Structural Studies of Bis-Catecholate, Bis-Dithiocatecholate, and Tetraalkoxy Diborane(4) Compounds

Abstract

X-ray structures are described for the bis-catecholate, bis-dithiocatecholate, and tetraalkoxy diborane(4) compounds B 2 (1,2-O 2 C 6 H 4 ) 2 ( 1 ), B 2 (1,2-O 2 -4-Bu t C 6 H 3 ) 2 ( 2 ), B 2 (1,2-O 2 -3,5-Bu t 2 C 6 H 2 ) 2 ( 3 ), B 2 (1,2-S 2 C 6 H 4 ) 2 ( 4 ), B 2 (1,2-S 2 -4-MeC 6 H 3 ) 2 ( 5 ), and B 2 (OCH 2 CMe 2 CH 2 O) 2 ( 6 ). All the compounds adopt structures in the solid-state in which the B 2 O 4 or B 2 S 4 units are planar or very nearly so. In compounds 2 and 3, the dihedral angles between the two BO 2 C 2 planes are 17.3 and 31.8° respectively whereas in 1, 4 and 5 these angles are exactly 0°. In 6, a 3-fold disorder precluded our obtaining accurate positions for the two boron atoms, yet a dihedral angle of 0° is required by the 3̄ site symmetry. The structure of the bis(Lewis base) adduct of B 2 Cl 4, [B 2 Cl 4 (NHMe 2 ) 2 ] ( 7 ), is also described and structures of the salt [NH 2 Me 2 ][B(1,2-O 2 C 6 H 4 ) 2 ] ( 8 ) and the NMe 2 -bridged dimer [{BCl 2 (μ-NMe 2 )} 2 ] ( 9 ) are available in the Supporting Information. Compound 1 crystallized in the monoclinic space group P 2 1 / c with a = 4.746(1) Å, b = 16.427(3) Å, c = 7.053(2) Å, β = 98.59(2)°, and Z = 2. Crystals of 2 were monoclinic, space group P 2 1 / c with a = 6.847(1) Å, b = 18.871(5) Å, c = 15.270(2) Å, β = 93.16(2)°, and Z = 4. Crystals of 3 were triclinic, space group P 1̄ with a = 9.478(4) Å, b = 10.355(4) Å, c = 15.082(7) Å, α = 105.71(3)°, β = 100.31(4)°, γ = 94.58(3)°, and Z = 2. Crystals of 4 were monoclinic, space group P 2 1 / c with a = 15.364(3) Å, b = 4.0502(4) Å, c = 21.532(3) Å, β = 99.320(7)°, and Z = 4. Crystals of 5 were monoclinic, space group P 2 1 / c with a = 6.0458(9) Å, b = 7.5319(11) Å, c = 16.552(2) Å, β = 96.291(3)° and Z = 2. Compound 6 crystallized in the rhombohedral space group R 3̄ m with a = 8.876(2) Å, c = 13.821(3) Å and Z = 3. Crystals of 7 were monoclinic, space group P 2 1 / c with a = 11.831(3) Å, b = 19.458(5) Å, c = 14.823(5) Å, β = 96.63(4)°, and Z = 12.