Rearrangement of
fac-[Cr(CO)
3(
2-L
2)(
1-L
2)]
+ to
mer-[Cr(CO)
3(
2-L
2)(
1-L
2)]
+ (L
2 is abidentate phosphine or arsine ligand) is a rapid thermally activated process. Loss of COfrom
mer-[Cr(CO)
3(
2-L
2)(
1-L
2)]
+ to form
trans-[Cr(CO)
2(
2-L
2)
2]
+ is shown to be a cleanphotochemical process, perhaps the first example of a quantitative photochemical transformation for a Cr(I) complex. The bidentate phosphonite ligand, L
2 = (MeO)
2PCH
2CH
2P(OMe)
2,behaves quite differently:
fac-[Cr(CO)
3(
2-L
2)(
1-L
2)]
+ undergoes photochemical loss of COto form a five-coordinate complex which converts slowly via thermal activation to
trans-[Cr(CO)
2(
2-L
2)
2]
+.