Dinitrogen Splitting and Functionalization in the Coordination Sphere of Rhenium

Abstract

[ReCl3(PPh3)2(NCMe)] reacts with pincer ligand HN(CH2CH2PtBu2)2 (HPNP) to five coordinate rhenium(III) complex [ReCl2(PNP)]. This compound cleaves N2 upon reduction to give rhenium(V) nitride [Re(N)Cl(PNP)], as the first example in the coordination sphere of Re. Functionalization of the nitride ligand derived from N2 is demonstrated by selective C-N bond formation with MeOTf.

Conversion of Dinitrogen into Acetonitrile under Ambient Conditions

“…We recently reported dinitrogen splitting upon reduction of rhenium(III) pincer complex [ReCl 2 (PNP)] (1,P NP = N(CH 2 CH 2 PtBu 2 ) 2 )w ith Na/Hg or CoCp* 2 and methylation of the resulting rhenium(V) nitride [Re(N)Cl(PNP)] (2)t o methylimido complex 3a (Scheme 2). [15] In analogy,t he ethylimido complex 3b is obtained upon reaction of nitride 2 with ethyl triflate in essentially quantitative isolated yield. [16] TheN MR spectroscopic features of 3b are close to 3a, suggesting square-pyramidal geometry with the imide in the apical position as confirmed by X-ray diffraction for 3a.…”

“…[16] TheN MR spectroscopic features of 3b are close to 3a, suggesting square-pyramidal geometry with the imide in the apical position as confirmed by X-ray diffraction for 3a. [15] Ethylimide 3b is deprotonated quantitatively with KN-(SiMe 3 ) 2 giving the red-brown 1-azavinylidene rhenium(III) complex [Re(N = CHCH 3 )Cl(PNP)] (4;S cheme 3). [16] The synthesis of 4 can also be carried out as ao ne-pot reaction directly from 2 by successive ethylation and deprotonation in benzene with almost quantitative spectroscopic and over 80 %i solated yield.…”

“…Thes tructural assignment of 4 is confirmed by singlecrystal X-ray diffraction (Figure 1a). Thecoordination geometry around the rhenium ion is close to that in the methyl imide 3a [15] and all N-Re-N and N-Re-Cl bond angles of the two structures are the same within 58 8.H owever, the almost linear Re-N-C moiety of 4 exhibits considerably longer ReÀN (Dd =+0.12 ) and shorter C À N(Dd = À0.17 ) bonds than 3a,i nl ine with the changes in Re À Na nd C À Nb ond orders and with the only other structurally characterized rhenium 1azavinylidene complex reported. [17] Thek etimido complex 4 can be further deprotonated if the resulting rhenium(I) ion is stabilized by strong p-acceptor ligands.F or example,t he reaction of 4 with KN(SiMe 3 ) 2 and tert-butylisonitrile (2 equiv) gives the bis-isonitrile complex [Re(CNtBu) 2 (PNP)] (5)i na lmost quantitative yield with concomitant release of acetonitrile (Scheme 3).…”

“…Rhenium-mediated dinitrogen splitting and alkylation. [15] Scheme 3. Synthesis of acetonitrile upon double deprotonation of N 2derived ethylimide 3b.…”

Direct Synthesis of Silylamine from N2 and a Silane: Mediated by a Tridentate Phosphine Molybdenum Fragment

“…Our strategy for N 2 functionalization relied on the splitting of N 2 in af irst step,a nd this process has only been reported to occur at af ew molybdenum, [10] rhenium, [11] and iron [12] centers (thermally or photochemically). We recently reported that the [(P Ph P 2 Cy )Mo(N 2 ) 2 (m-N 2 )Mo(N 2 ) 2 (P Ph P 2 Cy )] molybdenum(0) dimer complex did not result in N 2 splitting, although it could be used as catalyst for the reduction of N 2 into N(SiMe 3 ) 3 (Scheme 1a).…”