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288. RING: A Coordinate Transformation Program for
Evaluating the Degree and Type of Puckering of a Ring
Compound
by D. Cremer, Lehrstuhl für Theoretische Chemie, Universität Köln, Köln, FRG RING is a coordinate transformation program written to provide the quantitative data which aid the interpretation of ring conformations. These data are termed "ring puckering coordinates," for they describe the nonplanar character of a ring in a unique way; a set of puckering amplitudes qm and phase angles fm determines the amount and type of puckering coordinates, i.e., the three-membered ring is always planar (q1 and f1 are not defined), the four-membered ring has just one possible puckering mode described by the amplitude q2, the puckered five-membered ring conformations are characterized by the amplitude-phase pair (q2, f2), the six-membered ring forms are defined by the pair (q2, f2) and an additional amplitude q3, etc. For odd-membered rings, there are 1/2(N-3) amplitude- phase pairs (qm, fm) with m = 2,3...(N-1)/2. For even-membered rings, there are 1/2(N-4) amplitude- phase pairs (qm, fm) with m = 2,3...(N-2)/2 and an additional puckering amplitude q(N/2). FORTRAN IV (CDC) Lines of Code: 789 Recommended Citation: D. Cremer, QCPE 11, 288 (1975). |