Late-metal nitrosyl cations: synthesis and reactivity of [Ni(NO)(MeNO2)3][PF6

The reaction of NO]PF(6)] with excess Ni powder in CH(3)NO(2), in the presence of 2 mol % NiI(2), results in the formation of Ni(NO)(CH(3)NO(2))(3)]PF(6)] (1), which can be isolated in modest yield as a blue crystalline solid. Also formed in the reaction is Ni(CH(3)NO(2))(6)]PF(6)](2) (2), which can be isolated in comparable yield as a pale-green solid. In the solid state, 1 exhibits tetrahedral geometry about the Ni center with a linear nitrosyl ligand Ni1-N1-O1 = 174.1(8)°] and a short Ni-N bond distance 1.626(6) ?]. As anticipated, the weakly coordinating nitromethane ligands in 1 are easily displaced by a variety of donors, including Et(2)O, MeCN, and piperidine (NC(5)H(11)). More surprisingly, the addition of mesitylene to 1 results in the formation of an η(6)-coordinated nickel arene complex, Ni(η(6)-1,3,5-Me(3)C(6)H(3))(NO)]PF(6)] (6). In the solid state, complex 6 exhibits a long Ni-C(cent) distance 1.682(2) ?], suggesting a relatively weak Ni-arene interaction, a consequence of the strong π-back-donation to the nitrosyl ligand. The addition of anisole to 1 also results in the formation of a η(6) nickel arene complex, Ni(η(6)-MeOC(6)H(5))(NO)]PF(6)] (7). This complex also exhibits a long Ni-C(cent) distance 1.684(1) ?].