Formation and structure of iBu)PPh2-P,P'>2(CO)> - a cage molecule-pair or an ion-pair complex?

Article abstract of DOI:10.1016/0022-328X(94)80170-3

The strong ?-acid ligand Ph2PN(ⁱBu)PPh2 reacts with Co2(CO)5 (1:1) to give Co2<μ-Ph2PN(ⁱBu)PPh2>(μ-CO)2(CO)4 (1); however,when the ratio is 2:1 a novel species iBu)PPh2-P,P'>2(CO)> (2) has been obtained.