Selective derivatisation of resorcarenes: 1. The regioselective formation of tetra-benzoxazine derivatives

1997

Abstract Four 5,6-benzo-1,3-oxazine rings are formed by the condensation of resorcarenes with various aliphatic or aromatic primary amines and formaldehyde. From four possible regioisomers only the C4 symmetrical compound is isolated in yields of up to 90%. Semiempirical calculations confirm its relative stability, which is due to the possible formation of four intramolecular OH…O hydrogen bonds. The regioselectivity of the reaction is further established for two examples by single crystal X-ray analysis. A solvent molecule is included in the extended cavity.

Concave π-prismand hydrocarbon [2.2.2]cyclophanes and their crystalline Ag-triflate complexes

1999

New small concave hydrocarbon cyclophanes were prepared via the well-known HD-2SO2-method. The cyclophanes obtained are isomers of the very well-known [2.2.2]p,p,p-cyclophane, C24H24, a π-prismand efficiently complexing Ag+-ion. X-ray crystal structure determinations showed the bis-sulfide 7 (1,10-dithia[3.3.2]m,p,p-cyclophane) to be helically chiral and that the conformation of the parent hydrocarbon cyclophane 13 ([2.2.2]m,p,p-cyclophane) does not change dramatically upon complexation with the Ag+-ion. The 16- and 17-membered [2.2.2]m,m,p- and [2.2.2]m,p,p-cyclophane (15 and 16) also act as π-prismands and form surprisingly similar crystalline 1:1 Ag-triflate complexes (π-prismates) as th…

ChemInform Abstract: Concave π-Prismand Hydrocarbon [2.2.2]Cyclophanes and Their Crystalline Ag-Triflate Complexes.

2010

New small concave hydrocarbon cyclophanes were prepared via the well-known HD-2SO2-method. The cyclophanes obtained are isomers of the very well-known [2.2.2]p,p,p-cyclophane, C24H24, a π-prismand efficiently complexing Ag+-ion. X-ray crystal structure determinations showed the bis-sulfide 7 (1,10-dithia[3.3.2]m,p,p-cyclophane) to be helically chiral and that the conformation of the parent hydrocarbon cyclophane 13 ([2.2.2]m,p,p-cyclophane) does not change dramatically upon complexation with the Ag+-ion. The 16- and 17-membered [2.2.2]m,m,p- and [2.2.2]m,p,p-cyclophane (15 and 16) also act as π-prismands and form surprisingly similar crystalline 1:1 Ag-triflate complexes (π-prismates) as th…

Selective derivatisations of resorcarenes - 2. Multiple regioselective ring closure reactions

1997

Abstract The condensation of the C-pentyl resorcarene 1 with long chain aliphatic diamines 3a-d and excess formaldehyde leads under high dilution conditions to tetrabenzoxazine derivatives 4a-d in which pairs of adjacent oxazine rings are connected by an aliphatic chain. Six new rings are formed per resorcarene molecule during this reaction in a regioselective way. For one example (4a) the chiral cleft-like structure with C2 symmetry was proved by single crystal X-ray analysis. Hydrolysis of the oxazine rings gives the secondary amine derivatives 5a,b with C2v symmetry in high yield.

Ferrocenylbis(ylene) phosphoranes

1997

The ferrocenylbis(methylene)phosphorane Fc-P(=CTms 2 ) 2 ( 1 ) (Fc = −C 5 H 4 FeC 5 H 5 ) can be synthesized starting from ferrocenyldichlorophosphane FcPCl 2 or ferrocenyldilithiophosphane FcPLl 2 . The X-ray structure of ( 1 ) shows some unusual structural features, which indicate considerable electronic interaction of the ferrocenyl group and the σ 3 λ 5 -phosphorane unit. As a consequence of this interaction, the rotational barrier of the methylene bonds is extraordinary low. Therefore, in contrast to other bis(methylene)phosphoranes, the endo - and exo -Tms groups are indistinguishable on the NMR time scale even at −100°C. The analogous ferrocenylbis(imino)phosphorane Fc-P(=NTms) 2 ( 9…

Synthesis and reactivity of P-ferrocenylalkylidenephosphanes and related iminophosphanes and diphosphenes

1997

P-Ferrocenyl-substituted alkylidenephosphanes have been prepared and characterized spectroscopically. Their ready conversion to the corresponding acylphosphanes and 1,2-diacyldiphosphanes, as well as a new type of phosphirene synthesis are presented. The X-ray structure of the tetraferrocenyl-substituted diacyldiphosphane has been investigated. Furthermore, P-ferrocenyl iminophosphanes and their complexation behaviour are described. Diferrocenyldiphosphene, which is known to be unstable, has been stabilized by complexation; this has been confirmed by NMR-spectroscopy and X-ray structure analysis.

Syntheses and reactivity of aminobis(diorganylamino)phosphanes

1996

Aminobis(diorganylamino)phosphanes (R2N)2PNH2 (R = iPr, c-Hex, Ph) (2a–c), were obtained by treatment of the corresponding chlorobis(diorganylamino)phosphanes 1a–c with lithium amide in liquid ammonia. The transition metal phosphane complex (R2N)2(H2N)PNi(CO)3 (3) was prepared by reaction of 2a with tetracarbonylnickel. N-Complexation of 2a with trimethylalane affords the iminophosphorane-alane adduct (R2N)2HP=N(H)AlMe3 (4) by 1,2-H shift from the nitrogen to the phosphorus atom. The corresponding reaction with aluminium trichloride leads to the formation of the salt [(R2N)2HP=N(H)]2AlC12+[AlC14]− (5), in which two iminophosphorane moieties are linked by an AlCl2 bridge. Lithiation of 2a an…

A linear open-chain piperazine-pyridine ligand and its meso-helical Co complex

1998

Abstract An oligomeric ligand (HPPy) 2 P, N , N ′-bis[2-(6-( N -( N ′-(2-hydroxyethyl)piperazinyl)methyl)]piperazine, was designed to resemble structurally open-chain aza-crowns. Owing to the all- trans configuration of piperazine and pyridine free electron pairs, it should adopt a near linear overall structure in solvent. Theoretical calculations at ab initio level confirm the overall linear structure of free ligand. The crystal structure of the complex [(HPPy) 2 P][Co(NO 3 ) 2 ] 2 shows a contraction from ∼3 to 2 nm structure. Each coordination site creates either a Δ or Δ configuration around the metal ion, thus causing a ligand with an even number of coordination centres to be meso -hel…

Macrocyclic Ethers and Their Inclusion Complexes

1997

Island Homoaromaticity in the W-Shaped 2,4-Diphospha-3-arsapentadienide Anion and Related Compounds - Theoretical and Experimental Investigations

2012

A series of anions with general formula (R2C=P)2Pn– (Pn = N, P, As, Sb; R = H, Me, CF3, SiH3, SiMe3, SiF3) was investigated theoretically at the DFT (RI-BP86/TZVP) and RI-MP2/TZVP levels of approximation. Significantly sharpened central PPnP bond angles were predicted for the species with π-acceptor R substituents. The corresponding bond angle values decrease in the order Pn = N >> P > As > Sb. This finding is in agreement with the previously published structural data for [(Me3Si)2C=P]2P–. An island homoaromaticity was proposed as a suitable explanation for the observed effect. In more detail, it consists of shifting negative charge to the electron-withdrawing terminal groups with formation…

Concave macrobicycles: Absorption spectra, luminescence properties, and endocavital complexation of neutral organic guests

1996

By a mild modified Eglinton coupling a series of diynebridged macrobicyclic hosts capable of endocavital complexation were synthesized and their structures and complexation properties investigated by X-ray analysis. The inclusion of DMSO in 7 suggests a direct correlation between steric fit and orientation of the guest. On the basis of this hypothesis, the orientation of acetone in an endocavital inclusion of 2 was predicted and verified by X-ray analysis. Comparison of the single-crystal X-ray structures of the vacant macrobicycle 3 and of a family of macrobicycles showing endocavital or “pocket” complexation of neutral organic guests suggests that torsion of the cavities upon complexation…

Synthesis of a tetradentate piperazine ligand and a structural study of its coordination compounds

1999

Abstract A tetradentate ligand N,N′-bis(2-pyridylmethyl)piperazine (L1) and seven structures of its transition metal coordination compounds are described. Most of the compounds are of the general formula [M(L1)(NO3)2], with M=Cu2+, Co2+, Mn2+and Cd2+. In addition, a dimeric copper(II) compound, [Cu2(L1)(Ac)4](H2O)3, and polymeric silver(I) compounds, [Ag(L1)]n(NO3)n(EtOH)n and [Ag(L1)]n(SO3CF3)n, were formed. The overall structure of L1 in the metal complexes A–G varies with the size and electronic properties of the metal ions. Mononuclear complex A is a five-coordinated, B is a six-coordinated, and C and D are eight-coordinated metal complexes. The dinuclear Cu complex, E, is four-coordina…