Stereoselectivity and chiral recognition in copper(I) olefin complexes with a chiral diamine

Monoanionic, Bis(pyrazolyl)methylborate [(Ph3B)CH(3,5-(CH3)2Pz)2)]- as a Supporting Ligand for Copper(I)-ethylene, cis-2-Butene, and Carbonyl Complexes

The monoanionic bidentate ligand [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂)]^- has been prepared from lithium bis(pyrazolyl)methanide and triphenylborane. This useful new ligand is closely related to the well-established bis(pyrazolyl)borate and bis(pyrazolyl)methane ligands but has key differences to both analogues as well. The ethylene, cis-2-butene, and carbon monoxide adducts [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂]Cu(L) (where L = C₂H₄, cis-CH₃HC═CHCH₃, and CO) have been prepared from [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂)]Li(THF), copper(I) triflate, and the corresponding coligand. These complexes have been characterized by NMR spectroscopy and X-ray crystallography. In all cases the bis(pyrazolyl) moiety is bound in κ²N fashion with the BPh₃ group rotated to sit over the metal center, sometimes coordinating to the metal via phenyl carbons as in [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂)]Li(THF) and [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂]Cu(CO) or simply hovering above the metal site as in [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂)]Cu(C₂H₄) and [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂)]Cu(cis-CH₃HC═CHCH₃). The ¹³C and ¹H resonances of the ethylene carbon and protons of [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂)]Cu(C₂H₄) appear at δ 81.0 and 3.71 ppm in CD₂Cl₂, respectively. The characteristic CO frequency for [(Ph₃B)CH(3,5-(CH₃)₂Pz)₂]Cu(CO) has been observed at υ̅ 2092 cm^-1 by infrared spectroscopy and is lower than that of free CO suggesting moderate M → CO π-back-donation. A detailed analysis of these complexes has been presented herein.

Rhodium diphosphite pincer complexes. Rare preferred in-plane olefin conformation in square-planar compounds

Square-planar ethylene rhodium derivatives bearing pincer diphosphite ligands have been prepared and characterized, they display a rare in-plane coordination which, based on DFT calculations, has been mainly attributed to steric effects.

Synthesis and properties of gold alkene complexes. Crystal structure of [Au(bipyoXyl)(η2-CH2CHPh)](PF6) and DFT calculations on the model cation [Au(bipy)(η2-CH2CH2)]+

Unprecedented 16-electron gold(i) olefin complexes of general formula [Au(bipy(R,R'))(eta(2)-olefin)](PF(6)) and [Au(2)(bipy(R,R'))(2)(mu-eta(2):eta(2)-diolefin)](PF(6))(2) (bipy(R,R') = 6-substituted-2,2'-bipyridine) have been prepared by reaction of dinuclear gold(III) oxo complexes [Au(2)(bipy(R,R'))(2)(mu-O)(2)](PF(6))(2) with the appropriate olefin. The X-ray crystal structures of two mononuclear complexes (olefin = styrene) show in-plane coordination of the olefin and a C[double bond, length as m-dash]C bond distance considerably lengthened with respect to the free olefin. The spectroscopic properties of the complexes are discussed and compared with those of analogous d(10) metal derivatives. Both structural and spectroscopic information indicate a substantial contribution of pi-back-donation to the Au-olefin bond in the three-coordinate species. Theoretical calculations carried out at the hybrid-DFT level on the model compound [Au(bipy)(eta(2)-CH(2)[double bond, length as m-dash]CH(2))](+) show excellent agreement with the experimental findings giving in addition an estimate of a pi-back-bonding contribution higher than that of the sigma-bonding.

Dual chirality control of palladium(ii) complexes bearing tropos biphenyl diamine ligands

Axial and center chirality of Pd complexes with tropos biphenyl secondary diamine ligands is shown to be controlled by chiral amide (R)-DABNTf, which can efficiently discriminate between two enantiomeric Pd complexes.

Highly stable olefin–Cu(i) coordination oligomers and polymers

Highly stable Cu(I)-olefin coordination oligomers and polymers have been successfully prepared and applied to construct metal-organic frameworks (MOFs) with interesting physical and chemical functions in recent years. In this review, we present the olefin-Cu(I) coordination oligomers and polymers and their novel physical properties. From structure to functions, particular emphasis is placed on the coordination and organometallic chemistry of olefin-Cu(I) coordination oligomers and polymers, their structures and potential applications as solids possessing unusual physical functional properties such as electrochemical, chiral separation, fluorescent sensing and ferroelectricity.

Reaction of gold(iii) oxo complexes with alkenes. Synthesis of unprecedented gold alkene complexes, [Au(N,N)(alkene)][PF6]. Crystal structure of [Au(bipyip)(η2-CH2CHPh)][PF6] (bipyip= 6-isopropyl-2,2′-bipyridine)

Gold alkene complexes [Au(bipyR)(eta2-alkene)][PF6] (bipyR = 6-alkyl-2,2'-bipyridine) have been obtained by reaction of gold(III) oxo complexes [Au2(bipyR)2(mu-O)2][PF6]2 with alkenes. The crystal structure of the styrene adduct [Au(bipy(ip))(eta2-CH2=CHPh)][PF6] (bipy(ip) = 6-isopropyl-2,2'-bipyridine) has been solved by X-ray analysis.

Transition metals and carbohydrates: the methyl-4,6-O-benzylidene-2,3-diazo-2,3-dideoxy-alpha-D-mannopyranoside skeleton as building block for new chiral nitrogen chelates

This paper describes a straightforward strategy for the synthesis of new nitrogen chelates by employing the chirality of readily available sugars. Thus, diimino and diamino ligands can be attained easily by using the methyl-4,6-O-benzylidene-2,3-diazo-2,3-dideoxy-alpha-D-mannopyranoside skeleton. The coordinating ability of one ligand has also been assessed by preparing a square-planar palladium complex [PdCl2(N,N-chelate)].