Steinborn, Dirk; Neumann, Olaf; Bruhn, Clemens; Ruffer, Tobias; Boese, Roland; Heinemann, Frank W.:

(P,P-Dimethylphosphino)methyl chromate(II) complexes - [{Li(thf)}2Cr2(CH2PMe2)6], the first homoleptic (phosphino)methyl transition metal complex.

In: Chemistry--A European Journal, Jg. 4 (1998) ; Nr. 11, S. 2204-2210
ISSN: 0947-6539
Zeitschriftenaufsatz / Fach: Chemie
[CrCl2(THF)2] reacts with LiCH2PMe2 in Et2O at -50 Deg to give [{Li(THF)}2Cr2(CH2PMe2)6] (1; skeleton shown as I) as red, pyrophoric crystals (Tdecomp = 130-135 Deg; cg = 0.0096 * 10-6 cm3 g-1, meff = 0.81 mB/Cr). Treatment of 1 with MeOD and S or with LiAlD4 and S gave S:PMe2(CH2D) (degree of deuteration > 95 %). Complex 1 reacts with N,N,N',N'-tetramethylethylenediamine (tmeda) to give [{Li(tmeda)}2Cr2(CH2PMe2)6] (1a) (Tdecomp = 140-145 Deg; cg = -0.834 * 10-6 cm3 g-1) and [{Li2Cr2(CH2PMe2)6(tmeda)}...] (1b). The structures of 1, 1a, and 1b were detd. by single-crystal x-ray analyses. They are dinuclear with short Cr-Cr quadruple bonds (193.9(1)-195.0(2) pm) that are bridged by two m-h2-CH2PMe2ligands. Also, each Cr atom is coordinated by two h1-CH2PMe2 ligands. In complex 1 Li is coordinated by two P atoms, one O atom of a THF ligand, and one methylene C atom of the bridging CH2PMe2 ligand (Li coordination: P2OC). In 1a TMEDA acts as a bidentate chelate ligand, and in 1b it acts as a bridging ligand forming a 1-dimensional coordination polymer. Thus, Li coordinations P2N2 and P2NC exist in complexes 1a and 1b, resp.