A method of making a metal complex comprises combining a 1-monoacyldipyrromethane with a compound of the formula R.sup.1R.sup.2MX, wherein M is boron, R.sup.1 and R.sup.2 are each independently organic substituents; and X is an anion leaving group; to produce a metal complex of the formula DMR.sup.1R.sup.2 wherein DH is a 1-monoacyldipyrromethane. The methods and complexes are useful for the purification and synthesis of dipyrromethanes and porphyrins.