(P,P-DIMETHYLPHOSPHINO)METHYL CHROMATE(II) COMPLEXES - [(LI(THF))(2)CR-2(CH2PME2)(6)], THE FIRST HOMOLEPTIC (PHOSPHINO)METHYL TRANSITION-METAL COMPLEX

[CrCl2(thf)(2)] reacts with LiCH2PMe2 in diethyl ether at -50 degrees C to give [{Li(thf)}(2)Cr-2(CH2PMe2)(6)] (1) as red, pyrophoric crysta ls (T-decomp = 130-135 degrees C; chi(g) = 0.0096 x 10(-6) cm(3)g(-1), mu(eff) = 0.81 mu(B)/Cr). Treatment of 1 with MeOD and S or with LiAI D(4) and S results in the formation of S=PMe2(CH2D) (degree of deutera tion>95%). Complex 1 reacts with N,N,N',N'-tetramethylethylenediamine (tmeda) to give [{Li(tmeda)}(2)-Cr-2(CH2PMe2)(6)] (la) (T-decomp = 140 -145 degrees C; chi(g) = -0.834 x 10(-6) cm(3)g(-1)) and [{Li2Cr2(CH2P Me2)(6)(tmeda)}(x)] (Ib), The structures of 1, la, and Ib were determi ned by single-crystal X-ray analysts. They are dinuclear with short Cr -Cr quadruple bends(193.9(1)-195.0(2) pm) that are bridged by two mu-e ta(2)-CH2PMe2 ligands, Furthermore, each chromium atom is coordinated by two eta(1)-CH2PMe2 ligands. In complex 1 hi is coordinated by two P atoms, one O atom of a THF ligand, and one methylene C atom of the br idging CH2PMe2 ligand (Li coordination: P,QC). In la TMEDA acts as a b identate chelate ligand, and in Ib it acts as a bridging ligand formin g a one-dimensional coordination polymer. Thus, Li coordinations P2N2 and P2NC result in complexes la and 1b, respectively.