A new synthesis and some reactions of rhenium nitrene complexes

Rhenium nitrene complexes, Re(PPh 3 ) 2 (NAr)Cl 3 (I) (Ar = C 6 H 5 (Ia), p -MeC 6 H 4 (Ib), p -MeOC 6 H 4 (Ic)), have been obtained from the reactions of Re(PPh 3 ) 2 (O)Cl 3 and the corresponding sulphynil-amines, ArNSO, with the concomitant formation of sulphur dioxide. A carbonyl derivative, Re(PPh 3 )(CO)(NAr)Cl 3 (II) (Ar = p -MeOC 6 H 4 ), has been isolated from the reaction of (Ic) with carbon monoxide. The CO group is weakly bound in this complexand can be easily substituted by PPh 3 giving back (Ic) and by R′NH 2 (R′ = p -MeC 6 H 4 ) leading to Re(PPh 3 )(R′NH 2 )(NAr)Cl 3 (III). On the other handd the nitrene residue is involved in the reactions of (I) with NaBH 4 in the presence of CO or PPh 3 , ReH(CO) 3 (PPh 3 ) 2 and ReH x (PPh 3 ) 3 (IV) (x probably five) being formed respectively, while the NAr groups are recovered as the corresponding amines. Similarly, the reactions of (I) with granular zinc in ethanol in the presence of CO give trans - Re(PPh 3 ) 2 (CO) 3 Cl and Zn(ArNH 2 ) 2 Cl 2 . Finally, a remarkable reaction has been observed when (I) and dioxygen reacted in boiling toluene, Re(OPPh 3 )(ArNO)Cl 3 (V) being isolated.