An official website of the United States government
The reaction of 1,3,5-( i Pr 2 PO) 3 C 6 H 3 with Co 2 (CO) 8 leads to the isolation of a POCOP-type mononuclear pincer complex {κ P ,κ C ,κ P -2,4,6-( i Pr 2 PO) 3 C 6 H 2 }Co(CO) 2 (1) or a tetranuclear species {κ P -{κ P ,κ C ,κ P -2,4,6-( i Pr 2 PO) 3 C 6 H 2 }Co(CO) 2 } 2 Co 2 (CO) 6 (2), depending on the ligand to cobalt ratio employed. The latter compound can be an impurity during the synthesis of {2,6-( i Pr 2 PO) 2 -4-Me 2 N-C 6 H 2 }Co(CO) 2 , when the ligand precursor 5-(dimethylamino)resorcinol is contaminated with phloroglucinol due to incomplete monoamination. Similarly, the reaction of 1,3,5-( i Pr 2 PO) 3 C 6 H 3 with NiCl 2 in the presence of 4-dimethylaminopyridine provides {κ P ,κ C ,κ P -2,4,6-( i Pr 2 PO) 3 C 6 H 2 }NiCl (3) bearing an appended phosphinite group. Structures 1–3 have been studied by X-ray crystallography.
more »
« less
A closed-shell monomeric rhenium(1−) anion provided by m -terphenyl isocyanide ligation
The mixed isocyanide/carbonyl complexes cis - and trans -[Re(CO) 3 Br(CNAr Dipp2 ) 2 ] (Ar Dipp2 = 2,6-(2,6-(i-Pr) 2 C 6 H 3 ) 2 C 6 H 3 ) can be synthesized from reactions of [Re(CO) 5 Br] and CNAr Dipp2 depending on the conditions applied. Reduction of the neutral Re( i ) species gives the monoanionic complex [Re(CO) 3 (CNAr Dipp2 ) 2 ] − or the neutral [Re(CO) 3 (CNAr Dipp2 ) 2 ], which contain rhenium in the formal oxidation states “−1” and “0”, respectively.
more »
« less
- Award ID(s):
- 1802646
- PAR ID:
- 10163055
- Date Published:
- Journal Name:
- Chemical Communications
- ISSN:
- 1359-7345
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract The first consistent series of mononuclear 17‐electron complexes of three Group 7 elements has been isolated in crystalline form and studied by X‐ray diffraction and spectroscopic methods. The paramagnetic compounds have a composition of [M0(CO)(CNp‐F‐ArDArF2)4] (M=Mn, Tc, Re; ArDArF2=2,6‐(3,5‐(CF3)2C6H3)2C6H2F) and are stabilized by four sterically encumbering isocyanides, which prevent the metalloradicals from dimerization. They have a square pyramidal structure with the carbonyl ligands as apexes. The frozen‐solution EPR spectra of the rhenium and technetium compounds are clearly anisotropic with large99Tc and185,187Re hyperfine interactions for one component. High‐field EPR (Q band and W band) has been applied for the elucidation of the EPR parameters of the manganese(0) complex.more » « less
-
Three routes are explored to the title halide/cyanide complexes trans -Fe(CO)(NO)(X)(P((CH 2 ) 14 ) 3 P) ( 9c-X ; X = Cl/Br/I/CN), the Fe(CO)(NO)(X) moieties of which can rotate within the diphosphine cages (Δ H ‡ /Δ S ‡ (kcal mol −1 /eu −1 ) 5.9/−20.4 and 7.4/−23.9 for 9c-Cl and 9c-I from variable temperature 13 C NMR spectra). First, reactions of the known cationic complex trans -[Fe(CO) 2 (NO)(P((CH 2 ) 14 ) 3 P)] + BF 4 − and Bu 4 N + X − give 9c-Cl /- Br /- I /- CN (75–83%). Second, reactions of the acyclic complexes trans -Fe(CO)(NO)(X)(P((CH 2 ) m CHCH 2 ) 3 ) 2 and Grubbs’ catalyst afford the tris(cycloalkenes) trans -Fe(CO)(NO)(X)(P((CH 2 ) m CHCH(CH 2 ) m ) 3 P) ( m /X = 6/Cl,Br,I,CN, 7/Cl,Br, 8/Cl,Br) as mixtures of Z / E isomers (24–41%). Third, similar reactions of trans -[Fe(CO) 2 (NO)(P((CH 2 ) m CHCH 2 ) 3 ) 2 ] + BF 4 − and Grubbs’ catalyst afford crude trans -[Fe(CO) 2 (NO)P((CH 2 ) m CHCH(CH 2 ) m ) 3 P)] + BF 4 − ( m = 6, 8). However, the CC hydrogenations required to consummate routes 2 and 3 are problematic. Crystal structures of 9c-Cl /- Br /- CN are determined. Although the CO/NO/X ligands are disordered, the void space within the diphosphine cages is analyzed in terms of horizontal and vertical constraints upon Fe(CO)(NO)(X) rotation and the NMR data. The molecules pack in identical motifs with parallel P–Fe–P axes, and without intermolecular impediments to rotation in the solid state.more » « less
-
We report the synthesis of molybdenum and tungsten bromo dicarbonyl complexes (POCOPtBu)MIIBr(CO)2(M = Mo or W; POCOPtBu = κ3-C6H3-1,3-[OP( tBu)2]2) supported by an anionic PCP pincer ligand, and the chromium complex (PNPtBu)Cr0(CO)3(PNPtBu = 2,6-bis(di- tert-butyl-phosphinomethyl)pyridine) bearing a neutral PNP pincer scaffold. The three group six complexes described in this study have been characterized by Liquid Injection Field Desorption Ionization Mass Spectrometry (LIFDI-MS), NMR, and IR spectroscopy. Single crystal X-ray diffraction studies show the MoIIand WIIcomplexes adopt a six-coordinate distorted trigonal prismatic geometry, whereas the Cr0complex exhibits a distorted octahedral geometry.more » « less
-
High-valent nitridorhenium( v ) complexes containing PNP ligands: implications of ligand flexibilityThe synthesis of (PNP)Re(N)X (PNP = [2-P(CHMe 2 ) 2 -4-MeC 6 H 3 ] 2 N, X = Cl and Me) complexes is described. The methylnitridorhenium complex 3 was found to react differently with CO and isocyanides, leading to the isolation of a Re( v ) acyl complex 4 and an isocyanide adduct 6 . Two parallel pathways were observed for the reaction of 3 with CO: (1) CO inserts into the Re–Me bond to afford 4 , and (2) 3 isomerizes by distortion of the aryl backbone of the PNP ligand to afford the isomer 3′ . This is followed by the reaction of 3′ with CO to afford the tricarbonyl complex 5 , which was fully characterized. The contrasting reaction of 3 with 2,6-dimethylphenyl isocyanide lends further support for the proposed isomerization pathway. DFT (M06) calculations suggest that insertion of CNR into the Re–Me bond (27.2 kcal mol −1 ) is inaccessible at room temperature. Instead the substrate adds to the metal center via the most accessible face i.e. syn to the rhenium–nitrido bond, to afford 6 . The addition of CO to isomer 3′ is proposed to proceed with a similar mechanism to 2,6-dimethylphenyl isocyanide.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d0cc03043k
