Kinetic Destabilization of Metal–Metal Single Bonds: Isolation of a Pentacoordinate Manganese(0) Monoradical

Abstract

The 17e(-) monoradical [Mn(CO)5 ] is widely recognized as an unstable organometallic transient and is known to dimerize rapidly with the formation of a MnMn single bond. As a result of this instability, isolable analogues of [Mn(CO)5 ] have remained elusive. Herein, we show that two sterically encumbering isocyanide ligands can destabilize the MnMn bond leading to the formation of the isolable, manganese(0) monoradical [Mn(CO)3 (CNAr(Dipp2) )2 ] (Ar(Dipp2) =2,6-(2,6-(iPr)2 C6 H3 )2 C6 H3 ). The persistence of [Mn(CO)3 (CNAr(Dipp2) )2 ] has allowed for new insights into nitrosoarene spin-trapping studies of [Mn(CO)5 ].

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.…”

Distibanes and Distibenes from Reduction of Sb(NONR)Cl by using MgIReagents

“…[7] The relative arrangements of the NON R -ligands about the SbÀSb bond also differs considerably.C ompounds [2a] [2 b] 2 [b] [2 c] 2 [b] Sb1ÀSb ¥ 2.9015(2)2 .8908 (4) 3.0352 (5) (4) N1-Sb1-N298.69 (7)9 7.09 (10) 95.71 (15) N3-Sb2-N499.70(7)9 9.17 (10) 95.34 (16) . It is well documented that this motif mayb ef ormed through cleavage of one P-P bond of the P 4 tetrahedron promoted by isolated metal-based radicals, [25] or homolytically cleaved M-M bonds that form radicals in situ. [26] We see this as further evidence that, in solution, dimer [2c] 2 has aw eak Sb-Sb bond that promotes reactivity consistent with the stibyl radical, [Sb(NON Dmp )]C.U nfortunately,a ttempts to crystallize 3c were unsuccessful, precluding structural characterization.…”

Bi−P Bond Homolysis as a Route to Reduced Bismuth Compounds and Reversible Activation of P4

“…X‐ray diffraction analysis confirmed the bridging μ,η 1:1 ‐P 4 unit in 7 (Figure ). This is an unusual structural motif that has been crystallographically characterized in only seven other metal systems, dominated by transition metals (Fe×2, Ni×2, Cr, Mn). A single example involving tin has also been documented .…”