Fe as Hydrogen/Halogen Bond Acceptor in Square Pyramidal Fe(CO)(5)

Hydrogen bonded complexes formed between the square pyramidal Fe(CO)(5) with HX (X = F, Cl, Br), showing X-H center dot center dot center dot Fe interactions, have been investigated theoretically using density functional theory (DFT) including dispersion correction. Geometry, interaction energy, and large red shift of about 400 cm(-1) in the FIX stretching frequency confirm X-H center dot center dot center dot Fe hydrogen bond formation. In the (CO)(5)Fe center dot center dot center dot HBr complex, following the significant red shift, the HBr stretching mode is coupled with the carbonyl stretching modes. This clearly affects the correlation between frequency shift and binding energy, which is a hallmark of hydrogen bonds. Atoms in Molecule (AIM) theoretical analyses show the presence of a bond critical point between the iron and the hydrogen of FIX and significant mutual penetration. These X-H center dot center dot center dot Fe hydrogen bonds follow most but not all of the eight criteria proposed by Koch and Popelier (J. Phys. Chem. 1995, 99, 9747) based on their investigations on C-H center dot center dot center dot O hydrogen bonds. Natural bond orbital (NBO) analysis indicates charge transfer from the organometallic system to the hydrogen bond donor. However, there is no correlation between the extent of charge transfer and interaction,energy, contrary to what is proposed in the recent IUPAC recommendation (Pure Appl.. Chem. 2011, 83, 1637). The ``hydrogen bond radius'' for iron has been determined to be 1.60 +/- 0.02 angstrom, and not surprisingly it is between the covalent (127 angstrom) and van der Waals (2.0) radii of Fe. DFT and AIM theoretical studies reveal that Fe in square pyramidal Fe(CO)(5) can also form halogen bond with CIF and ClH as ``halogen bond donor''. Both these complexes show mutual penetration as well, though the Fe center dot center dot center dot Cl distance is closer to the sum of van der Waals radii of Fe and Cl in (CO)5Fe center dot center dot center dot ClH, and it is about 1 angstrom less in (CO)(5)Fe center dot center dot center dot ClF

Is Tuberculosis a Spot inside or outside?

Objectives: 1. To find out the proportion of patients who encountered stigma in their families. 2. To describe various forms of stigma experienced by the patients.Methodology: 200 TB patients who were registered for treatment under RNTCP during 3rd quarter of 2014 in Mysore district were interviewed. The interview was conducted using a semi-structured questionnaire at their place of residence.Results: Out of 200 patients interviewed, 150 were males and 50 were females. 132 patients out of 200 (66%) faced stigma within their families (p value <0.05). Patients also faced social isolation and were deserted by their families. Also, there were instances where married female patients were forced to undergo treatment at their parents’ houses.Conclusion: A significant majority of patients with tuberculosis were found to have been stigmatized within their own families, showing that TB is indeed a spot inside as well as outside. Such stigmatization may act as a major barrier in achieving the control of tuberculosis. There is an urgent need for the program to take necessary steps to overcome stigma against the disease in the community