HALIDE ION ADDITION TO BISMUTH-CONTAINING IRON CARBONYL-COMPOUNDS - SYNTHESIS AND CHARACTERIZATION OF THE 2 BRIDGED-BUTTERFLY CLUSTER COMPOUNDS [ET4N][(MU-H)FE-2(CO)(6)BI-2(MU-FE(CO)(4))] AND 2NME3)((MU-H)FE-2(CO)(6)BI-2(MU-CL)(2))](INFINITY) AND STABILIZATION OF REDUCED-HYPERVALENT BISMUTH CENTERS BY COORDINATION TO A METAL CENTER IN [PHCH2NME3](3)[BI3CL4(MU-CL)(4)(FE(CO)(3))]

The reaction of [Q](2)[Bi4Fe4(CO)(13)] ([Q](2)[1]; [Q] = [Et4N](+), [P hCH2NMe3](+)) with MePCl2 in MeCN is a complicated reaction which give s different results depending upon the stoichiometry of the reaction. At a ratio of 1:1.33 (cluster:phosphine), the reaction yields a mixtur e of the new bismuth-iron carbonyl compounds [Q][(mu-H)Fe-2(CO)(6)Bi-2 {Fe(CO)(4)}] ([Q][2]), which has a tetrahedral Fe2Bi2 core edge-bridge d across the bismuth centers by an [Fe(CO)(4)](2-) fragment, and [Q](3 )[Bi3Cl4(mu-Cl)(4){Fe(CO)(3)}] ([Q](3)[3]), containing a reduced compl ex ion [Bi3Cl8](-) stabilized by coordination to an iron tricarbonyl f ragment. Extended Huckel molecular orbital calculations on this unusua l anion are consistent with each bismuth atom possessing the same redu ced oxidation state of +2.33. The compound [Et4N][2] crystallizes in t he triclinic space group P (1) over bar (No. 2) with a = 10.246(2) Ang strom, b = 11.859(2) Angstrom, c = 12.474(2) Angstrom, alpha = 71.11(3 )degrees, beta = 79.60(3)degrees, gamma = 76.37(3)degrees, V = 1384.7( 4) Angstrom(3), and Z = 2; while [PhCH2NMe3](3)[3].0.87Et(2)O was char acterized in the orthorhombic space group Pbca (No. 61) with a = 20.80 1(4) Angstrom, b = 19.937(4) Angstrom, c = 25.480(5) Angstrom, V = 105 66.8(36) Angstrom(3), and Z = 8. When the reaction is carried out at a ratio of 1:2, the novel hydride [{Q}{(mu-H)Fe-2(CO)(6)Bi-2{mu-Cl}(2)} ](infinity) ([{Q}{4}](infinity)) is isolated. This cluster also has a ''tetrahedral'' core, with the Bi-Bi vector bridged by a chloride Liga nd and the molecules joined into infinite polymeric chains in the soli d state by the second intermolecularly-bridging chloride ligand. [{PhC H2NMe3}{4}](infinity) crystallizes in the monoclinic space group P2(1) /n (No. 14) with a = 7.864(2) Angstrom, b = 22.465(4) Angstrom, c = 13 .797(3) Angstrom, beta = 105.96(3)degrees, V = 2343.5(9) Angstrom(3), and Z = 4. The metal framework of [4](-) is similar to that of [2](-) with the notable exception that the Bi-Bi bond present in [2](-) is mi ssing in [4](-) because of the additional electrons provided by the ch loride ions. At stoichiometries greater than 2:1, the previously repor ted [Fe(CO)(4)Bi2Cl6](2-) ion is formed.