The reaction of [LAlH2 ] (L=HC(CMeNAr)2 , Ar=2,6-iPr2 C6 H3 ) with MeOTf (Tf=SO2 CF3 ) resulted in the formation of [LAlH(OTf)] (1) in high yield. The triflate substituent in 1 increases the positive charge at the aluminum center, which implies that 1 has a strong Lewis acidic character. The excellent catalytic activity of 1 for the hydroboration of organic compounds with carbonyl groups was investigated. Furthermore, it was shown that 1 effectively initiates the addition reaction of trimethylsilyl cyanide (TMSCN) to both aldehydes and ketones. Quantum mechanical calculations were carried out to explore the reaction mechanism.

The well-defined aluminum dihydride LAlH2 (L = HC(CMeNAr)2, Ar = 2,6-Et2C6H3) (1) operates in catalysis like a transition metal complex. The catalytic activity of 1 for hydroboration of terminal alkynes was investigated. Furthermore, catalyst 1 effectively initiated the dehydrocoupling of boranes with amines, thiols, and phenols, respectively, to form compounds with B-E bonds (E = N, S, O) under elimination of H2. Quantum mechanical calculations indicate that hydroboration and dehydrocoupling reactions occur via three consecutive cycloaddition reactions involving the activation of the X-H (X = Al, B, C, and O) σ-bonds.

The bisadduct (cAAC)2NiIICl2 [1; cAAC = cyclic (alkyl)(amino)carbene] was directly synthesized by treating cAAC with NiCl2. Compound 1 was reduced to (cAAC)2Ni0 (2) by using lithium diisopropylamide or KC8. Crystals of 2 were stable under an inert gas for several months and decomposed upon heating above 165 °C. On the basis of the calculated natural bond orbital charge values of the nickel atom in 2, the oxidation state of nickel was determined to be between NiI and Ni0 (+0.34). Theoretical calculations suggested a closed‐shell singlet electronic configuration of 2 with little biradical character. Ab initio multiconfigurational C(R)ASSCF/CASPT2 calculations predicted a closed‐shell singlet electronic configuration (Ni0), whereas excited spin states possessed NiI character with unpaired electrons on neighboring carbon atoms. The catalytic activity of complex 2 was investigated for the homocoupling of various unactivated aryl chlorides/fluorides. The biaryls were obtained in good yields at moderate temperature. Theoretical studies showed that an intermediate containing NiIII was more favored than one with NiIV.

Crystal data and structure refinement for 1 CSD reference 609043 Empirical formula C19 H27 B Cl Fe N O2 Formula weight 403.53 Temperature 150(2) K Wavelength 0.71073 A Crystal system, space group monoclinic, P2(1)/c Unit cell dimensions a = 11.845(2) A alpha = 90 deg. b = 11.833(2) A beta = 97.51(3) deg. c = 14.089(3) A gamma = 90 deg. Volume 1957.8(7) A^3 Z, Calculated density 4, 1.369 Mg/m^3 Absorption coefficient 0.918 mm^-1 F(000) 848 Crystal size 0.25 x 0.20 x 0.20 mm Theta range for data collection 2.92 to 27.11 deg. Limiting indices -15<=h<=15, -13<=k<=15, -17<=l<=17 Reflections collected / unique 16902 / 4210 [R(int) = 0.0978] Completeness to theta = 27.11 97.3 % Max. and min. transmission Sortav 0.965 and 0.286 Refinement method Full-matrix least-squares on F^2 Data / restraints / parameters 4210 / 0 / 226 Goodness-of-fit on F^2 1.051 Final R indices [I>2sigma(I)] R1 = 0.0496, wR2 = 0.1181 R indices (all data) R1 = 0.0656, wR2 = 0.1286 Largest diff. peak and hole 1.010 and -1.026 e.A^-3 C(17)-Fe(1)-C(15) 65.69(12) C(16)-Fe(1)-C(15) 39.32(12) C(19)-Fe(1)-C(15) 38.42(12) B(1)-N(1)-C(3) 120.5(2) B(1)-N(1)-C(9) 127.2(2) C(3)-N(1)-C(9) 112.31(19) O(1)-C(1)-Fe(1) 178.3(2) O(2)-C(2)-Fe(1) 178.2(3) N( 1)-C(3)-C(8) 112.8(2) N(1)-C(3)-C(4) 112.6(2) C(8)-C(3)-C(4) 111.6(2) C(5)-C(4)-C(3) 111.3(2) C(6)-C(5)-C(4) 111.1(2) C(7)-C(6)-C(5) 111.1(2) C(6)-C(7)-C(8) 111.1(2) C(3)-C(8)-C(7) 110.2(2) N(1)-C(9)-C(14) 113.7(2) N(1)-C(9)-C(10) 114.0(2) C(14)-C(9)-C(10) 111.4(2) C(11)-C(10)-C(9) 109.6(2) C(12)-C(11)-C(10) 111.2(2) C(11)-C(12)-C(13) 110.9(2) C(12)-C(13)-C(14) 110.8(2) C(9)-C(14)-C(13) 109.6(2) C(19)-C(15)-C(16) 107.8(3) C(19)-C(15)-Fe(1) 70.05(17) C(16)-C(15)-Fe(1) 69.61(16) C(17)-C(16)-C(15) 107.8(3) C(17)-C(16)-Fe(1) 70.08(17) C(15)-C(16)-Fe(1) 71.07(17) C(18)-C(17)-C(16) 108.0(3) C(18)-C(17)-Fe(1) 70.20(19) C(16)-C(17)-Fe(1) 70.68(17) C(17)-C(18)-C(19)108.0(3) C( 17)-C(18)-Fe(1) 70.66(18) C(19)-C(18)-Fe(1) 70.80(18) C(15)-C(19)-C(18) 108.5(3) C(15)-C(19)-Fe(1) 71.54(18) C(18)-C(19)-Fe(1) 69.74(17) N(1)-B(1)-Cl(1) 116.6(2) N(1)-B(1)-Fe(1) 130.3(2) Cl(1)-B(1)-Fe(1) 112.88(15)

Compound (Me2 -cAAC:)2 Co(0) (2; Me2 -cAAC:=cyclic (alkyl) amino carbene; :C(CH2 )(CMe2 )2 N-2,6-iPr2 C6 H3 ) was synthesized by the reduction of the precursor (Me2 -cAAC:)2 Co(I) Cl (1) with KC8 in THF. The cyclic voltammogram of 1 exhibited one-electron reduction, which suggests that synthesis of a bent 2-metallaallene (2) from 1 should be possible. Compound 2 contains one cobalt atom in the formal oxidation state zero, which is stabilized by two Me2 -cAAC: ligands. Bond lengths from X-ray diffraction are 1.871(2) and 1.877(2) Å with a C-Co-C bond angle of 170.12(8)°. The EPR spectrum of 2 exhibited a broad resonance attributed to the unique quasi-linear structure, which favors near degeneracy and gives rise to very rapid relaxation conditions. The cAACCo bond in 2 can be considered as a typical Dewar-Chatt-Duncanson type of bonding, which in turn retains 2.5 electron pairs on the Co atom as nonbonding electrons.