Quadruply bonded complexes containing η2- or η3-tridentate phosphine ligands;: syntheses, structures and 31P{1H} NMR spectra of Mo2Cl4(η3-etp)(L) and Mo2Cl4(η2-etp)2 (L = CH3OH, PMe3 and PEt3;: etp = Ph2PCH2CH2P(Ph)CH2CH2PPh2)

The reactive complex Mo2Cl4(eta(3)-etp)(CH3OH) (etp = Ph2PCH2CH2P(Ph)CH2CH2PPh2) (1) was synthesized by reacting (NH4)(5)Mo2Cl9 with 1 equiv. of etp in CH3OH. Reactions of 1 with PMe3 and PEt3, in THF gave Mo2Cl4(eta(3)-etp) (PMe3) (2) and Mo2Cl4(eta(3)-etp)(PEt3) (3) respectively. The complex alpha-Mo2Cl4(eta(2)-etp)(2) (4) was synthesized by refluxing Mo2Cl4(eta(3)-etp)(CH3OH) with 1 equiv. of etp in CH3OH, where eta(3)-etp is transformed to eta(2)-etp. Complex 4 can also be prepared by reacting (NH4)(5)Mo2Cl9 with 2 equiv. of etp in refluxing CH3OH. Their UV-Vis and P-31 NMR spectra were recorded and the structures of 3 and 4 were determined. Crystal data for 3 . C7H8: space group P2(1)/n, a = 11.846(2), b = 29.349(3), c = 15.429(3) Angstrom, beta = 112.52(1)degrees, V = 4955(2) Angstrom(3), Z = 4, with final residuals R = 0.0797 and R-w = 0.0811. Crystal data for 4 . 2C(7)H(8): space group P2(1)/c, a = 14.555(2), b = 14.988(2), c = 20.220(3) Angstrom, beta = 106.80(1)degrees, V = 4222(1) Angstrom(3), Z = 2, with final residuals R = 0.0882 and R-w = 0.0893. The tp ligands in 13 are coordinated to the Mo centers in tridentate fashion with chelating/bridging bonding modes. The etp ligands in 4 are chelated to the Mo centers in bidentate fashion through the central phosphorus atom and one terminal phosphorus atom. Complex 4 appears to be the first binuclear biligate complex chelated by linear tridentate ligands. Study of the P-31{H-1} NMR spectrum of 3 leads to the conclusion that the through metal-metal quadruple bonding coupling /(3)J(P-Mo-Mo-P)/ is in the range from 18.18 to 24.28 Hz for complexes of the type Mo2Cl4(eta(3)-etp)(L) (L = monodentate ligand). (C) 1998 Elsevier Science S.A. All rights reserved.