Zhiqiang Weng

An efficient algorithm for automatic phase correction of NMR spectra based on entropy minimization

A new algorithm for automatic phase correction of NMR spectra based on entropy minimization is proposed. The optimal zeroorder and first-order phase corrections for a NMR spectrum are determined by minimizing entropy. The objective function is constructed using a Shannon-type information entropy measure. Entropy is defined as the normalized derivative of the NMR spectral data. The algorithm has been successfully applied to experimental 1 H NMR spectra. The results of automatic phase correction are found to be comparable to, or perhaps better than, manual phase correction. The advantages of this automatic phase correction algorithm include its simple mathematical basis and the straightforward, reproducible, and efficient optimization procedure. The algorithm is implemented in the Matlab program ACME—Automated phase Correction based on Minimization of Entropy.

One-step formation of cyclometallated Au(III) N,S-heterocyclic carbene: crystallographic analysis

Gold(I) N,S-heterocyclic carbene AuBr(NSHC) (NSHC = N-allylbenzothiazolin-2-ylidene) (1) with an allyl pendant is oxidised by iodine to give [AuI2(NSHC)2]+[I3]- (2) and a cyclometallated byproduct AuBr2(-C6H4SCNCH2CHCH2Br-C,C) (3). The latter can be prepared directly from bromination of 1. Similar reaction with the crotyl (but-2-en-1-yl) derivative AuBr(NSHC) (NSHC = N-crotylbenzothiazolin-2-ylidene) (4) gives an oxidative addition product AuBr3(C6H4SCNCH2CHCHCH3) (5). X-Ray single-crystal crystallographic analysis of 3 reveals a 5-membered cyclometallated ring in a sq planar metal that gives two types of AuIII-C bonds. Similar structural analysis has also been carried out in 1, 2 and 5.

Chemistry of cyclopentadienyl tricarbonylchromium dimer. Cleavage of bis(thiophosphinyl)disulfanes and bis(thiophosphoryl)disulfanes. Syntheses of CpCr(CO)2(S2PPh2) and CpCr(S2PPh2)2. X-ray crystal structure of CpCr(S2PPh2)2

Abstract The facile reaction of [CpCr(CO) 3 ] 2 with one mole equivalent of bis(diphenylthiophosphinyl)disulfane, Ph 2 P(S)SSP(S)PPh 2, led to the isolation of dark purplish brown solids of CpCr(CO) 2 (S 2 PPh 2 ) ( 2 ) and blue solids of CpCr(S 2 PPh 2 ) 2 ( 3 ) in 50 and 10% yields, respectively. Proton NMR spectral studies demonstrated that 3 is derived from 2 , the primary product. IR spectral data indicated that 2 possesses cis CO ligands and a bidentate SP(S)Ph 2 ligand, whilst 3 contains both a unidentate and a bidentate ligand, as confirmed by its X-ray diffraction analysis. Variable temperature 1 H and 31 P spectral studies showed the occurrence of very rapid unidentate–bidentate exchange between the ligands in 3 in the temperature range −80–60°C.