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This study presents the synthesis of analogues of bioactive Amaryllidaceae alkaloids that contain a five‐membered ring C and a quaternary carbon centre. The synthesis was carried out in a divergent manner, starting from a common intermediate, keto aldehyde 1 a. This intermediate was obtained by oxidative cleavage of a carbocyclic ring present in the previously synthesised tetracyclic compounds. Subsequent closure of a new heterocyclic ring B using different methods led to products with structural cores found in naturally occurring alkaloids such as pretazettine, tazettine or macronine. In addition, an analogue of egonine was prepared from the same intermediate. Our approach thus provides access to multiple structural types of potentially bioactive molecules. [ABSTRACT FROM AUTHOR]

Racemic carboxylic acid, a Diels‐Alder cycloadduct derived from 5‐bromo‐3‐phenyl‐α‐pyrone and acrylate dienophile, was resolved into enantiomers by diastereomeric salt crystallization. Quinidine was used as a sole resolving base. The salt of (+)‐acid crystallized from aqueous acetonitrile solution. Once this salt was separated by filtration, quinidine salt with (−)‐acid crystallized from mother liquor. As a result, both enantiomers of Diels‐Alder cycloadduct were isolated in high enantiomeric purity. [ABSTRACT FROM AUTHOR]

Large single crystals of polar tetragonal thallium antimony(III) tartrate dihydrate, Tl2[Sb2((+)C4H2O6)2]·2H2O, are grown. The crystal structure (s.g. P41), which contains the binuclear complex group [Sb2(C4H2O6)2]2− and dimer groups [Tl2O8(H2O)2], is given, together with vibrational spectra, refractive indices and their dispersion, and an analysis of SHG phase matching possibility and SHG powder measurements. The crystals allow type I phase matching for laser wavelengths ≥ 1.0103 µm. In addition, a new monoclinic (s.g. C2) antimony(III) tartrate of composition Mg[Sb3((+)C4H2O6)2((+)C4H4O6)((+)C4H5O6)]·11H2O and its crystal structure, which contains a novel type of antimony tartrate complex group [Sb3(C4H2O6)2(C4H4O6)(C4H5O6)], is presented. [ABSTRACT FROM AUTHOR]

We report a Brønsted acid‐catalyzed synthesis of tetrasubstituted allenyl compounds decorated with heterocyclic sulfenyl group. The reaction proceeds readily from available propargylic alcohols in the presence of pentacarboxycyclopenatadienes (PCCPs) as organocatalysts. The developed strategy provides tetrasubstituted allene derivatives in high yields (from 55 to 98 %) and under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Phosphines bearing guanidine substituents at the backbone are attractive hybrid ligands that have not yet received adequate attention. This paper describes group 11 metal complexes of a guanidine-substituted triphenylphosphine, viz., N′′-[2-(diphenylphosphino)phenyl]-N,N′-diisopropylguanidine (1). Reactions of 1 with Cu(I) and Ag(I) precursors yielded the P,N-chelate complexes [M(1-κ2P,N)2]X, where M/X = Cu/BF4, Cu/Br, Ag/SbF6 and Ag/Br. Conversely, reacting 1 and the hydrochloride 1·HCl with [AuCl(SMe2)] produced the corresponding phosphine complexes [AuCl(1-κP)] and [AuCl(1H-κP)]Cl, which were further converted into [{μ(P,N)-1}2Au2][SbF6]2 and [AuCl(1H-κP)][SbF6], respectively, by reacting with Ag[SbF6]. These compounds and the bis-phosphine complex [Au(1-κP)2][SbF6] were studied as precatalysts in the Au-mediated cyclisation of N-propargylbenzamide and the addition of benzoic acid across terminal alkynes. Of the Au(I)-1 complexes studied, the complex [{μ(P,N)-1}2Au2][SbF6]2 was particularly attractive as a stable and well-defined, silver-free precatalyst, which can be conveniently activated in situ by the addition of a protic acid (either as an additive or a substrate). [ABSTRACT FROM AUTHOR]

Ferrocene phosphines have been extensively studied as ligands for coordination chemistry and catalysis. Among the vast number of compounds reported to date, 1,1′-bis(diphenylphosphino)ferrocene (dppf) still holds a prominent place due to its versatile coordination behavior and wide catalytic applications. This paper describes the synthesis of four semihomologous dppf congeners with a carbonyl spacer inserted between the ferrocene unit and one of the phosphine moieties, R2PfcC(O)PR′2 (R/R′ = Ph/Ph, Ph/Cy, Cy/Ph and Cy/Cy; Cy = cyclohexyl and fc = ferrocene-1,1′-diyl). These compounds were prepared from the respective borane-protected phosphinocarboxylic acids R2PfcCO2H·BH3 by chlorination with oxalyl chloride, reaction with HPR′2/NEt3 and subsequent removal of the protecting group. The compounds were further converted to selenides R2P(Se)fcC(O)P(Se)R′2 to evaluate their electronic properties through the 1JPSe coupling constants. In addition, two series of palladium complexes were prepared, viz. the Pd(II) chelate complexes cis-[PdCl2(R2PfcC(O)PR′2-κ2P,P′)] and the Pd(0) complexes [Pd(η2-mi)(R2PfcC(O)PR′2-κ2P,P′)] (mi = N-methylmaleimide). The latter compounds were applied as catalysts for the Stille cross-coupling reaction of 4-fluorobenzoyl chloride with phenyl-tributylstannane to produce 4-fluorobiphenyl. The best catalytic results were obtained with the [Pd(η2-mi)(Ph2PfcC(O)PPh2-κ2P,P′)] complex that contained the least electron-rich ligand. [ABSTRACT FROM AUTHOR]

Combining a phosphinoferrocene fragment with extended multidonor moieties affords novel, flexible multidonor pro-ligands. This contribution describes the synthesis of two structurally similar functional phosphines, Ph2PfcNHC(O)CH2PPh2 (1) and Ph2PfcNHCH2CH2PPh2 (2, fc = ferrocene-1,1′-diyl), and their coordination behaviour towards Pd(II). The former amidophosphine reacts with [PdCl2(MeCN)2] to produce the chelate complex [PdCl2(1-κ2P,P′)] as a mixture of cis and trans isomers, which convert into bis-chelate [PdCl2(Ph2PfcNC(O)CH2PPh2-κ3P,P′,N)] upon reacting with a strong base (KOt-Bu). In contrast, the more flexible and more basic phosphinoamine 2 directly forms the cationic bis-chelate complex [PdCl(2-κ3P,P′,N)]Cl via spontaneous self-ionisation. Subsequent halogen abstraction with Ag[SbF6] results either in counter ion exchange to give [PdCl(2-κ3P,P′,N)][SbF6] or in the formation of a structurally unique complex [PdCl(2-κ4Fe,P,P′,N)][SbF6]2 with an Fe → Pd dative interaction, depending on the amount of silver(I) salt used (1 or 2 equiv.). [ABSTRACT FROM AUTHOR]

Herein, we report the first chiral phosphoric acid (CPA)-catalyzed asymmetric addition of α-fluoro(phenylsulfonyl)methane (FSM) derivatives to in situ generated cyclic N-acyliminium. This process enables metal-free expeditious access to sulfone and fluorine incorporating contiguous all substituted quaternary stereocenters ingrained in biorelevant isoindolinones in excellent stereoselectivities (up to 99% ee and up to 50 : 1 dr). [ABSTRACT FROM AUTHOR]

The reactions of the gold(I) metalloligand [Au2{μ(P,C)-Ph2Pfc}2], where fc stands for ferrocene-1,1′-diyl, with bare or ligand-stabilised group 11 metal ions open access to diverse oligometallic clusters stabilised by Au–Au, Au–Ag and Au–Cu interactions. These capping reactions and the unique structures of the products stem from unparalleled properties of the bridging ferrocene groups, namely their structural flexibility and electron-rich nature, which enable accommodating the capping moieties and supporting ligands and facilitate electrophilic metalation, respectively. While the Au+ and Ag+ ions behave similarly, capping reactions with Cu+ proceed differently, with an accentuated role of the counter ions and other ligands in the system. Such behaviour reflects the relative strengths of the Au–M metallophilic interaction (M = Au, Ag and Cu), among which the Au–Cu interactions are the weakest, as confirmed by DFT calculations. [ABSTRACT FROM AUTHOR]

The present study investigates an enantioselective cyclization of enals with imidazolone derivatives catalyzed by a combination of achiral Pd(0) complex and chiral secondary amine. Corresponding spirocyclic imidazolones were produced in high yields with moderate diastereoselectivity and excellent enantioselectivity. The developed co-operative catalytic methodology provides a highly substituted spirocyclic scaffold with four stereogenic centers under mild conditions. [Display omitted] • Synergistically catalyzed reaction leading to spirocyclic compounds. • Combination of chiral secondary amine and achiral palladium complex as catalysts. • Preparation of a wide variety of chiral spiroimidazolones. • Readily derivatization of prepared chiral spiroimidazolones. [ABSTRACT FROM AUTHOR]

This contribution focuses on the coordination behaviour of 2-[2-(diphenylphosphino)phenyl]-1,3-diisopropylguanidine (1), which is a representative of the unique P,N-ligands combining phosphine moieties with strongly basic guanidinium substituents. This compound was prepared by the reaction of 2-(diphenylphosphino)aniline with 1,3-diisopropylcarbodiimide in the presence of diethylzinc (10 mol%). When mixed with [MCl2L2] (M = Pd, Pt; L = a weakly bonding ligand), ligand 1 gives rise to P,N-chelate complexes [MCl2(1-κ2P,N)]. However, in the case of kinetically inert Pt(II), the products of partial substitution and chloride ionisation, [PtCl(1-κ2P,N)(L)]Cl, where L = Me2SO or η2-cycloocta-1,5-diene, can be intercepted. Ionisation also occurs in the reaction with [PdCl(η3-C3H5)]2, leading to [Pd(η3-C3H5)(1-κ2P,N)]Cl, while [Pd(MeCN)4][BF4]2 produces the bis-chelate complex, cis-[Pd(1-κ2P,N)2][BF4]2. In contrast, the corresponding hydrochloride (1H)Cl behaves as a simple phosphine, reacting with PdCl2 surrogates to give the zwitterionic species [PdCl3(1H-κP)] and the bis-phosphine complex trans-[PdCl2(1H-κP)2]Cl2, depending on the metal-to-ligand ratio. [ABSTRACT FROM AUTHOR]

Versatile applications and unique performance of 1,1'‐bis(diphenylphosphanyl)ferrocene (dppf) in coordination chemistry and catalysis prompted the search for its analogs. This contribution describes the synthesis of the first donor‐unsymmetric dppf congeners bearing bulky and rigid 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphaadamantyl (CgP) donor groups, viz. Ph2PfcPCg (1) and Ph2PfcCH2PCg (2; fc=ferrocene‐1,1'‐diyl). Bis‐phosphanes 1 and 2 were converted into air‐stable Pd(0) complexes, [Pd(ma)(L^L)] (L^L=1 and 2; ma=maleic anhydride). Together with [Pd(ma)(dppf)], these complexes were applied as catalysts in Pd‐catalyzed C−H arylation of benzoxazoles with aryl chlorides in n‐butanol as an environmentally benign solvent. Among all catalysts tested in this study, complex [Pd(ma)(2)] performed the best, providing a high‐yield and selective synthesis of 2‐arylbenzoxazoles from a range of the generally less reactive chloroarenes at low catalyst loading (typically 1 mol.%). Under similar conditions, the structurally related heterocycles (e. g. 1‐methylbenzimidazole and benzothiazole) did not react. [ABSTRACT FROM AUTHOR]

Compared to phosphines with guanidinium tags, studied as polar ligands for aqueous catalysis, their counterparts bearing guanidine substituents received only limited attention. This contribution focuses on the coordination of phosphinoferrocene guanidine Ph2PfcN＝C(NHiPr)2 (1iPr, fc = ferrocene-1,1′-diyl) as a hybrid, P,N-donor ligand to Group 10 metals. In its native state, 1iPr coordinated as a P,N-chelating ligand, affording [M(X)(Y)(1iPr-κ2P,N)] (M/X/Y = Pd/Cl/Cl, Pd/Br/4-C6H4CN, Pt/Cl/Cl; the corresponding Ni(II) complex was not isolated). While [PdCl2(1iPr-κ2P,N)] converted into [PdCl(1iPr-κ3Fe,P,N)]+ species with Fe–Pd interaction, upon chloride removal, the analogous Pt(II) complex dimerised into [Pt2(μ-Cl)2(1iPr-κ2P,N)2]2+. Deprotonation of [PdCl2(1iPr-κ2P,N)] produced a unique, doubly chelating phosphinoguanidinate complex [PdCl{(1iPr–H)-κ3P,N,N′}], which was smoothly converted into [Pd(MeCN){(1iPr–H)-κ3P,N,N′}][SbF6]. The latter, a convenient starting material for substitution reactions, was used to prepare either [Pd(L){(1iPr–H)-κ3P,N,N′}][SbF6] (L = 4-(dimethylamino)pyridine and 2-phenylpyridine), by simple substitution, or the hydroxide and acetylacetonate (acac) complexes, [Pd2(μ-OH)2(1iPr-κ2P,N)2][SbF6]2 and [Pd(acac)(1iPr-κ2P,N)][SbF6], by substitution with concomitant proton transfer. In contrast, protonation of the guanidine moiety prevented its coordination, as shown in reactions of the salts (1iPrH)Cl and (1iPrH)[SbF6]. Depending on the metal-to-ligand ratio, adding (1iPrH)[SbF6] to [PdCl2(MeCN)2] produced [Pd2Cl2(μ-Cl)2(1iPrH-κP)2][SbF6]2 or [PdCl2(1iPrH-κP)2][SbF6]2. Analogous reactions involving (1iPrH)Cl were more complicated due to competing coordination of the chloride anion, leading to (in addition to other compounds) the zwitterionic complex [PdCl3(1iPrH-κP)], which was alternatively obtained by selective protonation of [PdCl2(1iPr-κ2P,N)] with HCl. Apparently, the protonation state of the guanidine moiety controls the coordination behaviour of phosphinoferrocene guanidines. [ABSTRACT FROM AUTHOR]

Introducing a ferrocene moiety into a molecule results in the incorporation of a metal center and a redox active moiety. This contribution describes the synthesis of FcN(CH2PPh2)2 (1; Fc=ferrocenyl), a ferrocene analog of the widely studied bis‐phosphane pincer ligands, RN(CH2PPh2)2. Compound 1 was studied as a ligand in complexes of Group 10 and 11 metal ions. The following compounds were synthesized and characterized using a combination of spectroscopic methods and single‐crystal X‐ray diffraction analysis: the square planar complexes [MX2(1‐κ2P,P')] (M/X=Ni/Cl, Pd/Cl, Pd/Br, Pd/I and Pt/Cl) and the tetrahedral complexes [M(1‐κ2P,P')2]X (M/X=Cu/PF6, Ag/SbF6 and Au/SbF6). Furthermore, a pair of open and cyclic digold(I) complexes containing bis‐phosphane 1 as a P,P‐bridging ligand, viz. [(μ(P,P')‐1)(AuCl)2] and [(μ(P,P')‐1)2Au2][SbF6]2, were isolated. Ligand 1, the corresponding phosphane selenide 1‐Se and all complexes (except for the poorly soluble [(μ(P,P')‐1)2Au2][SbF6] and unstable [Ag(1‐κ2P,P')2][SbF6]) were further analyzed by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Cooperative amino‐ and palladium catalysis utilizing heterocyclic systems containing strongly coordinating and adsorptive sulfur atom remains an underdeveloped area. Herein, we describe an enantioselective cyclization of enals with thiazole derivatives catalyzed with the combination of achiral Pd(0) complexes and chiral secondary amines. Chiral spirocyclic thiazolones were produced in yields ranging from 41% to 98% with stereoselectivities (from 5:1 to 12:1 dr, and 95–99% ee). Moreover, the developed strategy allows access to highly substituted chiral cyclopentane derivatives by additional transformations of spirocyclic thiazolones. [ABSTRACT FROM AUTHOR]

Hybrid phosphines usually combine a phosphine moiety with another heteroatom secondary donor group in their structures while compounds equipped with hydrocarbyl π–donor moieties remain uncommon. This contribution reports the synthesis and structural characterization of the first P/π-allyl-chelating complexes that were obtained using the structurally flexible and redox-active ferrocene unit as the scaffold, viz. [PdCl(R2PfcCHCHCH2-η3:κP)] (1R; R = Ph and cyclohexyl (Cy); fc = ferrocene-1,1′-diyl). These compounds were synthesized from the respective phosphinoferrocene carboxaldehydes R2PfcCHO via reaction with vinylmagnesium bromide to generate 1-(phosphinoferrocenyl)allyl alcohols, which were subsequently acetylated. The resulting allyl acetates reacted smoothly with [Pd2(dba)3]/[Et3NH]Cl (dba = dibenzylideneacetone) to produce the target compounds. Complexes 1R and their nontethered analogues [PdCl(η3-C3H5)(FcPR2-κP)] (5R; Fc = ferrocenyl) were evaluated as pre-catalysts for the Pd-catalysed allylic amination of cinnamyl acetate with aliphatic amines and Suzuki–Miyaura-type cross-coupling of 4-tolylboronic acid with benzoyl chloride. In these reactions, better results were achieved with compounds 5R (particularly with 5Ph), presumably because they form more stable LPd(0)-type catalysts. [ABSTRACT FROM AUTHOR]

AuI complexes combining hard oxygen and soft (diphenylphosphanyl)ferrocene (L) ligands in their molecules were synthesized, viz. the gold hydroxides [Au(OH)(L‐κP)] (5) and [{Au(L‐κP)}2(μ‐OH)][BF4] (4), and the oxonium cluster [{Au(L‐κP)}3(μ3‐O)][BF4] (1). In‐situ auration of 1 produced [{Au(L‐κP)}4(μ4‐O)][BF4]2 (2), which spontaneously converted into a dimeric tetragold complex featuring bridging phosphanylferrocenyl groups geminally diaurated in position 2 of the ferrocene scaffold. The same complex and its isomer incorporating ferrocene‐1,1′‐diyl bridges resulted similarly from 4. Upon crystallization, compound 5 underwent a redox reaction, producing a structurally unique, crown‐like, mixed‐valent Au0/AuI cluster, [Au7(L‐κP)6]OH. Compounds 1 and 5 were used to prepare the analogous, N‐bridged complexes, [{Au(L‐κP)}3(μ3‐NFc)][BF4] (Fc=ferrocenyl) and [{Au(L‐κP)}4(μ4‐N)][BF4]. The compounds were structurally characterized and further studied by DFT calculations. [ABSTRACT FROM AUTHOR]

AuI complexes combining hard oxygen and soft (diphenylphosphanyl)ferrocene (L) ligands in their molecules were synthesized, viz. the gold hydroxides [Au(OH)(L‐κP)] (5) and [{Au(L‐κP)}2(μ‐OH)][BF4] (4), and the oxonium cluster [{Au(L‐κP)}3(μ3‐O)][BF4] (1). In‐situ auration of 1 produced [{Au(L‐κP)}4(μ4‐O)][BF4]2 (2), which spontaneously converted into a dimeric tetragold complex featuring bridging phosphanylferrocenyl groups geminally diaurated in position 2 of the ferrocene scaffold. The same complex and its isomer incorporating ferrocene‐1,1′‐diyl bridges resulted similarly from 4. Upon crystallization, compound 5 underwent a redox reaction, producing a structurally unique, crown‐like, mixed‐valent Au0/AuI cluster, [Au7(L‐κP)6]OH. Compounds 1 and 5 were used to prepare the analogous, N‐bridged complexes, [{Au(L‐κP)}3(μ3‐NFc)][BF4] (Fc=ferrocenyl) and [{Au(L‐κP)}4(μ4‐N)][BF4]. The compounds were structurally characterized and further studied by DFT calculations. [ABSTRACT FROM AUTHOR]

(Ferrocenylmethyl)phosphane (1) oxidation with hydrogen peroxide, elemental sulfur and grey selenium produced (ferrocenylmethyl)phosphane oxide 1O, sulfide 1S and selenide 1Se, respectively, as the first isolable primary phosphane chalcogenides lacking steric protection. At elevated temperatures, compound 1O disproportionated into 1 and (ferrocenylmethyl)phosphinic acid. In reactions with [(η6‐mes)RuCl2]2, 1O underwent tautomerization into a phosphane complex [(η6‐mes)RuCl2{FcCH2PH(OH)‐κP}], whereas 1S and 1Se lost their P‐bound chalcogen atoms, giving rise to the phosphane complex [(η6‐mes)RuCl2(FcCH2PH2‐κP)] (Fc=ferrocenyl, mes=mesitylene). No tautomerization was observed in the reaction of 1O with B(C6F5)3, which instead produced a Lewis pair FcCH2P(O)H2‐B(C6F5)3. Phosphane oxide 1O added to C=O bonds of aldehydes and ketones and even to cumulenes PhNCE (E=O and S). However, both PH hydrogens were only employed in the reactions with aldehydes and cyanates. [ABSTRACT FROM AUTHOR]

[((Diphenylphosphanyl)amino)carbonyl]ferrocene (1) has been synthesized and coordinated to light platinum metals, ruthenium, rhodium and palladium, in diverse coordination modes. Specifically, compound 1 was used to prepare the following phosphane complexes, [(η6‐mes)RuCl2(1‐κP)], [(η5‐C5Me5)RhCl2(1‐κP)], trans‐[PdCl2(1‐κP)2], and [(LNC)PdCl(1‐κP)] (mes=mesitylene, LNC=[2‐(dimethylamino‐κN)methyl]phenyl‐κC1). They were subsequently converted into cationic O,P‐chelate complexes by halide abstraction with AgClO4 and into neutral O,P‐chelate complexes by deprotonation with potassium tert‐butoxide. All coordination compounds and phosphane chalcogenides 1E (P‐bound chalcogen atom E=O, S and Se), which were also synthesised, were structurally characterised using spectroscopic methods (IR, multinuclear NMR and ESI MS) and single‐crystal X‐ray diffraction analysis. The electrochemical behaviour of the prepared compounds was studied by cyclic voltammetry, and the (LNC)Pd‐1 complexes were further studied by Mössbauer spectroscopy. [ABSTRACT FROM AUTHOR]

A structurally new heptadentate derivative of a 15-membered pyridine-based macrocycle containing two benzimidazol-2-yl-methyl N-pendant arms (L = 3,12-bis((1H-benzimidazol-2-yl)methyl)-6,9-dioxa-3,12,18-triazabicyclo[12.3.1]octadeca-1(18),14,16-triene) was synthesized and its complexes with the general formula [M(L)](ClO4)2·1.5CH3NO2 (M = MnII (1), FeII (2), CoII (3) and NiII (4)) were thoroughly investigated. X-ray crystal structures confirmed that all complexes are seven-coordinate with axially compressed pentagonal bipyramidal geometry having the largest distortion for NiII complex 4. FeII, CoII and NiII complexes 2, 3 and 4 show rather large magnetic anisotropy manifested by moderate to high obtained values of the axial zero-field splitting parameter D (7.9, 40.3, and −17.2 cm−1, respectively). Magneto-structural correlation of the FeII, CoII and NiII complexes with L and with previously studied structurally similar ligands revealed a significant impact of the functional group in pendant arms on the magnetic anisotropy especially that of the CoII and NiII complexes and some recommendations concerning the ligand-field design important for anisotropy tuning in future. Furthermore, complex 3 showed field-induced single-molecule magnet behavior described with the Raman (C = 507 K−n s−1 for n = 2.58) relaxation process. The magnetic properties of the studied complexes were supported by theoretical calculations, which very well correspond with the experimental data of magnetic anisotropy. Electrochemical measurements revealed high positive redox potentials for M3+/2+ couples and high negative redox potentials for M2+/+ couples, which indicate the stabilization of the oxidation state + II expected for the σ-donor/π-acceptor ability of benzimidazole functional groups. [ABSTRACT FROM AUTHOR]

This contribution expands the still narrow class of functional ferrocene phosphanes with polar cationic groups, focusing on the synthesis and catalytic use of a series of phosphanylferrocene ligands bearing positively charged guanidinium tags, [R2PfcCH2NHC(NH2)2]Cl (3a–d), where fc = ferrocene‐1,1′‐diyl, R = isopropyl (a), cyclohexyl (b), phenyl (c), and 2‐furyl (d). To probe the influence of phosphane substituents, these compounds were studied as supporting ligands in Pd‐catalyzed Suzuki–Miyaura cross‐coupling of acyl chlorides with arylboronic acids, in analogous coupling of aryl bromides with arylboronic acids, and in Rh‐catalyzed hydroformylation of 1‐hexene using trans‐[RhCl(CO){R2PfcCH2NHC(NH2)2‐κP}2]Cl2 complexes (4a–d) as pre‐catalysts. The outcome of the cross‐coupling reactions strongly depended on the starting materials, and no ligand generated a universally applicable catalyst when combined with Pd(OAc)2. In the hydroformylation reactions, the catalyst based on 4d led to lower conversions than all others, which performed rather similarly. Overall, the phenyl‐substituted phosphane 3c emerged as a good compromise, giving rise to reasonably efficient and stable catalysts in most cases (except for Suzuki–Miyaura biaryl cross‐couplings, wherein electron‐rich alkylphosphanes performed better than 3c). [ABSTRACT FROM AUTHOR]

A new polar phosphinoferrocene ligand, viz. 1'-(diphenylphosphino)ferrocene-1-phosphonic acid (H 2 L), was prepared by hydrolysis of the corresponding phosphonate ethyl ester. However, the compound is relatively unstable, gradually decomposing upon prolonged storage, ultimately affording phosphine oxide H 2 L O. When the phosphine moiety was protected (e.g., in phosphine oxide H 2 L O and adduct H 2 L ·BH 3), no decomposition was observed. An alternative approach to prepare more stable H 2 L surrogates by converting the phosphonic acid into ammonium salts (dabcoH)(H L) and [(OHCH 2 CH 2) 2 NH 2 ](H L) (dabco = 1,4-diazabicyclo[2.2.2]octane) resulted in no significant stabilisation. H 2 L reacted with [PdCl 2 (cod)] (cod = cycloocta-1,5-diene), producing the bis(phosphine) complex, trans -[PdCl 2 (H 2 L -κ P) 2 ]. When mixed with Pd(II)-acetylacetonate (acac) complexes with ortho -metallated auxiliary ligands, [(LCY)Pd(acac)] (LCY = 2-[(dimethylamino-κ N)methyl]phenyl-κ C 1 and 2-[(methylthio-κ S)methyl]phenyl-κ C 1), H 2 L gave rise to bis-chelate complexes of the [(LCY)Pd(H L -κ2 O , P)] type. H 2 L , the ammonium salts featuring the H L − anion, and all Pd(II) complexes were structurally characterised by single-crystal X-ray diffraction analysis. Variations in phosphonate P-O bond lengths observed in the crystal structures were rationalised by DFT computations. Image 1 • A new polar phosphinoferrocene phosphonate ligand was prepared. • The compound was converted to its ammonium salts. • Pd(II) complexes with native and deprotonated ligand were synthesised. • Crystal structures of the salts and Pd(II) complexes were determined. [ABSTRACT FROM AUTHOR]

Compared to their P,N-analogues, compounds combining P and Sb substituents remain less common. This contribution describes the synthesis of a new ferrocene phosphinostibine, Cy2PfcSbPh2 (3; fc = ferrocene-1,1′-diyl, Cy = cyclohexyl), and its derivatives modified at the phosphine and stibine moieties, viz., Cy2P(E)fcSbPh2 (E = BH3, O, S, AuCl), Cy2P(E)fcSbCl2Ph2 (E = BH3, S, AuCl) and stiboranes Cy2P(E)fcSb(O2C6Cl4)Ph2 (E = void, BH3, O, S and AuCl). The increased Lewis acidity of the Sb atom in the catecholatostiboranes Cy2PfcSb(O2C6Cl4)Ph2 and Cy2P(O)fcSb(O2C6Cl4)Ph2 resulted in intramolecular P → Sb and O → Sb dative interactions, which were not detected for the respective parent stibines or even in Cy2P(S)fcSb(O2C6Cl4)Ph2. While the P → Sb interaction in Cy2PfcSb(O2C6Cl4)Ph2 was stronger than that in the "all-phenyl" analogue Ph2PfcSb(O2C6Cl4)Ph2 due to the electron-donating effect of the cyclohexyl groups, the bonding situations in Cy2P(O)fcSb(O2C6Cl4)Ph2 and Ph2P(O)fcSb(O2C6Cl4)Ph2, where the substituent effect was only indirect, remained very similar according to DFT calculations. A coordination study with 3 resulted in isolation of phosphine ([AuCl(3-κP)]), P,Sb-bridging ([(μ(P,Sb)-3)(AuCl)2]), and P,Sb-chelate ([(arene)MCl(3-κ2P,Sb)]X, where (arene)M/X = (η6-p-cymene)Ru(II)/PF6, (η5-C5Me5)Rh(III)/Cl, and (η5-C5Me5)Rh(III)/PF6, and [MCl2(3-κ2P,Sb)], where M = Pd and Pt) complexes. For some of these compounds, structure determination revealed structural distortions suggesting weak intramolecular Cl–Sb interactions, which were confirmed by theoretical methods. [ABSTRACT FROM AUTHOR]

Gold(i) phosphine complexes are often used in catalysis, but the role of their auxiliary ligands still remains poorly understood. Thus, building on our previous research, we prepared a series of Au(i) complexes [Au2(μ-R2PfcCN)2][SbF6]2 (fc = ferrocene-1,1′-diyl) to assess the effect of phosphine groups PR2 on the catalytic properties of these highly catalytically active, dimeric compounds. Catalytic testing in Au-mediated cyclisation of N-propargyl amides to 2-substituted 5-methyleneoxazolines showed that weaker donating phosphines gave rise to more active, albeit partly destabilised, catalysts. Nevertheless, thanks to their self-stabilisation by reversible nitrile coordination, [Au2(μ-R2PfcCN)2]+ cations readily converted into catalytically active species (by dissociation) and, in addition, remained catalytically active even at very low metal loadings. The experimental results were supported by the trends in 1JPSe coupling constants for R2P(Se)fcCN as a measure of ligand basicity, and by DFT calculations. [ABSTRACT FROM AUTHOR]

We present a new class of dicationic palladium NHC complexes with two carbene ligands bearing different aryl substituents and a hemilabile pyrimidyl group. They can either be synthesized from the imidazolium salts via the silver transmetalation route to a halide-free palladium(ii) precursor or by direct deprotonation by palladium acetate. For four complexes we could determine their solid-state structures by X-ray diffraction experiments. Insight gained by NMR spectroscopy and DFT calculations revealed that in solution the two potentially bidentate ligands interchange between chelating and non-chelating coordination modes. The preference of these coordination modes is governed by the steric influence of the different ligands. The complexes were shown to be active catalysts for the hydroarylation of alkynes, and their performance was rationalized by DFT calculations. [ABSTRACT FROM AUTHOR]

Isomeric phosphinoferrocene ligands, viz. 1′-(diphenylphosphino)-1-cyanoferrocene (1) and 1′-(diphenylphosphino)-1-isocyanoferrocene (2), show markedly different coordination behaviours. For instance, the reactions of 1 with [PdCl2(MeCN)2] and [(LNC)Pd(μ-Cl)]2 (LNC = [2-(dimethylamino-κN)methyl]phenyl-κC1) produced the “phosphine” complexes [PdCl2(1-κP)2] (7) and [(LNC)PdCl(1-κP)] (8), and the latter was converted into the coordination polymer [(LNC)Pd(μ(P,N)-1)][SbF6] (9). Conversely, the reaction of 2 with [(LNC)Pd(μ-Cl)]2 involved coordination of the phosphine moiety and simultaneous insertion of the isocyanide group into the Pd–C bond, giving rise to the P,η1-imidoyl complex [PdCl(Ph2PfcN=CC6H4CH2NMe2-κ3C,N,P)] (10; fc = ferrocene-1,1′-diyl). Compound 10 was further transformed into the Fischer carbene [PdCl(Ph2PfcN(Me)CC6H4CH2NMe2-κ3P,C,N)][BF4] (11) by methylation with [Me3O][BF4]. The reactions of 2 with Pd–Me and Pd(η3-allyl) precursors also led to imidoyl complexes [Pd(μ-Cl)(Ph2PfcN=CR-κ2C,P)]2 (R = Me: 12, R = allyl: 15), which were cleaved with PPh3 into the corresponding monopalladium complexes [PdCl(PPh3)(Ph2PfcN=CR-κ2C,P)] (R = Me: 13, R = allyl: 16). The treatment of 12 and 15 with thallium(i) acetylacetonate (acac) produced [Pd(acac-O,O′)(Ph2PfcN=CR-κ2C,P)] (R = Me: 17, R = allyl: 18). Through proton transfer, these complexes reacted with Ph2PCH2CO2H, ultimately producing bis-chelate complexes [Pd(Ph2PCH2CO2-κ2O,P)(Ph2PfcN=CR)] (R = Me: 19, R = prop-1-enyl (sic!): 20). In addition, compound 13 was converted into the P-chelated carbene [PdCl(PPh3)(Ph2PfcN(Me)CMe-κ2C,P)][BF4] (14). Compounds 10, 11, 13 and 14 were studied by cyclic voltammetry and by DFT computations. [ABSTRACT FROM AUTHOR]

A simple and efficient access to a new P‐chiral, but so far racemic ligand class featuring ortho‐trityl and ortho‐biaryl motifs is reported. The phosphines are prepared by efficient three‐ to four‐step modular syntheses from simple branched alkyl(diphenyl)phosphine oxides in 52–63% overall yield. They form stable gold complexes, which were characterized by X‐ray crystallography and spectroscopic methods. Fundamental catalytic properties of the complexes were studied in 1,6‐enyne cycloisomerization reactions of achiral substrates to benchmark their activity against the efficient achiral catalyst (JohnPhos)AuCl. The results show that the new complexes can be applied in amounts down to 100 ppm allowing the cycloisomerization reactions to be performed with turnover frequencies of 20000 h−1 and turnover numbers of up to 10000 h−1. [ABSTRACT FROM AUTHOR]

Abstract: The newly discovered gold‐catalysed reaction of isocyanides with hydrazoic acid generated in situ from trimethylsilyl azide and methanol (or, alternatively, from NaN3/AcOH) produces either cyanamides or 1‐substituted 1H‐tetrazol‐5‐amines, depending on the amount of available HN3. The reaction proceeds selectively and in generally high yields of either product, thus providing a particularly convenient access to a wide range of substituted 1H‐tetrazol‐5‐amines that are rather difficult to access otherwise. [ABSTRACT FROM AUTHOR]

The combination of different donor moieties often results in unconventional coordination behavior. This contribution describes the synthesis of a new hybrid ligand, phosphanylferrocene amidine Ph2PfcN=CHNMe2 (1; fc=ferrocene‐1,1′‐diyl), and its coordination behavior toward the light platinum metals. Reacting compound 1 with [PdCl2(MeCN)2] produced the chelate complex [PdCl2(1‐κ2P,N)] and the bis (phosphane) complex trans‐[PdCl2(1‐κP)2], depending on the ligand‐to‐metal stoichiometry. Halide removal from [PdCl2(1‐κ2P,N)] with Na[BARF] afforded the chloride‐bridged dimer [Pd2(μ‐Cl)2(1‐κ2P,N)2][BARF]2, which was presumably in equilibrium with the mononuclear κ3‐complex [PdCl(1‐κ3Fe,P,N)][BARF] in solution (BARF=tetrakis [3,5‐bis(trifluoromethyl)phenyl]borate). The reactions of 1 with the isoelectronic precursors [(arene)MCl(μ‐Cl)]2 (M/arene=Ru(II)/p‐cymene, and Rh(III)/C5Me5) generated the respective bridge‐cleavage products [(arene)MCl2(1‐κP)], which transformed into the P,N‐chelate complexes [(arene)MCl(1‐κ2P,N)][BARF] when treated with Na[BARF] as a chloride scavenger. All this suggests preferential coordination the phosphane moiety to soft metal ions, while the coordination of the amidine moiety can be induced through changing the reaction stoichiometry or by generating a vacant coordination site at the metal ion. The compounds were characterized using a combination of standard spectroscopic methods (multinuclear NMR, IR, and ESI MS) and single‐crystal X‐ray crystallography, and compounds 1 and 3 were further studied by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

This study reports the synthesis and characterization of new molybdenum compounds bearing benz[e]indenyl and benz[f]indenyl ligands. The capability of the ligands to undergo η5-to-η3 haptotropic rearrangement was evidenced on reactions with tris(pyrazolyl)methane. Appearance of the η3-coordination mode was determined by NMR spectroscopy and X-ray structure analysis on a single crystal. [ABSTRACT FROM AUTHOR]

Sulfonation of (diphenylphosphinothioyl)ferrocene (1) with chlorosulfonic acid in acetic anhydride affords the crude sulfonic acid Ph2P(S)fcSO3H (2; fc = ferrocene-1,1′-diyl), which can be efficiently purified and isolated after conversion to Ph2P(S)fcSO3(HNEt3) (3). Methyl triflate/P(NMe2)3 can be used to convert compound 3 to the stable sulfonate salt Ph2PfcSO3(HNEt3) (4) and Ph2P(Me)fcSO3 (5) as a minor, zwitterionic byproduct. Alternatively, compound 4 can be prepared by lithiation of 1′-(diphenylphosphino)-1-bromoferrocene (6; Ph2PfcBr) and trapping of the lithiated intermediate with SO3·NMe3. Reactions of [(LNC)PdX]2 and [(LSC)PdX]2, where X = Cl, AcO, LNC = 2-[(dimethylamino-κN)methyl]phenyl-κC1, and LSC = 2-[(methylthio-κS)methyl]phenyl-κC1, with 4 uniformly produced the bis-chelate complexes [(LNC)Pd(Ph2PfcSO3-κ2O,P)] (7) and [(LSC)Pd(Ph2PfcSO3-κ2O,P)] (8), respectively. The reaction of [PdCl2(MeCN)2] with 4 afforded the bis(phosphine) complex trans-(Et3NH)2[PdCl2(Ph2PfcSO3-κP)2] (9). Complexes 7-9 were used as defined catalyst precursors for the Suzuki-Miyaura cross-coupling of boronic acids with acyl chlorides to give ketones. Reactions of aromatic substrates in the presence of Na3PO4 and 9, the base and Pd source that showed the best performance, in a toluene/water biphasic system provided the coupling products in good yields; however, aliphatic substrates typically resulted in poor conversions. Extensive tests of the reaction scope revealed that the transposition of the substituents between the reaction partners can have a substantial effect on the yield of the coupling product in otherwise complementary reactions, which highlights the importance of the judicious choice of starting materials for this particular reaction. [ABSTRACT FROM AUTHOR]

Two series of asymmetric ferrocene diphosphines, namely the dppf-type ligands R 2 PfcPPh 2 (protected as BH 3 adducts; fc = ferrocene-1,1′-diyl) and their semi-homologous counterparts R 2 PfcCH 2 PPh 2 (both in free and BH 3 -protected form), with diverse PR 2 groups (R = cyclohexyl, isopropyl and tert -butyl), were prepared and further converted into the respective phosphine selenides, R 2 P(Se)fcP(Se)Ph 2 and R 2 P(Se)fcCH 2 P(Se)Ph 2 , which were in turn used to evaluate the electronic properties of these diphosphines through 1 J SeP coupling constants. When reacted with [PdCl 2 (MeCN) 2 ] or [PdCl 2 (cod)] (cod = cycloocta-1,5-diene), the dppf-type ligands exclusively afforded the chelate complexes [PdCl 2 (R 2 PfcPPh 2 -κ 2 P , P ′)], whereas the more flexible, homologous ligands produced mixtures mainly containing the similar chelate complexes [PdCl 2 (R 2 PfcCH 2 PPh 2 -κ 2 P , P ′)] and the P , P ′-bridged dimers [PdCl 2 (μ(P,P′)-R 2 PfcCH 2 PPh 2 )]2. [ABSTRACT FROM AUTHOR]

[1′-(Diphenylphosphino)ferrocenyl]methylamine ( 1 ) reacts with Ph 2 PH/(CH 2 O) x or [Ph 2 P(CH 2 OH) 2 ]Cl to give mixtures of Ph 2 PfcCH 2 NHCH 2 PPh 2 and Ph 2 PfcCH 2 N(CH 2 PPh 2 ) 2 in which the triphosphine dominates (fc = ferrocene-1,1′-diyl). To avoid unwanted two-fold phosphinomethylation, the amine group in 1 was alkylated. As expected, the reaction of the N -methyl analogue Ph 2 PfcCH 2 NHMe ( 5 ), obtained by reductive methylation of the aldehyde Ph 2 PfcCHO, with [Ph 2 P(CH 2 OH) 2 ]Cl, only led to the diphosphine Ph 2 PfcCH 2 N(Me)CH 2 PPh 2 ( 6 ). The diphosphine was structurally characterized and further reacted with [PdCl 2 (MeCN) 2 ] and [PdCl(Me)(cod)] (cod = η 2 :η 2 -cycloocta-1,5-diene), affording the respective trans -chelate complexes [PdCl(X){Ph 2 PfcCH 2 N(Me)CH 2 PPh 2 -κ 2 P , P ′}] ( 7a : X = Cl; 7b : X = Me), which were also structurally authenticated by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The development of a practical synthesis of 1′-(diphenylphosphino)-1-aminoferrocene (2) and its P-borane adduct (2B) allowed the facile preparation of 1′-(diphenylphosphino)-1-isocyanoferrocene (1). This compound combining two specific soft-donor moieties was studied as a ligand for univalent Group 11 metal ions. The reactions of 1 with AgCl at 1 : 1 and 2 : 1 molar ratios only led to the coordination polymer [Ag2(μ-Cl)2(μ(P,C)-1)]n (6), while those with Ag[SbF6] provided the dimer [Ag2(Me2CO-κO)2(μ(P,C)-1)2][SbF6]2 and the quadruply-bridged disilver complex [Ag2(μ(P,C)-1)4][SbF6]2 (8), respectively. Addition of 1 to [AuCl(tht)] (tht = tetrahydrothiophene) afforded the mono- and the digold complex, [AuCl(1-κP)] (9) and [(μ(P,C)-1)(AuCl)2] (10), depending on the reaction stoichiometry. Finally, the reaction of 1 with [Au(tht)2][SbF6] or halogenide removal from 9 with AgNTf2 led to cationic dimers [Au2(μ(P,C)-1)2]X2 (11, X = SbF6 (a) or NTf2 (b)). Catalytic tests in the Au-mediated isomerization of (Z)-3-methylpent-2-en-4-yn-1-ol to 2,3-dimethylfuran revealed that 11a and 11b are substantially less catalytically active than their analogues containing 1′-(diphenylphosphino)-1-cyanoferrocene as the ligand, most likely due to a stronger coordination of the isonitrile moiety, which prevents dissociation of the dimeric complexes into catalytically active monomeric species. [ABSTRACT FROM AUTHOR]

Catalytic cyclotrimerization routes to symmetrical [9]helical indenofluorene were explored by using different transition–metal complexes and thermal conditions. Depending on the reaction conditions, the cyclotrimerizations were accompanied by dehydro‐Diels–Alder reaction giving rise to another type of aromatic compounds. Structures of both symmetrical [9]helical cyclotrimerization product as well as the dehydro‐Diels–Alder product were confirmed by single‐crystal X‐ray diffraction analyses. Limits of enantioselective cyclotrimerization were assessed as well. DFT calculations shed light on the reaction course and the origin of diminished enantioselectivity. [ABSTRACT FROM AUTHOR]

A new cyclam-based ligand bearing two methylene(2,2,2-trifluoroethyl)phosphinate pendant arms was synthesized and its coordination behaviour towards selected divalent transition metal ions [Co(II), Ni(II), Cu(II), Zn(II)] was studied. The ligand was found to be very selective for the Cu(II) ion according to the common Williams–Irving trend. Complexes with all the studied metal ions were structurally characterized. The Cu(II) ion forms two isomeric complexes; the pentacoordinated isomer pc-[Cu(L)] is the kinetic product and the octahedral trans-O,O′-[Cu(L)] isomer is the final (thermodynamic) product of the complexation reaction. Other studied metal ions form octahedral cis-O,O′-[M(L)] complexes. The complexes with paramagnetic metal ions showed a significant shortening of 19F NMR longitudinal relaxation times (T1) to the millisecond range [Ni(II) and Cu(II) complexes] or tens of milliseconds [Co(II) complex] at the temperature and magnetic field relevant for 19F magnetic resonance imaging (MRI). Such a short T1 results from a short distance between the paramagnetic metal ion and the fluorine atoms (∼6.1–6.4 Å). The complexes show high kinetic inertness towards acid-assisted dissociation; in particular, the trans-O,O′-[Cu(L)] complex was found to be extremely inert with a dissociation half-time of 2.8 h in 1 M HCl at 90 °C. Together with the short relaxation time, it potentially enables in vitro/in vivo utilization of the complexes as efficient contrast agents for 19F MRI. [ABSTRACT FROM AUTHOR]

Altering the donor properties of phosphane ligands through substituent variation is an established tool in coordination chemistry and catalysis. This contribution describes the synthesis of two new hybrid donors (L) combining 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphaadamantane‐8‐yl (PCg) and nitrile donor groups at different molecular scaffolds, viz. ferrocene‐1,1′‐diyl (fc) and 1,2‐phenylene. These ligands were used to prepare dimeric Au(I) complexes [Au2(μ(P,N)‐L)2][SbF6]2, which were evaluated as silver‐free, preformed catalysts in Au‐mediated cycloisomerization of (Z)‐3‐methylpent‐2‐en‐4‐yn‐1‐ol to 2,3‐dimethylfuran. The catalyst featuring the ferrocene‐based ligand, viz. [Au2(μ(P,N)‐CgPfcCN)2][SbF6]2, showed the best catalytic performance at low catalyst loading (0.5 or 0.15 mol.%), which exceeded that of its diphenylphosphanyl analog [Au2(μ(P,N)‐Ph2PfcCN)2][SbF6]2 studied earlier and the prototypical Au(I) precatalyst [Au(PPh3)(MeCN)][SbF6]. [ABSTRACT FROM AUTHOR]

Two homologous ferrocene phosphanylcarboxylic acids, viz., 1'-[(diphenylphosphanyl)methyl]ferrocene-1-carboxylic acid (HL1) and [1'-(diphenylphosphanyl)ferrocenyl]acetic acid (HL2), were synthesized and studied as ligands in PdII complexes. The addition of these hybrid donors to [PdCL2(MeCN)2] led to the bis-phosphane complexes trans-[PdCL2(HL1-κP)2] and trans-[PdCL2(HL2-κP)2]. In contrast, the reactions of HL1 and HL2 with the PdII acetylacetonate (acac) complexes [(LYC)Pd(acac)], where LYC = 2-[(dimethylamino-κN)methyl]phenyl-κC1 (LNC) and 2-[(methylthio-κS)methyl]phenyl-κC1 (LSC), proceeded under proton transfer and replacement of the acac ligand, giving rise to O,P-bridged phosphanylcarboxylate dimers [LYCPd(μ(P,O)- L1)]2 and molecular chelates [LYCPd(L2-κ2O,P)]2, respectively. The analogous reactions involving 1'-(diphenylphosphanyl)-1-ferrocenecarboxylic acid (Hdpf) provided the macrocyclic tetramer [LNCPd(μ(P,O)-dpf)]4 and the dimer [LSCPd(μ(P,O)-dpf)]2. The reactions of HL1 with [Pd(acac)2] only led to an ill-defined, insoluble material, whereas those with HL2 produced a separable mixture of the bis-chelate complexes trans-[Pd(L2-κ2O,P)2], cis- [Pd(L2-κ2O,P)2], and [Pd(acac)(L2-κ2O,P)]. [ABSTRACT FROM AUTHOR]

The enantioselective amination of Morita–Baylis–Hillman carbonates with silylated derivatives of tert-butylhydroxycarbamates using β-isocupreidine as an organocatalyst was investigated. The corresponding products were obtained in good yields with high enantioselectivities. The scope and limitations of the reported protocol were explored, and representative transformations of the adducts toward heterocyclic compounds were highlighted. [ABSTRACT FROM AUTHOR]

Phosphanylferrocene donors bearing polar guanidinium substituents, namely acylguanidinium chloride, [Ph2PfcCONHC(NH2)NH2]Cl ( 1), and amidoguanidinium chloride, [Ph2PfcCONHCH2CH2NHC(NH2)NH2]Cl ( 2; fc = ferrocene-1,1′-diyl), have been prepared and characterized. As functional phosphane donors, they were employed in the synthesis of PdII complexes bearing 2-[(dimethylamino)methyl-κ N]phenyl-κ C1 (LNC) and η3-allyl supporting ligands, [(LNC)PdCl(L-κ P)] and [(η3-C3H5)PdCl(L-κ P)] (L = 1 and 2), respectively. These defined complexes as well as their surrogates generated in situ from the respective palladium(II) precursor and the phosphanylferrocene ligand were evaluated as catalysts for the coupling of boronic acids with acyl chlorides to give ketones in an aqueous biphasic system. The coupling reaction proceeded best with a simple catalyst formed from Pd(OAc)2 and ligand 2, which (at 0.2 mol-% Pd loading) produced substituted benzophenones from benzoyl chlorides and benzeneboronic acids in very good yields. These yields could then be further improved by a proper choice of the reaction partners. Analogous reactions involving aliphatic substrates generally afforded lower yields. [ABSTRACT FROM AUTHOR]

A polar phosphanylferrocene donor equipped with a hydrophilic guanidinium pendant, Ph2PfcCH2NHC(NH)NH2 ·HCl ( 1·HCl; fc = ferrocene-1,1′-diyl), has been prepared from the corresponding amine hydrochloride, Ph2PfcCH2NH2 ·HCl ( 2·HCl), and studied as a ligand for PdII. The reactions of 1·HCl with [PdCl2(MeCN)2] in 1:1 and 1:2 Pd/ligand ratios led to an unexpected zwitterionic complex, [PdCl3( 1H-κ P)] ( 3), and the expected bis(phosphane) complex, trans-[PdCl2( 1H-κ P)2]Cl2 ( 4), which were structurally characterized. The defined and air-stable solvated complex 3·Me2CO and the in situ generated Pd(OAc)2/ 1·HCl system were found to be active catalysts for the Suzuki-Miyaura cross-coupling of anionic triolborates with aryl bromides, giving the corresponding biphenyls. These reactions, which do not require the presence of an additional base, were advantageously performed in aqueous ethanol, and the coupling products were isolated in good to excellent yields. [ABSTRACT FROM AUTHOR]

Three polymorphic modifications of bis( N -phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis( N -phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313 K, belongs to the monoclinic space group Cc ( a = 6.2560(2) Å, b = 18.6920(3) Å, c = 18.2980(5) Å, β = 96.249(1)°, V = 2127.0(1) Å 3 , Z = 4, R = 0.0314 for 4738 observed reflections). The centrosymmetric bis( N -phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298 K and belongs to the monoclinic space group P 2 1 / n ( a = 6.1335(3) Å, b = 11.7862(6) Å, c = 14.5962(8) Å, β = 95.728(2)°, V = 1049.90(9) Å 3 , Z = 4, R = 0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis( N -phenylbiguanidium(1+)) oxalate (III) ( a = 6.1083(2) Å, b = 11.3178(5) Å, c = 14.9947(5) Å, β = 93.151(2)°, V = 1035.05(8) Å 3 , Z = 4, R = 0.0345 for 2367 observed reflections and a temperature of 110 K), which also belongs to the monoclinic space group P 2 1 / n . The crystal structures of the three characterized phases are generally based on layers of isolated N -phenylbiguanidium(1 +) cations separated by oxalate anions and interconnected with them by several types of N-H ... O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90 K up to a temperature near the melting point of each crystal. The bis( N -phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147 K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range. [ABSTRACT FROM AUTHOR]

Ferrocene P,N-ligands have been extensively studied due to their favorable catalytic properties. This contribution focuses on a pair of new, isomeric ferrocene phosphinoamines, FcNHCH 2 CH 2 PPh 2 (1) and FcN(Me)CH 2 PPh 2 (2), which were prepared from aminoferrocene, converted to the respective phosphine selenides (1-Se and 2-Se) and further studied as ligands in Pd(II) complexes containing the 2-(dimethylamino-κ N)phenyl-κ C 1 auxiliary (LNC) ligand. Thus, cleavage of the dimeric precursor [(LNC)Pd(μ-Cl)] 2 with the phosphinoamines afforded the corresponding phosphine complexes [(LNC)PdCl(1 -κ P)] (5) and [(LNC)PdCl(2 -κ P)] (6) with trans -P,N configuration. The subsequent removal of the chloride ligand with AgClO 4 from 5 produced the cationic bis-chelate complex [(LNC)PdCl(1 -κ2 P,N)]ClO 4 (7), whereas an analogous reaction with 6 gave no defined product. The phosphinoamines and their complexes were characterized by elemental analysis and common spectroscopic methods, and the crystal structures of 1, 2 , and 7 were determined by single-crystal X-ray diffraction analysis. A cyclic voltammetry study, supported by DFT calculations, revealed that the primary electrochemical oxidation of these compounds occurs at the ferrocene unit. [ABSTRACT FROM AUTHOR]

Acylation of 1′-(diphenylphosphino)-1-(aminocarbonyl)ferrocene, Ph 2 PfcCONH 2 ( 1 ; fc = ferrocene-1,1′-diyl), afforded a series of acyl-ureas including Ph 2 PfcCONHCONHEt ( 1a ), Ph 2 PfcCONHCONHPh ( 1b ), and Ph 2 PfcCONHCONMe 2 ( 1c ) as well as the acetyl derivative Ph 2 PfcCONHAc ( 1d ). Compounds 1a-d were converted to the corresponding phosphine oxides ( 2a-d ) and further examined as ligands in Pd(II) complexes. The reactions of 1a-d with [PdCl 2 (cod)] (cod = cycloocta-1,5-diene) at a 2:1 ligand-to-metal ratio gave the bis(phosphine) complexes [PdCl 2 (L-κ P ) 2 ] ( 3a-d ; L = 1a-d ), whereas the reactions with [Pd(L NC )Cl] 2 (L NC = [2-(dimethylamino-κ N )methyl]phenyl-κ C 1 ) produced the bridge-cleavage products, [PdCl(L NC )(L-κ P )] ( 4a-d ). Removal of the Pd-bound halide from 4a-d with Ag[SbF 6 ] furnished the corresponding cationic bis-chelate complexes [Pd(L NC )(L-κ 2 O,P )][SbF 6 ] ( 5a-d ). All compounds were characterized by NMR and IR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. The crystal structures of 1a , 2a-c , 3a ·2CHCl 3 , 3b ·2CHCl 3 , 3d ·2CHCl 3 , 4a ·3CHCl 3 , 4b ·2.5CHCl 3 , 5a ·CHCl 3 , 5b ·2CH 2 Cl 2 , and 5d were determined by single-crystal X-ray diffraction analysis, which revealed that the hydrogen-bonded arrays formed in the crystals of free ligands are often preserved in the structures of their complexes. [ABSTRACT FROM AUTHOR]

The reaction of [1′-(diphenylphosphino)ferrocenyl]methylamine (1), generated in situ from its hydrochloride and triethylamine, with 2-sulfobenzoic anhydride afforded an anionic phosphino-amide, which was isolated as a triethylammonium salt, Ph2PfcCH2NHCOC6H4SO3(HNEt3) (2; fc = ferrocene-1,1′-diyl). A similar reaction of 1 with phthalic anhydride only furnished the salt (Ph2PfcCH2NH3)[C6H4CO2H(CO2)]. When it was reacted with [PdCl2(MeCN)2] and [LNCPd(μ-Cl)]2 (LNC = 2-[(dimethylamino-κN)methyl]phenyl-κC1), compound 2 gave rise to the bis-phosphine complex [PdCl2(2-κP)2] and the bridge-cleavage product [LNCPdCl(2-κP)], respectively. An analogue of the latter complex containing 2′-amino-[1,1′-biphenyl]-2-yl-κ2N,C2 as the auxiliary chelating ligand, compound 8, was prepared in a similar manner from 2 and the respective Pd precursor. Finally, the reaction of 2 with [LNCPd(acac)] proceeded with the replacement of the acetylacetonate ligand (acac), affording a dipalladium complex featuring two phosphinosulfonate anions as the O,P-bridges, [LNCPd(μ(P,O)-Ph2PfcCH2NHCOC6H4SO3)]2, which was structurally characterized by single-crystal X-ray diffraction analysis. All of these Pd(II) complexes, especially compound 8, formed active catalysts for Pd-mediated cross-coupling of aromatic boronic acids with benzoyl chlorides to produce substituted benzophenones in toluene (benzene)–water biphasic mixtures. This particular coupling reaction was employed during the preparation of 4′-chloro-4-hydroxybenzophenone, which was in turn converted to fenofibrate, a generic drug widely used to reduce cholesterol levels in blood. [ABSTRACT FROM AUTHOR]

1′-(Aminomethyl)-1-(diphenylphosphino)ferrocene ( 1 ) reacts with [Cu(MeCN) 4 ][BF 4 ] in a 2:1 molar ratio to afford the chelate complex [Cu( 1 -κ 2 N,P ) 2 ][BF 4 ] ( 2 ). A similar reaction of 1 with copper(I) chloride furnished an unexpected mixed-valence Cu(I)/Cu(II) octacopper complex, [Cu 4 (μ(P,N)- 1 ) 2 (μ-Cl) 5 Cl( 1 H-κ P )(H 2 O)] 2 ( 3 ), comprising P,N-coordinated 1 and chloride ions as the bridging ligands, and N -protonated phosphinoamine 1 H + as a monodentate phosphine donor. The structures of 2 ·AcOEt and 3 ·10CHCl 3 were determined by single-crystal X-ray diffraction analysis, and the redox behavior of 2 was examined by voltammetric techniques. [ABSTRACT FROM AUTHOR]

Removal of the chloride ligand from [AuCl( 1-κ P)] ( 2) containing a P-monodentate 1′-(diphenylphosphanyl)-1-cyanoferrocene ligand ( 1), by using silver(I) salts affords cationic complexes of the type [Au( 1)]X, which exist either as cyclic dimers [Au( 1)]2X2 ( 3 a, X=SbF6; 3 c, X=NTf2) or linear coordination polymers [Au( 1)] nX n ( 3 a′, X=SbF6; 3 b′, X=ClO4), depending on anion X and the isolation procedure. As demonstrated for 3 a′, the polymers can be readily cleaved by the addition of donors, such as Cl−, tetrahydrothiophene (tht) or 1, giving rise to the parent compound 2, [Au(tht)( 1-κ P)][SbF6] ( 5 a) or [Au( 1-κ P)2][SbF6] ( 4 a), respectively, of which the last two compounds can also be prepared by stepwise replacement of tht in [Au( 1-κ P)2][SbF6]. The particular combination of a firmly coordinated (phosphane) and a dissociable (nitrile) donor moieties renders complexes 3/3′ attractive for catalysis because they can serve as shelf-stable precursors of coordinatively unsaturated AuI fragments, analogous to those that result from the widely used [Au(PR3)(RCN)]X catalysts. The catalytic properties of the Au- 1 complexes were evaluated in model annulation reactions, such as the synthesis of 2,3-dimethylfuran from ( Z)-3-methylpent-2-en-4-yn-1-ol and oxidative cyclisation of alkynes with nitriles to produce 2,5-disubstituted 1,3-oxazoles. Of the compounds tested ( 2, 3 a′, 3 b′, 3 a, 4 a and 5 a), the best results were consistently achieved with dimer 3 c, which has good solubility in organic solvents and only one firmly bound donor at the gold atom. This compound was advantageously used in the key steps of annuloline and rosefuran syntheses. [ABSTRACT FROM AUTHOR]

An amidosulfonate-tagged phosphinobiphenyl, viz triethylammonium 2-(dicyclohexylphosphino)-4′-{[(sulfonatomethyl)amino]carbonyl}biphenyl ( 3 ), was prepared in two steps from 2-(dicyclohexylphosphino)biphenyl-4′-carboxylic acid and fully characterized including the crystal structure determination. As a highly polar phosphine ligand, compound 3 was employed in the Pd-catalyzed Suzuki–Miyaura cross-coupling of N -Boc protected 4-bromo and 4-chlorophenylalanine with aromatic boronic acids to afford the corresponding biphenyls in aqueous N,N -dimethylformamide or pure water. The coupling was demonstrated to proceed very well and without the loss of the Boc protecting group when the bromo-substituted substrate is reacted in the presence of 1 mol.% of Pd/ 3 catalyst in water at 40 °C. Reactions with boronic acids bearing electron-withdrawing substituents and, mainly, those with the less reactive chlorophenylalanine substrate required slightly higher reaction temperature and more catalyst to achieve similar results. [ABSTRACT FROM AUTHOR]

A phosphinoferrocene betaine, N-{[1′-(diphenylphosphino)ferrocenyl]methyl}-N,N-dimethyl-3-sulfo-1-propanaminium, inner salt, Ph2PfcCH2NMe2(CH2)3SO3 (2; fc = ferrocene-1,1′-diyl), was prepared by alkylation of Ph2PfcCH2NMe2 (1) with 1,3-propanesultone, and was studied as a ferrocenylmethylation agent. The treatment of 2 with NaOH in hot water–dimethyl sulfoxide produced phosphinoalcohol Ph2PfcCH2OH (3) in a 64% yield, whereas a similar reaction with MeONa in dimethylsulfoxide–methanol furnished the corresponding ether, Ph2PfcCH2OMe (4), in a 47% yield. In subsequent experiments, betaine 2 was employed in the synthesis of phosphinoferrocene sulfones, Ph2PfcCH2SO2R, where R = Me (6a), Ph (6b), and 4-tolyl (6c). Compounds 6a–c and some by-products of the ferrocenylmethylation reactions, namely alcohol 3, 1′-(diphenylphosphino)-1-methylferrocene (5), and 1-{[diphenyl(2,4-cyclopentadien-1-ylidene)phosphoranyl]methyl}-1′-(diphenylphosphino)ferrocene (7) structurally characterised. Reactions of 6a as the representative with ZnX2/NaX (X = Br and I) afforded unique coordination polymers [ZnNaX3(6a)(CH3OH)]n featuring tetrahedral Zn(ii) and octahedral Na(i) centres bridged by halide ions, solvating methanol and the sulfone ligands. The reaction of 6a with ZnBr2/KBr produced an analogous product, [ZnKBr3(6a)(CH3OH)]n, while that with ZnBr2/LiBr furnished a different, pseudodimeric complex [Zn2Li2Br6(6a)2(CH3OH)4(H2O)]·CH3OH, featuring tetrahedrally coordinated Zn(ii) and Li(i) centres bridged by 6a. Reactions of 6a with ZnBr2/MBr (M = Rb, Cs) and NaCl/ZnCl2 did not yield similar products because of an easy precipitation (low solubility) of the respective alkali metal halides. [ABSTRACT FROM AUTHOR]