C. Bianchini et al., New structurally rigid palladium catalysts for the alternating copolymerization of carbon monoxide and ethene, CHEM COMMUN, (9), 2000, pp. 777-778
Decreasing the flexibility of the Ph2PCH2CH2PPh2 (dppe) backbone by making
the central carbon atoms part of a cyclobutane ring leads to the formation
of Pd( II) catalysts for CO/ethene copolymerization that are more efficient
than those of dppe by a factor of ten.