“…The pattern of CO stretching bands in the IR spectrum of complex 52 (2012, 1885, 1856 cm Ϫ1 ) is similar to that seen for 54 (2018, 1889, 1832 cm Ϫ1 ), but different from that in the case of complex 51 (2070, 1978, 1834 cm Ϫ1 ). This latter spectrum closely resembles that of Ph 3 PW(CO) 5 (2075, 1980, 1938 cm Ϫ1 ) [40] .…”