Table 2.

Comparison of isomer shift and quadrupole splitting with Fe−C/C−O bond lengths of homoleptic, mononuclear iron carbonyls.

	[Fe(CO)4]2−	Fe(CO)5	[Fe(CO)5].+	[Fe(CO)6]2+
$\delta$ [mms−1]	−0.16(1)	−0.08(1)	0.17(1)	−0.001(6)[c]
$\Delta \mathbf{E}$ Q [mms−1]	0.19(1)	2.55(1)	0.53(1)	–
avg. d(Fe−C) [Å]	1.747(4)[a]	1.815(5)[b]	1.882(5)	1.911(5)[d]
avg. d(C−O) [Å]	1.175(5)[a]	1.142(9)[b]	1.124(6)	1.104(5)[d]

[a] Ref. [56]. [b] Ref. [52]. [c] Ref. [10]. [d] Ref. [57].