Synthesis and Reactivity of N,N‐Dialkylcarbamato Complexes of Titanium(III) and Vanadium(III). Crystal and Molecular Structure of an Anionic Dimeric Titanium(III) Derivative

The reaction of anhydrous trichlorides of titanium or vanadium with HNiPr2 and CO2 or the exchange reaction 1/2 M2(O2CNiPr2)6 + 3 HNEt2 → 1/n [M(O2CNEt2)3]n + 3 NHiPr2 yielded the N,N‐dialkylcarbamato derivatives 1, 2, 5 and 7. Further reaction of the uncharged dimeric complexes with O2CNR−2 yielded the ionic derivatives NH2R2[M2(O2CNR2)7] 3, 4 and 6. The equilibrium between uncharged dimeric complexes and anionic dimers has been observed spectroscopically in solution. The crystal and molecular structure of the titanium(III) derivative NH2iPr2[Ti2(O2CNiPr2)7] (3) has been solved by X‐ray diffraction methods. In the dimeric carbamato‐bridged anion, the titanium is hexacoordinated in a distorted pseudo‐octahedral geometry. These complexes promptly react with protic substances such as hydrogen chloride and acetylacetone to give the corresponding titanium(III) and vandium(III) complexes MCl3‐6 and M(C5H7O2)3, respectively. The diisopropyltitanium(III) derivative reacts with p‐benzoquinone and 9,10‐phenanthrenequinone to give 2:1 adducts of general formula [Ti2(O2CNiPr2)6]quinone, which are better regarded as phenolato and catecholato complexes of titanium(IV), respectively.