Synthesis and Reactivity of [2]Ferrocenophanes with C−Ge and C−Sn Bridges

[n]Ferrocenophanes (n = 2, 3) with Nitrogen and Phosphorus in Bridging Positions

The in situ prepared dilithio derivative of the known species 1-bromo-1'-(trimethylsilylamino)ferrocene (1) reacted with tBuPCl2 to form the first example of a [2]ferrocenophane ([2]FCP) bridged by nitrogen and phosphorus (2). Sulfurization of 2 followed by column chromatography on silica gel gave the expected [2]FCP with a tBu(S)PN(SiMe3) bridging moiety (3a) and its desilylated counterpart with a tBu(S)PNH bridging moiety (3b). The molecular structure of 3b was determined by single-crystal X-ray analysis (α = 18.40(11)°). Using a common synthetic methodology, two new 1-amino-1'-bromoferrocene derivatives were prepared, one species with a PhCH2 (6a) and another with a tBuCH2 group (6b) on nitrogen. Dilithiation of 6a followed by addition of tBuPCl2 gave a mixture of three constitutional isomers: the targeted [2]FCP (7a), the 1,1'-disubstituted ferrocene derivative (tBuPH)(PhCH═N)fc (8a), and the [3]FCP bridged by a (NH)(CHPh)PtBu moiety (9a). NMR spectroscopy revealed that 8a is the precursor for 9a. The salt-metathesis reaction of the dilithio derivative of 6b with tBuPCl2 exclusively gave the 1,1'-disubstituted ferrocene derivative (tBuPH)(tBuCH═N)fc (8b), which does not isomerize to the respective [3]FCP. DFT calculations at the M06/6-311+G(d,p) level were used to better rationalize these unexpected results.

Synthesis of chelating diamido Sn(IV) compounds from oxidation of Sn(II) and directly from Sn(IV) precursors

Three dimethyltindiamides containing chelating diamide ligands were synthesised from the reaction of the dilithiated diamine and Me2SnCl2; [SnMe2(L1)] 1 (L1 = κ(2)-N(Dipp)C2H4N(Dipp)), [SnMe2(L2)] 2 (L2 = κ(2)-N(Dipp)C3H6N(Dipp)) and [SnMe2(L3)] 3 (L3 = κ(2)-N(Dipp)SiPh2N(Dipp)), Dipp = 2,6-(i)Pr2C6H3. Reaction of (L2)H2 with SnCl4 and NEt3 led to the formation of the diamidotin dichloride [SnCl2(L2)] 4 whereas reaction of (L1)H2 with SnCl4 and NEt3, or [Sn(L1)] with SnCl4, led to the exclusive formation of the amidotin trichloride [SnCl3{κ(2)-DippN(H)C2H4N(Dipp)}] 5. Reactions of [Sn(L1)] with sulfur and selenium formed [{Sn(L1)(μ-E)}2] (E = S 10 and Se )11. MeI reacted with N-heterocyclic stannylenes to generate the Sn(iv) addition products [Sn(Me)I(L1)] 12, [Sn(Me)I(L2)] 13, [Sn(Me)I(L3)] 14 and [Sn(Me)I(L4)] 15 (L4 = κ(3)-N(Dipp)C2H4OC2H4N(Dipp)), and subsequent reaction with AgOTf (OTf = OSO2CF3) generated the corresponding Sn(iv) triflates [Sn(Me)OTf(L1)] 16, [Sn(Me)OTf(L2)] 17 and [Sn(Me)OTf(L4)] 19 with [Sn(Me)OTf(L3)] 18 formed only as a mixture with unidentified by-products. All of the compounds were characterised by single crystal X-ray diffraction.

Sandwich complex-containing macromolecules: property tunability through versatile synthesis

Sandwich complexes feature unique properties as the physical and electronic properties of a hydrocarbon ligand or its derivative are integrated into the physical, electronic, magnetic, and optical properties of a metal. Incorporation of these complexes into macromolecules results in intriguing physical, electrical, and optical properties that were hitherto unknown in organic-based macromolecules. These properties are tunable through well-designed synthetic strategies. This review surveys many of the synthetic approaches that have resulted in tuning the properties of sandwich complex-containing macromolecules. While the past two decades have seen an ever-growing number of research publications in this field, gaps remain to be filled. Thus, we expect this review to stimulate research interest towards bridging these gaps, which include the insolubility of some of these macromolecules as well as expanding the scope of the sandwich complexes.

Synthesis, structure and a nucleophilic coordination reaction of Germanetellurones

A germylene germanetellurone adduct L(Cp)GeTe(GeCl₂), a pentafluorophenyl gold(i) germanethione and germaneselone compounds L(Me)GeE(AuC₆F₅) (E = S and Se) are herein reported.

Synthesis and reactivity of ferrocenyl functionalized Sn/S cages

Depending on the solvent used, the mono-stannylated FcSnCl(3) (1) reacts with Na(2)S to give ionic [Na(6)(Me(2)CO)(4)(OH(2))(6)] [(FcSn)(3)S(6)](2) (2), with a yet unprecedented thiostannate anion, or the adamantane-type Sn/S-cluster [(FcSn)(4)S(6)] (3). Complex 2 reacts readily with [Ni(acac)(2)], yielding the mixed-metallic complex [{Na(thf)(3.5)}(2){(FcSn)(8)Ni(3)S(16)}] x 2 THF (4 x 2 THF); the structures of 1-4 are discussed as well as Mössbauer spectra.

Strained metallocenophanes and related organometallic rings containing pi-hydrocarbon ligands and transition-metal centers

The structures, bonding, and ring-opening reactions of strained cyclic carbon-based molecules form a key component of standard textbooks. In contrast, the study of strained organometallic molecules containing transition metals is a much more recent development. A wealth of recent research has revealed fascinating nuances in terms of structure, bonding, and reactivity. Building on initial work on strained ferrocenophanes, a broad range of strained organometallic rings composed of a variety of different metals, pi-hydrocarbon ligands, and bridging elements has now been developed. Such strained species can potentially undergo ring-opening reactions to functionalize surfaces and ring-opening polymerization to form easily processed metallopolymers with properties determined by the presence of the metal and spacer. This Review summarizes the current state of knowledge on the preparation, structural characterization, electronic structure, and reactivity of strained organometallic rings with pi-hydrocarbon ligands and d-block metals.

Polyferrocenylsilane-Based Polymer Systems

The study of metallopolymers has blossomed into a mature field over the last few decades. Especially, polyferrocenylsilane (PFS) chemistry has taken a tremendous leap and continues to raise intense interest. Since the discovery of thermal ring-opening polymerization (ROP) of sila[1]ferrocenophanes, PFSs have been also accessed by anionic, cationic, transition-metal-catalyzed, and photolytic anionic ROP methodologies. A plethora of synthetic strategies have been devised, enabling access to a wide variety of copolymers, polyelectrolytes, and nanostructured materials. The distinctive physical properties and functions of many PFS-based polymers have been explored, leading to their apt exploitation in technical applications. Therefore, it is conceivable that PFS-related platforms might be indispensable nano-objects in the near future, as they stand on the verge of a new generation of sophisticated materials.

Synthesis and characterization of bis(ferrocenylcarboxylato)telluranes

A convenient route to the synthesis of the first bis(ferrocenyl carboxylato) telluranes has been developed. Reactions of 1,1,2,3,4,5,6-heptahydro-1,1-(dihydroxo)tellurane and 1,1,2,3,4,5-hexahydro-1,1-(dihydroxo)tellurophene with ferrocene carboxylic acid give 1,1,2,3,4,5,6-heptahydro-1,1-bis(ferrocenyl carboxylato)tellurane (3) and 1,1,2,3,4,5,-hexahydro-1,1-bis(ferrocenyl carboxylato)tellurophene (5), respectively. The X-ray structure of 3 shows that it contains a tellurium heterocycle (C5H10Te), present in a chair conformation, sandwiched between two ferrocene units with carboxylate groups acting as spacers. Compound 3 also exhibits modest second harmonic generation (SHG) efficiency. The electrochemical studies of 3 and 5 through cyclic voltammetry show only one oxidation wave, indicating the presence of independent redox centers leading to reversible single-step two-electron redox systems.Key words: tellurane, ferrocenylcarboxylate, SHG efficiency, electrochemistry.