109333-83-7Relevant academic research and scientific papers
Synthesis and structural characterization of copper(I) cupracarboranes. A novel pinwheel cluster
Kang, Han Chyul,Do, Youngkyu,Knobler, Carolyn B.,Hawthorne, M. Frederick
, p. 1716 - 1725 (2008/10/08)
Synthesis and structural characteristics of copper(I) complexes of [nido-7,8-C2B9H10L]n- (1, L = H, n = 2; 2, L = 4-(C5H4N)CO2CH3, n = 1) are reported. Reaction systems with variable 1:CuCl:PPh3:(PPN)Cl and 2:CuCl:PPh3 mole ratios have resulted in the following cupracarboranes: [closo-3-(PPh3)-3,1,2-CuC2B9H 11]- (3), [closo-exo-4,8-{(μ-H)2Cu(PPh3)}-3-(PPh 3)-3,1,2-CuC2B9H9] (4), [closo-3-(PPh3)-4-L-3,1,2-CuC2B9H10] (5, L = 4-(C5H4N)CO2CH3), and [Cu3(μ-H)3(C2B9H 9L)3] (6, L = 4-(C5H4N)CO2CH3). These compounds have been structurally characterized by single-crystal X-ray diffraction. Crystallographic parameters are as follows (compound: crystal system; space group; crystal parameters; Z; unique data (I > 3σ(I)); R, Rw). PPN[3]: monoclinic; P21/n; a = 11.507 (1) A?, b = 14.772 (1) A?, c = 30.751 (2) A?, β = 90.284 (2)°; 4; 4831; 6.4, 7.6. 4: monoclinic; P21/n; a = 10.005 (2) A?, b = 20.693 (4) A?, c = 18.998 (3) A?, β = 92.664 (6)°; 4; 5071; 4.5, 6.1. 5: monoclinic; P21/c; a = 13.798 (1) A?, b = 12.072 (1) A?, c = 18.845 (2) A?, β = 95.111 (3)°; 4; 2290; 7.1, 8.3. 6-n-C7H16: rhombohedral; R3; a = 17.280 (4) A?, c = 28.630 (7) A?; 6; 2309; 6.5, 10.6. The polyhedral CuC2B9 framework is a common structural feature displayed by all four cupracarboranes. The geometry of this cage framework varies in such a way that opening of the (d10-M)C2B9 icosahedra increases in the order of 3, 4, 5, and 6, resulting in closo geometry for 3 and 4, nido geometry for 6, and an intermediate geometry for 5. Two copper(I) centers in 4 are associated with one carborane cage via the open pentagonal C2B3 face and two B-H-Cu bridges. Both bridging BH units originate from the upper pentagonal belt of the dicarbollide moiety, resulting in an interatomic Cu(I)-Cu(I) distance of 2.576 (1) A?. In a formal sense, 4 is a zwitterion composed of an anionic 3 complexed with a [Cu(PPh3)]+ cation. The dinuclear structural integrity of 4 remains intact upon dissolution, although fluxional processes become operative, as revealed by variable-temperature multinuclei FT NMR spectroscopy. The trinuclear cupracarborane 6 contains three [CuC2B9H10-(C5H4N)CO 2CH3)] units, which are linked by both Cu-H-B and Cu-Cu (2.519 (2) A?) interactions about a crystallographic 3-fold axis such that a pinwheel ligand array around an equilateral Cu3 core results. Compound 6 represents an example of a clustered cluster . The extent of metal-metal interactions in 4 and 6, as implied by their relatively short copper-copper distances, is discussed. Structural comparison of these copper(I) complexes suggests that the substituent at boron is not electronically innocent with respect to molecular distortions.
