CHEMISTRY OF BIS(DIALKOXYPHOSPHINO)METHYLAMINES - MONOMETALLIC AND BIMETALLIC COMPLEXES OF CHROMIUM(0), MOLYBDENUM(0), TUNGSTEN(0), RHODIUM(I), AND RUTHENIUM(II)

The ligating behavior of the “short-bite” ligands CH3N(P(OR2)2 (R = CH3 (L2), i-C3H7 (L2’), CH2- (L2”)) has been investigated. With [M(CO)3(η6-C7H8)] (M = Cr, Mo, W) the primary products are the ligand-bridged dimers [M2(CO)6(CH3N(P(OR)2)2)2(μ-CH3N(P(OR)2)2)], which have been obtained as all-mer, all-fac, and mer-fac isomers depending on the ligand and conditions used. With an excess of L{2’, mer-[Mo(CO)3-(η2-L2’) (η1-L2/)] could be obtained in high yield and was used to prepare heterobimetallic complexes [MoM(CO)4C1(L2’)2] (M = Rh (20), Ir (21)). Low yields of mer-[M(CO)3(η2-L2)(η1-L2)] and mer-[M-(CO)3(η2-L2’)(η1-L2’)] (M = Cr, W) were also obtained. Attempts to prepare related ruthenium complexes were unsuccessful, and only [(η5-C5H5)RuCl(L2)] (27) was obtained. The ligand L2’ is evidently too bulky to form dimeric complexes with rhodium as the product isolated was [Rh(L2’)2]C1O4. An interesting minor product obtained during the synthesis of mer-[W2(CO)6(L2)2(g-L2)] was shown to be [W2(CO)6(CH3N(P-(OCH3)2)2)(CH3OP(N(CH3)P(OCH3)2)2)] (16), which contains a bridging tridentate ligand, a semibridging carbonyl group, and possibly a metal-metal bond. The31P NMR spectra of the group VI metal complexes are discussed. The structures of mer-[W2(CO)6(L2)2)(μ-L2)] (12), 16, 20, 21, and 27 have been determined by X-ray crystallography. 12: monoclinic, P21/c, a = 17.421 (3), b = 15.581 (5), c = 17.116 (6) Å, β = 117.26 (2)°, Z = 4, 4282 data (I ≥ 3σ(I)), R = 0.035, Rw = 0.044. 16: orthorhombic, P212121, a = 14.512 (3), b = 15.202 (4), c = 15.577 (3) Å, Z = 4, 2233 data (I ≥ 3σ(I), R = 0.031, Rw = 0.037. 20: orthorhobmic, Pna21 a = 16.561 (4), b = 12.964 (3), c = 21.530 (5) Å, Z = 4, 2685 data (I ≥ 2σ(I)), R = 0.045, Rw = 0.054. 21: orthorhombic, Pna21 a = 16.545 (3), b = 12.921 (2), c = 21.595 (5) Å, Z = 4, 2923 data (I ≥ 3σ(I)), R = 0.040, Rw = 0.053. 27: monoclinic, P21/n,a = 7.6964 (8), b = 8.8436 (6), c = 23.8778 (23) Å, β = 96.856 (8)°, Z = 4, 2791 data (I ≥ 3σ(7)), R = 0.026, Rw = 0.039. © 1990, American Chemical Society. All rights reserved.