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Polynuclear chromium carbonyl complexes of the general formula [Cr4(CO)12^3-OR)4]4-(R = H, C6H5) have been prepared as their Et4N+ salts. Reaction of Cr(CO)6 with excess hydroxide ion in aqueous THE solution yields [Cr4(CO)12(^3-OH)4]4". The X-ray structure of [Et4N]4[Cr4(CO)12(g3-OH)4] has been determined. The structural features of the tetraanion consist of a cubane-like A4B4 (A = chromium, B = oxygen) arrangement with triply bridging M3-hydroxide groups and Cr(CO)3 units. The Cr-Cr distance within the Cr404 core is nonbondiitg (3.33 (5) Á (average)), consistent with a closed-shell metal configuration.The crystals are monoclinic (space group 12/a) with cell constants a = 21.827 (7) Á, b = 12.236 (2) A, c = 22.899 (4) A, ß = 116.49 (2)°, V = 5474 (5) A* 3, and Z = 8. The µ3-1 derivative, [Et4N]4[Cr4(CO)12^3-OC6H5)4], has been prepared by treatment of Cr(CO)3(CH3CN)3 with [Et4N] [OC6H5] in equimolar concentrations and characterized by spectroscopic methods. Polynuclear Chromium Carbonyl Tetraanions Table II. Selected Bond Distances (Á) and Angles (deg) for [Cr4(CO)12(M3-OH)4]4-Cr-0", Cr(l)-0(7) 2.126 (4) Cr(2)-0(7) 2.145 (3) Cr(l)-0(8) 2.122 (4) Cr(2)-Q(7) 2.107 (3) Cr(l)-0(8) 2.111 (3) Cr(2)-0(8) 2.112 (4) Cr--C Cr(l)-C(l) 1.787 ib) Cr(2)-C(4) 1.770 (b) Cr(l)-C(2) 1.787 (7) Cr(2)-C(5) 1.791 (b) Cr(l)-C(3) 1.803 (8) Cr(2)-C(6) 1.798 (7) C-O C(l)-0(1) 1.189 (7) C(4)-0(4) 1.201 (b) C(2)-0(2) 1.174 (7) C(5)-0(5) 1.178 (7) C(3)-0(3) 1.168 (8) C(b)-0(6) 1.174 (7)Cr-OwrCr Cr(l)-0(7)-Cr(2) 100.5 (2) Cr(l)-Q(8)-Cr(l) 106.1 (2) Cr(l)-G(7)-Cr(2) 102.7 (2) Cr(l)-G(8)-Cr(2) 102.7 (2) Cr(2)-0(7)-Cr(2) 106.5 (1) Cr(l)-Q(8)-Cr(2) 102.1 (2)0"3-Cr-0M3 0(7)-Cr(l)-0(8) 74.8 (1) 0(7)-Cr(2)-Q( 7) 72.7 (1) 0(7)-Cr(l)-0(8) 76.1 (1) 0(7)-Cr(2)-0(8) 75.7 (1) 0(8)-Cr(l)-0(8) 72.9 (2) 0(7)-Cr(2)-0(8) 75.4 (1)Cr-C-O Cr(l)-C(l)-0(1) 174.0 (5) Cr(2)-C(4)-Q(4) 174.6 ( 6)Cr(l)-C(2)-0(2)174.3 (6) Cr(2)-C(5)-0(5) 173.5 (6) Cr(l)-C(3)-0(3) 173.7 (6) Cr(2)-C( 6)-Q( 6) 169.4 (6)

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