Picture of boy being examining by doctor at a tuberculosis sanatorium

Understanding our future through Open Access research about our past...

Strathprints makes available scholarly Open Access content by researchers in the Centre for the Social History of Health & Healthcare (CSHHH), based within the School of Humanities, and considered Scotland's leading centre for the history of health and medicine.

Research at CSHHH explores the modern world since 1800 in locations as diverse as the UK, Asia, Africa, North America, and Europe. Areas of specialism include contraception and sexuality; family health and medical services; occupational health and medicine; disability; the history of psychiatry; conflict and warfare; and, drugs, pharmaceuticals and intoxicants.

Explore the Open Access research of the Centre for the Social History of Health and Healthcare. Or explore all of Strathclyde's Open Access research...

Image: Heart of England NHS Foundation Trust. Wellcome Collection - CC-BY.

Insertion and cycloaddition reactivity of a transition-metal N-metalloimine

Hevia, E and Perez, J and Riera, V and Miguel, D (2002) Insertion and cycloaddition reactivity of a transition-metal N-metalloimine. Angewandte Chemie, 41 (20). pp. 3858-3860.

Full text not available in this repository. Request a copy from the Strathclyde author

Abstract

The presence of electron-releasing main-group-metal substituents on the nitrogen atom increases the reactivity of imines A towards dipolar reagents such as isocyanates1 and ketenes.2 We speculated that, in addition to this inductive effect, a low-oxidation transition-metal substituent would contribute a destabilizing interaction between the lone pair on the nitrogen atom and the filled metal d orbitals.3 However, all structurally characterized M(NCR2) complexes have essentially linear M-N-C geometries4 as a result of π donation of the lone pair on the nitrogen atom to empty metal orbitals. Thus, these azavinylidene5 complexes B are more related to alkylideneammonium cations than to imines.6 Herein we report the synthesis, structure, and a preliminary account of the reactivity of an N-metalloimine (type A) which contains a transition-metal fragment. The reaction of KNCPh2 with [Re(OTf)(CO)3(bpy)] (bpy=2,2′-bipyridine) afforded the complex [Re(NCPh2)(CO)3(bpy)] (1), which was characterized spectroscopically and by X-ray diffraction (Figure 1 a). For comparison, the structure of the imine complex [Re(HNCPh2)(CO)3(bpy)]+ (2), synthesized as its triflate salt by reaction of 1 with HOTf, was also determined (Figure 1 b). The Re-N-C angle (133.9(4)°) for the alkylideneamido group of 1, even smaller than the Re-N-C angle (138.9(2)°) of 2, indicates the absence of N-to-Re π donation. The larger deviations from linearity in previously known azavinylidene complexes (152.9(4)° and 157.2(4)° for [OsCl(NCMe2)(CCH3)(PiPr3)2][OTf]7 and [OsCl(NCMe2)(CHPh)(PiPr3)2],8 respectively) can be related to the presence of bulky ancillary ligands, whereas such effects are absent in 1. The ReNCPh2 distance (2.113(4) Å) in 1 is comparable to the ReN(H)CPh2 distance (2.192(3) Å) in 2, which is in agreement with the lack of multiple-bond character of the ReN bond.