The syntheses, structures and reactivity of bis(tert-butylcyclopentadienyl)molybdenum derivatives: nitrogen alkylation of an η2-acetonitrile ligand and influence of the chalcogen on the barrier to inversion of chalcogenoether adducts

Abstract

An investigation of the chemistry of the tert-butyl-substituted molybdenocene system, {(Cp Bu t) 2 Mo} (Cp Bu t = C 5 H 4 Bu t ), has demonstrated that the η 2 -acetonitrile ligand in (Cp Bu t ) 2 Mo(η 2 -MeCN) may be alkylated by RI (R = Me, Et) at nitrogen to give iminoacyl derivatives, [(Cp Bu t ) 2 Mo(η 2 -MeC᎐ ᎐ NR)] ϩ , which is a new type of reactivity for mononuclear acetonitrile complexes. A series of chalcogenolate-hydride complexes (Cp Bu t ) 2 Mo(EPh)H (E = S, Se, Te) have been obtained by reaction of (Cp Bu t ) 2 MoH 2 with Ph 2 E 2 , and may be alkylated by MeI to give the chalcogenoether adducts [(Cp Bu t ) 2 Mo(PhEMe)H]I. Dynamic NMR studies on [(Cp Bu t ) 2 Mo(PhEMe)H]ϩ indicate that the barrier to inversion at the chalcogen increases in the sequence S < Se < Te. The oxo complex (Cp Bu t ) 2 MoO reacts with 2 equivalents of Me 3 SiX (X = Cl, Br, I, O 2 CMe, O 3 SMe) to yield (Cp Bu t) 2 MoX 2 ; for X = CN and NCS, (Cp Bu t ) 2 -Mo(OSiMe 3 )X, the product of reaction with 1 equivalent may be isolated. (Cp Bu t) 2 Mo(OSiMe 3 )X (X = CN, NCS) reacts with Me 3 SiNCS to give the thiocyanate complex (Cp Bu t ) 2 Mo(SCN)X, rather than the isocyanate isomer, (Cp Bu t) 2 Mo(NCS)X, thereby indicating that the reactions do not involve a simple metathesis of the Si-NCS bond. Other complexes that are reported include:

Spacially Confined M2Centers (M = Fe, Co, Ni, Zn) on a Sterically Bulky Binucleating Support: Synthesis, Structures and Ethylene Oligomerization Studies

“…In the IR spectra of 2c(NCMe), the ν(CdN) imine band is seen at 1590 cm -1 with an additional band at 2300 cm -1 corresponding to the ν(CtN) absorption for the η 1 -bound acetonitrile molecule. 22 The paramagnetic properties (µ eff ) 3.5 µ B ; Evans balance at room temperature) of 2c(NCMe) are comparable to that found for 2c.…”

“…In the solution state, however, the solid-state properties of L 2 -H are not maintained, and the molecule possesses a C 2 plane of symmetry about the O(1)-C(25)-C (22) axis. Similarly in L 1 , the 1 H NMR spectrum reveals each pyridylimine unit to be equivalent.…”

X‐ray Absorption Spectroscopic, Crystallographic, Theoretical (DFT) and Chemical Evidence for a Chalcogen–Chalcogen Two‐Center/Three‐Electron Half Bond in an Unprecedented “Subselenide” Se23− Ligand

“…The single sharp peak at 880 ppm indicates chemical equivalence of the two Se centers consistent with the solid‐state structure. In comparison to literature examples, we note that transition metal complexes bearing the Se 2 2− ion generally show 77 Se NMR resonances at <−250 ppm,13, 14 whereas the signals for Se 2− species have appeared as disparately as −996 or +1241 ppm 13. 15 Thus, the 77 Se NMR spectroscopy data do not allow for an unequivocal oxidation state assignment for 1 , but disfavor a Se 2 2− assignment.…”

Metal‐Mediated Production of Isocyanates, R3ENCO from Dinitrogen, Carbon Dioxide, and R3ECl

“…[8,13] , and the structural identities of these heterocumulene products were confirmed by 1 H, 13 C, and 15 NN MR spectra and comparison with literature values. [8,20] Even more satisfying,t he 9a!1a transformation could be achieved by simply photolyzing 9a in the presence of CO 2 and excess equivalents of Me 3 SiCl, to directly produce 1a in high yield and without the need to isolate the intermediate terminal oxo complex 4a. [19] In the present work, it was determined that both 4a and 4b react with excess equivalents of Me 3 SiCl in benzene solution to produce one equivalent of hexamethyldisiloxane, Me 3 Si-O-SiMe 3 ,a nd the desired respective products 1a and 1b (see Scheme 6).…”