Reaction of photochem. generated [(Z)-cyclooctene]Cr(CO)5 (I) with metal-substituted phosphaarsenes (h5-C5H4R)Fe(CO)(PPh3)As:PR1 [R = H, Me; R1 = C6H2(CMe3)3-2,4,6] afforded the deep red compds. (h5-C5H4R)Fe(CO)(PPh3)As[Cr(CO)5]:PR1 (same R, R1). Thermolabile (h5-C5Me5)Fe(CO)2As:PR1 (same R1) was trapped as Cr(CO)5 adduct II by treatment with I. The mol. structure of II was established by single-crystal x-ray diffraction.