336:
increases dramatically and the ligand "bows" which causes a change in the orientation of the lone pairs of electrons on the nitrogen atoms. These lone pairs are what is responsible for forming bonds with the metal centers so forcing them to move closer together also forces the metal centers to be positioned closer together. Thus, decreasing the length of the quintuple bond. In the case where this ligand is bound to quintuply bonded dimolybdenum the quintuple bond length goes from 201.87 pm to 201.57 pm when the hydrogen in replaced with a phenyl group. Similar results have also been demonstrated in dichromium quintuple bond complexes as well.
493:
326:
204:
288:
172:
20:
150:
In 2007 the shortest-ever metal–metal bond (180.28 pm) was reported to exist also in a compound containing a quintuple chromium-chromium bond with diazadiene bridging ligands. Other metal–metal quintuple bond containing complexes that have been reported include quintuply bonded dichromium with
98:
methods, which were also used to elucidate the role of the terphenyl ligand, in which the flanking aryls were shown to interact very weakly with the chromium atoms, causing only a small weakening of the quintuple bond. A 2007 theoretical study identified two global minima for quintuple bonded RMMR
335:
The above example shows the ligand used in the dimolybdenum complex shown earlier. When the carbon between the two nitrogens in the ligand has a hydrogen bound to it, the steric repulsion is small. However, when the hydrogen is replaced with a much more bulky phenyl ring the steric repulsion
267:
Molecular orbital calculations have elucidated the relative energies of the orbitals created by these bonding interactions. As shown in the figure below, the lowest energy orbitals are the π bonding orbitals followed by the σ bonding orbital. The next highest are the δ bonding orbitals which
315:
to occur the metal atoms must move closer together, thereby shortening the quintuple bond length. The two ways in which to obtain shorter metal–metal distances is to either reduce the distance between the chelating atoms in the ligand by changing the structure, or by using
506:
La
Macchia, Giovanni; Gagliardi, Laura; Power, Philip P.; Brynda, Marcin (2008). "Large Differences in Secondary Metal−Arene Interactions in the Transition-Metal Dimers ArMMAr (Ar = Terphenyl; M = Cr, Fe, or Co): Implications for Cr−Cr Quintuple Bonding".
81:
In some cases of high-order bonds between metal atoms, the metal-metal bonding is facilitated by ligands that link the two metal centers and reduce the interatomic distance. By contrast, the chromium dimer with quintuple bonding is stabilized by a bulky
682:
Kreisel, Kevin A.; Yap, Glenn P. A.; Dmitrenko, Olga; Landis, Clark R.; Theopold, Klaus H. (2007). "The
Shortest Metal–Metal Bond Yet: Molecular and Electronic Structure of a Dinuclear Chromium Diazadiene Complex".
284:, they in fact are not. This is because the model shown here is a simplification and that hybridization of s, p, and d orbitals is believed to take place, causing a change in the orbital energy levels.
764:
Tsai, Yi-Chou; Hsu, Chia-Wei; Yu, Jen-Shiang K.; Lee, Gene-Hsiang; Wang, Yu; Kuo, Ting-Shen (2008). "Remarkably Short Metal–Metal Bonds: A Lantern-Type
Quintuply Bonded Dichromium(I) Complex".
851:
Hsu, Chai-Wei; Yu, Jen-Shiang K.; Yen, Chun-Hsu; Lee, Gene-Hsiang; Wang, Yu; Tsa, Yi-Chou (2008). "Quintuply-Bonded
Dichromium(I) Complexes Featuring Metal–Metal Bond Lengths of 1.74 Å".
808:
Tsai, Yi-Chou; Chen, Hong-Zhang; Chang, Chie-Chieh; Yu, Jen-Shiang K.; Lee, Gene-Hsiang; Wang, Yu; Kuo, Ting-Shen (2009). "Journey from Mo–Mo
Quadruple Bonds to Quintuple Bonds".
320:
to force a conformational change in the ligand that bends the molecule in a way that forces the chelating atoms closer together. An example of the latter is shown below:
166:
to the metal centers, giving them the needed number of electrons to participate in quintuple bonding. Below is a figure of a typical quintuple bond synthesis.
894:
Noor, Awal; Glatz, Germund; Muller, Robert; Kaupp, Martin; Demeshko, Serhiy; Kempe, Rhett (2009). "Carboalumination of a chromium–chromium quintuple bond".
720:
Noor, Awal; Wagner, Frank R.; Kempe, Rhett (2008). "Metal–Metal
Distances at the Limit: A Coordination Compound with an Ultrashort Chromium–Chromium Bond".
300:
Quintuple bond lengths are heavily dependent on the ligands bound to the metal centers. Nearly all complexes containing a metal–metal quintuple bond have
1037:
304:
bridging ligands, and even those that do not, such as the terphenyl complex mentioned earlier, have some bridging characteristic to it through metal–
986:"Low-Valent Aminopyridinato Chromium Methyl Complexes via Reductive Alkylation and via Oxidative Addition of Iodomethane by a Cr–Cr Quintuple Bond"
218:
As stated above metal-metal quintuple bonds have a σπδ configuration. Among the five bonds present between the metal centers, one is a
465:
272:. Because the 10 valence electrons of the metals are used to fill these first 5 orbitals, the next highest orbital becomes the
1275:
1030:
78:, e.g. and . In a quintuple bond, ten electrons participate in bonding between the two metal centers, allocated as σπδ.
90:. The species is stable up to 200 °C. The chromium–chromium quintuple bond has been analyzed with multireference
1068:
1023:
190:
bridging ligands was reported with a Mo–Mo bond length of 202 pm. The compound was synthesised starting from
191:
373:
1306:
305:
369:"Quintuple Bond Makes Its Debut: First stable molecule with fivefold metal–metal bonding is synthesized"
939:
Ni, Chengbao; Ellis, Bobby D.; Long, Gary J.; Power, Philip P. (2009). "Reactions of Ar′CrCrAr′ with N
1331:
1296:
1280:
95:
492:
1255:
281:
457:"Quantum Chemical Study of the Quintuple Bond between Two Chromium Centers in [PhCrCrPh]:
949:
123:
455:
Brynda, Marcin; Gagliardi, Laura; Widmark, Per-Olof; Power, Philip P.; Roos, Björn O. (2006).
158:
Synthesis of quintuple bonds is usually achieved through reduction of a dimetal species using
1215:
1210:
766:
722:
1181:
905:
621:
603:
411:
8:
1301:
1195:
909:
625:
415:
392:
Nguyen, Tailuan; Sutton, Andrew D.; Brynda, Marcin; Fettinger, James C.; Long, Gary J.;
198:
quadruple bond) and a lithium amidinate, followed by reduction with potassium graphite:
876:
833:
790:
746:
645:
581:
533:
437:
159:
104:
664:
398:"Synthesis of a Stable Compound with Fivefold Bonding Between Two Chromium(I) Centers"
1270:
1063:
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921:
868:
837:
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738:
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are rarer and are currently known only among the transition metals, especially for
649:
325:
1220:
985:
599:
1163:
1142:
1058:
552:
317:
203:
59:
347:
Quintuple-bonded dichromium complexes appear to act like magnesium to produce
1325:
1236:
1176:
1171:
1152:
1046:
456:
39:
424:
397:
287:
248:
orbitals on each metal mixing. Finally the δ-bonds come from mixing of the d
151:(2,4,6-trimethylphenyl)amine bridging ligands and a dichromium complex with
970:
925:
872:
864:
829:
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529:
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433:
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171:
1015:
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orbital on each metal center. The first π-bond comes from mixing of the d
55:
51:
47:
633:
1119:
1103:
1093:
311:
The bidentate ligand can act as a sort of tweezer in that in order for
227:
219:
67:
1001:
917:
821:
698:
569:
521:
114:
In 2005, a quintuple bond was postulated to exist in the hypothetical
1241:
962:
312:
301:
152:
83:
35:
947:(1-Ad): complete cleavage of the Cr–Cr quintuple bond interaction".
1108:
295:
71:
63:
43:
550:
1098:
223:
115:
75:
242:
orbitals from each metal while the other π-bond comes from the d
186:
In 2009 a dimolybdenum compound with a quintuple bond and two di
604:"Quantum chemical calculations show that the uranium molecule U
126:. Diuranium compounds are rare, but do exist; for example, the
87:
505:
280:
orbital. Though the π and δ orbitals are represented as being
111:-bent geometry with the R substituent in a bridging position.
187:
551:
Merino, Gabriel; Donald, Kelling J.; D'Acchioli, Jason S.;
454:
391:
273:
269:
19:
681:
984:
Noor, Awal; Schwarz, Stefan; Kempe, Rhett (9 Feb 2015).
344:
Efforts continue to prepare shorter quintuple bonds.
893:
555:(2007). "The Many Ways To Have a Quintuple Bond".
230:. The σ-bond is the result of mixing between the d
1323:
983:
938:
296:Ligand role in metal–metal quintuple bond length
807:
719:
181:
1031:
598:
16:Chemical bond involving ten bonding electrons
763:
1045:
850:
1038:
1024:
291:MO diagram of a metal–metal quintuple bond
423:
324:
286:
254:orbitals as well as mixing between the d
202:
170:
18:
1324:
366:
1019:
602:; Roos, Björn O. (24 February 2005).
207:dimolybdenum quintuple bond synthesis
662:
329:Steric effects on a bidentate ligand
367:Ritter, Steve (26 September 2005).
13:
339:
14:
1343:
1069:Introduction to quantum mechanics
663:Dumé, Belle (23 February 2005).
491:
977:
932:
887:
844:
801:
757:
374:Chemical & Engineering News
192:potassium octachlorodimolybdate
42:, first reported in 2005 for a
713:
675:
656:
592:
544:
499:
448:
385:
360:
175:Cr–Cr quintuple bond synthesis
58:are commonplace in chemistry.
1:
665:"New look for chemical bonds"
461:-Bent versus Linear Geometry"
354:
194:(which already contains a Mo
182:Dimolybdenum quintuple bonds
7:
1011:
10:
1348:
264:orbitals from each metal.
213:
1289:
1263:
1254:
1229:
1203:
1194:
1161:
1117:
1086:
1079:
1054:
107:and surprisingly another
1256:Molecular orbital theory
950:Chemical Communications
425:10.1126/science.1116789
124:computational chemistry
865:10.1002/anie.200803859
779:10.1002/anie.200801286
735:10.1002/anie.200801160
478:10.1002/anie.200600110
330:
308:-carbon interactions.
292:
208:
176:
38:is an unusual type of
27:
767:Angew. Chem. Int. Ed.
723:Angew. Chem. Int. Ed.
608:has a quintuple bond"
466:Angew. Chem. Int. Ed.
328:
290:
206:
174:
22:
853:Angew. Chem. Int. Ed
1196:Valence bond theory
910:2009NatCh...1..322N
816:(35): 12534–12535.
693:(46): 14162–14163.
634:10.1038/nature03249
626:2005Natur.433..848G
564:(49): 15295–15302.
416:2005Sci...310..844N
331:
293:
209:
177:
160:potassium graphite
155:bridging ligands.
105:molecular geometry
28:
1319:
1318:
1315:
1314:
1290:Constituent units
1271:Molecular orbital
1250:
1249:
1230:Constituent units
1190:
1189:
1064:Quantum mechanics
1002:10.1021/om501230g
996:(11): 2122–2125.
957:(17): 2332–2334.
918:10.1038/NCHEM.255
859:(51): 9933–9936.
822:10.1021/ja905035f
773:(38): 7250–7253.
729:(38): 7246–7249.
699:10.1021/ja076356t
689:(Communication).
686:J. Am. Chem. Soc.
620:(7028): 848–851.
570:10.1021/ja075454b
558:J. Am. Chem. Soc.
522:10.1021/ja0771890
516:(15): 5104–5114.
510:J. Am. Chem. Soc.
472:(23): 3804–3807.
410:(5749): 844–847.
349:Grignard reagents
164:valence electrons
23:The structure of
1339:
1332:Chemical bonding
1261:
1260:
1201:
1200:
1182:Exchange-coupled
1084:
1083:
1047:Chemical bonding
1040:
1033:
1026:
1017:
1016:
1006:
1005:
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963:10.1039/b901494b
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897:Nature Chemistry
891:
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842:
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810:J. Am. Chem. Soc
805:
799:
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761:
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600:Gagliardi, Laura
596:
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427:
394:Power, Philip P.
389:
383:
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364:
276:which is the δ*
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1221:Lewis structure
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990:Organometallics
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553:Hoffmann, Roald
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340:Research trends
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60:Quadruple bonds
26:
17:
12:
11:
5:
1345:
1335:
1334:
1317:
1316:
1313:
1312:
1310:
1309:
1307:Antibonding MO
1304:
1302:Non-bonding MO
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1211:Hybrid orbital
1207:
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1088:
1081:
1080:Types of bonds
1077:
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1073:
1072:
1071:
1061:
1059:Atomic orbital
1055:
1052:
1051:
1043:
1042:
1035:
1028:
1020:
1013:
1010:
1008:
1007:
976:
944:
940:
931:
904:(4): 322–325.
886:
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543:
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318:steric effects
297:
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268:represent the
255:
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226:, and two are
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195:
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32:quintuple bond
24:
15:
9:
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2:
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1237:Covalent bond
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1148:5 (quintuple)
1146:
1144:
1143:4 (quadruple)
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99:compounds: a
97:
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86:(2,6-phenyl)
85:
79:
77:
73:
69:
65:
61:
57:
53:
49:
45:
41:
40:chemical bond
37:
33:
21:
1153:6 (sextuple)
1147:
1120:multiplicity
993:
989:
979:
954:
948:
934:
901:
895:
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852:
846:
813:
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185:
162:. This adds
157:
149:
113:
108:
100:
91:
80:
56:triple bonds
52:double bonds
48:Single bonds
31:
29:
1087:By symmetry
278:antibonding
228:delta bonds
1297:Bonding MO
1281:MO diagram
1138:3 (triple)
1133:2 (double)
1128:1 (single)
669:PhysicsWeb
355:References
282:degenerate
222:, two are
220:sigma bond
118:molecule U
46:compound.
44:dichromium
1242:Lone pair
1216:Resonance
1104:Delta (δ)
1094:Sigma (σ)
838:207144833
538:207046428
313:chelation
302:bidentate
153:amidinate
122:based on
92:ab initio
84:terphenyl
36:chemistry
1326:Category
1264:Concepts
1204:Concepts
1012:See also
971:19377676
926:21500603
881:46033904
873:19016281
830:19685872
787:18683844
751:30480347
743:18698657
707:17967028
642:15729337
586:18838267
578:18004851
530:18335988
486:16671122
442:42853922
434:16179432
396:(2005).
224:pi bonds
1177:Singlet
1172:Triplet
1109:Phi (φ)
906:Bibcode
795:5510753
622:Bibcode
412:Bibcode
403:Science
214:Bonding
147:anion.
116:uranium
88:ligands
1099:Pi (π)
1049:theory
969:
943:O or N
924:
879:
871:
836:
828:
793:
785:
749:
741:
705:
650:421380
648:
640:
613:Nature
584:
576:
536:
528:
484:
440:
432:
103:-bent
74:, and
54:, and
877:S2CID
834:S2CID
791:S2CID
747:S2CID
646:S2CID
582:S2CID
534:S2CID
459:trans
438:S2CID
381:(39).
188:amido
109:trans
101:trans
1276:LCAO
1164:spin
967:PMID
955:2009
922:PMID
869:PMID
826:PMID
783:PMID
739:PMID
703:PMID
638:PMID
574:PMID
526:PMID
482:PMID
430:PMID
306:ipso
274:LUMO
270:HOMO
94:and
1162:By
1118:By
998:doi
959:doi
914:doi
861:doi
818:doi
814:131
775:doi
731:doi
695:doi
691:129
630:doi
618:433
566:doi
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