Steric effects of bulky diazolylmethane ligands (N-N) on syntheses and structures of [Mo(N-N)(CO)4]
Resource
Journal of Organometallic Chemistry 469 (2): 169-178
Journal
Journal of Organometallic Chemistry
Journal Volume
469
Journal Issue
2
Pages
169-178
Date Issued
1994
Author(s)
Abstract
The N-N ligands of PhHC(3,5-Me2Pz)2, H2C(3,5-Me2;4-BzPz)2, H2C(3-tBuPz)2 and H2C(3(5)-PhPz)2 wsere prepared readily from PhHCCl2 or CH2Cl2 by the same procedure as for H2C(3,5-Me2Pz)2 (Pz = pyrazol-1-yl). Subsequent reactions with either [Mo(pip)2(CO)4] (pip = piperidine) or [Mo(CO)6], however, gave only [MoPhHC(3,5-Me2Pz)2(CO)4] (1), [MoH2C(3-PhPz)(5-PhPz)(CO)4] (2) and [MoH2C(3,5-Me2;4-BzPz)2(CO)4] (3). The structural characteristics of 1-3, [WH2C(3,4,5-Me3Pz)2(CO)4], [WH2C(3,5-Me2Pz)2(CO)4] and [MoH2C(3,5-Me2Pz)2(CO)4], reported previously, suggest firstly that the presence of a bulky substituent such as a phenyl or tert-butyl group at the pyrazolyl skeleton may afford strong nonbonded interaction in [MO(N-N)(CO)4] and inhibit the formation of the stable complexes, [MoH2C(3-tBuPz)2(CO)4] or [Mo(H2C(3-PhPz)2 (CO)4] and secondly, that the phenyl substituent at the carbon end of the six-membered boat metallacyle, formed by the N-N ligand and the central metal atom, is cis to the most distorted carbonyl in 1. This explains the facile formation of the η2-arene compound, [MoPhHC(3,5-Me2Pz)2(CO)3] as well as the regiospecific formation of [MoPhHC(3,5-Me2Pz)2(CO)2(η3-allyl)(Br)]. 1, monoclinic, P 21/n, a = 9.718(2), b = 14.198(4), c = 16.076(4) Å, β = 96.62(2), Z = 4, R = 0.034, Rw = 0.037, based on 2538 reflections with I ≫ 3σ(I); 2, monoclinic, P 21/n, a = 18.093(12), b = 13.138(4), c = 18.745(6) Å, β = 98.79(6), Z = 8, R = 0.040, Rw = 0.031, based on 4465 reflections with I ≫ 2σ(I); and 3, orthorhombic, Pbca, a = 12.2387(18), b = 22.525(4), c = 20.028(5) Å, Z = 8, R = 0.035, Rw = 0.032, based on 2095 reflections with I≫ 2σ(I). © 1994.
SDGs
Type
journal article