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-κC 1, and LSC = 2-[(methylthio-κS)­methyl]­phenyl-κC 1, with 4 uniformly produced the bis-chelate complexes [(LNC)­Pd­(Ph2PfcSO3-κ2 O,P)] (7) and [(LSC)­Pd­(Ph2PfcSO3-κ2 O,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.

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)].

1-(N,N-Dimethylaminomethyl)-1′-(diphenylphosphanyl)ferrocene (1) was synthesized in good yield by lithiation of 1-bromo-1′-(diphenylphosphanyl)ferrocene and subsequent reaction with Eschenmoser's salt (dimethylmethylideneammonium iodide). Making use of an easily accessible, nontoxic starting material, this procedure represents a convenient alternative to the original synthetic protocol based on stepwise lithiation/functionalization of 1,1′-bis(tributylstannyl)ferrocene and reductive amination [M. E. Wright, Organometallics 1990, 9, 853–856]. Compound 1 has typical hybrid-donor properties. When reacted with [AuCl(tht)] (tht=tetrahydrothiophene), it afforded the expected AuI phosphane complex [AuCl(1-κP)] (2). An attempted removal of the chloride ligand from 2 with AgClO4 produced an ill-defined material formulated as Au(1)ClO4. The uncoordinated amine substituent reacted with traces of hydrogen chloride formed by slow decomposition typically occurring in solution. In this manner, complexes [AuCl(Ph2PfcCH2NHMe2)]Cl (3, fc=ferrocene-1,1′-diyl) and [AuCl(Ph2PfcCH2NHMe2)]ClO4 (4) were isolated from crystallizations experiments with 2 and Au(1)ClO4, respectively. On a larger scale, complex 3 was prepared easily from 2 and hydrogen chloride. The course of reactions between [PdCl2(cod)] (cod=cycloocta-1,5-diene) and 1 were found to depend on the ligand-to-metal ratio. Whereas the reaction with two equivalents of 1 afforded bis(phosphane) complex trans-[PdCl2(1-κP)2] (5), that of a Pd:P ratio 1:1 produced ligand-bridged dimer [(μ-1)PdCl2]2 (6). With hydrogen chloride, complex 6 reacted to afford zwitterionic complex [PdCl3(1H-κP)] (7), which was also formed when ligand 1 and [PdCl2(cod)] were allowed to react slowly by liquid-phase diffusion of their chloroform solutions. The compounds were characterized by spectroscopic methods (multinuclear NMR and ESI–MS), and the molecular structures of complex 2–4, 6⋅2CHCl3 and 7⋅1.5CHCl3 were determined by single-crystal X-ray diffraction analysis.

Mechanochemistry has proven to be an excellent sustainable, efficient and fast tool for the discovery of new crystal forms of old drugs.

Platinum(II) complexes [Pt(C^C*)(acac)], where C^C* = 3‐R‐1‐(phenyl‐κC2)‐1H‐benzimidazol‐2‐ylidene‐κC2 (R = Me, Ph) and acac = pentane‐2,4‐dionate, reacted with functionalized acetic acids YCH2CO2H (Y = NMe2, SMe and PPh2) with elimination of acetylacetone to produce the bis‐chelate complexes of the type [Pt(C^C*)(YCH2CO2)]. Whereas the Pt(II) precursor with the less bulky methyl substituent (R) gave rise to single products having trans‐C(NHC),Y geometry, its phenyl congener reacted less selectively, affording exclusively the product with trans‐S,C(Ph) configuration for Y = SMe and mixtures of cis and trans isomers for Y = NMe2 and PPh2. These observations were well reproduced by different DFT functionals at the double‐ξ level of theory, which suggested rather small energy differences between the geometric isomers. The photophysical measurements showed that complexes [Pt(C^C*)(YCH2CO2)] are emissive in the blue region (λem 460–490 nm) with photoluminescence quantum yields up to 36 % and emission lifetimes in the range of 3–5 µs.