Synthesis of 1,3-Dimetallo-1,3-diphosphetane-2,4-diones. X-ray Structure Analysis of Cp*(CO)2FeP[Cr(CO)5]C(O)P[Fe(CO)2Cp*]C(O) (Cp* = η5-C5Me5)

Reaction of the lithoxy phosphaalkyne (DME) 2 LiOC⋮P ( 1 ) with 1 equiv of the complexes (η 5 -C 5 R 5 )(CO) 2 FeBr ( 2 ); C 5 R 5 = C 5 Me 5 ( a ), 1,3- t -Bu 2 C 5 H 3 ( b ), 1,2,4- i -Pr 3 C 5 H 2 ( c )) afforded the 1,3-diferrio-1,3-diphosphetane-2,4-diones (η 5 -C 5 R 5 )(CO) 2 FePC(O)P[Fe(CO) 2 (η 5 -C 5 R 5 )]C(O) ( 3a − c ) as red amorphous solids in 32−37% yield. By treatment with (( Z )-cyclooctene)Cr(CO) 5, compound 3a was converted into the red complex Cp*(CO) 2 FeP[Cr(CO) 5 ]C(O)P[Fe(CO) 2 Cp*]C(O) ( 4 ). Constitutions and configurations of 3a − c and 4 were determined by elemental analyses and spectra (IR, 1 H, 13 C, and 31 P NMR, MS). The molecular structure of 4 was established by a single-crystal X-ray analysis.