MACROCYCLIC DIMER-OF-DIMERS TYPE TETRANUCLEAR COPPER(II) COMPLEXES WITH 2 BRIDGING HYDROXY-GROUPS IN A FACE-TO-FACE MANNER

Macrocyclic tetranuclear copper(II) complexes of the general formula [ Cu(4)L(OH)(2)][X](2)[Y](2) (L = L(1), X = Y = CIO4- or X = MeCO(2), Y = PF6: L = L(2), X = Y = CIO4 or X = Y = PF6-) have been obtained by t emplate reactions, where L denotes the macrocycles formed by the [2 2] condensation of 2,6-diformyl-4-methylphenol with 3,6-diazaoctane-1, 8-diamine (L = L(1)) or 3,6-dithiaoctane-1,8-diamine (L = L(2)). The v ery efflorescent solvate complex [Cu(4)L(1)(OH)(2)][MeCO(2)](2)[PF6](2 ) . 4MeCN . 2Pr(i)OH crystallizes in the monoclinic crystal system, sp ace group P2(1)/a, with a = 13.038(5), b = 21.251(5), c = 12.757(3) An gstrom, beta = 113.38(2)degrees. The refinement converges with R = 0.1 215 and R' = 0.1187. The tetranuclear cation {Cu(4)L(1)(OH)(2)((PrOH)- O-i)(2)(MeCN)(2)}(4+) contains two dinuclear Cu-2(II) units in a 'dime r-of-dimers' arrangement. In each unit two copper(II) ions are bridged by an endogenous phenolic oxygen of (L(1))(2-) and an exogenous hydro xide oxygen with a Cu ... Cu separation of 2.949(4) Angstrom. A propan -2-ol molecule resides on the axial site of one copper ion and an acet onitrile molecule on the axial site of the other copper ion, affording a square-pyramidal geometry about both copper(ll) ions. The two dinuc lear skeletons assume a near coplane and the two bridging OH- groups a re facing each other with an O ... O separation of 3.32(2) Angstrom. T he efflorescent solvate complex [Cu(4)L(2)(OH)(2)][PF6](4) . 4MeCN . 4 H(2)O crystallizes in the triclinic crystal system, space group P $($) over bar$$ 1, with a = 12.576(9), b = 13.082(6), c = 11.682(6) Angstr om, alpha = 109.54(4), beta = 106.99(5), gamma = 69.02(5)degrees. The refinement converges with R = 0.0835 and R' = 0.0812. The centrosymmet ric cation {Cu(4)L(2)(OH)(2)(MeCN)(4)}(4+) assumes a similar 'dimer-of -dimers' structure with two facing OH- groups where an acetonitrile mo lecule co-ordinates at the axial site of each copper((II)) ion. The Cu ... Cu separation in the dinuclear unit is 2.976(2) Angstrom and the O ... O separation between the two facing OH- groups is 3.80(1) Angstr om. In all the tetranuclear complexes the two dinuclear units are magn etically isolated from each other and a significant antiferromagnetic interaction operates within each Cu-2(II) unit (-J = 229-357cm(-1) bas ed an ($) over cap H = -2JS(1) . S-2).