Salen-type compounds of calcium and strontium

Salen complexes of the heavy alkaline-earth metals, calcium and strontium, were prepared by the reaction of various salen(t-Bu)H-2 ligands with the metals in ethanol. Six new calcium and strontium compounds, [Ca(salen-(t-Bu))(HOEt)(2)(thf)] (1), [Ca(salen(t-Bu))(HOEt)(2)] (2), [Ca(salpen(t-Bu))(HOEt)(3)] (3), [Ca(salophen(t-Bu))(HOEt)(thf)] (4), [Sr(salen(t-Bu))(HOEt)(3)] (5), and [Sr(salophen(t-Bu))(HOEt)(thf)(2)] (6), were formed in this way with the quatridentate Schiff-base ligands N,N'-bis(3,5-di-tert-butylsalicylidene)ethylenediamine (salen(t-Bu)H-2), N,N'-bis(3,5-di-teIt-butyl-salicylidene)-1,3-propanediamine (salpen(t-Bu)H-2), and N,N'-o-phenylenebis(3,5-di-tert-butylsalicylideneimine (salophen(t-Bu)H-2). Initially, ammonia solutions of the metals were combined with the salen(t-Bu)H2 ligands, and in the reaction of strontium with salen(t-Bu)H-2, the unusual tetrametallic cluster [{OC6H2(t-Bu)(2)CHN(CH2)(2)NH2}Sr(mu(3)-salean(t-Bu)H-2)Sr(mu(3)-OH)](2) (7) was produced (salean(t-Bu)H-4 = N,N'-bis(3,5-di-tert-butyl-2-hydroxybenzyl)ethylenediamine). In this compound, the imine bonds of the salen(t-Bu)H2 ligand were reduced to form the known ligands salean(t-Bu)H-4 and (HO)C6H2(t-Bu)(2)CHN(CH2)(2)NH2- Compounds 1, 5, 6, and 7 were structurally characterized by single-crystal X-ray diffraction. Crystal data for 1 (C44H74CaN2O6): triclinic space group P (1) over bar, a = 8.3730(10) Angstrom, b = 14.8010(10) Angstrom, c = 18.756(2) Angstrom, alpha = 72.551 (10)degrees, beta = 81.795(10)degrees, y = 78.031 (10)degrees, Z = 2. Crystal data for 5 (C38H64SrN2O5): monoclinic space group P2(1)/c, a = 23.634(3) Angstrom, b = 8.4660(10) Angstrom, c = 24,451(3) Angstrom, = 101.138(10)degrees, Z = 4. Crystal data for 6 (C46H67N2O5Sr): orthorhombic space group P2(1)2(1)2(1), a = 10.5590(2) Angstrom, b = 16.2070(3) Angstrom, c = 26.7620(6) Angstrom, Z = 4. Crystal data for 7 (C98H156N8O8Sr4): triclinic space group P (1) over bar, a 14.667(1) Angstrom, b = 15.670(1) Angstrom, c = 18.594(2) Angstrom, alpha = 92.26(1)degrees, beta = 111,84(1)degrees, y = 11 7.12(1)degrees, Z = 4.