33:
951:, combines the properties of Cp and Cp*: it possesses the steric bulk of Cp* but has electronic properties similar to Cp, the electron-donation from the methyl groups being "canceled out" by the electron-accepting nature of the trifluoromethyl substituent. Its steric bulk stabilizes complexes with fragile ligands. Its bulk also attenuates intermolecular interactions, decreasing the tendency to form polymeric structures. Its complexes also tend to be more soluble in non-polar solvents. The methyl group in Cp* complexes can undergo
907:
215:
140:
24:
621:
605:
419:
630:
919:
475:
1323:
Kuwabara, Takuya; Tezuka, Ryogen; Ishikawa, Mikiya; Yamazaki, Takuya; Kodama, Shintaro; Ishii, Youichi (2018-06-25). "Ring
Slippage and Dissociation of Pentamethylcyclopentadienyl Ligand in an (η 5 -Cp*)Ir Complex with a κ 3 - O , C , O Tridentate Calixarene Ligand under Mild Conditions".
938:
Complexes of pentamethylcyclopentadienyl differ in several ways from the more common cyclopentadienyl (Cp) derivatives. Being more electron-rich, Cp* is a stronger donor and dissociation, like ring-slippage, is more difficult with Cp* than with Cp. The fluorinated ligand,
1359:
Gassman, Paul G.; Mickelson, John W.; Sowa, John R. (1992-08-01). "1,2,3,4-Tetramethyl-5-(trifluoromethyl)cyclopentadienide: a unique ligand with the steric properties of pentamethylcyclopentadienide and the electronic properties of cyclopentadienide".
579:) and read as "C P star", the "star" signifying the five methyl groups radiating from the core of the ligand. Thus, the 1,2,3,4,5-pentamethylcyclopentadiene's formula is also written Cp*H. In contrast to less-substituted
427:
399:
488:
884:
878:
694:
1178:
King, R. B.; Bisnette, M. B. (1967). "Organometallic chemistry of the transition metals XXI. Some π-pentamethylcyclopentadienyl derivatives of various transition metals".
1056:
De Vries, L. (1960). "Preparation of 1,2,3,4,5-Pentamethyl-cyclopentadiene, 1,2,3,4,5,5-Hexamethyl-cyclopentadiene, and 1,2,3,4,5-Pentamethyl-cyclopentadienylcarbinol".
906:
264:
620:
604:
1129:
832:
893:
induced rearrangement of hexamethyl Dewar benzene to a substituted pentamethylcyclopentadiene prior to reaction with the hydrate of either
1180:
1112:
Fendrick, C. M.; Schertz, L. D.; Mintz, E. A.; Marks, T. J. (1992). "Large-Scale
Synthesis of 1,2,3,4,5-Penta-Methylcyclopentadiene".
1162:
1040:
229:
629:
960:
378:
495:
596:
172:
97:
193:
1234:
Criegee, R.; Gruner, H. (1968). "Acid-catalyzed
Rearrangements of Hexamethyl-prismane and Hexamethyl-Dewar-benzene".
1401:
1002:
874:
32:
418:
1268:
135:
889:, but has been discontinued with the increased commercial availability of Cp*H. Such syntheses rely on a
977:
898:
894:
441:
411:
1295:(1968). "Conversion of Dewar Hexamethylbenzene to Pentamethylcyclopentadienylrhodium(III) Chloride".
45:
210:
1208:
649:
63:
952:
1266:(1968). "Mechanisms of Reactions of Dewar Hexamethylbenzene with Rhodium and Iridium Chlorides".
1154:
808:
1377:
1341:
1297:
1236:
1158:
1147:
1125:
1090:
1036:
764:
Some representative reactions leading to such Cp*–metal complexes follow: Deprotonation with
1406:
1369:
1333:
1305:
1273:
1244:
1216:
1188:
1117:
1066:
361:
287:
181:
117:
23:
1206:
Paquette, L. A.; Krow, G. R. (1968). "Electrophilic
Additions to Hexamethyldewarbenzene".
972:
956:
890:
580:
511:
73:
214:
139:
1015:
355:
55 to 60 °C (131 to 140 °F; 328 to 333 K) at 13 mmHg (1.7 kPa)
765:
734:
466:
1220:
1192:
1395:
1292:
1263:
1058:
612:
350:
128:
1084:
Threlkel, S.; Bercaw, J. E.; Seidler, P. F.; Stryker, J. M.; Bergman, R. G. (1993).
592:
546:
1337:
877:. This method was traditionally used for preparation of the chloro-bridged dimers
161:
591:
Pentamethylcyclopentadiene is commercially available. It was first prepared from
1085:
454:
1121:
309:
108:
1381:
1345:
1032:
392:
1248:
447:
1277:
1373:
1309:
1070:
918:
1149:
Organotransition Metal
Chemistry: Fundamental Concepts and Applications
595:
and 2-butenyllithium, via 2,3,4,5-tetramethylcyclopent-2-enone, with a
340:
148:
831:
This method is analogous to the route to the related Cp complex, see
807:
Synthesis of (pentamethylcyclopentadienyl)iron dicarbonyl dimer from
758:
558:
465:
Except where otherwise noted, data are given for materials in their
514:
96:
86:
791:
Synthesis of (pentamethylcyclopentadienyl)titanium trichloride:
330:
557:
1,2,3,4,5-Pentamethylcyclopentadiene is the precursor to the
963:
are known that are far more sterically encumbered than Cp*.
198:
873:
A now-obsolete route to Cp* complexes involves the use of
838:
Some Cp* complexes are prepared using silyl transfer:
483:
1016:
https://www.sigmaaldrich.com/GB/en/sds/aldrich/214027
640:
1146:
238:InChI=1S/C10H16/c1-6-7(2)9(4)10(5)8(6)3/h6H,1-5H3
583:derivatives, Cp*H is not prone to dimerization.
248:InChI=1/C10H16/c1-6-7(2)9(4)10(5)8(6)3/h6H,1-5H3
160:
939:(trifluoromethyl)tetramethylcyclopentadienyl, C
615:followed by acid-catalyzed dehydrocyclization:
72:
8:
213:
138:
116:
15:
997:
995:
993:
180:
50:1,2,3,4,5-Pentamethylcyclopenta-1,3-diene
1362:Journal of the American Chemical Society
917:
611:Alternatively, 2-butenyllithium adds to
575:
571:
549:
540:
536:
528:
524:
520:
1029:Organometallics: A Concise Introduction
989:
269:
234:
209:
1086:"1,2,3,4,5-Pentamethylcyclopentadiene"
1027:Elschenbroich, C.; Salzer, A. (1989).
1003:"1,2,3,4,5-Pentamethylcyclopentadiene"
934:, a prototypical bulky cyclopentadiene
459:114 °C (237 °F; 387 K)
129:
833:cyclopentadienyliron dicarbonyl dimer
562:1,2,3,4,5-pentamethylcyclopentadienyl
241:Key: WQIQNKQYEUMPBM-UHFFFAOYSA-N
7:
508:1,2,3,4,5-Pentamethylcyclopentadiene
251:Key: WQIQNKQYEUMPBM-UHFFFAOYAI
151:
1116:. Vol. 29. pp. 193–198.
14:
905:
628:
619:
603:
473:
417:
299:
31:
22:
469:(at 25 °C , 100 kPa).
961:Bulky cyclopentadienyl ligands
914:Comparison to other Cp ligands
379:Occupational safety and health
293:
1:
1338:10.1021/acs.organomet.8b00257
1221:10.1016/S0040-4039(00)89761-0
1193:10.1016/S0022-328X(00)91042-8
597:Nazarov cyclization reaction
554:. It is a colorless liquid.
1237:Angew. Chem. Int. Ed. Engl.
17:Pentamethylcyclopentadiene
1423:
1122:10.1002/9780470132609.ch47
1100:, vol. 8, p. 505
637:Organometallic derivatives
1262:Kang, J. W.; Mosley, K.;
737:compounds containing the
643:
564:, which is often denoted
463:
398:
376:
371:
280:
260:
225:
56:
44:
39:
30:
21:
875:hexamethyl Dewar benzene
761:, commonly called Cp*.
733:Cp*H is a precursor to
1249:10.1002/anie.196804672
935:
815:2 Cp*H + 2 Fe(CO)
1145:Yamamoto, A. (1986).
978:Methylcyclopentadiene
921:
899:rhodium(III) chloride
895:iridium(III) chloride
1278:10.1039/C19680001304
644:Cp*–metal complexes
272:CC1=C(C)C(C)C(C)=C1C
46:Preferred IUPAC name
1374:10.1021/ja00043a065
1310:10.1021/ja01014a063
1181:J. Organomet. Chem.
1114:Inorganic Syntheses
1071:10.1021/jo01080a623
362:Solubility in water
317: g·mol
18:
1155:Wiley-Interscience
936:
809:iron pentacarbonyl
496:Infobox references
367:Sparingly soluble
16:
1368:(17): 6942–6944.
1332:(12): 1829–1832.
1304:(12): 3259–3261.
1298:J. Am. Chem. Soc.
1272:(21): 1304–1305.
1215:(17): 2139–2142.
1209:Tetrahedron Lett.
1131:978-0-470-13260-9
1098:Collected Volumes
1091:Organic Syntheses
957:tuck-in complexes
731:
730:
517:with the formula
504:Chemical compound
502:
501:
442:Hazard statements
325:Colorless liquid
194:CompTox Dashboard
98:Interactive image
1414:
1402:Cyclopentadienes
1386:
1385:
1356:
1350:
1349:
1320:
1314:
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1288:
1282:
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1259:
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1075:
1074:
1053:
1047:
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1007:
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999:
909:
757:
756:
755:
747:
746:
641:
632:
623:
607:
578:
552:
544:
533:, often written
532:
486:
480:
477:
476:
449:
421:
316:
301:
295:
288:Chemical formula
218:
217:
202:
200:
184:
164:
153:
142:
131:
120:
100:
76:
35:
26:
19:
1422:
1421:
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1416:
1415:
1413:
1412:
1411:
1392:
1391:
1390:
1389:
1358:
1357:
1353:
1326:Organometallics
1322:
1321:
1317:
1290:
1289:
1285:
1261:
1260:
1256:
1233:
1232:
1228:
1205:
1204:
1200:
1177:
1176:
1172:
1165:
1157:. p. 105.
1144:
1143:
1139:
1132:
1111:
1110:
1106:
1096:
1083:
1082:
1078:
1055:
1054:
1050:
1043:
1026:
1025:
1021:
1014:
1010:
1001:
1000:
991:
986:
973:Cyclopentadiene
969:
950:
946:
942:
933:
929:
925:
922:Structure of Bu
916:
891:hydrohalic acid
887:
881:
868:
864:
860:
856:
849:
845:
826:
822:
818:
802:
798:
787:
783:
779:
775:
754:
751:
750:
749:
745:
742:
741:
740:
738:
724:
720:
709:
698:
686:
676:
666:
653:
639:
599:as a key step.
589:
581:cyclopentadiene
577:
573:
569:
551:
547:
542:
538:
534:
530:
526:
522:
518:
505:
498:
493:
492:
491: ?)
482:
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474:
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444:
430:
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389:
364:
314:
304:
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276:
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196:
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167:
154:
123:
103:
90:
79:
66:
52:
51:
12:
11:
5:
1420:
1418:
1410:
1409:
1404:
1394:
1393:
1388:
1387:
1351:
1315:
1293:Maitlis, P. M.
1283:
1264:Maitlis, P. M.
1254:
1243:(6): 467–468.
1226:
1198:
1187:(2): 287–297.
1170:
1163:
1137:
1130:
1104:
1076:
1048:
1041:
1035:. p. 47.
1019:
1008:
988:
987:
985:
982:
981:
980:
975:
968:
965:
953:C–H activation
948:
944:
940:
931:
927:
923:
915:
912:
911:
910:
885:
879:
871:
870:
866:
862:
858:
854:
851:
847:
846:SiCl → Cp*SiMe
843:
829:
828:
824:
820:
816:
805:
804:
800:
796:
789:
788:
785:
781:
780:Li → Cp*Li + C
777:
773:
766:n-butyllithium
752:
743:
735:organometallic
729:
728:
725:
722:
718:
714:
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638:
635:
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633:
625:
624:
609:
608:
588:
585:
545:, where Me is
503:
500:
499:
494:
472:
471:
467:standard state
464:
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211:DTXSID00193466
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1316:
1311:
1307:
1303:
1300:
1299:
1294:
1291:Kang, J. W.;
1287:
1284:
1279:
1275:
1271:
1270:
1269:Chem. Commun.
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1164:9780471891710
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1123:
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1099:
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1092:
1087:
1080:
1077:
1072:
1068:
1064:
1061:
1060:
1059:J. Org. Chem.
1052:
1049:
1044:
1042:9783527278183
1038:
1034:
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678:
673:
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661:
657:
655:
648:
647:
642:
636:
631:
627:
626:
622:
618:
617:
616:
614:
613:ethyl acetate
606:
602:
601:
600:
598:
594:
586:
584:
582:
567:
563:
560:
555:
553:
516:
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352:
351:Boiling point
349:
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329:
328:
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130:ECHA InfoCard
127:
126:
119:
115:
114:
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110:
107:
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95:
94:
92:
88:
83:
82:
75:
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68:
65:
61:
60:
55:
47:
43:
38:
34:
29:
25:
20:
1365:
1361:
1354:
1329:
1325:
1318:
1301:
1296:
1286:
1267:
1257:
1240:
1235:
1229:
1212:
1207:
1201:
1184:
1179:
1173:
1148:
1140:
1113:
1107:
1097:
1089:
1079:
1065:(10): 1838.
1062:
1057:
1051:
1028:
1022:
1011:
955:leading to "
937:
872:
837:
830:
806:
795:Cp*Li + TiCl
790:
763:
732:
610:
593:tiglaldehyde
590:
565:
561:
556:
507:
506:
433:
400:
388:Main hazards
377:
57:Identifiers
679:red-violet
455:Flash point
428:Signal word
382:(OHS/OSH):
322:Appearance
281:Properties
136:100.021.586
1396:Categories
984:References
842:Cp*Li + Me
712:colorless
412:Pictograms
345:0.87 g/cm
310:Molar mass
182:DSE3MRZ77C
109:ChemSpider
85:3D model (
64:CAS Number
1382:0002-7863
1346:0276-7333
861:→ Cp*TiCl
799:→ Cp*TiCl
717:Cp*Mo(CO)
706:Cp*Re(CO)
587:Synthesis
403:labelling
393:Flammable
74:4045-44-7
967:See also
772:Cp*H + C
372:Hazards
1407:Ligands
853:Cp*SiMe
727:orange
701:orange
663:Cp*TiCl
658:yellow
489:what is
487: (
434:Warning
341:Density
315:136.238
149:PubChem
1380:
1344:
1161:
1128:
1039:
857:+ TiCl
850:+ LiCl
827:+ 6 CO
803:+ LiCl
759:ligand
559:ligand
512:cyclic
484:verify
481:
265:SMILES
40:Names
819:]] →
515:diene
510:is a
335:Mild
230:InChI
162:77667
118:70069
87:JSmol
1378:ISSN
1342:ISSN
1159:ISBN
1126:ISBN
1037:ISBN
883:and
869:SiCl
865:+ Me
689:red
669:red
448:H226
331:Odor
173:UNII
1370:doi
1366:114
1334:doi
1306:doi
1274:doi
1245:doi
1217:doi
1189:doi
1118:doi
1067:doi
1033:VCH
959:".
897:or
823:+ H
650:Cp*
566:Cp*
523:(CH
401:GHS
199:EPA
152:CID
1398::
1376:.
1364:.
1340:.
1330:37
1328:.
1302:90
1153:.
1124:.
1095:;
1088:.
1063:25
1031:.
992:^
947:CF
943:Me
901:.
835:.
811::
786:10
768::
748:Me
721:CH
654:Fe
574:Me
548:CH
539:Me
405::
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