METATHETIC REACTIONS INVOLVING DITUNGSTEN HEXAPIVALATE - PREPARATION AND STRUCTURES OF W-2(O(2)C(T)BU)(2)(O(T)BU)(2)((NPR2)-PR-I)(2), W-2(O(2)C(T)BU)(4)((NPR2)-PR-I)(2), W-2(O(2)C(T)BU)(2)(O(T)BU)(4) AND NA(2)W(4)O(4)CP(2)(O(2)C(T)BU)(6) SOLVATE WHERE CP=C5H5

The reactions between W-2(O(2)C(t)Bu)(6)(M(3)-M) and each of Na/Hg, Na BH4, LiHBEt(3) and LiMe in hydrocarbon/THF solutions yield W-2(O(2)C(t )Bu)(4)(M(4)-M). W-2(O(2)C(t)Bu)(6) and KO(t)Bu (2 equiv.) or W-2(O(t) Bu)(6) react to give W-2(O(2)C(t)Bu)(2)(O(t)Bu)(4) (1) by ligand redis tribution. Crystal data for 1 at -172 degrees C: a = 11.200(3), b = 16 .331(5), c = 10.490(3) Angstrom, alpha = 95.71(2), beta = 111.14(1), g amma = 71.82(1)degrees Z = 2, D-calc = 1.685 g cm(-3), space group P $ ($) over bar$$ 1. A similar reaction involving W-2(O(2)C(t)Bu)(6) and LiNPr2i (2 equiv.) yields an isomeric mixture of W-2(O(2)CBu)(4)((NPr2 )-Pr-i)(2), for which one isomer, 2, has been crystallographically cha racterized. Crystal data for 2 at -164 degrees C: a = 41.858(9), b = 1 0.009(2), c = 41.481(9) Angstrom, beta = 112.37(1)degrees Z = 16, D-ca k 1.608 g cm(-3), space group C2/c. Compound 2 was shown to react with KO(t)Bu (2 equiv.) to give a 6:1:1 mixture of products from which the major product W-2((O2CBU)-B-t)(2)((NPr2)-Pr-i)(2)(O(t)Bu)(2) (3) was characterized. Crystal data for 3 at -174 degrees C: a = 10.675(4), b = 9.836(4), c = 35.795(14) Angstrom, beta = 96.76(2)degrees Z = 4, D-c ak = 1.631 g cm(-3), space group P2(1)/c. The reaction between W-2(O(2 )C(t)Bu)(6) and NaCp (2 equiv.) in THF gave an orange hydrocarbon solu ble crystalline compound Na(2)W(4)O(4)Cp(2)(O(2)C(t)Bu)(6) . 4(t)BuCOO H . toluene, (4 . solvate). Crystal data for 4 . solvate at -170 degre es C: a = 13.065(2), b = 14.941(2), c = 12.996(2) Angstrom, alpha = 90 .06(1), beta = 114.90(1), gamma = 71.69(1)degrees, Z = 1, D-cak = 1.67 (2) g cm(-3), space group P $($) over bar$$ 1. In compounds 1, 2 and 3 there are W-3-W bonds and each metal atom is coordinated to four liga nd atoms. The M(3)-M bond is spanned by a pair of cis-pivalate ligands . The structure of the W(4)O(4)Cp(2)(O(2)C(t)Bu)(6)(2-) anion is a cen trosymmetric bis-oxo bridged dimer [(eta(5)-C5H5)(eta(1)-O(2)C(t)Bu)(2 )W(mu-eta(1), eta(1)-O(2)C(t)Bu)W(=O)(mu-O)](2) with a W-W bonding dis tance of 2.537(1) Angstrom.