_P.-Powell-auth.-Principles-of-Organometallic-Chemistry-Springer-Netherlands-1988

Table 11.3. Isolobal fragments and cluster formation
Main Group B BH BH 2
fragments c CH CH 2 CH, CH 4
p PH PH, PH,
s SH SH,
No. of electrons
contributed to p.e.c. 3 4 5 6 7 (8)
Transition metal
fragments Co(CO), Ni(C0) 2 CuL 2
Carbonyls Mn(CO), Fe(CO), Co(CO), Ni(CO),
Mn(C0) 4 Fe(C0) 4 Co(C0) 4 Ni(C0) 4
Mn(CO), Fe(CO),
Cyclopentadienyls CoCp NiCp CuCp
Mixed CpMn(CO) CpFe(CO) CpCo(CO) CpNi(CO) CpCuL
CpMn(C0) 2 CpFe(C0) 2 CpCo(C0) 2
CpCr(CO), CpMn(CO),
No. of electrons
contributed to p.e.c. 13 14 15 16 17 (18)
Type of cluster t 4m+2* 5m 6m 7m 8m
l4t + 2* 15t 16t l7t 18t
Deltahedra Electron Rings Dimer Closed
precise shell
molecules
*Closo.
trsoelectronic replacement e.g. BH by CH or additional electron required.