TERT-BUTYLIMIDO COMPLEXES OF CHROMIUM AND VANADIUM - X-RAY CRYSTAL-STRUCTURES OF CR(NBUT)CL-3(MEOCH2CH2OME), CR[C6H4(NH)2-ORTHO]CL2(PME2PH)2, CR(NBUT)2(OSIPH3)2, CR(NBUT)-CL(OC9H6N)2 AND [(PPH3)2][CR(NBUT)(S2C2(CN)2)2]

The compound Cr(NBu(t))Cl3, isolated as its adducts with tetrahydrofuran (thf) and 1,2-dimethoxyethane (dme), has been prepared by chlorination of Cr(NBu(t))2Cl2. These materials have been used as sources of other chromium compounds such as the neutral adducts Cr(NBu(t))Cl3(PR3)2 (R3 = Me3, Et3, Me2Ph or EtPh2) or Cr(NBu(t))Cl2(NC7H13) (NC7H13 = quinuclidine) or anionic complexes such as [PPh4][Cr(NBu(t))Cl4]. The tertiary phosphine complexes in the presence of excess of phosphine are photochemically or thermally reduced to CrCl3(PR3)3 and the tertiary phosphinimine. Halide-substitution reactions on Cr(NBu(t))Cl3(dme) or [Cr(NBu(t))Cl4]- with O,N, (O,N) and S ligands give rise to compounds such as cis-Cr(NBu(t))Cl(OC9H6N)2 (OC9H6N = quinolin-8-olate), [Cr(NBu(t))(mnt)2]- (mnt = maleonitriledithiolate) and Cr(NBu(t))Cl(S2CNEt2)2; cyclic voltammetry of the last two complexes is reported. Evidence for the disproportionation 2Cr(v) --> Cr(VI) + Cr(IV) in reactions of alkoxides is given. Reduction of Cr(NBu(t))Cl3(dme) in the presence of 1,2-bis(dimethylphosphino)ethane (dmpe) gives the chromium(IV) species [Cr(NBu(t))(dmpe)2Cl]Cl. The EPR (X-band) spectra of chromium(V) species at room temperature show hyperfine splitting for Cr-53, N-14 and P-31 in appropriate compounds with g(iso) values at 77 K of ca. 2.00. The compounds [V(NBu(t))(NHBu(t))(mu-NBu(t))]2 and [V(mu-NBu(t))(OSiMe3)2]2 are also described. The X-ray structures of five compounds have been determined: Cr(NBu(t))Cl3(dme) is octahedral with a mer arrangement of the three chlorines; Cr[C6H4(NH)2-o]Cl2(PMe2Ph)2 is also octahedral, having C2 symmetry with trans phosphines and cis chlorines; Cr(NBu(t))2(OSiPh3)2 is distorted tetrahedral; Cr(NBu(t))Cl(OC9H6N)2 is octahedral with the chelating quinolin-8-olato groups arranged to give trans O,O and cis N,N geometry; and [Cr(NBu(t))(mnt)2]- has a square-pyramidal structure with an axial imido group.