X-RAY CRYSTAL-STRUCTURES OF PPN[FE-2(MU-CO)(CO)(6)(MU-PBU(2)(T))] =(PPH(3))(2)N-2(MU-CO)(CO)(6)(MU-H)(MU-PBU(2)(T))] AND STRUCTURAL COMPARISON WITH THE CLUSTER FE-2(MU-AG(PPH(3)))(MU-CO)(CO)(6)(MU-PBU(2)(T))](] AND [FE)

[Fe-2(mu-CO)(CO)(6)(mu-H)(mu-PBu(2)(t))] (2) has been synthesized from Na[Fe-2(mu CO)(CO)(6)(mu-PBu(2)(t))] and CH3COOH and structurally cha racterized by X-ray analysis. Also the crystal structure of PPN[Fe-2(m u-CO)(CO)(6)(mu-PBu(2)(t))] (1) containing the parent complex anion to 2 has been determined. The two structures were refined to conventiona l R values of 0.034 and 0.021 for 5481 and 2825 observed reflections, respectively. Structural comparisons of 1 and Et(4)N[Fe-2(mu-CO)(CO)(6 )(mu-PPh(2))] (4) as well as of 1, 2 and the isolobal cluster compound s to 2, [Fe-2{mu-Ag(PPh(3))} (mu-CO)(CO)(6)(mu-PBu(2)(t))] (3) and [Fe -2{mu Cu(PPh(3))} (mu-CO)(CO)(6)(mu-PPh(2))] (5) are made. Unexpectedl y the Fe-Fe bond in 2 is significantly shorter than in the deprotonate d parent anion of 1.