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NHC-nickel( NHC = N-heterocyclic carbene) complexes are efficient catalysts for the CÀCl bond borylation of aryl chlorides using NaOAc as ab ase and B 2 pin 2 (pin = pinacolato) as the boron source.T he catalysts [Ni 2 (ICy) 4 (m-(h 2 :h 2 )-COD)] (1,I Cy = 1,3-dicyclohexylimidazolin-2-ylidene;C OD = 1,5-cyclooctadiene), [Ni(ICy) 2 (h 2 -C 2 H 4 )] (2), and [Ni(ICy) 2 (h 2 -COE)] (3,C OE = cyclooctene) comparew ell with other nickel catalysts reported previously for aryl-chloride borylation with the advantage that no further ligandsh ad to be added to the reaction. Borylation also proceeded with B 2 neop 2 (neop = neopentylglycolato)a st he boron source. Stoichiometrico xidative addition of different aryl chlorides to complex 1 was highly selectivea ffording trans-[Ni(ICy) 2 (Cl)(Ar)]

The synthesis of a series of cobalt NHC complexes of the types [Co­(NHC)2(CO)­(NO)] (NHC = iPr2Im (2), nPr2Im (3), Cy2Im (4), Me2Im (5), iPr2ImMe (6), Me2ImMe (7), MeiPrIm (8), MetBuIm (9); R2Im = 1,3-dialkylimidazolin-2-ylidene) and [Co­(NHC)­(CO)2(NO)] (NHC = iPr2Im (13), nPr2Im (14), Me2Im (15), iPr2ImMe (16), Me2ImMe (17), MeiPrIm (18), MetBuIm (19)) from the reaction of the NHC with [Co­(CO)3(NO)] (1) is reported. These complexes have been characterized using elemental analysis, IR spectroscopy, multinuclear NMR spectroscopy, and in many cases by X-ray crystallography. Bulky NHCs tend to form the mono-NHC-substituted complexes [Co­(NHC)­(CO)2(NO)], even from the reaction with an stoichiometric excess of the NHC, as demonstrated by the synthesis of [Co­(Dipp2Im)­(CO)2(NO)] (11), [Co­(Mes2Im)­(CO)2(NO)] (12), and [Co­(MecAAC)­(CO)2(NO)] (20). For tBu2Im a preferred coordination via the NHC backbone (“abnormal” coordination at the 4-position) was observed and the complex [Co­(tBu2 aIm)­(CO)2(NO)] (10) was isolated. All of these complexes are volatile, are stable upon sublimation and prolonged storage in the gas phase, and readily decompose at higher temperatures. Furthermore, DTA/TG analyses revealed that the complexes [Co­(NHC)2(CO)­(NO)] are seemingly more stable toward thermal decomposition in comparison to the complexes [Co­(NHC)­(CO)2(NO)]. We thus conclude that the cobalt complexes of the type [Co­(NHC)­(CO)2(NO)] and [Co­(NHC)2(CO)­(NO)] have potential for application as precursors in the vapor deposition of thin cobalt films.

The reaction of one and two equivalents of the N‐heterocyclic carbene IMes [IMes = 1,3‐bis(2,4,6‐trimethyl‐phenyl)imidazolin‐2‐ylidene] or the cyclic (alkyl)(amino)carbene cAACMe [cAACMe = 1‐(2,6‐diisopropyl‐phenyl)‐3,3,5,5‐tetra‐methylpyrrolidin‐2‐ylidene] with [TiCl4] in n‐hexane results in the formation of mono‐ and bis‐carbene complexes [TiCl4(IMes)] 1, [TiCl4(IMes)2] 2, [TiCl4(cAACMe)] 3, and [TiCl4(cAACMe)2] 4, respectively. For comparison, the titanium(IV) NHC complex [TiCl4(IiPrMe)] 5 (IiPrMe = 1,3‐diisopropyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene) has been synthesized and structurally characterized. The reaction of [TiCl4(IMes)] 1 with PMe3 affords the mixed substituted complex [TiCl4(IMes)(PMe3)] 6. The reactions of [TiCl3(THF)3] with two equivalents of the carbenes IMes and cAACMe in n‐hexane lead to the clean formation of the titanium(III) complexes [TiCl3(IMes)2] 7 and [TiCl3(cAACMe)2] 8. Compounds 1–8 have been completely characterized by elemental analysis, IR and multinuclear NMR spectroscopy and for 2–5, 7 and 8 by X‐ray diffraction. Magnetometry in solution, EPR and UV/Vis spectroscopy and DFT calculations performed on 7 and 8 are indicative of a predominantly metal‐centered d1‐radical in both cases.

The dehydrocoupling of primary phosphines with N-heterocyclic carbenes (NHCs) to yield NHC-phosphinidenes is reported. The reaction of two equivalents of the NHCs Me 2 Im (1,3dimethylimidazolin-2-ylidene), Me 4 Im (1,3,4,5-tetramethylimidazolin-2-ylidene), iPr 2 Im (1,3-di-iso-propylimidazolin-2ylidene) and Mes 2 Im (2,4,6-trimethylphenylimidazolin-2-ylidene) with PhPH 2 and MesPH 2 led to the NHC stabilized phosphinidenes (NHC)PAr: (iPr 2 Im)PPh ( 1), (Mes 2 Im)PPh ( 2), (Me 4 Im)PPh ( 3), (Mes 2 Im)PMes ( 4), (Me 2 Im)PMes ( 5), (Me 4 Im)PMes ( 6) and (iPr 2 Im)PMes ( 7). The reaction of tBuPH 2 with two equivalents of the NHCs afforded the corresponding NHC stabilized parent phosphinidenes (NHC)PH: (iPr 2 Im)PH ( 8), (Mes 2 Im)PH ( 9) and (Me 4 Im)PH (10). Reaction of 1 with oxygen and sulfur led to isolation of iPr 2 Im-P(O) 2 Ph (11) and iPr 2 Im-P(S) 2 Ph (12), whereas the reaction with elemental selenium and tellurium gave (NHC) PPh cleavage with formation of (iPr 2 Im)Se ( 13), iPr 2 ImTe (14) and different cyclo-oligophosphines. Furthermore, the complexes [{(iPr 2 Im)PPh}W(CO) 5 ] (15), [Co(CO) 2 (NO){(iPr 2 Im)PPh}] (16) and [(η 5 -C 5 Me 5 )Co(η 2 -C 2 H 4 ){(iPr 2 Im)PPh}] (17) have been prepared starting from 1 and a suitable transition metal complex precursor. The complexes 16 and 17 decompose in solution upon heating to ca. 80°C to yield the NHC complexes [Co(iPr 2 Im)(CO) 2 (NO)] and [(η 5 -C 5 Me 5 )Co(iPr 2 Im)(η 2 -C 2 H 4 )] with formation of cyclo-oligophosphines. The reaction of 1 with [Ni(COD) 2 ] afforded the diphosphene complex [Ni(iPr 2 Im) 2 (trans-PhP = PPh)] 18.