Late-Metal Nitrosyl Cations: Synthesis and Reactivity of [Ni(NO)(MeNO₂)₃][PF₆]

Abstract

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) Å]. 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) Å], 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) Å].

Biological and Bioinspired Inorganic N–N Bond-Forming Reactions

“…While examples of biological systems competent for N–N bond formation containing Ni have not yet been realized, synthetic systems that may offer insight into analogous Fe- and Cu-mediated biological mechanisms have been reported since the mid-1900s, although the transformation was not initially investigated in depth . Wright and co-workers reported the Ni species [Ni­(NO)­(CH 3 NO 2 ) 3 ]­(PF 6 ) (Figure a), which they synthesized via the reaction of NOPF 6 with excess Ni powder in CH 3 NO 2 in the presence of NiI 2 . Byproducts of this reaction include N 2 O, which was initially suggested to be formed via Ni-mediated NO coupling.…”

“…Structures of (a) [Ni­(NO)­(CH 3 NO 2 ) 3 ]­(PF 6 ), (b) [Ni­(NO)­(bpy) 2 ]­(PF 6 ) (bpy = 2,2′-bipyridine), (c) L 2 NiCl 2 (L = bis­(2-ethyl-4-methylimidazol-5-yl)­methane), (d) ( i Pr 2 NN F 6 )­Ni­(NO) ( i Pr 2 NN F 6 = 1,1,1,5,5,5-hexafluoro-2-(2,6-diisopropylphenylamino)-4-(2,6-diisopropylphenylimino)­pent-2-ene, and (e) [KL­(Ni–H) 2 ] …”

Synthesis and Structural Characterization of an Unusual Platinum π-Arene Complex: (η6-C6H3Me3)Pt[(C2F5)2PMe]Me+

“…11 We have more recently reported the formation of the complex (dfepe)Pt(η 6 -C 6 H 6 ) 2+ (dfepe = (C 2 F 5 ) 2 PCH 2 CH 2 P(C 2 F 5 ) 2 ) with limited solution stability under superacidic conditions. 12 In 2008 we reported a highly active chelating perfluoroalkylphosphine (PFAP) platinum ethylene dimerization catalyst, [(dfepe)Pt(Me)(NC 5 F 5 )] + (B(C 6 F 5 ) 4 ) − . 13 This complex was shown to be orders of magnitude more reactive than the corresponding diimine platinum analogue; 14 considering the extensive use of diimine ancillary ligands in group 10 alkene oligomerization chemistry, 15 and the recognized importance of group 10 alkene oligomerization catalysts, 16 the expansion of group 10 alkyl cation chemistry to a broader range of ligand sets such as phosphines, and more specifically PFAPs, is clearly warranted.…”

“…7,8 In contrast, there is only a single clear example of a Pd(II) analogue, (η 6 -arene)M(allyl) + . 9 For platinum only a single Pt(II) arene complex has been isolated and structurally characterized, (η 6 -C 6 Me 6 )Pt(η 4 -C 4 Me 4 ) 2+ , 10 and (η 6 -C 6 Me 6 )Pt(η 3 -2-methylallyl) + has been characterized as a thermally unstable solution species by NMR. 11 We have more recently reported the formation of the complex (dfepe)Pt(η 6 -C 6 H 6 ) 2+ (dfepe = (C 2 F 5 ) 2 PCH 2 CH 2 P(C 2 F 5 ) 2 ) with limited solution stability under superacidic conditions.…”

Reductive Activation of Nitric Oxide and Nitrosobenzene at a Dinickel(II) Dihydride Complex and New Pyrazole-Based Diiron Compounds

“…36 Other compounds reported by the same group involve pseudo-tetrahedral geometries, like in the [Ni(NO)(CH3NO2)][PF6] complex, where it was shown that the nitromethane ligand undergoes substitution upon treatment with MeCN, piperidine and even arenes. 37 The latter case was rather interesting, as the arene group showed a η 6 binding mode, which is rare for Ni(arene) compounds. 38 In contrast with the pseudo tetrahedral geometry usually adopted by four-coordinated nickel nitrosyl compounds, the addition of NO to (PNP)Ni (PNP = ( t Bu2PCH2SiMe2)2N) afforded (PNP)Ni(NO), which features a distorted square planar geometry, probably originated from the rigidity of the PNP ligand backbone.…”