A MOLECULAR CAVITY FOR TETRAHEDRAL AND Y-SHAPED ANIONS - SYNTHETIC AND STRUCTURAL STUDIES OF MACROCYCLIC DICOPPER(I) AND DISILVER(I) COMPOUNDS OF 1,6-BIS(DIPHENYLPHOSPHINO)HEXANE

New binuclear macrocyclic systems of 1,6-bis(diphenylphosphino)hexane (dpph) and 1,4-bis(diphenylphosphino)-butane (dppb), [Cu-2(dppb)(2)(ClO4)(2)] (2), [Cu-2(dPPh)(2)(mu-X)(2)] (X = ClO4 (3), NO3 (4), PF2O2 (5), CH3CO2 (7), C2H5CO2 (8)), and [Ag-2(dpph)(2)(mu-ClO4)(2)] (6), have been synthesized and structurally characterized. A mononuclear copper(I) complex, [Cu-2(dppp)(2)]ClO4 (1) (dppp = 1,3-bis(diphenylphosphino)propane), was also prepared. The crystals of 1-6 are all triclinic, space group P $($) over bar$$ 1, with Z = 1 (2) and 2 (1, 3-5). Dimensions of the unit cells: 1, a = 12.221(6) Angstrom, b = 18.425(7) Angstrom, c = 11.981(7) Angstrom, alpha = 96.19(4)degrees, beta = 102.42(4)degrees, gamma = 70.57(4)degrees; 2, a = 11.978(8) Angstrom, b = 12.755(8) Angstrom, c = 19.372(4) Angstrom, alpha = 97.83(5)degrees, beta = 111.24(4)degrees, gamma = 64.85(5)degrees; 3, a = 12.154(7) Angstrom, b = 12.728(5) Angstrom, c = 10.007(7) Angstrom, alpha = 92.67(4)degrees; beta = 101.57(4)degrees, gamma = 101.56(6)degrees; 4, a = 15.421(3) Angstrom, b = 18.354(4) Angstrom, c = 10.066(4) Angstrom, alpha = 90.23(3)degrees, beta = 97.06(2)degrees, gamma = 89.27(2)degrees; 5, a = 12.060(2) Angstrom, b = 12.808(1) Angstrom, c = 10.120(1) Angstrom, alpha = 86.134(7)degrees, beta = 101.299(9)degrees, gamma = 102.367(8)degrees; 6, a = 12.035(7) Angstrom, b = 12.820(6) Angstrom, c = 10.240(5) Angstrom, alpha = 92.76(4)degrees, beta = 101.49(4)degrees, gamma = 101.39(4)degrees. For complexes of 3-5 each copper atom shares a tetrahedral geometry with the P2O2 donor set, giving a molecular structure having two rings: the common outer large ring of CuP(CH2)(6)PCuP(CH2)(6)P is composed of copper atoms and the bridging diphosphine ligands while the inner ring is CuOXOCuOXO (X = Cl, N, P) for 3-5, respectively. The distances of Cu-O fall within the shortest range for copper(I) complexes of each anion, indicating that copper-anion binding is strong even for anions having weak coordination ability. The size of cavity for the anion trap is estimated as the distance L between the two metal atoms in a molecule. The L values are 4.99-5.22 Angstrom for 3-5. Compound 1 shows a typical mononuclear structure with chelating dppp, while 2 gives a binuclear geometry, [Cu-2(mu-dppb)(2)(ClO4)(2)], with terminally coordinated ClO4 anions and a single macrocycle (L = 4.63 Angstrom) of CuP(CH2)(4)PCuP(CH2)(4)P. The ClO4- ion is prevented from bridging coordination, and this is accounted for by the ring size and spatial blocking of the phenyl groups of dppb. On this basis, the ligand having six methylene groups provides a cavity able to include anions such as tetrahedral ClO4- and Y-shaped NO3-. By P-31 NMR, the mononuclear and binuclear copper(I) compounds in solution were also examined, and their exchange processes are discussed. The silver compound (6) as a structural analog of 3 also affords the double ring, but the Ag-O distance is not so sufficiently short that the silver atom binds ClO4 as strongly as copper does. Other compounds with CH3CO2- (7), C2H5CO28, and VO3- (9) were also examined by IR and V-51 NMR spectroscopy. By using the copper(I) ion and diphosphine, we have succeeded in building large macrocyclic systems, where various small molecules or anions are included, proposing a new host-guest chemistry.