277:
265:
1024:
118:
126:
1018:
216:
208:
1030:
289:
lengthening of the P–C distance is often hidden by an opposing effect: as the phosphorus lone pair is donated to the metal, P(lone pair)–R(bonding pair) repulsions decrease, which acts to shorten the P–C bond. The two effects have been deconvoluted by comparing the structures of pairs of metal-phosphine complexes that differ only by one electron. Oxidation of R
223:
As in metal–carbonyls, electrons are partially transferred from a d-orbital of the metal to antibonding molecular orbitals of the alkenes and alkynes. This electron transfer strengthens the metal–ligand bond and weakens the C–C bonds within the ligand. In the case of metal-alkenes and alkynes, the
133:
The electrons are partially transferred from a d-orbital of the metal to anti-bonding molecular orbitals of CO (and its analogs). This electron-transfer strengthens the metal–C bond and weakens the C–O bond. The strengthening of the M–CO bond is reflected in increases of the vibrational frequencies
288:
Phosphines accept electron density from metal p or d orbitals into combinations of P–C σ* antibonding orbitals that have π symmetry. When phosphines bond to electron-rich metal atoms, backbonding would be expected to lengthen P–C bonds as P–C σ* orbitals become populated by electrons. The expected
191:
can either be raised (for example, upon complexation with weak π-donor metals, such as Pt(II)) or lowered (for example, upon complexation with strong π-donor metals, such as Ni(0)). For the isocyanides, an additional parameter is the MC=N–C angle, which deviates from 180° in highly electron-rich
293:
P–M complexes results in longer M–P bonds and shorter P–C bonds, consistent with π-backbonding. In early work, phosphine ligands were thought to utilize 3d orbitals to form M–P pi-bonding, but it is now accepted that d-orbitals on phosphorus are not involved in bonding as they are too high in
176:, RNC, are another class of ligands that are capable of π-backbonding. In contrast with CO, the σ-donor lone pair on the C atom of isocyanides is antibonding in nature and upon complexation the CN bond is strengthened and the ν
314:
process with donation of electrons from the filled π-orbital or lone electron pair orbital of the ligand into an empty orbital of the metal (donor–acceptor bond), together with release (back donation) of electrons from an
134:
for the M–C bond (often outside of the range for the usual IR spectrophotometers). Furthermore, the M–CO bond length is shortened. The weakening of the C–O bond is indicated by a decrease in the wavenumber of the
764:
Fey, N.; Orpen, A. G.; Harvey, J. N. (2009). "Building ligand knowledge bases for organometallic chemistry: Computational description of phosphorus(III)-donor ligands and the metal–phosphorus bonds".
705:
Dunne, B. J.; Morris, R. B.; Orpen, A. G. (1991). "Structural systematics. Part 3. Geometry deformations in triphenylphosphine fragments: A test of bonding theories in phosphine complexes".
244:
to assume the character of a metallacyclopropane. Alkenes and alkynes with electronegative substituents exhibit greater π backbonding. Some strong π backbonding ligands are
1483:
106:
728:
Gilheany, D. G. (1994). "No d
Orbitals but Walsh Diagrams and Maybe Banana Bonds: Chemical Bonding in Phosphines, Phosphine Oxides, and Phosphonium Ylides".
240:
bond is reflected in bending of the C–C–R angles which assume greater sp and sp character, respectively. Thus strong π backbonding causes a metal-alkene
644:
Orpen, A. G.; Connelly, N. G. (1990). "Structural systematics: the role of P–A σ* orbitals in metal–phosphorus π-bonding in redox-related pairs of M–PA
1117:
1273:
1316:
1235:
1162:
843:
158:
353:
192:
systems. Other ligands have weak π-backbonding abilities, which creates a labilization effect of CO, which is described by the
809:
689:
603:
536:
511:
436:
411:
384:
461:
1331:
1157:
338:
1423:
628:
486:
17:
1589:
1458:
1453:
1418:
1082:
1584:
1468:
1463:
1448:
906:
1097:
1473:
1351:
933:
894:
884:
766:
164:
Many ligands other than CO are strong "backbonders". Nitric oxide is an even stronger π-acceptor than CO and ν
50:
on an adjacent ion or molecule. In this type of interaction, electrons from the metal are used to bond to the
1266:
889:
836:
1524:
319:
d orbital of the metal (which is of π-symmetry with respect to the metal–ligand axis) into the empty π*-
1529:
553:
1579:
1341:
1152:
1142:
1132:
1107:
1077:
1413:
1377:
1282:
1259:
923:
1184:
1087:
1059:
829:
1558:
1443:
169:
1478:
1228:
1189:
1223:
310:
A description of the bonding of π-conjugated ligands to a transition metal which involves a
1433:
1296:
1147:
1038:
901:
860:
241:
8:
1553:
1372:
1346:
1301:
1049:
913:
879:
348:
253:
245:
1213:
1367:
1321:
968:
677:
249:
276:
1548:
1519:
1509:
1438:
1199:
988:
948:
938:
805:
746:
685:
624:
599:
573:
532:
507:
482:
457:
432:
407:
380:
333:
264:
1514:
1408:
1311:
1306:
1240:
980:
953:
797:
774:
738:
730:
710:
659:
565:
343:
141:
band(s) from that for free CO (2143 cm), for example to 2060 cm in Ni(CO)
59:
1387:
1382:
1218:
1092:
963:
650:
150:
102:
95:
55:
1504:
1403:
1127:
154:
79:
47:
43:
778:
569:
1573:
1499:
1176:
1136:
1069:
1023:
998:
871:
852:
577:
400:
Cotton, Frank Albert; Wilkinson, Geoffrey; Murillo, Carlos A., eds. (1999).
1251:
1122:
750:
401:
374:
1428:
1208:
958:
714:
320:
742:
663:
219:π backbonding from electrons in metal center d-orbital to alkene's LUMO.
215:
193:
173:
91:
207:
117:
1540:
1336:
943:
918:
801:
379:(2nd ed.). Upper Saddle River, N.J: Prentice Hall. p. 338.
71:
63:
31:
794:
IUPAC. Compendium of
Chemical Terminology, 2nd ed. (the "Gold Book")
621:
479:
211:σ bonding from electrons in alkene's HOMO to metal center d-orbital.
129:π backbonding from electrons in metal center d-orbital to CO's LUMO.
1017:
187:. Depending on the balance of σ-bonding versus π-backbonding, the ν
125:
821:
311:
67:
39:
121:σ bonding from electrons in CO's HOMO to metal center d-orbital.
87:
83:
75:
51:
531:(3., compl. rev. and extended ed.). Weinheim: WILEY-VCH.
112:
552:
Zhao, Haitao; Ariafard, Alireza; Lin, Zhenyang (2006-08-01).
303:
596:
Organotransition metal chemistry: from bonding to catalysis
527:
Elschenbroich, Christoph; Elschenbroich, Christoph (2011).
504:
Organotransition metal chemistry: from bonding to catalysis
78:
involved in π backbonding can be broken into three groups:
1484:
Arene complexes of univalent gallium, indium, and thallium
1029:
526:
202:
554:"In-depth insight into metal–alkene bonding interactions"
560:. Protagonists in Chemistry: Professor D.M.P. Mingos.
399:
180:
increased. At the same time, π-backbonding lowers the
682:
454:
94:. Compounds where π backbonding is prominent include
707:
Journal of the
Chemical Society, Dalton Transactions
431:(2nd ed.). Pearson Prentice-Hall. p. 702.
297:
62:
with low oxidation states that have ligands such as
149:, and 1790 cm in the anion . For this reason,
791:
1571:
704:
598:. Sausalito (Calif.): University science books.
506:. Sausalito (Calif.): University science books.
426:
551:
763:
619:Elias, Anil J.; Gupta, B D (January 1, 2013).
477:Elias, Anil J.; Gupta, B D (January 1, 2013).
42:interaction between a filled (or half filled)
1267:
837:
796:. Oxford: Blackwell Scientific Publications.
643:
1281:
372:
259:
373:Miessler, Gary L.; Tarr, Donald A. (1999).
306:definition of back donation is as follows:
113:Metal carbonyls, nitrosyls, and isocyanides
1368:Oxidative addition / reductive elimination
1274:
1260:
844:
830:
618:
476:
58:and stabilizes the metal. It is common in
456:(6th ed.). Wiley. pp. 105–106.
427:Housecroft, C. E.; Sharpe, A. G. (2005).
1317:Polyhedral skeletal electron pair theory
1236:Polyhedral skeletal electron pair theory
727:
684:(5th ed.). Wiley. pp. 99–100.
676:
451:
275:
263:
214:
206:
159:infrared spectroscopy of metal carbonyls
153:is an important diagnostic technique in
124:
116:
107:molybdenum and iron dinitrogen complexes
46:of a transition metal atom and a vacant
792:McNaught, A. D.; Wilkinson, A. (2006).
648:complexes (A = R, Ar, OR; R = alkyl)".
593:
501:
203:Metal–alkene and metal–alkyne complexes
14:
1572:
1255:
825:
589:
587:
27:Form of interaction between two atoms
1424:Transition metal fullerene complexes
623:(2nd ed.). Universities Press.
481:(2nd ed.). Universities Press.
612:
54:, which dissipates excess negative
24:
1459:Transition metal carbyne complexes
1454:Transition metal carbene complexes
1419:Transition metal indenyl complexes
851:
584:
25:
1601:
1469:Transition metal alkyne complexes
1464:Transition metal alkene complexes
495:
470:
406:(6th ed.). New York: Wiley.
298:IUPAC definition of Back Donation
1474:Transition-metal allyl complexes
1028:
1022:
1016:
594:Hartwig, John Frederick (2010).
502:Hartwig, John Frederick (2010).
1449:Transition metal acyl complexes
785:
757:
721:
698:
670:
637:
545:
520:
445:
420:
393:
366:
13:
1:
359:
452:Crabtree, Robert H. (2014).
403:Advanced inorganic chemistry
7:
1525:Shell higher olefin process
1332:Dewar–Chatt–Duncanson model
339:Dewar–Chatt–Duncanson model
327:
10:
1606:
1414:Cyclopentadienyl complexes
1378:β-hydride elimination
1352:Metal–ligand multiple bond
934:Metal–ligand multiple bond
161:discusses this in detail.
145:and 1981 cm in Cr(CO)
1538:
1492:
1479:Transition metal carbides
1396:
1360:
1289:
1198:
1175:
1106:
1068:
1048:
1037:
1014:
997:
979:
870:
859:
779:10.1016/j.ccr.2008.04.017
570:10.1016/j.ica.2005.12.013
260:Metal-phosphine complexes
1590:Organometallic chemistry
1283:Organometallic chemistry
224:strengthening of the M–C
170:metal–nitrosyl chemistry
168:is a diagnostic tool in
155:metal–carbonyl chemistry
1444:Half sandwich compounds
558:Inorganica Chimica Acta
1585:Coordination chemistry
1559:Bioinorganic chemistry
325:
323:orbital of the ligand.
285:
273:
220:
212:
130:
122:
82:and nitrogen analogs,
1530:Ziegler–Natta process
1434:Metal tetranorbornyls
308:
279:
267:
218:
210:
128:
120:
1539:Related branches of
1297:Crystal field theory
924:Coordinate (dipolar)
715:10.1039/dt9910000653
1554:Inorganic chemistry
1373:Migratory insertion
1347:Agostic interaction
1302:Ligand field theory
1098:C–H···O interaction
880:Electron deficiency
743:10.1021/cr00029a008
678:Crabtree, Robert H.
664:10.1021/om00118a048
429:Inorganic Chemistry
376:Inorganic chemistry
349:Ligand field theory
254:hexafluoro-2-butyne
246:tetrafluoroethylene
1439:Sandwich compounds
1397:Types of compounds
1322:Isolobal principle
1083:Resonance-assisted
286:
274:
250:tetracyanoethylene
221:
213:
131:
123:
18:Pi-acceptor ligand
1567:
1566:
1549:Organic chemistry
1520:Olefin metathesis
1510:Grignard reaction
1409:Grignard reagents
1249:
1248:
1200:Electron counting
1171:
1170:
1060:London dispersion
1012:
1011:
989:Metal aromaticity
811:978-0-9678550-9-7
767:Coord. Chem. Rev.
691:978-0-470-25762-3
605:978-1-891389-53-5
564:(11): 3527–3534.
538:978-3-527-29390-2
513:978-1-891389-53-5
438:978-0-130-39913-7
413:978-0-471-19957-1
386:978-0-13-841891-5
334:Bridging carbonyl
284:P–M π backbonding
60:transition metals
16:(Redirected from
1597:
1580:Chemical bonding
1515:Monsanto process
1312:d electron count
1307:18-electron rule
1276:
1269:
1262:
1253:
1252:
1241:Jemmis mno rules
1093:Dihydrogen bonds
1046:
1045:
1032:
1026:
1020:
954:Hyperconjugation
868:
867:
846:
839:
832:
823:
822:
816:
815:
802:10.1351/goldbook
789:
783:
782:
773:(5–6): 704–722.
761:
755:
754:
737:(5): 1339–1374.
725:
719:
718:
702:
696:
695:
674:
668:
667:
658:(4): 1206–1210.
641:
635:
634:
616:
610:
609:
591:
582:
581:
549:
543:
542:
524:
518:
517:
499:
493:
492:
474:
468:
467:
463:978-1-11813807-6
449:
443:
442:
424:
418:
417:
397:
391:
390:
370:
354:Pi-donor ligands
344:18-electron rule
21:
1605:
1604:
1600:
1599:
1598:
1596:
1595:
1594:
1570:
1569:
1568:
1563:
1534:
1488:
1404:Gilman reagents
1392:
1388:Carbometalation
1383:Transmetalation
1356:
1285:
1280:
1250:
1245:
1194:
1167:
1110:
1102:
1064:
1051:
1041:
1033:
1027:
1021:
1008:
993:
975:
863:
855:
850:
820:
819:
812:
790:
786:
762:
758:
726:
722:
703:
699:
692:
675:
671:
651:Organometallics
647:
642:
638:
631:
617:
613:
606:
592:
585:
550:
546:
539:
529:Organometallics
525:
521:
514:
500:
496:
489:
475:
471:
464:
450:
446:
439:
425:
421:
414:
398:
394:
387:
371:
367:
362:
330:
300:
292:
283:
271:
262:
239:
235:
231:
227:
205:
190:
186:
179:
167:
151:IR spectroscopy
148:
144:
140:
115:
99:
64:carbon monoxide
28:
23:
22:
15:
12:
11:
5:
1603:
1593:
1592:
1587:
1582:
1565:
1564:
1562:
1561:
1556:
1551:
1545:
1543:
1536:
1535:
1533:
1532:
1527:
1522:
1517:
1512:
1507:
1505:Cativa process
1502:
1496:
1494:
1490:
1489:
1487:
1486:
1481:
1476:
1471:
1466:
1461:
1456:
1451:
1446:
1441:
1436:
1431:
1426:
1421:
1416:
1411:
1406:
1400:
1398:
1394:
1393:
1391:
1390:
1385:
1380:
1375:
1370:
1364:
1362:
1358:
1357:
1355:
1354:
1349:
1344:
1339:
1334:
1329:
1324:
1319:
1314:
1309:
1304:
1299:
1293:
1291:
1287:
1286:
1279:
1278:
1271:
1264:
1256:
1247:
1246:
1244:
1243:
1238:
1233:
1232:
1231:
1226:
1221:
1216:
1205:
1203:
1196:
1195:
1193:
1192:
1187:
1181:
1179:
1173:
1172:
1169:
1168:
1166:
1165:
1160:
1155:
1150:
1145:
1140:
1130:
1125:
1120:
1114:
1112:
1104:
1103:
1101:
1100:
1095:
1090:
1085:
1080:
1074:
1072:
1066:
1065:
1063:
1062:
1056:
1054:
1043:
1039:Intermolecular
1035:
1034:
1015:
1013:
1010:
1009:
1007:
1006:
1003:
1001:
995:
994:
992:
991:
985:
983:
977:
976:
974:
973:
972:
971:
966:
956:
951:
946:
941:
936:
931:
926:
921:
916:
911:
910:
909:
899:
898:
897:
892:
887:
876:
874:
865:
861:Intramolecular
857:
856:
853:Chemical bonds
849:
848:
841:
834:
826:
818:
817:
810:
784:
756:
720:
697:
690:
669:
645:
636:
630:978-8173718748
629:
611:
604:
583:
544:
537:
519:
512:
494:
488:978-8173718748
487:
469:
462:
444:
437:
419:
412:
392:
385:
364:
363:
361:
358:
357:
356:
351:
346:
341:
336:
329:
326:
299:
296:
290:
281:
269:
261:
258:
237:
233:
229:
225:
204:
201:
188:
184:
177:
165:
157:. The article
146:
142:
138:
114:
111:
97:
26:
9:
6:
4:
3:
2:
1602:
1591:
1588:
1586:
1583:
1581:
1578:
1577:
1575:
1560:
1557:
1555:
1552:
1550:
1547:
1546:
1544:
1542:
1537:
1531:
1528:
1526:
1523:
1521:
1518:
1516:
1513:
1511:
1508:
1506:
1503:
1501:
1500:Carbonylation
1498:
1497:
1495:
1491:
1485:
1482:
1480:
1477:
1475:
1472:
1470:
1467:
1465:
1462:
1460:
1457:
1455:
1452:
1450:
1447:
1445:
1442:
1440:
1437:
1435:
1432:
1430:
1427:
1425:
1422:
1420:
1417:
1415:
1412:
1410:
1407:
1405:
1402:
1401:
1399:
1395:
1389:
1386:
1384:
1381:
1379:
1376:
1374:
1371:
1369:
1366:
1365:
1363:
1359:
1353:
1350:
1348:
1345:
1343:
1340:
1338:
1335:
1333:
1330:
1328:
1327:π backbonding
1325:
1323:
1320:
1318:
1315:
1313:
1310:
1308:
1305:
1303:
1300:
1298:
1295:
1294:
1292:
1288:
1284:
1277:
1272:
1270:
1265:
1263:
1258:
1257:
1254:
1242:
1239:
1237:
1234:
1230:
1227:
1225:
1222:
1220:
1217:
1215:
1214:Hückel's rule
1212:
1211:
1210:
1207:
1206:
1204:
1201:
1197:
1191:
1188:
1186:
1183:
1182:
1180:
1178:
1177:Bond cleavage
1174:
1164:
1161:
1159:
1156:
1154:
1151:
1149:
1146:
1144:
1143:Intercalation
1141:
1138:
1134:
1133:Metallophilic
1131:
1129:
1126:
1124:
1121:
1119:
1116:
1115:
1113:
1109:
1105:
1099:
1096:
1094:
1091:
1089:
1086:
1084:
1081:
1079:
1076:
1075:
1073:
1071:
1067:
1061:
1058:
1057:
1055:
1053:
1050:Van der Waals
1047:
1044:
1040:
1036:
1031:
1025:
1019:
1005:
1004:
1002:
1000:
996:
990:
987:
986:
984:
982:
978:
970:
967:
965:
962:
961:
960:
957:
955:
952:
950:
947:
945:
942:
940:
937:
935:
932:
930:
927:
925:
922:
920:
917:
915:
912:
908:
905:
904:
903:
900:
896:
893:
891:
888:
886:
883:
882:
881:
878:
877:
875:
873:
869:
866:
862:
858:
854:
847:
842:
840:
835:
833:
828:
827:
824:
813:
807:
803:
799:
795:
788:
780:
776:
772:
769:
768:
760:
752:
748:
744:
740:
736:
733:
732:
724:
716:
712:
708:
701:
693:
687:
683:
679:
673:
665:
661:
657:
653:
652:
640:
632:
626:
622:
615:
607:
601:
597:
590:
588:
579:
575:
571:
567:
563:
559:
555:
548:
540:
534:
530:
523:
515:
509:
505:
498:
490:
484:
480:
473:
465:
459:
455:
448:
440:
434:
430:
423:
415:
409:
405:
404:
396:
388:
382:
378:
377:
369:
365:
355:
352:
350:
347:
345:
342:
340:
337:
335:
332:
331:
324:
322:
318:
313:
307:
305:
295:
278:
272:P–M σ bonding
266:
257:
255:
251:
247:
243:
217:
209:
200:
198:
196:
183:
175:
171:
162:
160:
156:
152:
137:
127:
119:
110:
108:
104:
100:
93:
89:
85:
81:
77:
73:
69:
65:
61:
57:
53:
49:
45:
41:
37:
36:π backbonding
33:
19:
1493:Applications
1429:Metallocenes
1326:
1219:Baird's rule
939:Charge-shift
928:
902:Hypervalence
793:
787:
770:
765:
759:
734:
729:
723:
706:
700:
681:
672:
655:
649:
639:
620:
614:
595:
561:
557:
547:
528:
522:
503:
497:
478:
472:
453:
447:
428:
422:
402:
395:
375:
368:
316:
309:
301:
287:
222:
194:
181:
163:
135:
132:
103:Zeise's salt
35:
29:
1342:spin states
1209:Aromaticity
1185:Heterolysis
1163:Salt bridge
1108:Noncovalent
1078:Low-barrier
959:Aromaticity
949:Conjugation
929:Pi backbond
321:antibonding
174:Isocyanides
1574:Categories
1290:Principles
1137:aurophilic
1118:Mechanical
731:Chem. Rev.
360:References
92:phosphines
72:phosphines
1541:chemistry
1361:Reactions
1337:Hapticity
1229:spherical
1190:Homolysis
1153:Cation–pi
1128:Chalcogen
1088:Symmetric
944:Hapticity
578:0020-1693
302:The full
80:carbonyls
40:π-bonding
32:chemistry
1158:Anion–pi
1148:Stacking
1070:Hydrogen
981:Metallic
872:Covalent
864:(strong)
751:27704785
680:(2009).
328:See also
312:synergic
294:energy.
1123:Halogen
969:bicyclo
914:Agostic
709:: 653.
242:complex
232:and M–C
88:alkynes
84:alkenes
76:ligands
68:olefins
48:orbital
44:orbital
1224:Möbius
1052:forces
1042:(weak)
808:
749:
688:
627:
602:
576:
535:
510:
485:
460:
435:
410:
383:
252:, and
197:effect
105:, and
96:Ni(CO)
90:, and
74:. The
56:charge
52:ligand
1202:rules
1111:other
999:Ionic
907:3c–4e
895:8c–2e
890:4c–2e
885:3c–2e
304:IUPAC
70:, or
38:is a
964:homo
919:Bent
806:ISBN
747:PMID
686:ISBN
625:ISBN
600:ISBN
574:ISSN
533:ISBN
508:ISBN
483:ISBN
458:ISBN
433:ISBN
408:ISBN
381:ISBN
86:and
798:doi
775:doi
771:253
739:doi
711:doi
660:doi
566:doi
562:359
195:cis
30:In
1576::
804:.
745:.
735:94
654:.
586:^
572:.
556:.
256:.
248:,
199:.
189:CN
185:CN
178:CN
172:.
166:NO
139:CO
109:.
101:,
66:,
34:,
1275:e
1268:t
1261:v
1139:)
1135:(
845:e
838:t
831:v
814:.
800::
781:.
777::
753:.
741::
717:.
713::
694:.
666:.
662::
656:9
646:3
633:.
608:.
580:.
568::
541:.
516:.
491:.
466:.
441:.
416:.
389:.
317:n
291:3
282:3
280:R
270:3
268:R
238:2
236:R
234:2
230:4
228:R
226:2
182:ν
147:6
143:4
136:ν
98:4
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
