Synthesis and Structural Characterization of N,N-disubstituted Acylguanidines

A series of five N,N-disubstituted acylguanidines R~1C(O)N=C[N(H)R~2]NR~3(R~1=Mes or Ph; R~2=Ar??or Ar?; R~3=Cy, Bn, iPr, or Et)(Mes=2,4,6-MeCH, Ar??=2,6-iPrCH, Ar?=2,6-MeCH) was synthesized from the reactions of parent acylthioureas with respective secondary amines. According to structutral characterization by single-crystal X-ray diffraction, the rough reduction of the steric hindrance of R substitutents of R~1 C(O)N=C[N(H)R~2]NR~3(also abbreviated as R~1-R~2-R~3 for comparison purposes) led to the slight enlongation of N(1)–C(1) bond lengthes and small decrease of N(1)–C(1)–N(3) bond angles from Mes–Ar??–Cy(1) to Ph–Ar??–Bn(2), Ph–Ar??–iPr(3) and Ph–Ar?–Cy(4). At the same time, the N(1)–H(1)···O(1) intramolecular hydrogen bonds were observed in these cases. When R~3=Et, an interesting compound Ph-Ar?-Et(5) was obtained with the formation of intermolecular hydrogen bonds instead. 1 belongs to the monoclinic system, space group P2with a=9.6488(3), b=28.5318(8), c=11.9155(3) ?, b=91.439(2)o, V=3279.27(16) ?~3, and Z=4. 2 belongs to the triclinic system, space group P1 with a=9.6759(7), b=10.8613(8), c=15.7642(12) ?, a=70.429(3), b=79.257(4), g=69.052(4)o, V=1453.63(19) ?~3 and Z=2. 3 belongs to the monoclinic system, space group P2with a=11.1393(4), b=13.0643(4), c=17.6600(6) ?, b=101.866(2)o, V=2515.09(15) ?~3 and Z=4. 4 belongs to the monoclinic system, space group C2/c with a=17.8466(3), b=13.6126(2), c=21.6710(4) ?, b=90.7310(10)o, V=4992.72(14) ?~3 and Z=8. 5 is of orthorhombic system, space group P222with a=10.5555(2), b=11.8913(2), c=14.9558(4) ?, V=1877.23(5) ?~3 and Z=4.