Comparison of the neutral benzyldiphenylphosphine complexes C6H6Cr(CO)2PPh2Bz and C5H5Mn(CO)2PPh2Bz with the isoelectronic manganiobenzyldiphenylphosphonium salts [C5R5Mn(CO) (NO)PPh2Bz]BF4

Article abstract of DOI:10.1016/s0020-1693(97)05873-8

The photolytically or thermally induced substitution reactions of C₆H₆Cr(CO)₃, C₅H₅Mn(CO)₃ or [C₅R₅Mn(CO)₂(NO)]BF₄ (R = H, CH₃) with PPh₂Bz led to isoelectronic benzyldiphenylphosphine complexes of half sandwich type C₆H₆Cr(CO)₂PPh₂Bz (1), C₅H₅Mn(CO)₂PPh₂Bz (2), [C₅H₅Mn(CO)(NO)(PPh₂Bz)]BF₄ (3a) and [C₅Me₅Mn(CO)(NO)(PPh₂Bz)] BF₄ (3b). In contrast to the neutral compounds 1 and 2, the phosphonium salts 3a, 3b can be deprotonated at the α-methylene group by bases such as DBU and LDA to give the neutral manganiodiphenylalkylidenephosphoranes C₅R₅Mn(CO)(NO)(PPh₂=CHPh) (4a, 4b). ¹H-. ¹³C-, ³¹P{ ¹H)-NMR, IR and mass spectra of 1-4 are given. Crystals of 1 are orthorhombic, space group Pbca, with a = 19.960(3), b = 16.599(3) and c = 14.573(3) A?, Z = 8 and R = 0.0521 for 2433 observed reflections. Crystals of 2 and 3a are monoclinic, space group P21/c, with a = 9.730(3), b = 23.123(6) and c = 9.784(3) A?, Z = 4 and R = 0.0430 for 2512 observed reflections for 2, and a = 12.457(3), b = 10.597(3) and c = 18.764(5) A?, Z = 4 and R = 0.0477 for 2765 observed reflections for 3a.