Reactions between primary amines and magnesium or zinc dialkyls: Intermediates in metal imide formation

The reactions of several different primary amines with diorganomagnesium or dialkylzinc compounds are reported. Treatment of Mg(eta(5)-C5H5)(2) with t-BuNH(2) or DippNH(2) (Dipp=2,6-i-Pr2C6H3-) leads to the adduct Mg(eta(5)-C5H5) (eta(2)-C5H5) {NH2(t-Bu)}THF (1a) or the amide Mg(eta(5)-C5H5)(NHDipp)THF (1b). Reaction between Mg(t-Bu)(2) or commercially available Mg'Bu'(2) ('Bu' = statistical mixture of n-Bu and s-Bu groups) gave the dimeric amide species [t-BuMg{NH(t-Bu)}THF](2) (2a) or ['Bu'Mg{NH(t-Bu)}THF](2) (2b). In contrast, reaction of Mg'Bu'(2) with MesNH(2) or TriphNH(2) (Mes=2,4,6-Me(3)C(6)H(2)-; Triph=2,4,6-Ph(3)C(6)H(2)-) gave, after suitable workup, the bisamides Mg(NHMes)(2){OP(NMe(2))(3)}(2) (3a) or Mg(NHTriph)(2)(THF)(2) . THF (3b . THF). A bisamide, the dimer {Mg(NCy(2))(2)}(2) (4), was isolated in almost quantitative yield by the reaction of dibutylmagnesium with 2 equiv. of HNCy(2) (Cy = cyclohexyl) whereas the trimetallic amide Mg-3(mu-NHDipp)(4){N(SiMe(3))(2)}(2) (5) was isolated from the transamination reaction between DippNH(2) and [Mg{N(SiMe(3))(2)}(2)](2). A unique product with a rare dodecameric ring structure, (EtMgNHDipp)(12) (6), was observed when MgEt(2) reacts with DippNH(2). Reaction between ZnEt(2) or Zn(CH(2)SiMe(3))(2) and a variety of primary amines afforded a selection of structurally diverse products. The compounds isolated were: (EtZn(NHPh)THF)(3) (7), {EtZn(NHMes)THF}(2) . 0.5THF (8 . 0.5THF), Et(2)Zn(4)(NHDipp)(4)(OEt)(2) (9), (EtZnNH(t-Bu))(3) (10) and (Me(3)SiCH(2)ZnNHDipp)(2) (11). Crystal data: 1a, a=10.863(2), b=9.299(2), c=17.787(5) Angstrom, beta=98.56(2)degrees, monoclinic, space group P2(1)/c, Z=4, R=0.048 for 2337 (1>2 sigma(I)) data; 2a, a=8.922(2), b=16.101(4), c=11.132(2) Angstrom, beta=111.18(2)degrees, monoclinic, space group P2(1)/n, Z=2, R=0.081 for 2076 (I>2 sigma(I)) data; 3a, a=11.174(2), b=18.161(4), c=18.808(6) Angstrom, beta=92.34(3)degrees, monoclinic, space group P2(1)/n, Z=8, R=0.145 for 4945 (I>2 sigma(I)) data; 4, a=22.828(5), b=10.768(2), c=21.350(4) Angstrom, beta = 117.74(3)degrees, monoclinic, space group P2(1)/c, Z=4, R=0.067 for 6264 (I>2 sigma(I)) data; 5, a=21.754(5), b=15.214(2), c=20.657(4) Angstrom, orthorhombic, space group Pbcn, Z=4, R=0.063 for 2338 (I>2 sigma(I)) data; 6, a=26.063(5), b=35.332(4), c=24.535(4) Angstrom, orthorhombic, space group Pnma, Z=4, R=0.178 for 10408 (I>2 sigma(I)) data; 7, a=12.715; (3), b=13.606(3), c=22.339(5) Angstrom, alpha=90.53(3), beta=96.20(3), gamma=93.85(3)degrees, triclinic, space group <P(1)over bar>, Z=4, R=0.143 for 4483 (I>2 sigma(I)) data; 8 . 0.5THF, a=43.58(2), b=8.724(2), c=38.90(1) Angstrom, beta=117.49(2)degrees; monoclinic, space group C2/c, Z=16, R=0.058 for 5587 (I>2 sigma(I)) data; 9, a=10.875(2), b=11.669(2), c=11.968(2) Angstrom, alpha=76.17(2), beta=86.52(2), gamma=69.69(2)degrees triclinic, space group <P(1)over bar>, Z=1, R=0.043 for 2733 (I>2 sigma(I)) data; 10, a=11.281(3), b=14.891(4), c=15.103(5) Angstrom, beta=90. 88(2)degrees monoclinic, space group P2(1)/n, Z=4, R=0.060 for 2363 (I>2 sigma(I)) data; 11, a=10.147(2), b=11.640(2), c=17.521(2) Angstrom, alpha=71.23(1), beta=77.50(1), gamma=69.78(1)degrees, triclinic, space group <P(1)over bar>, Z=2, R=0.065 for 4752 (I>2 sigma(I)) data.