Comparison of the neutral benzyldiphenylphosphine complexes C 6H 6Cr(CO) 2PPh 2Bz and C 5H 5Mn(CO) 2PPh 2Bz with the isoelectronic manganiobenzyldiphenylphosphonium salts [C 5R 5Mn(CO)(NO)PPh 2Bz]BF 4

Abstract

The photolytically or thermally induced substitution reactions of C 6H 6Cr(CO) 3, C 5H 5Mn(CO) 3 or [C 5R 5Mn(CO) 2(NO)]BF 4 (CH, CH 3) with PPh 2Bz led to isoelectronic benzyldiphenylphosphine complexes of half sandwich type C 6H 6Cr(CO) 2PPh 2Bz ( 1), C 5H 5Mn(CO) 2PPh 2Bz ( 2), [C 5H 5Mn(CO)(NO)(PPh 2Bz)]BF 4 ( 3a) and [C 5Me 5Mn(CO)(NO)(PPh 2Bz)]BF 4 ( 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 C 5R 5Mn(CO)(NO)(PPh 2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.