Nitrosyl derivatives of the unsaturated dihydrides [Mn 2(μ-H) 2(CO) 6(μ-L 2)] (L 2 = Ph 2PCH 2PPh 2, (EtO) 2POP(OEt) 2)

Abstract

The title dimanganese complexes react with NO (5% in N 2) at room temperature to give as major products the corresponding hexanitrosyl derivatives [Mn 2(NO) 6(μ-L 2)] in moderate yields, and they react rapidly with NO 2 to give the corresponding hydride derivatives [Mn 2(μ-H)(μ-NO 2)(CO) 6(μ-L 2)], these having a nitrite ligand bridging the dimetal centre through the N and O atoms. The dppm-bridged dihydride also reacts selectively at 273 K with (PPN)NO 2 to give first the nitro derivative (PPN)[Mn 2(μ-H)(H)(NO 2)(CO) 6(μ-dppm)], which then transforms into the nitrosyl complex (PPN)[Mn 2(μ-CO)(CO) 5(NO)(μ-dppm)] at room temperature or above (dppm = Ph 2PCH 2PPh 2; PPN + = [N(PPh 3) 2] +). The latter anion reacts with (NH 4)PF 6 to give the hydride-bridged nitrosyl complex [Mn 2(μ-H)(μ-NO)(CO) 6(μ-dppm)] and with [AuCl(PPh 3)] to give the trinuclear cluster [AuMn 2(μ-NO)(CO) 6(μ-dppm)(PPh 3)] (Mn–Au = ca. 2.68 Å; Mn–Mn = 2.879(2) Å). Both products are derived from the addition of the added electrophile at the intermetallic bond and rearrangement of the nitrosyl ligand into a bridging position. In contrast, methylation of the anion with CF 3SO 3Me takes place at the nitrosyl ligand to yield the unstable methoxylimide derivative [Mn 2(μ-NOMe)(CO) 6(μ-dppm)]. Analogous reactions at the nitrosyl ligand take place upon the addition of HBF 4·OEt 2 to the nitrosyl-bridged hydrides [Mn 2(μ-H)(μ-NO)(CO) n(μ-dppm) m] (n = 6, m = 1; n = 4, m = 2) to give the corresponding hydroxylimide derivatives [Mn 2(μ-H)(μ-NOH)(CO) n(μ-dppm) m]BF 4, which were also thermally unstable and could not be isolated nor fully characterized.