Crystal structures of four dibromomethylene-functionalized cage compounds

Crystal structures of four dibromomethylene-functionalized hexa- and heptacyclotetradecane cages are reported. 7-(Dibromomethylene)heptacyclo[6.6.0.0^2,6.0^3,13.0^4,11.0^5,9.0^10,14]tetradecane (3): orthorhombic, Pnma, a = 14.744(1), b = 11.237(1), c = 7.4625(7) Å Z = 4; R = 0.0531 for 504 observed reflections. 7,12-Bis(dibromomethylene)heptacyclo[6.6.0.0^2,6.0^3,13-0^4,11 .0^5,9.0^10,14]tetradecane (4): monoclinic, I2/a, a = 11.257(1), b = 9.5844(8), c = 13.884(2) Å, = 92.254(8)° Z = 4; R = 0.0413 for 663 observed reflections. 10,14-bis(dibromomethylene)hexacyclo[6.6.0.0^2,6.0^3,13.0^4,11.0^5,9]tetradecane (6): monoclinic, P2₁/n, a = 8.118(1), b = 15.273(4), c = 12.826(3) Å, = 104.20(1)° Z = 4; R = 0.0384 for 1392 observed reflections. 14-(dibromomethylene)hexacyclo[6.6.0.0^2,6.0^3,13.0^4,11.0^5,9]tetradecan-10-one (7): monoclinic, P2₁/n, a = 8.2879(7), b = 15.273(1), c = 10.0565(9) Å, = 92.271(8)° Z = 4; R = 0.0320 for 1402 observed reflections. The functional groups lead to slight shortening of bond lengths.     

Regiospecific ligand addition to the donor–acceptor compound Ru2(CO)6(bpcd): syntheses and X-ray diffraction structures of Ru2(CO)5L(bpcd) and Ru2(CO)5L[μ-C=C(PPh2)C(O)CH2C}(O)](μ2-PPh2) (where L = PMe3 and tBuNC)

Thermal and Me₃NO-assisted activation of the donor–acceptor complex Ru₂(CO)₆(bpcd) (1) [where bpcd = 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione] with PMe₃ or ^tBuNC affords the mono-substituted complexes Ru₂(CO)₅L(bpcd), as a result of regiospecific ligand attack at the diphosphine-substituted ruthenium center. Solution NMR measurements (¹H and ³¹P) reveal that the PMe₃ derivative exists as a noninterconverting mixture of axial (3a) and equatorial (3e) isomers, with the only the equatorial isomer being observed for Ru₂(CO)₅(^tBuNC)(bpcd) (5). Near-UV irradiation of 1 in the presence of added ligand yields Ru₂(CO)₅L(bpcd), in addition to the known ₂-phosphido complex Ru²(CO)⁶ [-C=C(PPh₂)C(O)CH₂C(O)](₂-PPh₂) (2) and the corresponding phosphido-substituted complexes Ru²(CO)_5L[-{C =C(PPh₂)C(O)CH₂C}(O)]₂-PPh₂)[4 (L = PMe₃); 6 (L = ^tBuNC)]. As with compounds 3a, 3e, and 5, both 4 and 6 exhibit ligand attachment at the diphosphine-substituted ruthenium center. The molecular structures of 3e, 4, 5, and 6 were determined by X-ray crystallography. 3e, as the 1/2 C₆H₆ solvate, crystallizes in the monoclinic space group C2/c: a = 40.573(3) Å, b = 10.2663(9) Å, c = 18.347(1) Å, = 95.371(6)°, V = 7609(1) ų and Z = 8; 4, crystallizes in the monoclinic space group P2₁/n: a = 10.8241(8) Å, b = 18.074(1) Å, c = 19.194(1) Å, = 96.968(6)°, V = 3727.3(5) ų, and Z = 4; 5, as the 1/2CH₂Cl₂ solvate, crystallizes in the monoclinic space group C2/c: a = 40.955(3) Å, b = 9.7230(6) Å, c = 20.542(1) Å, = 106.596(5)°, V = 7839.2(9) ų, and Z = 8; 6, as the 1/2C₅H₁₂ solvate, crystallizes in the monoclinic space group P2₁/c: a = 21.773(2) Å, b = 10.907(3) Å, c = 18.744(4) Å, = 114.68(1)°, V = 4045(1) ų, and Z = 4. The site occupied by the PMe₃ and ^tBuNC ligands in these compounds is discussed relative to the steric size/electronic properties of the ancillary ligand and its interaction with the bpcd ligand.     

Molecular structures of (tBu)Ga(S2CNnPr2)2 and (iPrO)Ga(S2CNEt2)2: An example of an unusual ligand pseudorotation

The molecular structures of (^tBu)Ga(S₂CNⁿPr₂)₂ (1) and (ⁱPrO)Ga(S₂CNEt₂)₂ (2) have been determined. The variation in the geometries observed for bis-dithiocarbamate compounds of gallium, (X)Ga(S₂CNMe₂)₂ (X=Cl, ⁱPrO, ^tBu) do not lie along the Berry pseudorotation pathway for the square-based pyramid to trigonal bipyramid geometrical transition. Instead, the structures appear to lie on an unusual ligand two-step, Texas, pseudorotation mechanism which results in a highly distorted trigonal bipyramidal geometry. Crystal data: (1) monoclinic, P2₁,/c, a = 9.786(1), b = 29.218(3), c = 9.452(1) Å, = 108.379(9)°, V = 2564.7(5) ų, and Z = 4. (2) Monoclinic, P2₁ /c, a = 10.980(3), b = 15.673(4), c = 12.461(3) Å, = 97.47(2)°, V = 2126.2(9) ų and Z = 4.     

Tetracyclo[6.3.0.04,11.05,9]undecane-2,7-dione

The compound crystallizes in the triclinic space group, , witha=6.7702(4),b=7.0180(4),c=9.1960(7) Å, =92.457(6), =96.150(6), =93.444(5)°, andZ=2. The structure contains a rather short intramolecular H...H contact of 2.26(4) Å.     

Stereospecific solid-state NaBH4-promoted reduction of 1-methylpentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione

NaBH₄ reduction of a cage dione proceeds in a stereospecific fashion to give theendo,endo-diol. This reactivity is related to the crystal structure.     

Reaction of (t-BuGaCl2)2 with Ar′PHLi (Ar′ = 2,4,6-t-Bu3C6H2): Preparation of the chloride-bridged dimer (t-BuGa(Cl)P(H)Ar′)2

The reaction of (t-BuGaCl₂)₂ with Ar′P(H)Li (AR′ = 2,4,6-t-Bu₃C₆H₂) affords the chloride-bridged dimer [t-BuGa(Cl)P(H)Ar′]₂ ( 1 ). The structure of 1 has been established by X-ray crystallography. Compound 1 , C₄₄H₇₈Cl₂Ga₂P₂, crystallizes in the monoclinic space group P2₁/n with Z = 2, a = 10.468(1), b = 14.967(1), c = 16.182(2) Å, and Å = 94.48(1)β. The reaction of 1 with t-BuLi is described.