Regioselective Formation of (E)‐β‐Vinylstannanes with a Topologically Controlled Molybdenum‐Based Alkyne Hydrostannation Catalyst

Abstract

The regioselective formation of (E)-β-vinylstannanes has been a long-standing challenge in transition-metal-catalyzed alkyne hydrostannation. Herein, we report a well-defined molybdenum-based system featuring two encumbering m-terphenyl isocyanides that reliably and efficiently delivers (E)-β-vinylstannanes from a range of terminal and internal alkynes with high regioselectivity. The system is particularly effective for aryl alkynes and can discriminate between alkyl chains of low steric hindrance in unsymmetrically substituted dialkyl alkynes. Catalytic hydrostannation with this system is also characterized by an electronic effect that leads to a decrease in regioselectivity when electron-withdrawing groups are present on the alkyne substrate.

Oxidorhenium(V) and Rhenium(III) Complexes with m‐Terphenyl Isocyanides

“…But the example of the Re(III) complex also shows that the corresponding IR frequencies are sensitive to other structural features such as the trans ligand (here Cl – vs. PPh 3 ). Similar findings have been reported earlier for various complexes with m ‐terphenylisocyanides . Thus, the absolute values of these stretches should be regarded with suspicion in the discussion of the bonding situation in such compounds.…”

“…This dual property allows isocyanides to bind well to transition metals in a range of formal oxidation states. It has been previously reported that m ‐terphenyl isocyanides can stabilize unusual low‐valent complexes of both manganese and molybdenum,, but also some medium to high valent m ‐terphenyl isocyanide complexes of Mn and Mo have been isolated via chemical oxidation of low‐valent precursors,, thereby demonstrating the utility of these encumbering ligands across a range of metal‐based redox states. Very recently, we studied reactions of m ‐terphenyl isocyanides with technetium complexes of various oxidation states and found that even technetium(V) complexes with these ligands are stabilized when strong donors such as nitrido or phenylimido ligands are present .…”

“…m ‐Terphenyl isocyanides have been shown to be useful ancillary ligands for the isolation of unusual and highly reactive transition metal complexes . These encumbering ligands stabilize transition metal centers featuring high degrees of coordinative and electronic unsaturation.…”

Transformations of the cyclo-P4 ligand in [Cp′′′Co(η4-P4)]

“…14 This inspired the synthesis of other complexes containing cyclo-P 4 ligands a few of which were recently reported as e.g. being based on rare earth metals like [{(DippForm) 2 Sm} 2 (m,h 4 :h 4 -P 4 )], 15 group ve metals, [Cp R M(CO) 2 (h 4 -P 4 )] (M ¼ V, Nb, Ta (A)), 16 on chromium, [L 2 Cr 2 (h 2 :h 2 :h 1 :h 1 -P 4 )] (L ¼ (2,6-diisopropylphenyl)-{6-(2,6dimethylphenyl)-pyridin-2-yl}-amide)), 17 on iron, [ Ph PP 2 Cy Fe(h 4 -P 4 )] (B), 18 on molybdenum, [(Ar Dipp CN) 2 Mo(CO) 2 (h 4 -P 4 )] (C) 19 and on the anionic iron complex [Cp Ar Fe(h 4 -P 4 )] À (ref. 20) as well as on the anionic cobalt complex [(PHDI)Co(h 4 -P 4 )] À (D).…”

Photolytic Reductive Elimination of White Phosphorus from a Mononuclear cyclo‐P4 Transition Metal Complex

“…)), which serves as a reactive source of the 14efragment [Mo(CO)2(CNAr Dipp2 )2] by virtue of facile displacement of its  2 -C,H: 1 -N-diisopropylamine chelate. [20] and 5 (bottom). [40] Treatment of 1 with 1.0 equiv of white phosphorus in an npentane/toluene mixture proceeds in near-quantitative yield with the exclusive formation of a single diamagnetic product, as assayed by 1 H and 31 P NMR spectroscopy.…”