Synthesis, Structures, and Photochemistry of Tricarbonyl Metal Polyoxoanion Complexes, [X₂W₂₀O₇₀{M(CO)₃}₂]^12– (X = Sb, Bi and M = Re, Mn)

A new series of complexes containing two electron donating groups, {M­(CO)₃}⁺ ions, M = Re or Mn, on one polytungstate electron acceptor group have been prepared and characterized. These complexes containing two electron donating groups, {M­(CO)₃}⁺ ions, M = Re or Mn, on one polytungstate electron acceptor group have been prepared and characterized. These two-component polyoxometalate (POM) compounds have been made by reaction of solvated {M­(CO)₃}⁺ ions (M = Re or Mn) with [X₂W₂₂O₇₄(OH)₂]^12– (X = Sb or Bi) POM multidentate ligands in aqueous solution. These syntheses reveal that the <i>fac</i>-{WO­(OH)₂}²⁺ groups in the terminal positions of these two POM ligands are easily replaced by the topologically equivalent units <i>fac</i>-{M­(CO)₃}⁺. Four compounds, [X₂W₂₀O₇₀{M­(CO)₃}₂]^12– (<b>1a</b>: X = Sb, M = Re; <b>1b</b>: X = Bi, M = Re; <b>2a</b>: X = Sb, M = Mn; <b>2b</b>: X = Bi, M = Mn) have been isolated and characterized of X-ray crystallography, spectroscopic, and computational methods. The charge transfer dynamics, investigated by femtosecond transient absorption (TA) spectroscopy of <b>1a</b> and <b>1b</b> combined with the density functional theory (DFT) calculations indicate that both complexes exhibit metal-to-polyoxometalate charge-transfer (MPCT) from the Re centers to the POM ligands, while MPCT from the Mn centers to the POM ligands in <b>2a</b> and <b>2b</b> leads to decomposition of starting compounds. The studies suggest a general synthetic route to a potentially very large class of POM-based hybrid compounds