[Bis­(di­phenyl­phosphino)­methane][1,3-bis­(di­phenyl­phosphino)­propane]­platinum(II) dibromide

The asymmetric unit of the title compound, [Pt(C₂₅H₂₂P₂)(C₂₇H₂₆P₂)]Br₂ or [Pt(dppm)(dppp)]Br₂, where dppm is bis­(di­phenyl­phosphino)­methane and dppp is 1,3-bis­(di­phenyl­phosphino)­propane, consists of a discrete [Pt(dppm)(dppp)]²⁺ cation and two Br⁻ anions at van der Waals distances. This is the first reported platinum(II) complex containing both dppm and dppp ligands. Noticeable features are that the coordination of platinum by the differing dppm and dppp ligands produces a distorted coordination geometry with differing ligand bite angles (and to a lesser extent bond distances), and that the strain induced by the formation of the four-membered dppm chelate ring has a marked effect upon the bond angles at the P atoms of this ligand.     

A five coordinate Pd(II) complex stable in solution and in the solid state

The treatment of the strained complex TrpyPdOAc(F) 1 with NaBAr(F), followed by the addition of trimethylphosphine, yields the stable cationic 16VE- or 18VE-complexes 3 and 4, depending on the amount of phosphane added.     

The twotrans-[NiL2(NCS)2] (L =N,N-dimethyl-1,3-propanediamine) isomers in the solid state and in solution

Summary Two complextrans-NiL₂ (NCS)2] (L =N, N-dimethyl-1,3-propanediamine) synthesised from solution in two isomeric forms (1) and (2), exhibit similar colours, magnetic moments and electronic spectra, but differ in their i.r. spectra and x-ray powder diffraction patterns. We suggest they possesstrans- chair-chair andcis-chair-chair chelate conformations, respectively. Complexes (1) (2) isomerise (temperature range 382–397.5 K; H = 5.12 kJ mol^–1) in the solid state. Isomer (2) is converted into isomer (1) upon recrystallisation from chloroform. Thetrans-[NiL₂NCSe)₂] complex does not isomerise upon heating. The compound [NiL(NCS)₂], prepared by thermal decomposition of [NiL₂(NCS)₂], possesses octahedral polymeric structure in which the diamine is chelated and all the thiocyanato groups are bridging.     

Guest-induced conformation shift of p-sulphonatothiacalix[4]arene in the solid state and solution manipulated by [Zn(dipy)3]2+

The ¹H NMR and X-ray analysis data reveal the guest-induced cone → partial cone and cone → 1,2-alternate conformational shift in aqueous methanol solutions and solid state for a p-sulphonatothiacalix[4]arene-[Zn(dipy)₃]²⁺ host–guest system. The experimental data, together with DFT calculations, show that the guest-induced conformational shift of p-sulphonatothiacalix[4]arene is facilitated by the deprotonation of phenolic groups.     

The crystal and molecular structure of [BPh4]{Ru(NO)[1,3-bis(diphenylphosphine)propane]2}

Summary The crystal structure of [BPh₄][Ru(NO)(DPP)₂] [DPP = 1,3-bis(diphenyIphosphine)propane ] has been determined by Patterson and Fourier methods using diffractometer data. Crystals are monoclinic, space group P21 /c, with a = 19.546(3), b = 19.139(3), c = 17.796(3) Å and = 98.04(5)°; Dc = 1.29 for Z = 4. The structure has been refined to R = 7.2% by least squares methods. The environment around the ruthenium atom is trigonal bipyramidal with two axial phosphorus atoms and two more phosphorus atoms and the nitrogen atom of the nitrosyl group in the equatorial plane. The Ru-P bond distances are chemically equivalent with a mean value of 2.39 A, and the Ru-N bond length is 1.72(2) A.     

Catalytic [2+2+2] and thermal [4+2] cycloaddition of 1,2-bis(arylpropiolyl)benzenes

We have determined that a cationic rhodium(I)/Segphos complex catalyzes an enantio- and diastereoselective intermolecular [2+2+2] cycloaddition of 1,2-bis(arylpropiolyl)benzenes with various monoalkynes at room temperature to give axially chiral 1,4-teraryls possessing an anthraquinone structure in good yields with good enantio- and diastereoselectivities. We have also determined that a thermal intramolecular [4+2] cycloaddition of 1,2-bis(arylpropiolyl)benzenes proceeds at 60 degrees C to give aryl-substituted naphthacenediones in moderate to good yields.     

Redox non-innocence of thioether crowns: elucidation of the electronic structure of the mononuclear Pd(III) complexes [Pd([9]aneS3)2]3+ and [Pd([18]aneS6)]3+

The Pd(II) complexes [Pd([9]aneS(3))(2)](PF(6))(2)·2MeCN (1) ([9]aneS(3) = 1,4,7-trithiacyclononane) and [Pd([18]aneS(6))](PF(6))(2) (2) ([18]aneS(6) = 1,4,7,10,13,16-hexathiacyclooctadecane) can be oxidized electrochemically or chemically oxidized with 70% HClO(4) to [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+), respectively. These centers have been characterized by single crystal X-ray diffraction, and by UV/vis and multifrequency electron paramagnetic resonance (EPR) spectroscopies. The single crystal X-ray structures of [Pd(III)([9]aneS(3))(2)](ClO(4))(6)·(H(3)O)(3)·(H(2)O)(4) (3) at 150 K and [Pd([18]aneS(6))](ClO(4))(6)·(H(5)O(2))(3) (4) at 90 K reveal distorted octahedral geometries with Pd-S distances of 2.3695(8), 2.3692(8), 2.5356(9) and 2.3490(6), 2.3454(5), 2.5474(6) ?, respectively, consistent with Jahn-Teller distortion at a low-spin d(7) Pd(III) center. The Pd(II) compound [Pd([9]aneS(3))(2)](PF(6))(2) shows a one-electron oxidation process in MeCN (0.2 M NBu(4)PF(6), 293 K) at E(1/2) = +0.57 V vs. Fc(+)/Fc assigned to a formal Pd(III)/Pd(II) couple. Multifrequency (Q-, X-, S-, and L-band) EPR spectroscopic analysis of [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+) gives g(iso) = 2.024, |A(iso(Pd))| = 18.9 × 10(-4) cm(-1); g(xx) = 2.046, g(yy) = 2.041, g(zz) = 2.004;?|A(xx(Pd))| = 24 × 10(-4) cm(-1), |A(yy(Pd))| = 22 × 10(-4) cm(-1), |A(zz(Pd))| = 14 × 10(-4) cm(-1), |a(xx(H))| = 4 × 10(-4) cm(-1), |a(yy(H))| = 5 × 10(-4) cm(-1), |a(zz(H))| = 5.5 × 10(-4) cm(-1) for [Pd([9]aneS(3))(2)](3+), and g(iso) = 2.015, |A(iso(Pd))| = 18.8× 10(-4) cm(-1); g(xx) = 2.048 g(yy) = 2.036, g(zz) = 1.998; |a(xx(H))| = 5, |a(yy(H))| = 5, |a(zz(H))| = 6 × 10(-4) cm(-1); |A(xx(Pd))| = 23× 10(-4) cm(-1), |A(yy(Pd))| = 22 × 10(-4) cm(-1), |A(zz(Pd))| = 4 × 10(-4) cm(-1) for [Pd([18]aneS(6))](3+). Both [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+) exhibit five-line superhyperfine splitting in the g(zz) region in their frozen solution EPR spectra. Double resonance spectroscopic measurements, supported by density functional theory (DFT) calculations, permit assignment of this superhyperfine to through-bond coupling involving four (1)H centers of the macrocyclic ring. Analysis of the spin Hamiltonian parameters for the singly occupied molecular orbital (SOMO) in these complexes gives about 20.4% and 25% Pd character in [Pd([9]aneS(3))(2)](3+) and [Pd([18]aneS(6))](3+), respectively, consistent with the compositions calculated from scalar relativistic DFT calculations.     

Aryl-aryl coupling reaction using a novel and highly active palladium reagent prepared from Pd(OAc)2, 1,3-bis[diphenylphosphino]propane (DPPP), and Bu3P

A palladium-assisted coupling reaction of aryl triflate with arene was investigated, and a novel Pd reagent prepared from equimolar Pd(OAc)2, 1,3-Bis[diphenylphosphino]propane (DPPP), and Bu3P was developed. This method is useful for intramolecular biaryl coupling reactions, not only between aryl triflate and arene (triflate-amide), but also between aryl halide and arene (halo-amide).     

Synthesis, luminescence and ion-binding properties of palladium(II) complexes with 1,2-bis[di(benzo-15-crown-5)phosphino]ethane (dbcpe)

A series of palladium(II) complexes with 1,2-bis[di(benzo-15-crown-5)phosphino]ethane ligand (dbcpe), [Pd(dbcpe)X2] (X = Cl 1, Br 2 and I 3), have been successfully synthesised and characterised. The X-ray crystal structure of dbcpe has also been determined. The cation-binding properties of the complexes have been studied and the stability constants with alkali metal cations determined. The crown-free analogue of dbcpe, 1,2-bis[bis(3,4-dimethoxyphenyl)phosphino]ethane (ddmppe), and the related complexes have also been prepared and comparison studies have been made.     

An efficient synthesis of 1,3-bis(1,4,7-triazacyclonon-1-yl)-2-hydroxypropane, [1,3-bis(TACN)-2-propanol]

Abstract

An efficient synthesis of 1,3-bis(1,4,7-triazacyclonon-1-yl)-2-hydroxypropane is described. In contrast to earlier procedures, an improved synthetic strategy led to the selection of suitable reagents and conditions that afforded the title compound in excellent overall yield with improved process efficiency and scalability. Moreover, the mildness and synthetic efficiency of the chosen conditions were particularly well-suited for the large-scale synthesis of the title compound, which is in increasing demand for a variety of applications, including the preparation of stationary phases for immobilized metal-ion affinity chromatography of recombinant proteins.     

Complex formation between Zn2+ ion and 1,3-bis[bis(pyridin-2-ylmethyl)amino]propan-2-ol

The dinucleating ligand 1,3-bis[bis(pyridin-2-ylmethyl)amino] propan-2-ol (I, LOH) is becoming of increasing interest due to the exceptional phosphate monoester binding and phosphate diester hydrolytic properties of its dizinc(II) complexes in water. Potentiometric pH titrations using a range of Zn:I ratios reveals the formation of mononuclear and dinuclear metal complexes. In fact, when the Zn:I ratio is 1:1 only mononuclear complexes are formed. Previous work reported the formation of only dinuclear species. Thus, the results presented here should be important to interpret correctly and more accurately phosphate ester binding and hydrolysis data. Moreover, based on these findings we suggest that the phosphate binding and hydrolytic properties of mixtures containing Zn(II) ions and I should depend not only on the pH but also on the Zn:I ratio used.     

Synthesis and Crystal Structure of trans-Rb2[Pd(NO2)2Cl2]. Structure Refinement of Na2[Pd(NO2)4]

The reaction products of palladium(II) nitration with sodium nitrite in the presence of rubidium salts are described. The crystal structure of rubidium dinitrodichloropalladoate(II) — trans-Rb₂[Pd(NO₂)₂Cl₂] — has been studied (KUMA automatic diffractometer, MoK radiation, graphite monochromator, /2 scan mode for 2 < 30°, 758 experimental reflections, R = 0.030; R = 0.023 for I>2(I)). Crystal data: a = 15.123(3), b = 7.750(2), c = 7.776(2) , V = 911.4(4) ³, space group Cmca, Z = 4, d _calc = 3.209 g/cm³. The structure consists of [Pd(NO₂)₂Cl₂]^2– complex anions and Rb⁺ cations. The planar square coordination of the Pd atom is completed to distorted octahedral by the chlorine atoms of the neighboring complexes at Pd...Cl distances of 3.18 . Chains of complexes with alternating orientations are formed. The geometrical characteristics of the complex anions, the coordination polyhedra of the cations, and the heavy atom sublattice are analyzed. The crystal structure of Na₂[Pd(NO₂)₄] has been refined, and refinement data are given.