Chiral C1-symmetric 2,2′:6′,2′′-terpyridine ligands: Synthesis,characterization, complexation with copper(II), rhodium(III) and ruthenium(II) ions and use of the complexes in catalytic cyclopropanation of styrene

Three new optically pure C₁-terpyridine ligands (L1–3) were prepared and the copper(II) complexes, of formula [Cu(L)Cl₂], the rhodium(III) complexes, of formula [Rh(L)Cl₃], and the ruthenium(II) complexes, of formula cis- or trans-[Ru(L)(X)Cl₂] (X = DMSO or CO), were synthesized. Structures of a chiral C₁-ligand, a copper complex, a rhodium complex and a ruthenium DMSO complex were analysed using X-ray crystal structure analysis. The copper, rhodium and ruthenium complexes were shown to be precursors of catalysts for cyclopropanation. Reaction of [Cu(L)Cl₂], [Rh(L)Cl₃] or cis- or trans-[Ru(L)(X)Cl₂] with AgOTf converted the complex to catalyst, which in the case of trans-[Ru(L)(CO)Cl₂] gave enantioselectivities of up to 67% ee for the cis-isomers of styrene cyclopropanes with t-butyl diazoacetate. Comparisons with C₂-analog of copper, rhodium and ruthenium catalysts were made.     

Rhodium(III)‐Catalyzed C?C and C?O Coupling of Quinoline N‐Oxides with Alkynes: Combination of C?H Activation with O‐Atom Transfer

[Cp*Rh^III]‐catalyzed C H activation of arenes assisted by an oxidizing N O or N N directing group has allowed the construction of a number of hetercycles. In contrast, a polar N O bond is well‐known to undergo O‐atom transfer (OAT) to alkynes. Despite the liability of N O bonds in both C H activation and OAT, these two important areas evolved separately. In this report, [Cp*Rh^III] catalysts integrate both areas in an efficient redox‐neutral coupling of quinoline N‐oxides with alkynes to afford α‐(8‐quinolyl)acetophenones. In this process the N O bond acts as both a directing group for C H activation and as an O‐atom donor.     

Photocatalytic properties of new cyclopentadienyl and indenyl rhodium(I) carbonyl complexes with water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) and tris(2-cyanoethyl)phosphine

Reactions of [(η⁵-R)Rh(CO)₂] (R = cp, ind) with water-soluble phosphines (L = 1,3,5-triaza-7-phosphaadamantane and tris(2-cyanoethyl)phosphine) give the new rhodium(I) complexes of the types [Rh(η⁵-cp)(CO)(PTA)] (1), [Rh(η⁵-cp)(CO)(P(CH₂CH₂CN)₃)] (2), [Rh(η⁵-ind)(CO)(PTA)] (3) and [Rh(η⁵-ind)(CO)(P(CH₂CH₂CN)₃)] (4) in isolated yields of 52-75%. All these compounds have been fully characterized by IR, ¹H, ³¹P{¹H} and ¹³C{¹H} NMR, FAB-MS spectroscopies and elemental analyses. Reactivity for the substitution of phosphine is greater for [(η⁵-ind)Rh(CO)(L)] comparing to [(η⁵-cp)Rh(CO)(L)] because of a flexibility of the indenyl ligand to undergo facile η⁵-η³ coordinative isomerizations. The obtained complexes are active catalyst precursors for the dehydrogenation of propan-2-ol, octane and cyclooctane under photoassisted conditions without any organic hydrogen transfer acceptors, giving TOFs of 26-56 using 3 as precatalyst.     

Chiral Phebox-rhodium complexes as catalysts for asymmetric direct aldol reaction

Chiral bis(oxazolinyl)phenyl-rhodium complexes act as catalysts in the combination of AgOTf for direct aldol reaction of ketones and aromatic aldehydes to give the corresponding β-hydroxyketones in high anti-selectivity and a good to high enantioselectivity up to 91% ee.     

含有1,2-二硫(硒、碲)碳硼烷的16和18电子体系CptRh化合物的合成及表征

有机半夹心结构过渡金属配位化学的研究是现代化学研究中十分活跃的一个领域[1,2].用一个6电子有机环戊二烯配体屏蔽过渡金属原子的一边,形成半夹心结构,而另一边与硫族元素配体结合形成各种结构的有机金属化合物[3～5].碳硼烷(H2C2B10H10)是由12个簇顶原子组成的球型化合物,其中2个碳原子上的氢具有一定的酸性,可与BuLi作用,形成Li2C2B10H10.元素硫(硒、碲)可定量地插入到Li-C键中,形成Li2E2C2B10H10(E=S,Se,Te,如图1).     

Reactions of half-sandwich rhodium(III) and iridium(III) compounds with pyridinethiolate ligands: Mono-, di-, and tri-nuclear complexes

Neutral trinuclear metallomacrocycles, [Cp^*RhCl(μ-4-PyS)]₃ (3) and [Cp^*IrCl(μ-4-PyS)]₃ (4) [Cp^* = pentamethylcyclopentadienyl, 4-PyS = 4-pyridinethiolate], have been synthesized by self-assembly reactions of [Cp^*RhCl₂]₂ (1) and [Cp^*IrCl₂]₂ (2) with lithium 4-pyridinethiolate, respectively. In situ reaction of complex 3 with three equivalent of lithium 4-pyridinethiolate resulted in [Cp^*Rh(μ-4-PyS)(4-PyS)]₃ (5) containing both skeleton and pendent 4-PyS groups. Chelating coordination of 2-pyridinethiolate broke down the triangular skeleton to give mononuclear metalloligands Cp^*Rh(2-PyS)(4-PyS) (6) and Cp^*Ir(2-PyS)(4-PyS) (7) [2-PyS = 2-pyridinethiolate], which could also be synthesized from Cp^*RhCl(2-PyS) (10) and Cp^*IrCl(2-PyS) (11) with lithium 4-pyridinethiolate. The coordination reactions of 6 with complexes 1 and 2 gave dinuclear complexes [Cp^*Rh(2-PyS)(μ-4-PyS)][Cp^*RhCl₂] (8) and [Cp^*Rh(2-PyS)(μ-4-PyS)][Cp^*IrCl₂] (9), respectively. Molecular structures of 3, 4, 6 and 11 were determined by X-ray crystallographic analysis. All the complexes have been well characterized by elemental analysis, NMR and IR spectra.     

Synthese und Kristallstruktur von Sr2Rh7P6

Synthesis and Crystal Structure of Sr₂Rh₇P₆ Single crystals of Sr₂Rh₇P₆ were obtained by reaction of the elements in molten lead at 1100 °C and investigated by X-ray methods. The compound crystallizes tetragonally (a = 11.080(2), c = 4.098(1) Å) and forms a crystal structure (P 4 2₁m; Z = 2) with ThCr₂Si₂ analogous units, which are linked with each other in a new way. Therefore the RhP₄ tetrahedra form bands of edge sharing chains parallel to [001] anstead of layers as in the ThCr₂Si₂ type structure. The arrangement enables a part of the P atoms to form short P–P distances of 2,26 Å and space for additional Rh atoms with a likewise distorted tetrahedral coordination of P atoms is obtained.     

Synthesis and DNA-binding properties of apoptosis-inducing cytotoxic half-sandwich rhodium(III) complexes with methyl-substituted polypyridyl ligands

Half-sandwich organorhodium(III) complexes of the type [(η⁵-C₅Me₅)RhCl(pp)] (CF₃SO₃) containing polypyridyl ligands (pp) represent a promising class of cytostatic agents. Replacement of the polypyridyl ligands of complexes 1 (pp = phen) and 6 (pp = dppz) by methyl-substituted derivatives in 2-5 (pp = 4-Mephen, 5-Mephen, 4,7-Me₂phen, 5,6-Me₂phen) and 7 (pp = Me₂dppz) leads to a significant improvement in their antiproliferative activity towards human MCF-7 and HT-29 cancer cells. For instance, the IC₅₀ value towards HT-29 cells decreases from 4.3 ± 0.2 μM for 6 to 0.98 ± 0.49 μM for complex 7. In contrast, no activity (IC₅₀ > 100 μM) was observed for the HOOC and n-BuNHCO substituted dppz complexes 8 and 9. UV/vis, CD and NMR spectra for mixtures of complexes 7-9 with CT DNA were in accordance with intercalation of the substituted dppz ligands between the base pairs of the double helix and direct evidence for this binding mode was also provided by a 2D NOESY study for complex 7 with the hexanucleotide d(5′-CGTCGG-3′). Each of the methyl-substituted phen complexes 2-5 is significantly more active towards immortalized HEK-293 cells (IC₅₀ values 0.40 ± 0.02 to 0.94 ± 0.02 μM) than towards the cancer cells. Flow cytometric measurements of DNA fragmentation in BJAB cells following an incubation period of 72 h with 1, 5 and 6 indicate that the complexes induce specific apoptotic cell death in the non-adherent lymphoma cells.