNC3H3N)(CO)2{HB(pzMe2)3}] and N,N′-bis(trimethylsilyl)imidazolium bromide. The sulfenamide HN(SPh)2 afforded the thiolatocarbyne complex [Mo(≡CSPh)(CO)2{HB(pzMe2)3}] rather than the expected aminocarbyne complex [Mo{≡CN(SPh)2}(CO)2{HB(pzMe2)3}], while HN(PPh2S)2 failed to react. The complex 1 is unreactive toward 1,8-diazabicycloundecene (DBU); however prolonged heating results in the formation of [DBUH][Mo(O)3{HB(pzMe2)3}] via base-induced hydrolysis/oxidation.

SPh functionalized bridging-vinyliminium diiron and diruthenium complexes

The SPh functionalized vinyliminium complexes [Fe 2{μ-η 1:η 3-C γ(R′) C β(SPh)C α N(Me)(R)}(μ-CO)(CO)(Cp) 2][SO 3CF 3] [R = Xyl, R′ = Me, 2a; R = Me, R′ = Me, 2b; R = 4-C 6H 4OMe, R′ = Me, 2c; R = Xyl, R′ = CH 2OH, 2d; R = Me, R′ = CH 2OH, 2e; Xyl = 2,6-Me 2C 6H 3] are generated in high yields by treatment of the corresponding vinyliminium complexes [Fe 2{μ-η 1:η 3-C γ(R′) C β(H)C α N(Me)(R)}(μ-CO)(CO)(Cp) 2][SO 3CF 3] ( 1a– e) with NaH in the presence of PhSSPh. Likewise, the diruthenium complex [Ru 2{μ-η 1:η 3-C γ(Me) C β(SPh)C α N(Me)(Xyl)}(μ-CO)(CO)(Cp) 2][SO 3CF 3] ( 2f) was obtained from the corresponding vinyliminium complex [Ru 2{μ-η 1:η 3-C γ(Me) C β(H)C α N(Me)(Xyl)}(μ-CO)(CO)(Cp) 2] ( 1f). The synthesis of 2c is accompanied by the formation, in comparable amounts, of the aminocarbyne complex [Fe 2{μ-CN(Me)(4-C 6H 4OMe)}(SPh)(μ-CO)(CO)(Cp) 2] ( 3). The molecular structures of 2d, 2e and 3 have been determined by X-ray diffraction studies.

ChemInform Abstract: Aminocarbyne Complexes Derived from Isocyanides Activated Towards Electrophilic Addition

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Aminocarbyne complexes derived from isocyanides activated towards electrophilic addition

Aminocarbyne complexes derived from isocyanides activated towards electrophilic addition

Stereoselective insertion of GeCl 2 into tungsten–chlorine bonds of aminomethylene and aminocarbyne complexes

Treatment of Cp*(CO) 2WCNEt 2 ( 1) (Cp*=η 5-pentamethylcyclopentadienyl) with HCl affords the aminomethylene complex cis-Cp*(Cl)(CO) 2WC(H)NEt 2 ( 2). Complex 2 inserts stereoselectively GeCl 2 into the tungsten–chlorine bond to afford cis-Cp*(GeCl 3)(CO) 2WC(H)NEt 2 ( 3). Complex 3 can also be obtained directly from 1 and GeCl 2(diox) (diox=1,4-dioxane) in CH 2Cl 2. Similarly, treatment of Cp**(CO) 2WCNEt 2 ( 1a) (Cp**=η 5-ethyltetramethylcyclopentadienyl) with GeCl 2(diox) in toluene affords cis-Cp**(GeCl 3)(CO) 2WC(H)NEt 2 ( 3a). An isomerization equilibrium is established between 3 and trans-Cp*(GeCl 3)(CO) 2WC(H)NEt 2 ( 4) in the melt (208°C), which favors the trans isomer ( 3: 4 ratio=1:6). The aminocarbyne complex cis-Cp*(Cl) 2(CO)WCNEt 2 ( 5) reacts with GeCl 2(diox) to yield stereoselectively spy-5-14-Cp*(Cl)(GeCl 3)(CO)WCNEt 2 ( 6). Complexes 2– 6 were fully characterized and the crystal structures of the complexes 2, 3, 4 and 6 are presented.

Protonation and Methylation of Zerovalent Molybdenum Complexes of the Types trans-[Mo(CNR)(L)(Ph2PCH2CH2PPh2)2] (R = Ph or Bun; L = N2, CO, or Nitrile) and trans-[Mo(CO)(L‘)(Ph2PCH2CH2PPh2)2] (L‘ = N2 or Nitrile) To Give Carbyne or Hydrido Complexes1

Treatment of trans-[Mo(CNPh)(N2)(dppe)2] with aqueous HBF4 afforded an aminocarbyne complex, which was isolated as trans-[Mo(⋮CNHPh)(OCMe2)(dppe)2][BF4] (7) after crystallization of the crude product from acetone−hexane, whereas the reaction of trans-[Mo(CNBun)(N2)(dppe)2] with [Me2OH][BF4] resulted in the formation of the aminocarbene complex with an agostic α-C−H bond, trans-[MoF(CHNHBun)(dppe)2][BF4]. Analogous treatment of trans-[Mo(CNR)(L)(dppe)2] (R = Ph, Bun; L = p-MeOC6H4CN, CO (4)) with [Me2OH][BF4] gave aminocarbyne complexes trans-[Mo(⋮CNHR)(NCC6H4OMe-p)(dppe)2][BF4] and cis-[Mo(⋮CNHR)(CO)(dppe)2][BF4] (10). In solution at room temperature, the latter complexes gradually isomerized to the hydrido complexes [MoH(CNR)(CO)(dppe)2][BF4] (12). Related aminocarbyne complexes cis-[Mo(⋮CNMeR)(CO)(dppe)2][BF4] (13) were obtained from the reactions of 4 with [Me3O][BF4]. For comparison, carbonyl complexes trans-[Mo(CO)(N2)(dppe)2] and trans-[Mo(CO)(p-MeOC6H4CN)(dppe)2] were allowed to react with aqueous ...

Intramolecular Carbyne–Isocyanide Coupling to an Alkyne Ligand at a d4 Tungsten Center

Oxidative decarbonylation of Cp*(CO)2W≡CNEt2 (1) with PhICl2 affords the aminocarbyne complex cis-Cp*(Cl)2(CO)W≡CNEt2 (2), which reacts with tBuNC to give the CO substitution product cis-Cp*(Cl)2(tBuNC)W≡CNEt2 (3) (Cp* = C5Me5). Complex 3 undergoes a carbyne–isocyanide coupling reaction with HCl to yield the alkyne complex Cp*(Cl)3W[η2-tBu(H)NC≡CNEt2] (4). In comparison, the reaction of cis-Cp*(Cl)2[P(OMe)3]W≡CNEt2 (5) with HCl affords the 16e carbene complex Cp*(Cl)3W=C(H)NEt2 (6) after elimination of P(OMe)3. Complex 5 was obtained from the CO ligand-exchange reaction of 2 with P(OMe)3. Treatment of 6 with tBuNC yields the cationic 18e carbene complex [Cp*(Cl)2(tBuNC)2W=C(H)NEt2]Cl (7). The mechanism of the C–C coupling reaction of 3 to give 4 is discussed and the crystal structures of 4 and 6 are described.

Intramolecular Carbyne–Isocyanide Coupling to an Alkyne Ligand at a d4 Tungsten Center

Oxidative decarbonylation of Cp*(CO)2W≡CNEt2 (1) with PhICl2 affords the aminocarbyne complex cis-Cp*(Cl)2(CO)W≡CNEt2 (2), which reacts with tBuNC to give the CO substitution product cis-Cp*(Cl)2(tBuNC)W≡CNEt2 (3) (Cp* = C5Me5). Complex 3 undergoes a carbyne–isocyanide coupling reaction with HCl to yield the alkyne complex Cp*(Cl)3W[η2-tBu(H)NC≡CNEt2] (4). In comparison, the reaction of cis-Cp*(Cl)2[P(OMe)3]W≡CNEt2 (5) with HCl affords the 16e carbene complex Cp*(Cl)3W=C(H)NEt2 (6) after elimination of P(OMe)3. Complex 5 was obtained from the CO ligand-exchange reaction of 2 with P(OMe)3. Treatment of 6 with tBuNC yields the cationic 18e carbene complex [Cp*(Cl)2(tBuNC)2W=C(H)NEt2]Cl (7). The mechanism of the C–C coupling reaction of 3 to give 4 is discussed and the crystal structures of 4 and 6 are described.

Synthesis, Reactivity, and Molecular Structures of Bis(diphenylphosphanyl)amine- and Bis(diphenylphosphanyl)amide-Bridged Heterobimetallic μ-Isonitrile- and μ-Aminocarbyne Complexes (Fe−Pt)

Addition of isonitriles to [(OC)3Fe(μ-CO)(μ-Ph2PNHPPh2)Pt(PPh3)] 1 produces the μ-isonitrile complexes [(OC)3Fe(μ-C=NR)(μ-Ph2PNHPPh2)Pt(PPh3)] 2, which are transformed to the μ-aminocarbyne complexes [(OC)3Fe{μ-CN(El)R}(μ-Ph2PNHPPh2)Pt(PPh3)]+;3 and 4 by electrophilic addition of [El][BF4] or [El][OSO2CF3] (El = H, Me). The dppa backbone of 4 is readily deprotonated by KOSiMe3 to yield the very stable zwitterionic aminocarbyne complex [(OC)3Fe{μ-CN(Me)2,6-xylyl}(μ-Ph2PNPPh2)Pt(PPh3)] 5.

Interaction of Triosmium Complexes with Hydrogen Chloride: A Model for Fine-Tuning Regioselective Protonation in Metal Clusters

The reaction of Os3(CO)10(CNR)(NCMe) (1) with HCl was studied and this system was found to be a good model for observing the fine-tuning of site-selective protonation in metal complexes. Three products including the protonated species [(e-H)Os3(CO)10(CNR)(NCMe)]+Cl− (2), the bridging aminocarbyne complex (µ-Cl)Os3(CO)10(µ2-C = NHR) (3), and the hydrido derivative (e-H)Os3Cl(CO)10(CNR) (4) were obtained for the reaction. The site of protonation, either on the Os center or on the nitrogen atom of coordinated isocyanide, was tuned in a sensitive manner by the nature of the coordinated isocyanides, the polarity of the solvents, and the strengths of the acids, leading to different product distributions. The more electron withdrawing isocyanides (CNCH2Ph, CNPh) favor the formation of the aminocarbyne complex 3. In a nonpolar solvent like cyclohexane the reaction afforded 3 as the main product. Furthermore, complex 2 was converted to (e-H)Os3(CO)10(e2-CONHR) (5) upon hydrolysis, in which the coordinated isocyanide was transformed to a carboxamido group. This was verified by obtaining the deuterated species (e-H)Os3(CO)10(e2-CONDPr) when [(e-H)Os3(CO)10(CNPr)(NCMe)]+Cl− (2a) was treated with D2O in THF. The molecular structures of (µ2-Cl)Os3(CO)10(µ2-C = NHCH2Ph) (3b) and (e-H)Os3Cl(CO)10(CNPr) (4a) were determined by X-ray diffraction analyses. Complex 3b contains both bridging chloride and bridging aminocarbyne groups, whereas 4a contains a terminal chloride, a terminal isocyanide and a bridging hydride.

Metalcarbon multiple bonds: synthesis, structure, and electrochemistry of chromium aminocarbyne and phenylcarbyne complexes bearing phosphine or alkyl isonitrile ligands

The synthesis, structure and cyclic voltammetry studies of neutral and cationic chromium carbyne complexes bearing phosphine or alkyl isonitrile ligands are reported. Treatment of cis-X(CO) 2(pic) 2CrCN iPr 2 (pic: 4-methylpyridine) ( 1a: X  Cl; 1b: X  Br) with two equivalents of PMe 3 and PMe 2Ph, or one equivalent of 1,2-bis(diphenylphosphino)ethatne (dppe) affords the aminocarbyne complexes cis-Cl(CO) 2(PMe 3) 2CrCN iPr 2 ( 2a). cis-Cl(CO) 3(dppe)CrCN iPr 2 ( 2b) and cis-Br(CO) 2(PMe 2Ph) 2CrCN 1Pr 2 ( 2e) respectively. In comparison, reaction of 1a with two equivalents of P(OMe) 3 gives selectively the trans-isomer Cl(CO) 2[P(OMe) 3] 2CrCN 1Pr 2 ( 3). Complex 2c is converted with TIPF 6 and PMe 2Ph to the cationic aminocarbyne complex [ fac-(PMe 2Ph) 3(CO) 2CrCN 1Pr 2][PF 6] ( 4). Similarly, the cationic phenylcarbyne complex [ fac-[ tBuNC) 3 (CO) 2CrCph][PF 6] ( 6a) is obtained from cis-Br(CO) 2( tBuNC) 2CrCPh ( 5a), TIPF 6 and tBuNC, Treatment of 1a with four equivalents of isopropyl isonitrile affords the cationic aminocarbyne complex [ cis-( iPrNC) 4(CO)CrCN iPr 2]Cl ( 9a), which is converted with TIPF 6 to [ cis-( iPrNC) 4(CO)CrCN iPr 2][PF 6] ( 9b). Comparative cyclic voltammetry studies of the aminocarbyne complexes 2a, 2c, 4, cis-Br(CO) 2( tBuNC) 2CrCN iPr 2 ( 5b), [ fac-( tBuNC) 3(CO) 2CrCN iPr 2][PF 6] ( 6b), mer-Br( tBuNC) 3(CO)CrCN iPr 2 ( 7), [ cis-( tBuNC) 4(CO)CrCN iPr 2][PF 6] ( 8b), [( tBuNC) 5CrCN iPr 2IPF 6] ( 10) and the phenylcarbyne complexes 5a and 6a are reported. The crystal structures of the aminocarbyne complexes 2a and 2c are described.