Quintuply bonded Cr dimer, [(Ar-N=C(H)-(H)C=N-Ar)2Cr2] (1) (Cr-Cr=1.80�) (where Ar = 2,6 � diisopropylphenyl (�iPr�)), reacts with acetylenes RC=CR in diethyl ether solvent to form 1:1 adducts (HLiPr2Cr2)(RCCR), where R= Me (2a), Et (2b), Ph (2c), CF3 (2d). The single crystal X- ray structures have been obtained. All the complexes feature short Cr-Cr distances of 1.926 - 1.936 � and elongated multiple C-C bonds of 1.313 - 1.436 �. Variable temperature NMR spectroscopic studies of the adducts for R= Me, Et indicate the occurrence of a fluxional process. Dissolution of 1 with tetrahydrofuran gives a red solution of mononuclear complex HLiPrCr(THF)2 (3). The reactions of 3 with an excess of alkynes result in the formation of the corresponding hexaalkyl arene complexes. 

Alkyne chemistry of low valent Cr complexes supported by α-diimine ligands

240th National Meeting (2010)

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