Reduction of (pddi)Cr reveals redox noninnocence via C–C bond formation amidst competing electrophilicity: [(cpta)CrMe n ] − ( n = 0, 1) and [(pta)Cr] −
                        
                    
    
            Reversible cyclopropane formation is examined in a chromium diamide–diimine chelate complexviareduction. Sites of electrophilicity incur similar and divergent chemistry; structural, electrochemical, and calculational studies afford their rationale. 
        more » 
        « less   
        
    
    
                            - PAR ID:
- 10518578
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Chemical Communications
- Volume:
- 60
- Issue:
- 53
- ISSN:
- 1359-7345
- Page Range / eLocation ID:
- 6785 to 6788
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
- 
            Abstract The overarching goal of this study is to effect the elimination of platinum from adducts withcis–C≡C−Pt−C≡C‐ linkages, thereby generating novel conjugated polyynes. Thus, the bis(hexatriynyl) complextrans‐(p‐tol3P)2Pt((C≡C)3H)2is treated with 1,3‐diphosphines R2C(CH2PPh2)2to generate (R2C(CH2PPh2)2)2Pt((C≡C)3H)2(14; R=c,n‐Bu;e,p‐tolCH2). These condense with the diiodide complexes R2C(CH2PPh2)2PtI2(9 a,c) in the presence of CuI (cat.) and excess HNEt2to give the title macrocycles [(R2C(CH2PPh2)2)Pt(C≡C)3]4(16 c,e) as adducts of the byproduct [H2NEt2]+I−(30–66 %). DOSY NMR experiments establish that this association is maintained in solution, but NaOAc removes the ammonium salt. The bis(triethylsilylpolyynyl) complexes (n‐Bu2C(CH2PPh2)2)Pt((C≡C)nSiEt3)2(n=2, 3) are synthesized analogously to14 c. They react with I2at rt to give mainly the diiodide complex9 cand the coupling product Et3Si(C≡CC≡C)nSiEt3. The possibility of competing reactions giving IC≡C species is investigated. Analogous reactions of the Pt4C24macrocycle16 calso give9 c, but no sp13C NMR signals or mass spectrometric Cxz+ions (x=24–100) could be detected. It is proposed that some cyclo[24]carbon is generated, but then rapidly converts to other forms of elemental carbon. No cyclotetracosane (C24H48) is detected when this sequence is carried out in the presence of PtO2and H2.more » « less
- 
            Abstract Single crystals of disordered Mn4–xCrxAl11have been synthesized via the flux method. EDS on several crystals of various sizes and shapes revealed an average molar ratio of 17:9:74 for Mn:Cr:Al, while X-ray diffraction on three different crystals yield compositions Mn2.26Cr1.74Al11(Mn4–xCrxAl11,x= 1.74), Mn0.83Cr3.17Al11, and Mn1.07Cr2.93Al11. This compound crystallizes in space groupP–1, isostructural with both Mn4Al11and Cr4Al11. Magnetic measurements on several crystals show that this disordered compound is ferrimagnetic with a low effective moment ofμeff≈1.012±0.004 μB/f.u. and a non-reachable transition temperature. DFT calculations display opening of a bandgap in the spin-up channel near the Fermi level with increasing Cr content, an indication of half-metallicity.more » « less
 An official website of the United States government
An official website of the United States government 
				
			 
					 
					
 
                                    