Cluster conversion of [MoW2O2(O(2)CEt)(9)](-) to [MoW2O4(O(2)CEt)(8)](4-) by chromium hexacarbonyl crystal structures of Na[MoW2O2(O(2)CMe)(9)]center dot H2O, [MoW2O2(O(2)CEt)(6)(H2O)(3)]ZnCl4 center dot 2H(2)O, and Na2Cr2[MoW2O4(O(2)CEt)(8)](2)

Reactions of Mo(CO)(6) with Na2WO4 . 2H(2)O in refluxing carboxylic anhydride produce the triangular bioxo-capped mixed-metal carboxylate clusters Na[MoW2O2(O(2)CR)(9)] (R = Me, 1; Et, 2), the propionate being hydrolyzed in 2M HCl containing ZnCl2 to form [MoW2O2(O(2)CEt)(6)(H2O)(3)]ZnCl4 . 2H(2)O (3). Cluster 2 is converted to the incomplete cuboidal tetraanion [MoW2O4(O(2)CEt)(8)](4-) upon reacting with Cr(CO)(6) in propionic anhydride at 120 degrees, the latter species being trapped by Cr3+ and Na+ ions in the reaction mixture to afford the octanuclear heterometallic chain-like cluster Na2Cr2 [MoW2O4(O(2)CEt)(8)](2) (4). Clusters 1, 3 and 4 have been characterized by X-ray crystallography with the following crystal data, for 1: monoclinic, space group P2(1)/c, a = 16.666(8), b = 11.096(3), c = 16.541(7) Angstrom, beta = 94.60(4)degrees, V = 3048.9 Angstrom(3), Z = 4, R, Rw = 0.070, 0.079; for 3, monoclinic, space group Cm, a = 10.259(3), b = 15.756(3), c = 10.870(3) Angstrom, beta = 96.18(3)degrees, V = 1746.8 Angstrom(3), Z = 2, R, Rw = 0.028, 0.034; for 4, triclinic, space group P-1, a = 13.013(5), b = 14.005(4), c = 12.357(4) Angstrom,alpha = 109.71(2), beta = 117.77(3), gamma = 90.41(3)degrees, V = 1838.9 Angstrom(3), Z = 1, R, Rw = 0.037, 0.042.