Structure of a bifunctional organic reagent: 2,2'-bis(dimethylaminomethylene)-2,2'-sulfonyldiacetonitrile

Abstract

The title compound (Ia) was prepared as a potential cross-linking reagent for hemoglobin. CIoHI4N402S, Mr=254.31, monoclinic, P2Jn, a= 14.335 (6), b = 7.614 (4), c = 24.36 (1) A, fl= 107.54 (3) °, v= 2534 (2) A 3, z = 8, Dx= 1.33 g cm -3, 2(Mo Ks) = 0.71069 A, /1 = 2.41 cm -~, F(000) = 1072, T= 295 K. Final R = 0.051 for 2350 observed reflections. There are two independent mole- cules with different conformations. The bond distances to the central S atom are: S-O= 1.43 (3) and S-C = 1.75 (4)A. The observed bond lengths 01- S-CTC 4 and O2-S-C~-C 2 are compatible with a resonance hybrid structure which has bond delocaliza- tion over all atoms between the terminal amino N atoms, giving the molecule an anionic character. The distance between the potential cross-linking sites (5.680 A) is in the range required. Introduction. One of our current projects involves chemical modification of cell-flee hemoglobins for potential use as substitutes for blood in emergency transfusion. The need for such an alternative is becoming increasingly pressing in view of the scarcity of blood especially when rare types are needed, and the possible transmission of diseases such as AIDS or hepatitis associated with blood transfusion. Our aim is to exploit the abundantly available and the relatively inexpensive human and bovine hemoglobins as an alternative to blood for a cell-free oxygen carrier (for recent advances in this area, see Bolin, Beyer & Nemo (1983)). To this end, however, two major problems inherent in cell-free hemoglobins need be overcome: first, the retention time of the cell-flee hemoglobins is short such that most of the infused hemoglobin is quickly eliminated from the circulating blood and, second, the oxygen-binding affinity for cell-free hemoglobins is too