Synthesis of Zwitterionic Group 14 Centered Complexes: Traditional Coordination and Unusual Insertion Chemistry

At the limits of bisphosphonio-substituted stannylenes

Donor stabilization of Sn(II) and Pb(II) halides with 1,1'-ferrocenylene bridged bisphosphanes has been explored for Fe(C5H4P(C6H5)2)2 (dppf), and Fe(C5H4PH(C4H9))2. These bisphosphanes are reacted with SnBr2 and PbCl2 with and without additional Lewis acid (AlCl3) forming acyclic and cyclic donor adducts from which the latter represent bisphosphoniotetrylenes. Since dynamic exchange in solution is observed, characterization includes solution and solid-state NMR in addition to SC-XRD, amended by DFT calculations.

Synthesis and Reactivity of Fluorenyl-Based Germanium(II) Compounds

We present the synthesis of alkyl-substituted germylenes GeFlu2, Ge(FluTMS)2, and FluTMSGeCl (Flu = 9H-fluorenyl, FluTMS = 9-trimethylsilyl-9H-fluorenyl) using bulky fluorenyl ring systems and modifications of that. GeFlu2 can only be crystallized as its three-membered ring trimer, whereby the reaction is accompanied by the formation of several byproducts, such as [Li(THF)4][Ge(Ge3Flu7H)]. These results led to the modification of the fluorenyl framework by substitution the one H atom in the 9-position by a TMS group. With the synthesis of the corresponding Li salt LiFluTMS, Ge(FluTMS)2 could be isolated in good yields in a further reaction. The homoleptic Ge(FluTMS)2 is found in its crystalline form as a monomer and thus belongs to the series of monomeric alkyl-substituted germylenes. Also, the corresponding monoalkyl-substituted halogenido germylene was isolated as a four-membered ring tetramer [FluTMSGeCl]4 during an unselective reaction. However, FluTMSGeCl undergoes significant stabilization through the formation of the monomeric phosphane adduct FluTMSGeCl·PEt3, which greatly increases the selectivity of the reaction. During further reactions of Ge(FluTMS)2 with a GeBr solution (toluol/nPr3P), more impressions of the reactivity of Ge(I)X solutions with germylenes were achieved, showing that those germylenes take part in the disproportionation reaction of metastable Ge(I) solutions to give oxidized Ge(IV) compounds like (FluTMS)2GeBr2.

A comparison of the coordination behaviour of R2PCH2BMe2 (R = Me vs. Ph) ambiphilic ligands with late transition metals

A new synthesis that avoids the use of Me2PH is reported for (Me2PCH2BMe2)2, and this method was extended to the synthesis of (Ph2PCH2BMe2)2. The ligand precursor (Me2PCH2BMe2)2 did not react with [{M(μ-Cl)(cod)}2] (cod = 1,5-cyclooctadiene; M = Ir and Rh) or [PtCl2(cod)] at room temperature. However, after 12-48 hours at 65-70 °C, these reactions afforded (a) [Ir(cod)(μ-Cl)(Me2PCH2BMe2)] (1), (b) an equilibrium mixture of (Me2PCH2BMe2)2, [{Rh(μ-Cl)(cod)}2] and [Rh(cod)(μ-Cl)(Me2PCH2BMe2)] (2), and (c) cis-[Pt(μ-Cl)2(Me2PCH2BMe2)2] (3), respectively. By contrast, reactions between the phenyl-substituted analogue, (Ph2PCH2BMe2)2, and [{M(μ-Cl)(cod)}2] (cod = 1,5-cyclooctadiene; M = Ir and Rh) proceeded over the course of 1 hour at 20 °C to generate [M(cod)(μ-Cl)(Ph2PCH2BMe2)] (M = Ir (4) and Rh (5)), indicative of room temperature (Ph2PCH2BMe2)2 dissociation. Room temperature reactions of (Ph2PCH2BMe2)2 with [{Rh(μ-Cl)(coe)2}2] (coe = cyclooctene) using a 1 : 1 or 3 : 1 stoichiometry also afforded [{Rh(coe)(μ-Cl)(Ph2PCH2BMe2)}2] (6) or [RhCl(Ph2PCH2BMe2)3] (7), respectively, where the latter is a borane-appended analogue of Wilkinson's catalyst, and reactions of (Ph2PCH2BMe2)2 with [PtX2(cod)] (X = Cl or Me) yielded cis-[Pt(μ-Cl)2(Ph2PCH2BMe2)2] (8) and cis-[PtMe2(Ph2PCH2BMe2)2] (9). Compounds 1-9, (Me2PCH2BMe2)2 and (Ph2PCH2BMe2)2 were crystallographically characterized. In compounds 1-5 and 8, each chloride co-ligand is coordinated by the borane of an R2PCH2BMe2 ligand. Additionally, in the solid state structure of 6, each bridging chloride ligand interacts weakly with a pendent borane, and in 7, the chloride ligand is tightly coordinated to the borane of one Ph2PCH2BMe2 ligand and weakly coordinated to the borane of a second Ph2PCH2BMe2 ligand. By contrast, both boranes in 9 (and one of the three boranes in 7) are non-coordinated.

Phosphine-Stabilized Pnictinidenes

The reaction of the intramolecular germylene‐phosphine Lewis pair (o‐PPh₂)C₆H₄GeAr* (1) with Group 15 element trichlorides ECl₃ (E=P, As, Sb) was investigated. After oxidative addition, the resulting compounds (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)ECl₂ (2: E=P, 3: E=As, 4: E=Sb) were reduced by using sodium metal or LiHBEt₃. The molecular structures of the phosphine‐stabilized phosphinidene (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)P (5), arsinidene (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)As (6) and stibinidene (o‐PPh₂)C₆H₄(Ar*)Ge(Cl)Sb (7) are presented; they feature a two‐coordinate low‐valent Group 15 element. After chloride abstraction, a cyclic germaphosphene [(o‐PPh₂)C₆H₄(Ar*)GeP] [B(C₆H₃(CF₃)₂)₄] (8) was isolated. The ³¹P NMR data of the germaphosphene were compared with literature examples and analyzed by quantum chemical calculations. The phosphinidene was treated with [iBu₂AlH]₂, and the product of an Al−H addition to the low‐valent phosphorus atom (o‐PPh₂)C₆H₄(Ar*)Ge(H)P(H)Al(C₄H₉)₂ (9) was characterized.

Stabilization of bis(chlorogermyliumylidene)s within bifunctional PNNP ligand frameworks and their reactivity studies

The diiminodiphosphine (L_im) and diaminodiphosphines (l-NH and l-NMe) with a bifunctional PNNP ligand framework have been employed to host two [GeCl]⁺ units leading to the formation of bis(chlorogermyliumylidene) 1-3, respectively. The synthetic route involves a 1 : 2 stoichiometric reaction between the PNNP ligand and GeCl₂·dioxane and the subsequent addition of two equivalents of chloride abstracting agent. Compound 1 is unstable towards coordinating solvents and Lewis bases, resulting in the displacement of the GeCl unit and the formation of rearranged products 4 and 5. However, the diaminodiphosphine coordinated Ge(ii) bis(monocation)s 2 and 3 proved to be stable and revealed their electrophilic behaviour towards the Lewis bases studied.

Synthesis and characterization of a novel antibacterial material containing poly(sulfobetaine) using reverse atom transfer radical polymerization

A novel antibacterial agent was synthesized using 2-(dimethylamino)ethyl methacrylate (DM) and sodium 3-chloro-2-hydroxypropane sulfonate (CHPS). It was characterized by Fourier transform infrared spectroscopy (FTIR), NMR Spectroscopy (¹H NMR), and X-ray photoelectron spectroscopy (XPS). This new agent DMCHPS was then grafted onto a polyurethane (PU) substrate via surface-initiated reverse atom transfer radical polymerization (SI-RATRP). The modified PU was characterized by FTIR and XPS. The hydrophilic properties of the PU surface before and after the incorporation of DMCHPS were determined by static contact angle (SCA) measurements. The results showed that the hydrophilicity of the PU surface after the modification was remarkably improved. MIC tests and bacterial adhesion confirmed that modified PU has good antibacterial properties. Protein adsorption experiments show that the material has a certain ability to resist pollution. Furthermore, the high survival rate of HEK293 human embryonic kidney cells shows that the modified PU has a potential use as a medicinal material.

A novel antibacterial agent was synthesized using 2-(dimethylamino)ethyl methacrylate (DM) and sodium 3-chloro-2-hydroxypropane sulfonate (CHPS).

Reaction of stannylene phosphorus Lewis pairs with dichlorides of germanium, tin and lead - the formation of base stabilized stannyl stannylenes/germylenes and redox reaction with PbCl2

The reaction of intramolecular stannylene phosphorus Lewis pairs with heavier dichlorides of group 14 (GeCl2, SnCl2, PbCl2) is reported. Phosphine base stabilized stannyl germylenes/stannylenes were formed by the oxidative addition of an E-Cl bond to the stannylene tin atom (E = Ge, Sn). In solution, a dynamic equilibrium between two diastereomeric configurations was observed. With PbCl2 a redox reaction towards elemental lead and the dichlorinated tin(iv) compound was found. All compounds were characterized by X-ray diffraction, NMR spectroscopy and elemental analysis.

Different Complexation Behavior of P-Functionalized Ferrocene Derivatives Towards SnCl2 , SnCl4 and SnPh2 Cl2 : Auto-ionization and Redox-Type Reactions

The novel phosphonyl-substituted ferrocene derivatives [Fe(η(5) -Cp)(η(5) -C5 H3 {P(O)(O-iPr)2 }2 -1,2)] (Fc(1,2) ) and [Fe{η(5) -C5 H4 P(O)(O-iPr)2 }2 ] (Fc(1,1') ) react with SnCl2 , SnCl4 , and SnPh2 Cl2 , giving the corresponding complexes [(Fc(1,2) )2 SnCl][SnCl3 ] (1), [{(Fc(1,1') )SnCl2 }n ] (2), [(Fc(1,1') )SnCl4 ] (3), [{(Fc(1,1') )SnPh2 Cl2 }n ] (4), and [(Fc(1,2) )SnCl4 ] (5), respectively. The compounds are characterized by elemental analyses, (1) H, (13) C, (31) P, (119) Sn NMR and IR spectroscopy, (31) P and (119) Sn CP-MAS NMR spectroscopy, cyclovoltammetry, electrospray ionization mass spectrometry, and single-crystal as well as powder X-ray diffraction analyses. The experimental work is accompanied by DFT calculations, which help to shed light on the origin for the different reaction behavior of Fc(1,1') and Fc(1,2) towards tin(II) chloride.