First Example of Cage P4N4-Macrocycle Copper Complexes with Intracavity Location of Unusual Cu2I Fragments.

In this study, 28-membered macrocyclic 1,5(1,5)-di(1,5-diaza-3,7-diphosphacyclooctana)-2,4,6,8(1,4)-tetrabenzenacyclooctaphane were synthesized by condensation of pyridinephosphine, paraformaldehyde, and primary diamines (bis(4-aminophenyl)methane or -sulfide. The first representatives of binuclear copper(I) complexes of P,N-containing cyclophanes with two 1,5-diaza-3,7-diphosphacyclooctane rings incorporated into a macrocyclic core and intracavity location of unusual, developed angle Cu2I moiety were obtained. The structure of one complex was established by X-ray diffraction analysis. The complexation led to a slight distortion of the cyclophane conformations.

Dynamic Covalent Chemistry Approach toward 18-Membered P4N2 Macrocycles and Their Nickel(II) Complexes.

A dynamic covalent chemistry approach was used for the stereoselective synthesis of 1,10-diaza-3,8,12,17-tetraphosphacyclooctadecanes via condensation reaction of 1,4-bis(organylphosphino)butane, formaldehyde, and primary amines. The obtained 18-membered P4N2 macrocycles were isolated in pure form as meso- (RPSPSPRP) or rac- (RPRPRPRP/SPSPSPSP) isomers. The structural features of the individual stereoisomers were revealed by NMR spectroscopy and X-ray structure analysis. All P4N2 macrocycles form square-planar nickel(II) complexes with the RPSPSPRP isomer only, in which the orientation of the lone pairs of electrons at phosphorus favors this coordination mode, independent of the initial configuration of the ligand, indicating the ability of the 18-membered P4N2 macrocycles to stereoisomerize in the course of the complexation.

Synthesis and Structure of Iron (II) Complexes of Functionalized 1,5-Diaza-3,7-Diphosphacyclooctanes.

In order to synthesize new iron (II) complexes of 1,5-diaza-3,7-diphosphacyclooctanes with a wider variety of the substituents on ligands heteroatoms (including functionalized ones, namely, pyridyl groups) and co-ligands, it was found that these ligands with relatively small phenyl, benzyl, and pyridin-2-yl substituents on phosphorus atoms in acetonitrile formed bis-P,P-chelate cis-complexes [L2Fe(CH3CN)2]2+ (BF4)2-, whereas P-mesityl-substituted ligand formed only monoligand P,P-complex [LFe(CH3CN)4]2+ (BF4)2-. 3,7-dibenzyl-1,5-di(1'-(R)-phenylethyl)-1,5-diaza-3,7-diphosphacyclooctane reacted with hexahydrate of iron (II) tetrafluoroborate in acetone to give an unusual bis-ligand cationic complex of the composition [L2Fe(BF4)]+ BF4-, where two fluorine atoms of the tetrafluoroborate unit occupied two pseudo-equatorial positions at roughly octahedral iron ion, according to X-ray diffraction data. 1,5-diaza-3,7-diphosphacyclooctanes replaced tetrahydrofurane and one of the carbonyl ligands of cyclopentadienyldicarbonyl(tetrahydrofuran)iron (II) tetrafluoroborate to form heteroligand complexes [CpFeL(CO)]+BF4-. The structural studies in the solid phase and in solutions showed that diazadiphosphacyclooctane ligands of all complexes adopted chair-boat conformations so that their nitrogen atoms were in close proximity to the central iron ion. The redox properties of the obtained complexes were performed by the cyclic voltammetry method.

Structure and dynamics of P,N-containing heterocycles and their metal complexes in solution.

Conformations and dynamics of 1,5-diaza-3,7-diphosphacyclooctane (1) with chiral l-menthyl substituents on the phosphorus atoms and several metal complexes thereof were investigated by a variety of DNMR methods. In solution 1 adopts a C(2) symmetrical "crown"-like conformation (CW) and the conformational preference and dynamics of the complexes depend on the type of metal: for the Cu complex the CW form is preferred, whereas the Pd, Pt, or Mo complexes exist in an equilibrium of two "chair-boat"-like conformations (CB/CB*). The barriers of interconversion between these two conformations for the Pd and Pt complexes are about 2 times higher than for the Mo complex. Quantum chemical calculations (B3LYP/6-31G(d)) are in agreement with experimental findings.

First representative of optically active P-L-menthyl-substituted (aminomethyl)phosphine and its borane and metal complexes.

The first representative of 1,5-diaza-3,7-diphosphacyclooctanes (1) with chiral L-menthyl substituents on the phosphorus atoms was obtained by condensation of L-menthylphosphine with formaldehyde and p-toluidine. This optically active cyclic bisphosphine readily forms a stable P,P-complex with borane (2) and P,P-chelate complexes with platinum(II) (3) and palladium(II) dichloride (4). The structure of the bisphosphine 1 in solution was elucidated by employing a variety of 1D/2D NMR correlation experiments, and the molecular structure of complex 3 was studied by X-ray crystallography.

Structure, conformation, and dynamics of P,N-containing cyclophanes in solution.

3D structures in solution of highly symmetrical N,P-containing macrocycles were established by a variety of 2D NMR correlation techniques. It was shown that a number of magnetically equivalent fragments in such symmetrical systems can be estimated by NMR diffusion measurement. The title compounds adopt a helical conformation of the macrocycles in solution. The extent of twisting and the size of the intramolecular cavity are determined by steric hindrance of the aromatic substituents on the exocyclic phosphorus atoms with phenylene and dimethylmethylene groups forming the macrocycle. In solution these macrocycles host aromatic guests inside the cavity.

Self-assembly of novel macrocyclic aminomethylphosphines with hydrophobic intramolecular cavities.

Novel macroheterocyclic tetraphosphines, namely, 1,1',5,5'-bis(arylene)-bis(1,5-diaza-3,7-diphosphacyclooctanes) 2-6, were obtained without the use of high-dilution techniques or any matrix by the reaction of bis(hydroxymethyl)organylphosphines with primary aromatic diamines containing two p-phenylene fragments linked by various one-atom bridges in a molecular self-assembly process. The structures of 4, 5 and 6 were investigated by X-ray crystal structure analyses. The macrocyclic cavities can be described as a truncated rhombohedral prism with side faces formed by phenylene rings and 1,5-diaza-3,7-diphosphacyclooctanes in the truncated acute angles. In the crystals of these macrocycles, solvating DMF molecules are present, and a methyl group from each of two DMF molecules penetrates the macrocyclic cavities of 4 and 5 from either side, whereas only one disordered molecule of DMF penetrates the cavity of macrocycle 6. Different types of crystal packing are observed for the P-benzyl-substituted compounds 4 and 5 and for the P-mesityl-substituted compound 6: for 4 and 5 the formation of alternating layers containing the macrocycles and the DMF molecules is observed, in which the cavities of the macrocyclic molecules form channels and the DMF molecules are located in the centers of the channels; in the crystal of 6, six molecules are arranged around the 3 axis in the fashion of a six-bladed propeller.